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A novel and efficient process for the removal of Ce(IV) from aqueous solutions was sought, and a new magnetic porous biochar (PBC/ZF) was synthesized by loading ZnFe 2 O 4 (ZF) onto porous biochar (PBC) using a one-step hydrothermal method. The SEM observation of the external features showed that the cubic spinel structured ZnFe 2 O 4 (ZF) particles were loaded onto the porous biochar (PBC) surface. This resulted in a composite with superb paramagnetic properties as well as higher adsorption properties. In addition, the microstructure was characterized by FTIR, which demonstrated that the target material was supplied with a large amount of carboxyl groups (-COOH) by citric acid during the synthesis process. The BET showed that the target material had a higher specific surface area than ZnFe 2 O 4 with PBC, confirming the successful preparation of the target material after activation of the biomass using ZnCl 2 immersion as well. The effect of different factors on the adsorption effect was investigated experimentally. The results showed that PBC/ZF had a good adsorption effect on Ce(IV) with a short adsorption equilibrium time and a maximum adsorption capacity of 228.9 mg/g at room temperature with lower acidity (pH = 2.5). The adsorption kinetics and isotherm analysis showed that the Ce(IV) adsorption process fitted well with the quasi-secondary kinetic model and Langmuir model. It indicates that the process is a single molecular layer adsorption process. It was demonstrated that PBC/ZF also has high removal rate for high concentration Ce(IV) solution, and it is easy for solid-liquid separation under the action of applied magnetic field after adsorption. It provides a new treatment method and theoretical support for the adsorption treatment technology of Ce (IV) wastewater. [ABSTRACT FROM AUTHOR]

Military activities and the production or disposal of ammunition often lead to soil contamination with energetic compounds (ECs) such as dinitrotoluene, trinitrotoluene, and hexogen, posing significant threats to human health and the ecosystem. Biochar has emerged as a cost-effective and widely available solution for remediating contaminated sites characterized by its capacity for pollutant removal through adsorption and conversion process, along with minimal secondary pollution. This paper provides a comprehensive review of relevant literature on biochar's efficacy in eliminating ECs, including an analysis of the underlying mechanisms. The discussion addresses challenges and opportunities associated with biochar application in ECs remediation, offering insights for future research directions. In summary, the use of biochar for ECs removal presents a promising and eco-friendly approach, facilitating the remediation of contaminated sites while promoting soil function and ecosystem recovery. [Display omitted] • Reviewed the functions of biochar in the removal of ECs. • Biochar adsorbed ECs via π−π electron donor-acceptor and hydrophobic interactions. • Biochar facilitated ECs conversion through conductive planes and redox components. • Biochar offers both remediation and ecological advantages. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biochar-based atomic Fe catalyst was prepared via co-pyrolysis strategy. • Fe-pyridinic N 4 was obtained by co-pyrolyzing biochar and SOFs with Fe-N 3 moiety. • Fe-MCA@SS/PMS system could effectively remove 94.5 % aniline within 5 min. • Mediated electron transfer via [Fe-N 4 /PMS]* mainly accounted for aniline removal. Pollution of groundwater by electron-rich refractory organic pollutants (e-ROPs) is detrimental to ecological integrity and human health. Biochar (BC)-based single-atom Fe catalysts (Fe–SACs) triggering nonradical peroxymonosulfate (PMS) process has shown great potential in addressing this problem. Nevertheless, the successful formation and precise regulation of active sites on BC remain formidable challenges. Herein, co-pyrolysis of BC derived from shrimp shells and N-containing supramolecular organic frameworks with a hexagonal cavity structure of Fe3+–N 3 (Fe–SOFs) was, for the first time, used to prepare an efficient and inexpensive BC-based Fe–SAC (Fe–MCA@SS). The Fe–N bond was successfully grafted from Fe–SOFs onto BC and subsequently transformed into monoatomic Fe–pyridinic N 4. Moreover, Fe–MCA@SS successfully triggered an efficient nonradical PMS process, degrading 94.5 % of aniline (AN) within 5 min. Mediated electron transfer (MET) mechanism was primarily responsible for AN removal. MET was attributed to the following factors: the synergistic effect of the stronger chemical adsorption of PMS with an Fe atom in Fe–pyridinic N 4 active sites, the higher redox potential of [Fe–MCA@SS/PMS]*, and the value of the lowest unoccupied molecular orbital of AN being larger than the value of highest occupied molecular orbital of [Fe–MCA@SS/PMS]*. This study sheds new light on the preparation of BC-based SACs catalyst with efficient nonradical oxidation ability and an excellent feasibility to remove electron-rich organic pollutants in groundwater. [ABSTRACT FROM AUTHOR]

Heavy metal contamination poses a significant threat to soil quality, plant growth, and food safety, and directly affects multiple UN SDGs. Addressing this issue and offering a remediation solution are vital for human health. One effective approach for immobilizing heavy metals involves impregnating cypress chips with calcium hydroxide (Ca(OH) 2) to enhance the chemical adsorption capacity of the resulting woody charcoal. In the present study, un-treated cypress biochar (UCBC) and calcium-treated cypress biochar (TCBC), were introduced into pristine and contaminated soil, at rates of 3, 6, and 9% (w/w). Both BCs were alkaline (UCBC pH: 8.9, TCBC pH: 9.7) with high specific surface area, which improved the soil properties (pH, EC, and OM). Radish (Raphanus sativus) cultivated in pots revealed that both UCBC and TCBC demonstrated significant improvements in growth attributes and heavy metal immobilization compared to the control, with TCBC exhibiting superior effects. The TCBC surface showed highly active nanosized precipitated calcium carbonate particles that were active in immobilizing heavy metals. The application of TCBC at a rate of 9% resulted in a substantial reduction in Zn and Cu uptake by radish roots and shoots. In contaminated soil, Zn uptake by radish roots decreased by 55% (68.3–31.0 mg kg−1), and shoots by 37% (49.3–31.0 mg kg−1); Cu uptake decreased by 40% (38.6–23.2 mg kg−1) in roots and 39% (58.2–35.2 mg kg−1) in shoots. Uptake of Pb was undetectable after TCBC application. Principal component analysis (PCA) highlighted the potential of TCBC over UCBC in reducing heavy metal concentrations and promoting radish growth. Future research should consider the long-term effects and microbial interactions of TCBC application. [Display omitted] • To immobilize Zn, Cu, and Pb in soil, a novel biochar (TCBC) was prepared. • TCBC improved soil properties and radish growth attributes. • TCBC resulted in a substantial reduction in Zn, Cu, and Pb in radish roots and shoots. • Highly active nano-sized CaCO 3 particles in TCBC-immobilized heavy metals. • TCBC consistently outperformed UCBC in terms of immobilization properties. [ABSTRACT FROM AUTHOR]

As a new type of environmentally friendly adsorbent, biochar has been increasingly applied in water pollution treatment. Herein, a catalyzed and activated biochar adsorbent (CABC) which was derived from hazelnut shell and modified by FeCl 3 and ZnCl 2 was synthesized successfully. The CABC was applied to remove two typical Pharmaceutical and Personal Products (PPCPs), sulfamethoxazole (SMX) and diclofenac (DCF). The CABC obtained high specific surface area of 1413.02 m2/g. The removal rates for SMX and DCF by CABC could reach 97.04 % and 98.65 %, respectively. The adsorption process was consistent with the pseudo-second-order kinetic model and the Langmuir isothermal model, which illustrated that the adsorption process conformed to chemical adsorption and monolayer adsorption. The thermodynamics indicated that the adsorption process was endothermic and could occur spontaneously. After 5 cycles, the CABC still remained a high removal efficiency of 77.7 % and 80.5 % for SMX and DCF, which showed a good reusability. The removal rates of CABC for multiple PPCPs had achieved over 77.7–98.0 %. In different actual wastewater, the removal rates of CABC for SMX and DCF ranged from 56.7 % to 97 %, demonstrating its excellent universality and practical value for utilization. Furthermore, three machine learning models based on Decision Tree, Random Forest and Gradient Boosting Decision Tree algorithm were applied to predict the removal efficiency and determine the relative importance of different influencing factors. The gradient boosting regressor model obtained the best predict performance with R 2 at 0.9806 and 0.9840 for training set and testing set. And the importance analysis had shown that pH was the most important influencing factor with the importance value over 0.35. The adsorption mechanism between CABC and pollutants included pore adsorption, electrostatic interactions, intramolecular hydrogen bonding, the reaction with oxygen-containing functional groups and metal complexation. The prepared biochar adsorbent CABC possessed the potential for PPCPs removing. In addition, the machine learning method can play more and more undeniable role in subsequent water treatment. In future research, machine learning can be used to predict the adsorption performance of materials, enabling targeted design of materials. This will greatly save experimental time and cost losses, and can improve research efficiency. [Display omitted] ● Waste hazelnut shells were transformed into eco-friendly biochar for water treatment. ● The novel biochar effectively removed SMX, DCF and multiple PPCPs. ● Machine learning was used to model and predict the adsorption process. ● The biochar adsorbent exhibited high reusability, low cost in water treatment. [ABSTRACT FROM AUTHOR]

Millions of tons of cotton textile waste are generated annually worldwide, and most of it enters the municipal solid waste (MSW) stream for landfill or incineration disposal, resulting in a significant waste of resources and environmental pollution. This article developed an innovative low-temperature pyrolysis process for producing artificial humic acid (HA) from waste cotton textiles. Subsequently, Al3+ was introduced for a secondary pyrolysis to prepare an Al-doped biochar (Al/BC) with superior adsorption properties. The experimental results show that the presence of Al3+ has an important influence on the pyrolysis process of cotton fabric and the formation and structure of Al/BC. This is the first time to synthesize low-cost adsorbent by pyrolysis and aluminum mixing process of waste cotton cloth and explains the mechanism. This increased in defects (I D / I G = 0.76 to I D / I G = 0.92), a larger specific surface area (6.47 m2/g to 566.94 m2/g), and an increase in oxygen-containing functional groups (from none to C-O-C, O C-O, etc.) when compared to the undoped Al3+ biochar. The optimum Al3+-doped biochar (Al/BC-15) prepared with HA as a precursor exhibited a superior adsorption capacity for Cr(VI) of up to 176.23 mg/g, surpassing the results reported for similar materials in the literature. The adsorption mechanism of Cr(VI) is primarily based on physical adsorption, with some chemical adsorption. At a lower pH, the Al/BC-15 surface exhibits a high positive charge (46 mV). The Al3+-O-Cr(VI) association group is formed through rapid electrostatic attraction between C-Al and Cr(VI). Due to the strong positive electronegativity of Al3+ and the negative electronegativity of C in the vicinity of Al, Cr(VI) is further reduced to Cr(III) by C-Al. Therefore, the method proposed in this paper for preparing Al-doped carbon materials from waste cotton fabric offers a new approach and potential application for the production of high-performance adsorbent materials from waste cotton fabric. [Display omitted] [ABSTRACT FROM AUTHOR]

