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Herein, the impact of varying proportions of cellulose/lignin in bamboo on the production of hydrothermal biochar was investigated. Different characterization techniques were applied to explore the structure of hydrothermal biochar derived from three different genotypes (215, 30-A, 52-B) of Dendrocalamus farinosus, and the adsorption behavior of uranium by these hydrothermal biochars was evaluated. It was found that a decrease in cellulose/lignin ratio (3.08, 2.68, and 2.58) positively influenced the specific surface area and pore volume of hydrothermal biochar. Consequently, the prepared hydrothermal biochars exhibited adsorption capacities for U(VI) ions at levels of 14.78 mg/g, 24.68 mg/g, and 26.02 mg/g respectively under these three ratios. The adsorption process by 52-B-220 well complied with the Freundlich isotherm, which indicated that the multi-layer adsorption occurred on the solid liquid interface, but single-layer adsorption was evident in those prepared from genotypes 30-A and 215. This study demonstrated that adjusting biomass feedstock composition as an effective strategy for enhance the quality of biochar. [ABSTRACT FROM AUTHOR]

The disposal and treatment of antibiotic residues is a recognized challenge due to the huge production, high moisture content, high processing costs, and residual antibiotics, which caused environmental pollution. Antibiotic residues contained valuable components and could be recycled. Using a one-step controllable pyrolysis technique in a tubular furnace, biochar (OSOBs) was produced without the preliminary carbonization step, which was innovative and time- and cost-saving compared to traditional methods. The main aim of this study was to explore the adsorption and removal efficiency of tetracycline (TC) in water using porous biochar prepared from oxytetracycline fermentation residues in one step. A series of characterizations were conducted on the prepared biochar materials, and the effects of biochar dosage, initial tetracycline concentration, reaction time, and reaction temperature on the adsorption capacity were studied. The experimental results showed that at 298 K, the maximum adsorption capacity of OSOB-3-700 calculated by the Langmuir model reached 1096.871 mg/g. The adsorption kinetics fitting results indicated that the adsorption of tetracycline on biochar was more consistent with the pseudo-second-order kinetic model, which was a chemical adsorption. The adsorption isotherm fitting results showed that the Langmuir model better described the adsorption process of tetracycline on biochar, indicating that tetracycline was adsorbed in a monolayer on specific homogeneous active sites through chemical adsorption, consistent with the kinetic conclusions. The adsorption process occurred on the surface of the biochar containing rich active sites, and the chemical actions such as electron exchange promoted the adsorption process. [ABSTRACT FROM AUTHOR]

Olive mill waste (olive pomace, OP, and olive stone, OS) was used in this work to produce adsorbents for the removal of five phenolic acids typically found in olive mill wastewater. OP and OS were subjected to different treatments (combined or not) that were chemically modified (NaOH) or physically modified by two different methods, incipient wetness impregnation (IWI) and hydrothermal deposition (HD), and even biochar production obtaining a total of 16 materials. The materials were characterized by different analytical techniques such as N2 absorption, scanning electron microscopy, infrared spectroscopy, and pH zero-potential charge. The mixture of five phenolic acids was used to evaluate in batch conditions the adsorption capacity of the prepared materials. OS chemically modified with IWI (OSM-IWI) and OS biochar with HD (BOS-HD) presented better adsorption capacity at 157.1 and 163.6 mg/g of phenolic acids, respectively, from a total of 200 mg/g. For some materials, the surface area cannot be correlated with adsorption capacity, unlike pHzpc, where high values fit better adsorption rates. The infrared spectroscopy profile indicates the presence of O-H and N-H functional groups and, the last one, red-shifted in the IWI preparation compared to the HD one. In addition to this, the prepared material from olive mill waste can be suitably used for the mixture of phenolic compounds. [ABSTRACT FROM AUTHOR]