This work synthesized polyethyleneimine and chitosan modified winter melon-derived biochar (PEI-CTS@WBC) using chemical crosslinking method for uranium(VI) removal. The factors influencing uranium(VI) adsorption by PEI-CTS@WBC, including pH, adsorbent dosage, time, temperature, and initial U(VI) concentration were explored. The material's performance was characterized, and the underlying mechanism of U(VI) removal was analyzed using various techniques. Compared with other reported adsorbents, the maximum adsorption capacity of PEI-CTS@WBC for U(VI) was 411.44 mg g−1, which was higher than most existing adsorbents. The dynamics studies showed that adsorption was more in line with the second-order kinetic model, indicating that chemical adsorption was the main process. The K d and S U value of U(VI) by PEI-CTS@WBC could reach 11194.44 mL g−1 and 76.47 % respectively, which exhibited a high selective adsorption characteristics for U(VI) in aqueous solutions. The XPS analysis demonstrated that the adsorption process was primarily due to the formation of stable complexes with N-H, N-C, C-O and O-H. This research showed that the introduction of polyethyleneimine and chitosan greatly improved the adsorption effect of WBC on U(VI). PEI-CTS@WBC had high selective adsorption characteristics and good reusability for U(VI) in aqueous solutions. PEI-CTS@WBC was an economical, efficient and stable composite material. These findings provided a theoretical basis for the treatment of wastewater contaminated with U(VI). [Display omitted] • PEI-CTS@WBC had advantages of low cost, easy preparation and good stability. • The maximum adsorption capacity of PEI-CTS@WBC for U(VI) was 411.44 mg g−1. • PEI-CTS@WBC exhibited a high selective adsorption for U(VI). [ABSTRACT FROM AUTHOR]

[Display omitted] • The FBC was prepared via one-step pyrolysis method base on Phytolacca acinosa. • The FBC exhibited excellent V (V) adsorption performance. • The V (V) adsorption mechanism on the FBC was comprehensively investigated. Iron-loaded biochar (FBC) was synthesized via the dry-mixed co-pyrolysis of Phytolacca acinosa , Fe 2 (SO 4) 3 and NaOH and then used to remove aqueous vanadium (V (V)). FBC demonstrated the optimal adsorption performance for V (V) (57.67 mg/g) due to the loading of iron oxide, which increased the number of oxygen-containing functional groups. The adsorption of V (V) on FBC was pH-dependent, and the adsorption rate was high in the pH range of 2–8. Common cations and anions in water did not affect the adsorption of V (V) onto FBC, while NH 4 +, Na+, Ca2+, and Cd2+ can promoted its adsorption. The adsorption mechanism of FBC mainly included chemical adsorption, electrostatic adsorption, oxygen-containing functional group complexation and ion exchange. The easy preparation method, high adsorption capacity and adaptability makes FBC an ideal material for removing V (V) from wastewater. [ABSTRACT FROM AUTHOR]

Due to the importance and economic value of gold in various applications, recovering gold from waste streams like tailings and industrial wastewater is essential. Biochar with a high surface area and porosity is considered a potential low-cost adsorbent for gold reclaiming from aqueous media. Therefore, this study aims to develop a high-quality biochar with excellent physicochemical properties to efficiently remove gold from aqueous media. To accomplish this, biochar was obtained from pyrolysis of ironbark (IB) biomass at 500 °C which has a surface area of 493.79 m2/g. Subsequently, the biochar was investigated for adsorption of gold from aqueous media, which exhibited a maximum adsorption capacity of 858 mg/g. Isotherm results showed that the adsorption of gold by biochar followed the Langmuir model, indicating monolayer adsorption. Further, response surface methodology (RSM) and an artificial neural network (ANN) combined with the Salp Swarm Algorithm (SSA) were used to analyze the generated results (ANN-SSA). The RSM prediction model fit was adequate (R2 = 0.99). However, comparing the statistical data revealed that ANN-SSA outperformed RSM in predicting experimental results. Overall, this study suggested that biochar derived from IB biomass could be used as a potential adsorbent to recover gold from an aqueous solution. This article presents a unique and innovative study on the utilization of ironbark biochar for the purpose of gold adsorption. [Display omitted] • A novel biochar produced from ironbark was investigated for Au adsorption. • The biochar achieved a maximum Au adsorption of 858 mg/g under optimized conditions. • ANN model showed a better Au adsorption prediction compared to the RSM model. • Physisorption and electrostatic attraction were the dominant Au adsorption mechanism. • Au adsorption followed the Langmuir model, indicating a monolayer surface adsorption. [ABSTRACT FROM AUTHOR]

Acacia Senegal waste (ASW) is remaining biomass following gum Arabic harvesting and has no use mentioned in the literature as of yet. This study aims to convert ASW into valuable biochar via two comparative thermal and hydrothermal techniques, which include pyrochar ASW at 300 °C (PC ASW300) and hydrochar ASW at 180 °C (HC ASW180), respectively, for Cu (II) adsorption from aqueous solutions. SEM-EDS, FTIR, XRD, and XPS were used to characterize the biochar. Adsorption performance was studied as a function of pH, contact time, and adsorbent concentration. Adsorption kinetics were best fit for a pseudo-second-order model. And thermodynamics studies revealed that Cu (II) on biochar was endothermic, spontaneous, and best fitted to the Langmuir isotherm model. Pyrochar adsorption capacity (31.93 mg g−1) was seven times that of hydrochar (5.45 mg g−1). ASW treated with phosphorus (PC H 3 PO 4 and HC H 3 PO 4) prior to the carbonization altered the pore structure and surface functional groups as well (O–P–O, P–CH 3 , and P–OH) of biochar. It was found that treating with phosphorous acid increased adsorption capacity to 141.7 mg g−1 and 22.24 mg g−1 for PC H 3 PO 4 and HC H 3 PO 4 , respectively. The surface functional groups of biochar resulted from lignin, alkaloids, and polysaccharides combined with Cu (II) during the adsorption process via surface complexation accompanied by π-electron interaction and Cu (II) reduction. These findings shed light on the ASW biochar potential as a new green cost-effective adsorbent and drew an insightful understanding of Cu (II) adsorption performance and mechanism. It is concluded that ASW-derived biochar is highly effective and a promising alternative for Cu (II) decontamination from wastewater. [Display omitted] • Acacia Senegal waste biochar has a potential as Cu(II) cost-effective adsorbents. • Phosphorous activated biochar grew Cu(II) adsorption capacity up to five times. • Copper adsorption on surface of biochar was accompanied by Cu(II) reduction. • Surface complexation and π electron interaction played a key role on adsorption. • Pyrochar show greater adsorption capacity and removal efficiency than hydrochar. [ABSTRACT FROM AUTHOR]

Nitrogen atom doping is widely employed to prepare efficient adsorbents to handle target pollutants thanks to its similarity in radius to carbon atoms and excellent functionality. In this study, three types of nitrogen-enriched biochars (NBCs) were prepared to use the corn straw as the raw material and melamine as the nitrogen source by pyrolyzing at 700, 800, and 900 °C (named 700NBC, 800NBC and 900NBC), which were used to remove tetracycline (TC) from water. Results showed that the 900NBC exhibited the highest specific surface area (324.29 m2/g) as well as the maximum adsorption capacity (194.42 mg/g) for TC, compared to 800NBC (176.44 mg/g) and 700NBC (163.32 mg/g). What's more, the adsorption kinetics and adsorption isotherms were well-fitted by the pseudo-second-order and Langmuir models, indicating that for the adsorption of TC by NBCs, monolayer adsorption and chemisorption were dominant. Specifically, the excellent adsorption performance of NBCs for TC was mostly attributed to the pore filling, hydrogen bonding, π-π interactions, Lewis acid-base interactions, and electrostatic interactions. Importantly, the graphitic N serves as the primary TC adsorption site, followed by pyridinic N. This study would provide new insight into the impact of nitrogen configuration on the adsorption mechanism of NBCs for TC. [Display omitted] • Three types of nitrogen-enriched biochars were prepared at pyrolysed at 700, 800 and 900 °C. • Graphitic N played a key role in TC adsorption. • The main mechanisms were pore filling, π-π interactions and Lewis acid-base interactions. [ABSTRACT FROM AUTHOR]

[Display omitted] • A Fe/graphene-loaded biochar (FeGB) gel was prepared via a self-assembly method. • FeGB-gel showed a 4-fold increase in Sb(III) adsorption capacity than raw biochar. • Fe–O–Sb complexation and π–π stacking were key Sb(III) adsorption mechanisms. • The higher electron exchange capacity of FeGB-gel favored Sb(III) oxidation. • Graphene defects aided FeO x anchoring on biochar and promoted electron transfer. Environmental contamination posed by trivalent antimony [Sb(III)] in water has been globally recognized as a complex challenge, garnering considerable public concern. To enhance the adsorption efficiency of pristine biochar (BC) for Sb(III), a novel Fe/graphene-loaded biochar (FeGB) gel was synthesized through a facile in-situ self-assembly method. This study aimed to investigate the adsorption performance and elucidate the electron-scale adsorption mechanism for Sb(III) by the FeGB-gel. The Sb(III) adsorption isotherm data fitted well with the Langmuir model, and the maximum Sb(III) adsorption capacity of FeGB-gel (113.1 mg g−1) was significantly higher compared to that of BC (28.6 mg g−1). Spectroscopic investigations revealed that surface complexation and π–π stacking were the key mechanisms for Sb(III) adsorption. Electrochemical analyses confirmed an enhanced electron-accepting capacity (0.815 mmol e- g−1) of FeGB-gel, linked to the formation of Fe-related functional groups (Fe–O and Fe–O–OH), which contributed to a stronger Sb(III) oxidation capacity than BC (78.5% v.s. 49.3%). Density functional theory calculations highlighted that the presence of defects on graphene nanosheets enhanced the anchoring of FeO x on biochar, thereby elevating the Sb(III) adsorption energy of FeGB-gel to −1.96 eV. Additionally, the projected density of states profile suggested that the enhanced adsorption of FeGB-gel could be attributable to the orbital hybridization of Sb-p, O-p, and Fe-p/d orbitals (i.e., Fe–O–Sb bonding), which strengthened the electron transfer and chemical interaction during the Sb(III) removal process. The functionalization of biochar surface characteristics with Fe/graphene offers possibilities for a diverse range of biochar-based adsorbents and their application in addressing numerous environmental concerns. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel biochar (CHKBC) co-modified with KOH and chitosan was synthesized. • KOH activation significantly increased the loading of chitosan on biochar surface. • CHKBC showed strong adsorption for methylene blue in various environments. • Adsorption mechanisms were revealed by various characterization methods. The treatment of dye pollutants remains a challenge in the current management of the water environment. In this study, an innovative biochar material co-modified with KOH and chitosan was synthesized. The morphology and physicochemical properties of the modified biochar material were assessed by SEM, FTIR, XPS, XRD, and thermogravimetric analyses. The results revealed a significant enhancement in chitosan loading due to the pretreatment of biochar with KOH. The co-modified biochar with KOH and chitosan (CHKBC) exhibited an enriched composition of functional groups such as − COOH, −NH 2 , and − OH, leading to a substantial increase in the maximum adsorption of MB by the biochar from 8.83 mg g−1 to 62.04 mg g−1, a 7.03-fold increase. The excellent adsorption performance of CHKBC for MB was maintained at different solution temperature (288–––318 K) and pH (5–––11) conditions. The main adsorption mechanisms of MB removal by CHKBC involved ion exchange, pore filling, electrostatic attraction, π - π interactions, and hydrogen bonding. Overall, CHKBC has higher chitosan loading, more uniform chitosan distribution, and better adsorption efficiency of MB. It is a promising adsorption material with low cost and a simple production process. [ABSTRACT FROM AUTHOR]

[Display omitted] • The adsorption capacity of BC on MG is about 30 and 60 times that of SY and ENR. • The molecular mechanism of BC on MG was analyzed using statistical physical models. • Adsorption advantages are a combination of mesopore structure and high ash content. • The mesoporous structure provides adsorption space for multimolecular aggregates. • The ionic polarity sites in the ash are the main active sites for adsorption on BC. Adsorption is considered to be one of the most promising methods for treating organic wastewater. This paper focuses on the adsorption characteristics and molecular mechanisms of ionic organic pollutants (IOPs) on bone char (BC). It was found that BC had excellent adsorption performances for cationic organic pollutants with large molecular, especially malachite green (MG, triphenylmethane): the maximum adsorption capacity is 1.3–1.5 and 5.6–6.9 times higher than that of straw biochar (SBC) and activated carbon (AC), respectively, and 30 and 60 times higher than that of anionic and amphoteric organic pollutants. The adsorption mechanism of IOPs on BC was analyzed at the macroscopic level by comparing the differences in the physicochemical properties of the adsorbents and the changes before and after adsorption. Then, statistical physical modeling was used to investigate the mechanism of interaction between BC and IOPs at the molecular scale (mesoscopic level). The results showed that the rich mesoporous structure and ionic polarity sites of BC play an essential role in the adsorption of MG. PO 4 3-, CO 3 2–, and OH– are the effective sites for adsorption of BC, with the density of sites significantly higher than that of SBC and AC. It can be surmised that BC adsorbs the IOPs through pore filling and electrostatic interactions. Techno-economic analysis showed that the adsorption cost of BC could be reduced by 37.89% to 81.72% compared with modified biochar and commercial AC, indicating that BC has wide application prospects and market competitiveness. The results of this study can provide vital theoretical support for the practical application of BC. [ABSTRACT FROM AUTHOR]

The effects of adding green-synthesized magnetic iron-containing nanoparticles (GSMFe) onto biochar in aqueous solution for the adsorptive removal of hexavalent chromium [Cr(VI)] were investigated in this study. Nanocomposites, denoted as green synthesis magnetic biochar (GSMB), were created using a green synthesis technique with white tea residue to introduce GSMFe into biochar. Six adsorbents, varying in GSMFe content, were tested for their effectiveness in eliminating Cr(VI), a globally significant hazardous heavy metal. The results demonstrated that incorporating GSMFe into biochar led to significant improvements in adsorption capacity and saturation magnetization. With an increasing amount of GSMFe, the maximum adsorption capacity increased from 2.47 mg/g (EWTWB) to 9.11 mg/g (GSMB4). The highest saturation magnetization was achieved at 13.4 Am2/kg at GSMB4. Similarly, surface areas rose up to 72.9 m2/g at GSMB3 but declined thereafter due to GSMFe aggregation and pore blockage. Sorption behavior for Cr(VI) was assessed using five isotherm models, with the Redlich-Peterson model showing the best fit. The analysis of approximate site energy distribution (SED) indicates that the incorporation of GSMFe enhances the frequency of the entire range of sorption energy sites, while the biochar matrix contributes to a slight increase in medium sorption energy sites within the GSMFe. Among the GSMBs, the difference were more pronounced at low-energy sites than at high-energy sites. At higher energy sites (27,500–40,000 J/mol), sorption site frequencies remained similar, regardless of GSMFe content and associated physicochemical properties. For sorption energy site values exceeding 17,500 J/mol (Cr(VI) concentration below 50 mg/L), GSMB2 is regarded as a more practical choice due to its relatively large area under the frequency distribution curve and commendable cost-effectiveness. [Display omitted] • Ratio of synthesized iron-containing nanoparticles (GSMFe) on biochar was optimized. • Cr(VI) adsorption was predicted by site energy distribution. • GSMFe boosted low sorption energy sites, biochar raised medium energy sites. • Fe–OH groups from GSMFe closely correlated with Cr(VI) sorption capacity. [ABSTRACT FROM AUTHOR]

Microplastics (MPs), as emerging pollutants, have attracted the attention of environmentalists, statespersons, and the scientific community over the last few decades. To address the spread of MPs in the environment, it is imperative to develop various removal techniques and materials that are effective, scalable, and ecologically benign. However, to the best of our knowledge, no review has systematically examined the removal of MPs using adsorption or provided an in-depth discussion on various adsorbents. Adsorption is an inexpensive and effective technology for wastewater treatment. Recently, many researchers have conducted studies on MP remediation using diverse adsorbent materials, such as biochar, activated carbon, sponges, carbon nanotubes, metal-layered oxides, metal-organic frameworks (MOFs), and zeolites. Each adsorbent has advantages and disadvantages. To overcome their disadvantages, researchers have been designing and developing hybrid adsorbents for MP remediation. This review provides insights into these individual adsorbents and also discusses hybrid adsorbents for MP removal. Finally, the review elaborates on future possibilities and ways to enable more efficient, scalable, and environmentally friendly MP cleanup. Overall, this review bridges the gap between contemporary MP remediation using adsorption techniques and adsorbent development. [Display omitted] • Adsorption-based microplastic remediation was reviewed. • The factors affecting microplastic adsorption were thoroughly discussed. • A comprehensive analysis is presented on several microplastic adsorbents. • Microplastic adsorption challenges and future perspectives are examined. [ABSTRACT FROM AUTHOR]

Developing advanced carbon materials by utilizing biomass waste has attracted much attention. Herein, a novel carbon adsorbent derived from Spinach waste was prepared by using pyrolysis procedure with KMnO 4 as the activator. The preparation condition such as activator mass ratio (0–0.16) and activation temperature (200–800 °C) were comprehensively studied. The optimal sample (SBC-0.08–500) showed a 7.38-fold increase in specific surface area compared to the original biochar (SBC-500). Adsorption experiments revealed that SBC-0.08–500 had efficient removal capabilities for Cd(II), Pb(II), Cu(II), and Zn(II) ions. The maximum adsorption capacities for Cd(II), Pb(II), Cu(II), and Zn(II) ions at 298.15 K were 1.66, 2.88, 1.31, and 2.09 mmol∙g−1, respectively. Thermodynamic results indicated that the adsorption of Cd(II), Pb(II), and Zn(II) ions on SBC-0.08–500 was a spontaneous endothermic process. Additionally, SBC-0.08–500 had a high affinity for Pb(II) ions, making it a potential selective adsorbent for the removal of mixed heavy metal ions. The mechanism underlying the adsorption process was attributed to multiple interactions, including ion exchange, electrostatic interaction, and surface complexation. The as-prepared biochar by oxidative activation pyrolysis effectively solves the issues of subsequent chemical recycling and secondary pollution, thus providing greater potential for large-scale use. [Display omitted] • A novel spinach waste-derived biochar was prepared using KMnO 4 as an activator. • Such biochar was proven to have abundant hydroxyl, carboxyl, and manganese oxide groups. • Such biochar delivered superior adsorption performance towards Cd(II), Pb(II), Cu(II), and Zn(II) ions. • Adsorption mechanism was ascribed to ion exchange, electrostatic attraction, and surface complexation. [ABSTRACT FROM AUTHOR]

As the major form of antimony in the aqueous environment, the adsorption for the removal of Sb(OH) 6 - is a meaningful task. In this study, MgFe 2 O 4 -doped and iron(Ⅲ) alginate cross-linked biochar ternary composite adsorbents, Fe/(MgFeO-BC) beads, were synthesized. The typical characterization analysis showed the successful synthesis of Fe/(MgFeO-BC) beads with the significant synergistic effect on the adsorption activity of MgFe 2 O 4 , the foaming effect of BC and the dispersing effect of the bead skeleton. The adsorption experiments showed significantly increased adsorption capacity of Fe/(MgFeO-BC) compared to the comparative adsorbent with Q m = 125.65 mg/g. The adsorption was able to reach equilibrium within 350 min. At low initial Sb(OH) 6 - concentration, the adsorption of Fe/(MgFeO-BC) can still achieve the standard antimony concentration (≤0.02 mg/L), giving potential for practical applications. The introduction of MgFe 2 O 4 enhanced the adsorption capacity while imparting magnetic properties of composite beads, resulting in significant improvement in separation efficiency. The -OH in the structure of MgFe 2 O 4 is the adsorption active site of Fe/(MgFeO-BC), and the adsorption of Sb(OH) 6 - is accomplished mainly through ligand exchange and inner-sphere complexation. These results suggest that Fe/(MgFeO-BC) is a kind of promising Sb(OH) 6 - adsorbent with safe, green and recyclable properties, which provides a reference for the removal of Sb(OH) 6 - from wastewater, even at low concentrations. [Display omitted] [ABSTRACT FROM AUTHOR]

Given the serious threat of acetochlor (ACT) to the aquatic ecological environment, designing wastewater treatment–oriented adsorbents for the sustainable remediation of actual ACT-contaminated water is a promising yet challenging strategy. Herein, a novel P-doped biochar (PBC-800) with a high adsorption capacity (51.34 mg g−1) and a rapid reaction rate (47.35 mg g−1 h−1) for ACT was prepared through pyrolyzing of rice straw biomass pre-impregnated with potassium dihydrogen phosphate (KH 2 PO 4). Additionally, P-doped biochars synthesized at different pyrolysis temperatures exhibited significant variations in ACT adsorption performance, which was mainly ascribed to the distinction between hydrophilicity and sp2 conjugate C (I D /I G = 0.84–1.08). The adsorption behavior of ACT on PBC-800 followed the Elovich kinetics and Freundlich adsorption isotherm models. Thermodynamic calculations indicated that the adsorption of ACT by PBC-800 was a spontaneously disordered decreasing exothermic process. Besides, PBC-800 exhibited a powerful anti-interference for ACT adsorption within complex water matrices, highlighting its potential for various of practical applications. Through characterization analysis and further experiments, it was proved that the excellent adsorption performance of PBC-800 on ACT was ascribed to a combination of physical and chemical adsorption mechanisms, including 57.5% pore filling, 23.4% hydrophobic interaction, 12.7% π–π interaction, and 6.4% hydrogen bonding. Moreover, PBC-800 exerted a prominent adhesion impact upon Gram-positive and negative bacteria at 3 h. This study offers a new idea for the utilization of agricultural residues and provides insights into the mechanism of ACT adsorption through its derived biochar. [Display omitted] • A novel P-doped rice straw biochar was prepared through a one-step method. • PBC-800 exhibited a high adsorption capacity of 51.34 mg g−1 for ACT at 298K. • Hydrophobic interaction, pore filling, hydrogen bonding, and π–π interaction were main mechanisms. • The adhesion rate of PBC-800 on E. coli and E. faecalis was close to 30 % at 3 h. • This adsorbent has excellent potential for practical application. [ABSTRACT FROM AUTHOR]