In this study, biochars with different structures were prepared through HNO3 oxidation and secondary pyrolysis to study the relationship between the structure of biochar and its selectivity for the adsorption of light and heavy aromatics in bio‐oil. The results showed that the adsorption rates of biochar with different structures ranged from 2.90 to 4.00 g bio‐oil per g biochar. The influence of pore structure was dominant, followed by the influence of O‐containing functional groups and the degree of graphitization. The higher the adsorption capacity of biochar for bio‐oil, the smaller the concentrations of the light aromatic model compounds in the absorbed bio‐oil (ABO). Among the five light aromatics, biochar has the best adsorption selectivity for dihydroxybiphenyl and the worst for eugenol and propyl phenol. This is attributed to the diphenyl ring structure of dihydroxybiphenyl, which makes it more susceptible to adsorption, and other light model compounds only have one benzene ring. In summary, biochar demonstrates better adsorption selectivity for heavy aromatics than light aromatics. The more developed the pore structure is, the more enriched O‐containing functional groups are, and the higher the graphitization degree of biochar is, the better the selective adsorption of aromatic compounds in bio‐oil. [ABSTRACT FROM AUTHOR]

Ammonia becomes one of the indispensable raw materials in production and life, with the continuous development of industry. Ammonia pollution of the environment is becoming more and more serious, so the adsorption of ammonia is essential. In this paper, a new biochar material based on tannic acid was developed. The tannic acid was self-polymerized using different activators (K2CO3, KHCO3, KOH). Tannic acid biochar (TAB-X) was obtained by pyrolytic carbonization reaction at 800 ℃. The biochar was treated with phosphoric acid 10% by mass (TAB-X-10%PO4), and unlike other biochar materials, the specific surface area and hydroxyl content were increased after acidification, but there were no acidic functional groups. It is noteworthy that the specific surface area of TAB-KOH increased from 22 m2/g to 667 m2/g after acidification. The adsorption capacity of ammonia vapor reached 342.6 mg/g. It is proposed that the adsorption mechanism is an adsorption process in which hydroxyl groups on the surface of TAB-X firstly adsorb water, and after that ammonia gas is then dissolved in the water molecules on the surface of the biochar. These results highlight the great potential of TAB as an adsorbent for the adsorption of ammonia, in addition to the low price of raw materials and the simple preparation conditions of this preparation process, which corresponds with the conditions for mass production as well as practical application. [ABSTRACT FROM AUTHOR]

Biochar has a limited initial adsorption capacity and number of adsorption sites. Nevertheless, by employing physical or chemical techniques, the multi-level architecture of biochar can be altered to achieve substantial improvements in aquatic pollutant adsorption. This can unleash biochar's full potential for environmental remediation. This review provides a summary of the transformative effects of various modification techniques on the multi-level structure of biochar, as well as their unique adsorption mechanisms in different water conditions. Furthermore, the effectiveness of adapted biochar in its preparation and application will be deliberated, emphasizing its substantial potential in the restoration of water environments. The findings and recommendations presented in this literature review offer significant guidance for improving biochar production and utilization, thus contributing to a cleaner and healthier future. [ABSTRACT FROM AUTHOR]

Aging of biochar can affect its stability and persistence of heavy metals immobilizing in soil, resulting in changes in its inertness. Using peanut shell(PS) as raw material, peanut shell biochar (PSB) was prepared by pyrolysis under the condition of 600 °C and hypoxia. Oxidized biochar(OPSB), leached biochar(LPSB) and acidified biochar (APSB) were prepared Y by simulated field oxidation, leaching and acidification of PSB. The effects of these three aging methods on the adsorption efficiency and mechanisms of Cd2+ by the biochar were investigated using isothermal adsorption models, kinetic models, FT-IR and XRD. The results show that oxidative aging process an significantly enhance the accumulation of oxygen-containing functional groups (--COOH, --OH, etc.) on the surface of the biochar, thereby increasing the adsorption capacity of OPSB for Cd2+ by 10.13%. Leaching aging process can not cause significant changes in functional group content but result in substantial loss of soluble minerals, leading to a significant decrease adsorption capacity of LPSB for Cd2+ by 13. 35%. Acidification aging process can affect the adsorptive activity of Cd2+ on the surface of the biochar, resulting in a reduction in adsorption capacity of APSB for Cd2+ by 26. 52%. All four types of biochar exhibite effective adsorption for Cd2+, the OPSB showing optimal affinity followed by PSB, LPSB, and APSB. The Langmuir isothermal adsorption model provides better fitting for describing the Cd2+ adsorption process by all four types of biochars under low pH conditions. Furthermore, the adsorptions processes by all four types of biochars are predominantly governed by physical electrostatic interactions, which is suitable to be described by quasi-first-order kinetic model. [ABSTRACT FROM AUTHOR]