Carbofuran, a widely used carbamate insecticide, is frequently detected in water. In this study, a high-performance adsorbent (WAB4) for carbofuran was obtained from laboratory-synthesized biochars. The maximum adsorption of carbofuran by WAB4 reaches 113.7 mg/g approximately. The adsorption of carbofuran by biochar was a multi-molecular layer and the adsorption process conforms to the pseudo-second-order kinetic model (R2 = 0.9984) and Freundlich isotherm model (R2 = 0.99). Importantly, an in vivo rat model was used to assess the combined toxicological effects of biochar-carbofuran complexes. The toxicity of the complexes (LD 50 > 12 mg/kg) is lower than that of carbofuran (LD 50 = 7.9 mg/kg) alone. The damage of biochar-carbofuran complex on rat liver and lung is significantly less than that of carbofuran. The C max and bioavailability of carbofuran were found to be reduced by 64% and 68%, respectively, when biochar was present, by UPLC-MS/MS analysis of carbofuran in rat plasma. Furthermore, it was confirmed that the biochar-carbofuran complex is relatively stable in the gastrointestinal tract, by performing a carbofuran release assay in artificial gastrointestinal fluids in vitro. Collectively, biochar is a bio-friendly material for the removal of carbofuran from water. [Display omitted] • The maximum adsorption capacity of biochar for carbofuran was 113.7 mg/g. • A UPLC-MS/MS method was developed for carbofuran in rat plasma. • The toxicity of biochar-carbofuran in rats was evaluated for the first time. • Biochar reduces the acute toxicity of carbofuran in rats. • Biochar has a sequestration effect on carbofuran. [ABSTRACT FROM AUTHOR]

Spruce wood and Typha (wetland plant) derived biochars pyrolyzed at 350 °C and 600 °C were tested for their sorption affinity for organic pollutants (diclofenac, methylparaben, benzotriazole and sodium 1-decanesulfonate) and nutrients (nitrate, ammonium, phosphate and boron) commonly found in greywater. Batch and column studies combined with molecular dynamics modelling determined the sorption capacity, kinetics, and described the underlying mechanisms. The spruce biochar (600 °C) exhibited the highest sorption capacity mainly for the tested organics. The dynamic test performed for spruce biochar (600 °C) showed that the magnitude of desorption was low, and the desorbed amount ranged between 3 and 11 %. Molecular dynamics modelling (a computational tool for elucidating molecular-level interactions) indicated that the increased sorption of nitrate and boron on spruce biochar (600 °C) could be attributed to hydrophobic interactions. The molecular dynamics shows that predominant adsorption of organic pollutants was governed by π-π stacking, with a minor role of hydrogen-bonding on the biochar surface. In summary, higher pyrolysis temperature biochar yielded greater adsorption capacity greywater borne contaminants and the reaction temperature (10–34 °C) and presence of anionic surfactant had a limited effect on the adsorption of organic pollutants, suggesting efficacious application of biochar in general for greywater treatment in nature-based systems. [Display omitted] • Four biochars were produced from spruce and Typha at 350 °C and 600 °C. • Spruce biochar (600 °C) had the highest capacity for organics, phosphate and nitrate. • Reaction temperature (10–34 °C) and surfactants had low effect on the adsorption. • Molecular dynamics indicated π-π stacking mechanism to be predominant for organics. • Tested biochars (except Typha 350 °C) are good candidates for greywater treatment. [ABSTRACT FROM AUTHOR]

To solve the problem of biochar lack of adsorption sites for heavy metal ions and the difficulty of recycling, CoFe 2 O 4 magnetic nanoparticles confined in nitrogen, sulfur co-doped 3D network biochar matrix (C–CoFe 2 O 4 /N,S-BC) was designed and fabricated successfully. The obtained C–CoFe 2 O 4 /N,S-BC displays remarkable adsorption performance for both Pb2+ and ciprofloxacin (CIP) removal at the single or binary system due to the role of N,S as metal ion anchoring compared to the N,S-free sample (CoFe 2 O 4 /BC). N,S co-doped BC not only participates in adsorption reaction but also effectively inhibites the agglomeration of CoFe 2 O 4 nanoparticles and increases the active sites as a carrier at the same time. In the single system, CoFe 2 O 4 /N,S-BC demonstrates a fast adsorption rate (equilibrium time: 30 min) and high adsorption capacity (224.77 mg g−1 for Pb2+, 400.11 mg g−1 for CIP) towards Pb2+ and CIP. The adsorption process is befitted pseudo-second-order model, and the equilibrium data are in great pertinence with Langmuir model. In the binary system, the maximum adsorption capacity of CoFe 2 O 4 /N,S-BC for Pb2+ and CIP is 244.80 mg g−1 (CIP: 10.00 mg L−1) and 418.42 mg g−1 (Pb2+: 10.00 mg L−1), respectively. The adsorption mechanism is discussed based on the experimental results. Moreover, C–CoFe 2 O 4 /N,S-BC shows good practical water treatment capacity, anti-interference ability and stable reusability (the removal efficiency＞80% after eight cycles). The rapid, multifunctional, reusable, and easily separable adsorption properties make C–CoFe 2 O 4 /N,S-BC promising for efficient environmental remediation. This study also offers a viable method for the construction of adsorption material for complex wastewater treatment. [Display omitted] • N,S co-doped network biochar confined CoFe 2 O 4 nanoparticles adsorbent was fabricated. • It exhibits good adsorption property for Pb2+ and ciprofloxacin. • The synergistic and competitive adsorption of Pb2+ and ciprofloxacin was investigated. • Possible adsorption mechanisms in both single and binary systems were proposed. • It can be magnetic isolation and shows good stability and reusability after 8 cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • The BC was extracted from waste cardboard boxes, experimental waste reuse. • The BC-CoFe 2 O 4 -CS composite had excellent adsorption properties. • BC-CoFe 2 O 4 -CS composites enable secondary adsorption of cationic dyes (MB) • Adsorption mechanisms included electrostatic interaction, hydrogen bond and π-π interaction included electrostatic interaction, hydrogen bond and pai interaction In this study, BC-CoFe 2 O 4 -CS magnetic composite was successfully prepared from waste cardboard and investigated as an efficient adsorbent for the removal of amaranth and methyl orange in aqueous solution. First, the fibers obtained from the cardboard waste were carbonized by a hydrothermal process to produce biochar. Subsequently, the final magnetic composites were synthesized by in situ growth and Schiff base crosslinking reactions. The composites were characterized by zeta potential, Brunauer–Emmett–Teller measurements, Fourier transform Infrared spectroscopy, Scanning electron microscopy, Energy dispersive spectrometer,X-ray Diffraction, Thermogravimetry analysis and Vibrating sample magnetometer. The effects of adsorbent dosage and initial solution pH on dye removal efficiency were studied. The results showed that the maximum adsorption capacity of amaranth could reach 500.6 mg·g−1 at pH = 2, the adsorbent dosage of 0.5 mg·ml−1, and methyl orange could reach 644.0 mg·g−1 at pH = 4, the adsorbent dosage of 0.5 mg·ml−1. The adsorption process followed the pseudo-second order kinetic models and Langmuir isotherm. BC-CoFe 2 O 4 -CS was easily separated from the aqueous solution due to the loading of CoFe 2 O 4 magnetic nanoparticles. Besides, the BC-CoFe 2 O 4 -CS could be further used after the adsorption experiments with or without desorption and still showed good adsorption performance in the actual water samples. Therefore, it is expected that the composite material prepared from waste cartons can be used for the treatment of dye-containing wastewater due to its low cost, high efficiency, and simple application. [ABSTRACT FROM AUTHOR]

Magnetically modified carbon-based adsorbent (BC@γ-Fe 2 O 3) was prepared through facile route using activated sludge biomass and evaluated for the simultaneous removal of Sb(III) and Pb(II). BC@γ-Fe 2 O 3 exhibited outstanding Sb(III) and Pb(II) adsorption capacity when 200 mg of adsorbent was employed at pH 5.0 for 240 min, with the removal efficiency higher than 90%. The experiments demonstrated the excellent reusability and the potent anti-interference properties of the prepared absorbent. Freundlich and pseudo-second-order kinetic were prior to describe the adsorption process. The adsorption of Sb(III) and Pb(II) onto BC@γ-Fe 2 O 3 was spontaneous and endothermic. BC@γ-Fe 2 O 3 with high specific surface area revealed the exceptional competence to absorb Sb(III) and Pb(II) through pore filling, electrostatic adsorption and complexation. The adsorption mechanisms of Sb(III) and Pb(II) showed similarities with slight disparities. The removal of Sb(III) involved the Fe–O–Sb bond and π-π bond, while the adsorption of Pb(II) was closely related to ion exchange. Moreover, Sb(III) was oxidized to Sb(V) in a minor part during adsorption. The Fe–O–Cl active sites on BC allowed for the binding of γ-Fe 2 O 3 , guaranteeing the abundant adsorption sites and stability. BC@γ-Fe 2 O 3 provides an efficient and green insight into the simultaneous removal of complex heavy metals with promising application in wastewater treatment. [Display omitted] • BC@γ-Fe 2 O 3 could remove Sb(III) and Pb(II) from water simultaneously. • Magnetism is provided by γ-Fe 2 O 3 in activated sludge biochar, which is useful for adsorbent extraction and separation. • Sb(III) was mainly removed via an Fe–O–Sb bond complexation reaction and π–π bond adsorption. • Pb(II) was mainly removed via ion exchange. [ABSTRACT FROM AUTHOR]

Antimony (Sb) and arsenic (As) pollution in the water environment pose a threat to the ecological environment and human health. A lot of studies have been conducted on the removal of pollutants from water by modified biochar, but little attention has been paid to the simultaneous removal of Sb and As from water. This study aimed to simultaneously remediate the water contaminated by Sb and As and realize the resource utilization of solid waste. Herein, electrolytic manganese residue (EMR)-biochar composite (EB) was prepared by a one-step pyrolysis method using the mixture of EMR and distillers grains for the removal of As(III, V) and Sb(III, V) from water. The results indicated that the optimal pyrolysis temperature and EMR to distillers grains mass ratio for EB removal of As(III, V) and Sb(III, V) were 750 °C and 3∶1, respectively. The removal of As(III, V) and Sb(III, V) by EB was inhibited to varying degrees by HCO 3 −, PO 4 3−, and humic acid. The maximum adsorption capacities of EB for As(III), As(V), Sb(III), and Sb(V) were 40.92, 40.54, 34.36, and 9.42 mg/g, respectively. The main adsorption mechanisms of As(III, V) and Sb(III, V) included complexation, hydrogen bonding, and pore filling. Compared with other engineered biochar composites, EB can be utilized not only as a potential adsorbent to treat water contaminated with As(III, V) and Sb(III, V), but also to enable the hazard-free treatment and resource utilization of EMR and distillers grains, achieving the goal of treating pollution with waste. Future studies on the remediation performance and mechanisms of EB for practical Sb and As co-contaminated soil and water are necessary. [Display omitted] • Electrolytic manganese residue-biochar composite was prepared by one-step pyrolysis. • Competitive effect occurs in the adsorption process between As(III, V) and Sb(III, V). • Maximum adsorption capacity for Sb(III, V) and As(III, V) was 9.42–40.92 mg/g. • Pore filling, hydrogen bonding, and complexation dominate Sb and As adsorption. • EDB-3 is a promising adsorbent in Sb and As co-polluted water treatment. [ABSTRACT FROM AUTHOR]

• Tio x -loaded Pb@biochar (Pb@BC-TiO x) possessed superior potential to degrade pollutants under UV. • The heterojunction of PbO 2 and TiO x possessed excellent electron transfer performance and photoresponse. • The Pb@BC-TiO x /UV system enhanced the selective generation of superoxide radicals. • TiO 1.04 was more conducive to O 2 adsorption and ·OOH formation than TiO 2. • The Pb@BC-TiO x exhibited superior reusability and applicability. A novel TiO x -loaded Pb-hyperaccumulated biochar (Pb@BC-TiO x) was obtained from the hyperaccumulator Iris siberian L. Compared with other metal@BC-TiO 2 (Ce, Co, Ni, Fe), Pb@BC-TiO x showed a stronger potential for pollutant degradation under ultraviolet (UV) irradiation, achieving 97.9 % of 2,4-dichlorophenol (2,4-DCP) removal within 240 min. Quenching experiments exhibited the selective enhancement of superoxide radicals (·O 2 -) and singlet oxygen (1O 2) in the Pb@BC-TiO x /UV system (5.6 and 7.9 times than Pb@BC/UV system, respectively). The characterization revealed TiO x and PbO 2 in the Pb@BC-TiO x , and the photogenerated electrons (e-) and holes (h+) flowed between them. In TiO x , TiO 1.04 was formed due to the reductive effects of CO and/or Pb0. Moreover, the heterojunction schemes of TiO 1.04 and TiO 2 also exhibited a superior photogenerated e- transfer capability. Density functional theory calculations showed that TiO 1.04 on the surface of Pb@BC-TiO x induced Pauling-type adsorption of O 2 , which reduced the overall activation energy barrier (-1.76 eV), facilitated the maintenance of O-O bonds and the accumulation of ·OOH, and futher promoted the generation of ·O 2 -/1O 2 instead of H 2 O under UV irradiation. The Pb@BC-TiO x /UV system exhibited superior reusability and applicability, which was beneficial to practical wastewater treatments. This study provided a novel idea for the preparation of catalysts using metal-hyperaccumulated biomass produced after phytoremediation. [ABSTRACT FROM AUTHOR]

Biochar based on sapropel have been synthesized and the effect of chemical modification on their textural characteristics, acid-base and adsorption properties has been studied. It was found that preliminary treatment of raw sapropel with a weakly concentrated solution of alkali increases the fraction of micropores: from 0.006 cm3 g−1 (for BС-N) to 0.021 cm3 g−1 (for КОН-BC), and additional treatment with hydrofluoric acid leads to an increase in the fraction of micropores up 0.047 cm3 g−1 (for КОН-BC-HF) and also of specific surface area up to 211 m2 g−1 at a considerable decrease in the fraction of mineral part due to leaching of silicon-containing phases. The proposed chemical modification makes it possible not only to change the ratio of mineral and carbon parts and the pore space, but also to vary the surface properties of biochar: рН PZC , concentration and features of oxygen-containing groups. It is shown that the total content of acidic groups increases in the series BС-N (0.3290 mmol g−1) < КОН-BC (0.5567 mmol g−1) < КОН-BC-HF (1.3046 mmol g−1). Simultaneously the type of treatment affects the nature of oxygen-containing groups: the maximum amount of phenolic groups (0.4845 mmol g−1) in sample КОН-BC , the surface acidity of КОН-BC-HF is contented by the presence of a considerable amount of carboxyl groups (0.9198 mmol g−1). The analysis of the data obtained shows that the total content of acidic groups increases in the series The adsorption of Cu(II) ions from an aqueous solution on the synthesized samples of biochar was studied for the first time. Biochar obtained using the sapropel pretreated with alkali showed the maximum adsorption capacity toward copper ions of 27.9 mg g−1. Conceptual model identifying the mechanisms of adsorption copper (II) ions on biosorbent from sapropels was shown. The experimentally obtained isotherms were approximated using the Freundlich and Langmuir models. It was found that the adsorption of copper on the tested samples can be described quite adequately by the Langmuir monomolecular adsorption model (R2 ≥0.98). [Display omitted] • The high potential of sapropel as a raw material for the synthesis of promising carbon-mineral biochar. • A review of the chemical modification methods for sapropel-based adsorbents. • A successful description of the Cu2+ adsorption process by the Langmuir and Freundlich isotherm models. [ABSTRACT FROM AUTHOR]

• Pyrolysis temperature's effects on Ca/P crystal and N/O site in PBCs were clarified. • The low-temperature induced the generation of high adsorption sites and the FBS. • Spectroscopy elucidated the mechanisms underlying the capture of Cu2+ by PBC-500. • DFT calculations validate the critical roles of –OH, –CONH 2 , and -PO 4 3- sites. • PBC-500 verifies its versatility with excellent adsorption, pH and ions stability. The utilization of kitchen bones as a renewable resource for biochar production holds significant promise. In this study, three distinct pig-bone-based biochars (PBCs) were synthesized at varying pyrolysis temperatures to investigate the influences of Hydroxyapatite (HAP) self-doped on crystal morphology, formation of functional active sites, and Cu2+ efficient adsorption. The results showed that low-temperature-induced alterations in HAP crystal morphology led to the formation of a highly active "fluffy bread-like" structure (FBS) in PBC-500, exhibiting exceptional Cu2+ adsorption capacity (71.60 mg·L−1) with an 86% adsorption achieved within 15 min. Notably, PBC-500 demonstrated a unit-specific surface area adsorption capacity for Cu2+, which was 1.52 and 1.19 times higher than the nano-wire-like PBC-700 and the nano-spherical-like PBC-900, respectively. Modern Spectroscopic analyses established the presence of a range of active centers (–OH, –CONH 2 , -PO 4 3-) on PBC-500′s FBS carrier along with its highly efficient adsorption mechanism for Cu2+. These findings were strongly supported by electrostatic potentials and the frontier orbital theory of Quantum DFT methods, providing insights into the crucial chemical mechanisms by which active sites, such as phosphorus, nitrogen, and oxygen centers, enhance Cu2+ adsorption. Furthermore, PBC-500 exhibited superior adsorption binding energy and chemical reactivity, retaining high activity across a range of pH levels, inorganic ions, and organic matter. This study establishes empirical and theoretical foundations for the efficient utilization of kitchen pig bones as a sustainable resource and the eco-friendly synthesis of high-performance self-doped biochar, contributing to sustainable material innovation. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide (HP) was used to pretreat wheat straw (WS) for microwave biochar production at 100–600 W, the physicochemical properties of pretreated WS and biochar products as well as heavy metals adsorption performance were investigated. Results showed that HP enhanced specific surface area (SSA) and pore volume (PV) of WS, and the largest SSA (190.35 m2 g−1) and PV (0.1493 cm3 g−1) of biochar were obtained at microwave powers of 600 W (HPWS600) and 500 W (HPWS500), respectively. HPWS500 showed maximum adsorption capacities, which were 57.56, 190.21, and 65.16 mg g−1 for Cd2+, Pb2+, and Cu2+, respectively. Solution pH values and cation concentrations exhibited significant effects on adsorption capacities of biochar. The pseudo-second-order kinetic and Langmuir isotherm models fitted better for metal adsorption process. The FTIR results suggested that chemisorption mechanisms including precipitation with carbonate and complexation with oxygen-containing functional groups might be predominant adsorption mechanisms. These results suggest that HP pretreatment has excellent potential for biochar production. [Display omitted] • Hydrogen peroxide pretreatment enhanced porosity of wheat straw. • Biochar showed enhanced physico-chemical properties and adsorption capacities. • The maximum SSA and PV of biochar were 190.35 m2 g−1 and 0.1493 cm3 g−1. • Maximum adsorption capacities for Pb2+, Cd2+ and Cu2+ were 190.21, 57.56, and 65.16 mg g−1. • Adsorption mechanisms included surface complexation and precipitation. [ABSTRACT FROM AUTHOR]

Biochar is an adsorbent widely used to remove contaminants from polluted water. A series of biochar from corn straw, corncob and corn starch was prepared through one-step pyrolysis. The biochar was characterized, and the capacity for triazine pesticide (TRZ) removal from water was compared. P doped biochar from corn straw (CSWP) was able to remove six TRZs (>96%) from water after shaking five times. The removal was more rapid than that by four other commonly used adsorbents. The physicochemical properties of CSWP were characterized systematically, and carboxyl and metaphosphates on CSWP were found to provide adsorption sites. The experimental data were best fitted by a pseudo-second-order kinetic model and the Freundlich model. Adsorption equilibrium of atrazine on CSWP occurred within 20 min, and the maximum adsorption capacity reached up to 79.6 mg g−1 at 25 °C. The adsorption mechanism of CSWP for atrazine includes Van der Waals' forces, hydrogen bonding, electrostatic interactions and pore filling. CSWP can be reused at least five times and shows strong potential as a candidate for the rapid and efficient removal of TRZs. Image 1 • P doped biochar from corn straw (CSWP) was prepared by one-step methods. • The adsorption capacity of TRZs on CSWP was better than 4 commercial adsorbents. • The adsorption of atrazine on CSWP was fast with 20min equilibrium time. • The maximum adsorption capacity of atrazine was 79.6 mg g−1 at 25 °C. • –PO 3 and -COOH on the surface of CSWP could promote the adsorption. [ABSTRACT FROM AUTHOR]

[Display omitted] • Starch coated Zn/Fe nanoparticles modified biochar composite was firstly fabricated. • SZF@CBC exhibited excellent adsorption performance for Pb(II)/Cd(II). • The capture of Pb(II)/Cd(II) was a favorable and chemisorption process. • Complexation was the dominant mechanism for Pb(II)/Cd(II) removal. • SZF@CBC possessed favorable reusability and anti-interference ability. Two functionalized biochar composites (ZF@CBC and SZF@CBC) were fabricated and applied for capturing Pb(II) and Cd(II) from wastewater. SZF@CBC were achieved by loading Zn/Fe nanoparticles (NPs) and coating starch onto corn cobs biochar (CBC) surface, while ZF@CBC was realized by loading Zn/Fe NPs onto CBC surface. The characterization analysis (SEM-EDS, XRD and FTIR) revealed that Zn/Fe NPs and starch were successfully introduced onto CBC surface. The adsorption data of Pb(II) and Cd(II) by ZF@CBC and SZF@CBC conformed to the model of pseudo second order kinetic and Langmuir isothermal and the capture Pb(II) and Cd(II) was a chemisorption process. The maximum sorption capacities of SZF@CBC for Pb(II) and Cd(II) reached 199.98 mg/g and 183.93 mg/g, which were 3.37 and 3.84 times high as that of CBC, respectively. Due to the presence of plentiful exposed adsorption sites (–OH, –COOH, Zn-O and Fe-O) on SZF@CBC surface, which endowed it to accelerate Pb(II) and Cd(II) adsorption. In addition, complexation, electrostatic attraction, ion exchange and physical adsorption took part in the adsorption process. Besides, SZF@CBC still exhibited very good removal capacity for Pb(II) and Cd(II) even in the coexistence of multiple interfering ions and maintained stable adsorption capacity after five consecutive cycles. Therefore, SZF@CBC could be used as an excellent adsorbent for decontaminating Pb(II) and Cd(II) from wastewater with multiple pollutants, and also could be used in resource utilization of biomass waste, which possessed potential applications prospects. [ABSTRACT FROM AUTHOR]

Due to the adverse effects of long-term oxytetracycline (OTC) residues in aquatic environments, an effective treatment is urgently needed. Immobilized microbial technology has been widely explored in the treatment of various organic pollutants in aquatic environments with its excellent environmental adaptability. Nevertheless, studies on its application in the removal of antibiotics are relatively scarce and not in sufficient depth. Only a few studies have further investigated the final fate of antibiotics in the immobilized bacteria system. In this study, a novel kind of OTC-degrading bacteria Mycolicibacterium sp. was immobilized on straw biochar and magnetic biochar, respectively. Magnetic biochar was proved to be a more satisfactory immobilization carrier due to its superior property and the advantage of easy recycling. Compared with free bacteria, immobilized bacteria had stronger environmental adaptability under different OTC concentrations, pH, and heavy metal ions. After 5 cycles, immobilized bacteria could still remove 71.8% of OTC, indicating that it had a stable recyclability. Besides, OTC in real swine wastewater was completely removed by immobilized bacteria within 2 days. The results of FTIR showed that bacteria were successfully immobilized on biochar and O–H, N–H, and C–N groups might be involved in the removal of OTC. The fate analysis indicated that OTC was removed by simultaneous adsorption and biodegradation, while biodegradation (92.8%) played a dominant role in the immobilized bacteria system. Meanwhile, the amount of adsorbed OTC (7.20%) was rather small, which could effectively decrease the secondary pollution of OTC. At last, new degradation pathways of OTC were proposed. This study provides an eco-friendly and effective approach to remedy OTC pollution in wastewater. [Display omitted] • Magnetic biochar was a more ideal immobilization carrier than straw biochar. • Immobilized bacteria had superior environmental adaptability and recyclability. • Biodegradation played a dominant role in the immobilized bacteria system. • New degradation pathways of OTC by immobilized bacteria were proposed. [ABSTRACT FROM AUTHOR]

In order to solve the problem of efficient desorption of per- and polyfluoroalkyl substances (PFAS) and regeneration of adsorbents, a novel biochar composite was prepared based on the quaternary ammonium groups and hydrophobicity of sulfobetaine polymer, which can be used for the efficient removal of various PFASs and has great regeneration ability. Through adsorption, regeneration and degradation experiment, the comprehensive effect of the novel biochar composite on the whole process of removal of PFAS was systematically investigated. The results showed that the maximum adsorption capacity of PFOS, PFOA, PFBS, and PFBA reached 634 mg/g, 536 mg/g, 301 mg/g and 264 mg/g, respectively. The adsorption process involved hydrophobicity, electrostatic, pore diffusion and complexation. The NaI + NaOH solution was used at 50 °C to achieve efficient regeneration of the adsorbent, which can be recycled more than 4 times. When the vacuum-ultraviolet (VUV)/sulfite reduction system was used for deep degradation of the regenerated solution, the effect of hydrated electrons on PFAS was enhanced due to the inclusion of NaI and NaOH in the regeneration reagent, resulting in an increase in the degradation efficiency (89.1%–99.9%) and defluorination efficiency (63.3%–84.1%). Based on the performance of BC-P(SB-co-AM) and the treatment efficiency of PFAS, the design idea of the whole process treatment technology of PFAS proposed in this work is expected to hold great promise in environmental applications. This work provides a novel idea and system for the efficient adsorption removal and desorption of PFAS, and subsequent deep degradation. [Display omitted] • The adsorption of PFCs was dominated by hydrophobic and electrostatic interactions. • Heat treatment was beneficial to the efficient regeneration of BC-P(SB-co-AM). • I− and OH− in the regenerant promoted the degradation and defluorination of PFCs. [ABSTRACT FROM AUTHOR]

Abundant novel metal-modified biochars have been synthesized for phosphate removal under various preparation conditions, but optimal biochar adsorbents with low cost and high removal performance for application in real scenarios are still largely scarce. In this study, the optimal preparation conditions for metal-modified biochar were screened stepwise by determining their phosphate adsorption performance and cost with frequently used preparation conditions, including different feedstocks (total 7 biomass residues), pyrolysis temperatures (400 °C and 600 °C), modification methods (impregnation and coprecipitation), and modifying metals (Fe/La/Mg). Furthermore, the influences of preparation conditions on adsorption capacity and mechanisms were interpreted via multiple characterization methods by compared with the optimal preparation conditions. The results showed that Mg coprecipitated peanut shell biochar at 600 °C (denoted PS–600–C–Mg) was the optimal phosphate adsorbent with a maximum adsorption capacity of 50.58 mg g−1 and a cost benefit ratio (CBR) of 3.24 × 104 RMB t−1 based on adsorption capacity and cost‒benefit analysis via Monte Carlo simulations. The different mesoporous (2–50 nm) and macroporous structures (>50 nm), which were generated under various preparation conditions and favored the development of metal (hydr)oxides, could explain the greater adsorption capacity of this optimal biochar. Furthermore, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), zeta potential and Fourier transform infrared spectroscopy (FTIR) spectra jointly revealed that modification methods and modifying metal types changed adsorption mechanisms with phosphate significantly. The dominant role of electrostatic force in the adsorption of the optimal biochar towards phosphate was interpreted mainly by the unchanged FTIR spectra, negative surface charge, and further confirmed by the interaction region indicator (IRI) and localized orbital locator (LOL) at the molecular level by using density functional theory (DFT). • The optimal prepared conditions were screened based on adsorption and cost analysis. • Cost‒benefit analysis was performed by using Monte Carlo simulations. • Adsorption mechanisms under various modification methods and metals were revealed. • The dominant role of electrostatic force was confirmed by density functional theory. [ABSTRACT FROM AUTHOR]

Quinolone antibiotics are emerging environmental contaminants, which cause serious harm to the ecological environment and human health. How to effectively remove these emerging pollutants from water remains a major challenge worldwide. In this study, a novel Fe/Ti biochar composite (Fe/Ti-MBC) was prepared by facile one-step co-pyrolysis of wood chips with hematite and titanium dioxide (TiO 2) for adsorption and photocatalytic degradation of ciprofloxacin (CIP) and norfloxacin (NOR) in water. The results showed that the degradation efficiencies of Fe/Ti-MBC to CIP and NOR were 88.4% and 88.0%, respectively. The π-π interactions and polar interactions are the main adsorption mechanisms for CIP and NOR. In the photocatalytic process, h+ and ·OH are the main active substances for the oxidative degradation of CIP and NOR. This study shows that Fe/Ti-MBC is an effective and recyclable composite, providing a novel alternative way for antibiotics degradation. [Display omitted] • Fe/Ti-MBC shows good adsorption performance for NOR and CIP. • Solution pH is an important factor affecting adsorption and photocatalysis. • The π-π and polar interactions are the main adsorption mechanisms. • ·OH and h+ are the main active species for the photocatalytic degradation of CIP and NOR. • Fe/Ti-MBC has a good adsorption and degradation effect in the actual water. [ABSTRACT FROM AUTHOR]

Biochar (BC) is attracting increasing concerns on the scavenging of toxic contaminants from water because of its low-cost and environmental-friendly properties, however, the adsorption performance of pristine BC for common organic contaminants. Consequently, adopting available modification methods to strengthen the uptake performance of BC is necessary, unfortunately, there are few summaries on various functionalization techniques of BC with corresponding mechanisms on removing organic contaminants. Herein, this review aims to describe (i) the preparation methods of pristine BC and the influence of different pyrolysis parameters; (ii) various modification techniques for BC including liquid modification, gas modification, ball milling modification, metal nanoparticles loading, and near-nature BC-based immobilized materials; (iii) the applications of functionalized BC on organic pollutants removal with related adsorption mechanisms (iv) crucial factors (e.g. solution pH, contact time, and co-existing ions); influencing the removal process of functionalized BC on organic contaminants with application potential of modified BC as an adsorbent in environmental fields; (v) some useful and constructive proposals to improve the practical application of functionalized BC in future research. This review advanced the comprehensive understanding of application of functionalized BC as effective adsorbent with low-cost and high-performance properties for the remediation of contaminated water. [Display omitted] • Synthesis methods and removal performance of BC for organic pollutants are presented. • Advancements in the functionalization of BC for enhanced adsorption are summarized. • Adsorptive mechanisms of functionalized BC for organic pollutants are discussed. • Critical factors affecting adsorption performance of functionalized BC are analyzed. • Constructive suggestions for further applications of functionalized BC are proposed. [ABSTRACT FROM AUTHOR]

Dyestuff wastewater and pharmaceutical wastewater have become typical representatives of water pollution. In this study, a novel nano-silica-biochar composite (NSBC) was synthesized based on corn straw as raw material, by a combination of ball milling, pyrolysis and KOH activation. The modified biochar with rough surface had higher specific surface area (117.67–132.82 m2/g), developed pore structure (0.12–0.15 cm3/g) and abundant surface functional groups (-OH, –COOH, Si–O and aromatic C C were dominated). These provided abundant active sites for the adsorption of pollutants. The adsorption capacities of NSBC for Methylene Blue (MB) and Tetracycline (TC) were both higher than that of other similar products, the maximum adsorption capacity of Langmuir were 247.22 and 86.95 mg/g, respectively. After five adsorption-desorption cycle experiments, the adsorption capacities of NSBC for both were still excellent, reaching 99.30 and 19.87 mg/g, respectively. Due to the different structure and molecular size of MB and TC, the adsorption capacities of NSBC were significantly different, especially the influence of solution pH value. The adsorption mechanisms were comprehensively discussed by FTIR and XPS of the samples before and after adsorption, and combining experimental results of BET and simultaneously, which were manifested as monolayer chemisorption, specifically surface complexation, hydrogen bonding, n-π/π-π conjugation, electrostatic interaction and pore filling. [Display omitted] • Biochar was modified by combined process: ball milling-pyrolysis-alkali activation. • NSBC exhibited excellent adsorption properties for methylene blue and tetracycline. • FTIR, XPS, BET, pH experiments were used to explore the adsorption mechanism. • The adsorption mechanism of methylene blue and tetracycline is slightly different. [ABSTRACT FROM AUTHOR]

In this work, magnesium oxide nanoparticles supported biochar derived from tea wastes (MgO@TBC) was prepared as an effective adsorbent for removing hazardous o -chlorophenol (o-CP) from industrial wastewater. The surface area, porous structure, surface functional groups and surface charge of tea waste biochar (TBC) significantly enhanced after the modification process. The best uptake performance of o-CP was found at pH = 6.5 and 0.1 g of MgO@TBC adsorbent. According to the adsorption isotherm, the adsorption of o-CP onto MgO@TBC followed the Langmuir model with a maximum uptake capacity of 128.7 mg/g, which was 26.5% higher than TBC (94.6 mg/g). MgO@TBC could be reused for eight cycles with a high o-CP uptake performance (over 60%). Besides, it also exhibited good removal performance of o-CP from industrial wastewater with a removal rate of 81.7%. The adsorption behaviors of o-CP onto MgO@TBC are discussed based on the experimental results. This work may provide information to prepare an effective adsorbent for removing hazardous organic contaminants in wastewater. [Display omitted] • MgO modified biochar derived from tea wastes (MgO@TBC) was prepared. • Removal of o -chlorophenol by MgO@TBC was investigated. • Maximum adsorption capacity of o -chlorophenol was 128.7 mg/g. • 81.7% o -chlorophenol was removed from industrial wastewater. [ABSTRACT FROM AUTHOR]

In this study, microporous activated carbon was produced from jellyfish-based biomass to capture carbon dioxide (CO 2), toward addressing one of the biggest modern problems. The surface functional groups and porosity of activated carbon derived from jellyfish were investigated according to the activation conditions. It was confirmed that the jellyfish-based porous carbon prepared by NaOH activation comprised many micropores that facilitated CO 2 adsorption under the influence of Na and P present in the microstructure of the jellyfish. In addition, the JFBC-based activated carbon had surface functional groups such as nitrogen, calcium, and magnesium, which facilitated CO 2. The jellyfish-based activated carbon shows very excellent CO 2 adsorption capacity (9.52 mmol/g and 5.18 mmol/g at 273 K and 298 K, respectively) compared to activated carbon prepared from porous carbon-based adsorbents for CO 2 capture. This performance is attributed to the microstructure and various heteroatoms of the jellyfish biochar. Therefore, this study may provide insight into new biomass with competitive adsorption power and without requiring complicated manufacturing steps. [Display omitted] • Synergistic effect of NaOH and Na, P forms micropores internally. • JFBC surface has N, Ca, Mg functional groups, advantageous for CO 2 adsorption. • The microporosity is > 77% with a concentrated distribution of micropores. • CO 2 adsorption capacity can up to 9.52 mmol/g and 5.18 mmol/g at 273 K and 298 K. [ABSTRACT FROM AUTHOR]

• Phenol and 2-nitrophenol on a biopolymer derived biochar adsorbent was analyzed. • Theoretical analysis of phenol and 2-nitrophenol adsorption mechanisms was performed. • The role of adsorbate structure on tested adsorbents was theoretically explained. In this paper, the adsorption of phenol and 2-nitrophenol on a biopolymer-based biochar in single and binary systems was investigated at 298–328 K and pH 5. Experimental results indicated that the adsorption capacities of phenol were significantly reduced from single to binary systems compared to those obtained for 2-nitrophenol. This experimental evidence suggested an antagonistic effect between both adsorbates generating an inhibitive adsorption. In terms of modeling analysis, the single and binary adsorption isotherms were well reproduced by monolayer and competitive monolayer statistical physics models, respectively. These two models showed that phenol and 2-nitrophenol molecules have been mainly docked with an inclined and horizontal positions in single and binary systems, respectively. A detailed analysis of the number of captured phenol (n 1) and 2-nitrophenol (n 2) molecules per site in the binary systems demonstrated that its corresponding evolution varied with a completely inverse way thus corroborating the inhibition effect between phenol and 2-nitrophenol molecules. The monolayer and competitive monolayer models were used to estimate two adsorption energies to characterize the single and binary adsorption mechanisms. The analysis of the energetic parameters suggested that the adsorption process was a physisorption. The interpretation of all monolayer and competitive monolayer model parameters provided new insights that contributed to understand the single and binary adsorption mechanisms of phenol and 2-nitrophenol molecules on tested adsorbent. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Hydroxyapatite/biochar nanocomposites (HAP/BC-NCs) were hydrothermally synthesized. • HAP/BC-NCs were used for Cu(II) removal and exhibited high adsorption affinity. • The adsorption rate of Cu(II) was mainly controlled by film diffusion mechanism. • The maximum adsorption capacity was determined to be 99.01 mg/g at 298 K. • Adsorption mechanism involved cation exchange and inner-sphere surface complexation. Abstract In this study, hydroxyapatite/biochar nanocomposites (HAP/BC-NCs) were synthesized through a simple one-pot hydrothermal process and utilized as an adsorbent for the removal of copper(II) from aqueous media. Characterization results revealed that rod-shaped HAP nanoparticles were successfully incorporated on the surfaces of synthesized HAP/BC-NCs. A set of systematically designed batch experiments were carried out to determine the influences of adsorbent dosage, solution pH, ionic strength, and temperature on the adsorption behavior of the HAP/BC-NCs. Overall findings from batch experiments and extended X-ray absorption fine structure analysis demonstrated that the potential mechanisms responsible for the removal of Cu(II) from aqueous media are cation exchange between Cu2+ in solution and Ca2+ in the HAP on the surfaces of the as-synthesized nanocomposites and the formation of inner-sphere surface complexes on the surfaces of the HAP/BC-NCs. Kinetic studies revealed that the adsorption process follows the pseudo-second-order model and that the overall adsorption rate is controlled by film diffusion as the dominant mechanism and intraparticle diffusion as a secondary mechanism. Adsorption isotherms were accurately represented by a Langmuir isotherm model and the maximum adsorption capacity was determined to be 99.01 mg/g at 298 K, which represents a higher efficiency for Cu(II) adsorption compared to previously reported composite materials. Thermodynamic analysis indicated that the process is thermodynamically spontaneous and endothermic process. Overall, the findings presented in this paper suggest that HAP/BC-NCs have promising applicability for the removal of heavy metals from aqueous media as an alternative, low-cost, and eco-friendly adsorbent for environmental remediation. [ABSTRACT FROM AUTHOR]

To investigate the role of adsorption by biochar and biodegradation by bacteria in the wastewater treatment system of microorganisms immobilized on biochar, Nonylphenol (NP) removal (adsorption + degradation) rates and degradation rates from water by NP degrading bacteria immobilized on bamboo charcoal (BC) and wood charcoal (WC) were examined in a short-term and long-term. Results showed that cells immobilized on different biochar had different NP removal effects, and cells immobilized on bamboo charcoal (I-BC) was better. After eight rounds of long-term reuse, the cumulative removal rate and the degradation rate of NP in water by I-BC were 93.95% and 41.86%, respectively, significantly higher than those of cells immobilized on wood charcoal (69.60%, 22.78%) and free cells (64.79%, 19.49%) (P < 0.01). The rise in the ratio of the degradation rate to the removal rate indicated that the long-term NP removal effect is more dependent on biodegradation. The amount of residual NP in I-BC still accounted for about 50%, indicating that the secondary pollution in the disposal of carrier could not be ignored. In addition, promotion effect of biochar on microorganisms were observed by SEM, quantitative PCR and 16S rRNA. Pseudomonas , Achromobacter , Ochrobactrum and Stenotrophomonas were predominant bacteria for NP degradation. The addition of biochar (especially bamboo charcoal) also effectively delayed the transformation of their community structure. Image 1 • Cells immobilized on bamboo charcoal showed higher removal and degradation rate. • Nonylphenol removal was more dependent on degradation in microbe-biochar system. • Biochar could protect microorganism and delay the transform of community structure. • The amount of pollutants remaining in biochar could not be ignored. [ABSTRACT FROM AUTHOR]

The introduction of glyphosate, found in herbicides, to waterbodies is of concern due to its toxicity and hence potential threat to public health and ecological systems. The present study has compared glyphosate removal from aqueous solution with activated carbon and biochar. Box–Behnken design, and percent contribution with Pareto analysis techniques were used in surface response and efficiency calculations modelled the process conditions and their effects. The adsorption data better fitted the Freundlich isotherm model than the Langmuir model. The rate of glyphosate adsorption was found to follow a pseudo-second-order model. pH of the solutions was regulated by buffering during the adsorption process. Higher efficacy of glyphosate removal was obtained by optimising parameters such as operating pH, initial glyphosate concentration, temperature, adsorbent dose, and contact time. The conditions yielding the best removals were pH 8.0, 0.2 mg/L, 50.0 °C, 11.4 g/L, 1.7 h for activated carbon and pH 5.0, 0.7 mg/L, 50.0 °C, 12.3 g/L, 1.9 h for biochar, for the aforementioned parameters respectively. The maximum removal capacity and efficiency were 0.0173 mg/g and 98.45% for activated carbon, and 0.0569 mg/g and 100.00% for biochar. The test results indicated biochar could be important from the perspective of performance and affordability. • Box–Behnken design was used in surface response and efficiency calculations. • Impact on glyphosate removal: concentration > adsorbent dose > time > temperature > pH. • For better efficiency, pH should be lowered for biochar but increased for activated carbon. • Higher temperatures resulted in better glyphosate removal efficiencies. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the properties of biochar prepared at higher than normal biochar production temperature and to evaluate adsorption/desorption characteristics for three commonly used dyes of different charge and molecular nature: Methylene Blue (MB), Orange G (OG) and Congo Red (CR). The switchgrass-biochar was prepared at common pyrolysis temperature of 600 °C (SB600) and higher than normal temperature of 900 °C (SB900). The results showed that the carbon content of the two biochars was similar, but most carbon in SB900 was graphitized based on FTIR and XRD observation. Dye adsorption isotherms by SB600 and SB900 was well described Langmuir model with maximum adsorption capacity of MB, OG and CR being 37.6, 8.2 and 8.0 mg/g for SB600 and 196.1, 38.2 and 22.6 mg/g for SB900, respectively. The adsorption kinetics of dyes by both biochars were well described by pseudo-second order model. In addition, intraparticle diffusion model showed that MB adsorption was predominantly by inner pore diffusion rather than by outer boundary, while OG and CR were more adsorbed by the outer boundary. These results indicated that the strong dye adsorption by SB900 compared to SB600 was due to the significantly enhanced surface area at the high pyrolysis temperature. Additionally, the greater adsorption of cationic MB by SBs than that of anionic OG and CR was attributable to the small molecular weight, favorable electrostatic property, and strong π-π interaction of the former with biochar surface as opposed to the latter. Overall, the SB900 maintained > 85% adsorption of maximum capacity even after four adsorption-desorption consecutive cycles and could be used as an effective adsorbent for cationic dye removal from wastewater. [ABSTRACT FROM AUTHOR]

The adsorption capacity, isotherm, kinetics, thermodynamics and mechanism of four dyes with different properties on a novel economical sludge-rice husk biochar (SRHB) were determined. The sludge and rice husk with ratio of 1:1 were pyrolyzed at 500 °C, for 2 h in a tubular furnace. The SRHB was characterized using an element analyzer, Brunauer-Emmett-Teller (BET) method, X-ray diffraction, Fourier transform infrared spectroscopy, zeta potential measurement and X-ray photoelectron spectroscopy. Results of the adsorption experiments revealed that the adsorption capacities of these dyes on the SRHB followed the order: Direct Red 4BS (DR) > Acid Orange II (AO) > React Blue 19 (RB) > Methylene Blue (MB). Adsorption data of DR, RB, AO, MB all fitted both the Langmuir isotherm and Freundlich isotherm well, Temkin and D-R isotherm models verified the result. Kinetic data of the four dyes showed good correlation with the pseudo-second-order model. The adsorption of DR and AO onto SRHB were exothermic, while that of RB and MB were endothermic. Dyestuffs sorption on the SRHB involved surface participation, electrostatic interaction, π-π interactions, hydrogen bond. However the main adsorption mechanisms of the different dyes onto the SRHB varied. Therefore, the SRHB could be an effective adsorbent for removing dyestuffs from wastewater, and it is most effectively for direct dye adsorption, followed by acid and reactive dyes. However, the SRHB was apparently not effective for cationic dyes. • Dye adsorption capacities onto sludge-rice husk biochar: Direct Red 4BS > Acid Orange II > React Blue 19 > Methylene Blue • Temperature, pH, contact time, initial concentration had great influences on the adsorption results. • Chemisorption played a main role in the adsorption process. • Detailed adsorption mechanisms of the different dyes onto sludge-rice husk biochar varied. [ABSTRACT FROM AUTHOR]

Abstract In recent years, with the continuous development of industry and agriculture, the content of organic pollutants in the environment has been increasing, which has caused serious pollution to the environment. Adsorption has proven to be an effective and economically viable method of removing organic contaminants. Since biochar has many advantages such as various types of raw materials, low cost, and recyclability, it can achieve the effect of turning waste into treasure when used for environmental treatment. This paper summarizes the source and production of biochar, points out its research status in the removal of organic pollutants, expounds its adsorption mechanism on organic pollutants, introduces the relevant adsorption parameters, summarizes its regeneration methods, studies its application of engineering, and finally analyses of benefits and describes the development prospects. Highlights • Recent research on adsorbing organic contaminants by biochar were summarized. • Mechanism of organic contaminants adsorption using biochar. • The application of biochar as adsorbents in engineering was introduced. • Biochar as an adsorbent needs to continue to explore in the future was proposed. [ABSTRACT FROM AUTHOR]

Graphical abstract The main mechanism of DMP, DEP, DBP, DOP and DEHP adsorption onto MCB. Highlights • A new strategy to evaluate the different PAEs adsorption behavior and mechanism. • The effect of carbon chain structure on PAEs adsorption mechanism was elucidated. • Pore-filling and π-π EDA interactions play major role in short carbon chain PAEs adsorption. • Hydrophobic interaction is the main mechanism for long and branch carbon chain PAEs adsorption. Abstract With the widespread usage of plastic products, more and more phthalic acid esters (PAEs) pollutants entered into the environment, and then pose a potential threat to the ecosystems and human. In this work, mesoporous cellulose biochar (MCB) was taken as the adsorbent, and five different carbon chain structural phthalic acid esters (PAEs; DMP, DEP, DBP, DOP, DEHP) were selected as the adsorbates. The effects of CCS on the PAEs adsorption behaviors and mechanisms were systematically studied by the combination of experiments and molecular dynamics simulation. The adsorption capacity order of the five PAEs was as follows: DOP (74.42) > DMP (69.58) > DEP (68.91) > DBP (67.32) > DEHP (61.87). The adsorption processes were mainly driven by chemisorption. Therein, MCB adsorbed DMP, DEP, and DBP mainly through π-π electron-donor–acceptor (EDA) interaction, adsorbed DOP by the collaboration of hydrophobic and π-π EDA interactions, and adsorbed DEHP mainly via hydrophobic interaction. For the short carbon chain PAEs, the mainly adsorption mechanisms of PAEs onto porous biochar were π-π EDA interaction and pore-filling. With the increase of carbon chain length, the π-π EDA interaction and pore-filling would weaken, thus the hydrophobic interaction would enhance contrastingly. Owing the same carbon number of the carbon chain, the branched structure would accelerate the agglomeration of adsorbate molecules and weaken the adsorption force. Therefore, the current study could provide strategies for the preparation of highly effective biochar adsorbents, and improve selective adsorption efficiency of PAEs. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Engineered biochar showed strong batch adsorption ability to P in real secondary treated wastewater. • Engineered biochar in fixed-bed columns also effectively removed P from the wastewater. • Commonly used fixed-bed dynamic adsorption models describe the P breakthrough curves well. • Exhaust P-laden biochar promoted mung bean seed germination and seedling growth. Abstract Phosphorus (P), a vital growth-limiting nutrient, is often lost in wastewater discharge, which may not only deteriorate water quality but also accelerate P depletion. In this study, laboratory experiments were conducted to investigate the reclamation and reuse of P from secondary treated wastewater (STWW) by engineered biochar loaded with aluminum oxyhydroxides (AlOOH). Biochar loaded with colloidal and nanosized AlOOH crystalline flakes was successfully produced through direct pyrolysis of hickory wood chips pretreated with aluminum salt. STWW samples were collected from a local wastewater treatment plant to evaluate the P sorption ability of the engineered biochar. The real wastewater was used in batch sorption experiments and the results showed that the engineered biochar effectively removed P from the STWW with relatively fast kinetics (<8 h) and good capacity (8,346 mg-P/kg), mainly through the electrostatic attraction mechanism. When the engineered biochar was packed in fixed-bed columns, it also effective removed P from the real STWW. The P removal efficiencies of the fixed-bed columns were affected by biochar dosage and flow rate. Various fixed-bed filtration models were applied to simulate the column experimental data and the model results matched the experimental breakthrough curves of P well. After the use, the engineered biochar was laden with P and thus significantly stimulated seed (Vigna radiata R. Wilczek) germination and early seedling growth. Findings from this study demonstrate that engineered biochar has promising applications in wastewater treatment because it can not only reduce P level in discharge to benefit the environment but also reclaim it as an agricultural fertilizer to improve P biogeochemical cycling and sustainability. [ABSTRACT FROM AUTHOR]

Abstract Controlling of pre-oxidation conditions can effectively enhance the aimed active functional groups via promoting the oxidation and grafting reaction on biochar's surface. Here, the effect of different nitric acid pre-oxidation concentration (NAPOC) was investigated on the type and content of active oxygen-containing functional sites during the pre-oxidation stage, as well as the active nitrogen-containing binding sites for the following grafting process. And the possible reaction mechanisms for introducing nitrogen/oxygen-containing functional groups such as amide, pyridinic, carbonyl, carboxyl, etc., into the surface by ethylenediamine (EDA) were proposed. The samples were characterized by various analyses including N 2 adsorption/desorption, Boehm titration, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Results showed that the NAPOC played a crucial role in promoting the formation of oxygen-containing initiators, and difference of NAPOC resulted in different reaction principles. At higher NAPOC, more carbonyl, carboxyl and hydroxyl functional groups were formed, which facilitated the decoration of nitrogen binding active sites of amide and pyridinic for mercury ions adsorption into the carbon lattice of mesoporous biomass-derived biochar (MBB). The proportions of micropore and mesopore remained basically unchanged, indicating that the decorated nitrogen/oxygen sites were highly uniformly dispersed in MBB's frame and thus resulted in high activity. The comparison of adsorption properties of MBB showed that MBB-25-EDA had the highest adsorption capacity of 153 mg g−1 at pH 6, confirming that the 25% was the optimum NAPOC for introducing nitrogen/oxygen functional binding sites for effectively anchoring mercury. Graphical abstract Image 1 Highlights • Nitric acid pre-oxidation has a great effect on nitrogen/oxygen active decoration sites. • The decorated N/O sites on mesoporous biochar were uniformly dispersed. • More N/O active sites on biochar can be doped at 25% HNO 3 pre-oxidation concentration. • N/O active decoration sites promote the mercury adsorption on biochar. • The possible N/O doping and mercury adsorption mechanisms on biochar were proposed. [ABSTRACT FROM AUTHOR]

Abstract This study investigated the potential of biochar filters as a replacement for, or complement to, sand filters for removal of per- and polyfluoroalkyl substances (PFASs) from wastewater in on-site wastewater treatment systems (OWTSs). Concentrations and removal of nine perfluoroalkyl carboxylates (PFCAs; C 3-11) and three perfluoroalkane sulfonates (PFSAs; C 4 , 6 , 8) and one perfluorooctanesulfonamide (FOSA; C 8) were investigated over 22 weeks in four treatments with column filters: biochar (BC) without biofilm (BC-no-biofilm), biochar with active biofilm (BC-active-biofilm), biochar with inactive biofilm (BC-inactive-biofilm) and sand with active biofilm (Sand-active-biofilm). The filters were operated under hydraulic loading (50 L m−2 day−1) to mimic the loading rate in on-site filtration beds. The initial concentrations of the ΣPFASs in the influent were in the range of 1500–4900 ng L−1. In BC-no-biofilm, the removal efficiency (20–60%) and adsorption capacity (0–88 ng ΣPFASs g−1 BC) of short-chain PFCAs (C 3-6) and PFSA (C 4) was low, whereas the removal efficiency (90–99%) and the adsorption capacity (73–168 ng g−1) was high for C 7 -C 11 PFCAs, C 6 , C 8 PFSAs and FOSA. The relative removal was generally lower for C 3 - 9 PFCAs and C 4 , C 6 , C 8 PFSAs using BC-active-biofilm and BC-inactive-biofilm compared with BC-no-biofilm. This can be explained by the presence of biofilm and solids in BC-active-biofilm and the presence of wastewater solids in BC-inactive-biofilm, which decreased the availability and number of adsorption sites for PFASs compared with BC-no-biofilm. On the other hand, inactivation of the biofilm resulted in lower removal efficiencies for C 5 - 11 PFCAs, C 4 , C 6 , C 8 PFSAs and FOSA, probably because the biofilm degraded organic matter and thus increased the availability and number of adsorption sites compared with BC-inactive-biofilm. Sand-active-biofilm showed poor removal (0–70%) for all PFASs except FOSA (90%) and its adsorption capacity was low (0.0–7.5 ng g−1). In general, for all biochar treatments, shorter-chain PFASs were more resistant to removal than longer-chain PFASs. In addition, C 4 , C 6 and C 8 PFSAs showed 10–30%, 10–50% and 20–30% higher average removal efficiency, respectively, than PFCAs with corresponding perfluoroalkyl chain length. In conclusion, biochar is a promising filter medium for removal of PFASs in OWTSs, especially for PFASs with a perfluorocarbon chain longer than C 6. Graphical abstract Image 1 Highlights • Effects of biofilm on adsorption of PFASs in biochar (BC) filters were investigated. • Removal of PFCA (C 7 -C 11), PFSA (C 6 , 8) and FOSA (C 8) was efficient in BC-no-biofilm. • Biofilm in BC-active-biofilm decreased removal of PFCA (C 3 - 9) and PFSA (C 4 , 6 , 8). • Inactivation of biofilm deteriorates the removal of PFASs in BC-inactive-biofilm. • BC is a promising filter medium for removal of PFASs from OWTSs. [ABSTRACT FROM AUTHOR]