Biochars derived from apple pomace (AP-BC) and industrial wastewater sludge (IS-BC) were used to investigate adsorption performance and mechanism for removing carbendazim from water and compare its performance with commercial biochar (commercial BC). The results showed that the adsorption capacity of AP-BC and IS-BC were 76 mg g−1 and 82 mg g−1 respectively that was comparable with the commercial BC (80 mg g−1). The adsorption kinetics and isotherms were best described by the Pseudo-second-order and Langmuir models. Thermodynamic analysis suggested that higher temperatures can enhance the mobility of molecules, increased mobility facilitates more frequent and stronger interactions between the adsorbate molecules and the surface of the adsorbent material, leading to greater adsorption capacity. Density functional theory (DFT) calculations confirmed carbendazim's weak electrophilic nature, supporting the primary physisorption mechanism. Even after five cycles of recycling, both biochars maintained a consistent carbendazim removal efficiency of around 82%, highlighting their high reusability. In this study, the examination of waste-derived biochar's economic feasibility revealed that using biochars derived from waste biomass for large-scale wastewater treatment applications is an economically viable choice. [ABSTRACT FROM AUTHOR]

The present study aims to develop a low-cost and sustainable composite material from solid waste to efficiently treat acid mine drainage (AMD). A modified reactor was used to produce the biochar-CaO composite from solid waste, which was characterized using XRD and SEM to determine the crystal structure, size, and surface morphology. The composite exhibited high adsorption capacity for AMD species, including Fe, Mn, and Mg metals, with an equilibrium point achieved at 300 min of contact time. The percent removal of AMD species varied with pH conditions, and the Langmuir isotherm model was found to describe the adsorption behavior of the composite adequately. The biochar-CaO composite showed a maximum adsorption capacity of 440 mg/g and held significant potential as an economical and efficient solution for AMD remediation. [ABSTRACT FROM AUTHOR]

Using peanut shells, a sustainable agricultural waste product, as its raw material, the acid group-modified biochar (AMBC) was prepared through phosphoric acid activation, partial carbonization, and concentrated sulfuric acid sulfonation for efficient removal of lead ion from aqueous solutions. Characterization techniques such as N2 isothermal adsorption–desorption, SEM, XRD, FT-IR, TG-DTA, and acid–base titration were utilized to fully understand the properties of the AMBC. It was found that there were high densities of acidic oxygen-containing functional groups (-SO3H, -COOH, Ph-OH) on the surface of the AMBC. The optimal adsorption performance of the AMBC for Pb(II) in water occurred when the initial concentration of Pb(II) was 100 mg/L, the pH was 5, the dosage of the adsorbent was 0.5 g/L, and the contact time was 120 min. Under the optimal conditions, the removal ratio of Pb(II) was 76.0%, with an adsorption capacity of 148.6 mg/g. This performance far surpassed that of its activated carbon precursor, which achieved a removal ratio of 39.7% and an adsorption capacity of 83.1 mg/g. The superior adsorption performance of AMBC can be caused by the high content of acidic oxygen-containing functional groups on its surface. These functional groups facilitate the strong binding between AMBC and Pb(II), enabling effective removal from water solutions. [ABSTRACT FROM AUTHOR]

Immobilized microbial technology has recently emerged as a prominent research focus for the remediation of heavy metal pollution because of its superior treatment efficiency, ease of operation, environmental friendliness, and cost-effectiveness. This study investigated the adsorption characteristics and mechanisms of Cd2+ solutions by Lactobacillus plantarum adsorbed immobilized on distiller's grains biochar (XIM) and Lactobacillus plantarum–encapsulated immobilized on distiller's grains biochar (BIM). The findings reveal that the maximum adsorption capacity and efficiency were achieved at a pH solution of 6.0. Specifically, at an adsorption equilibrium concentration of cadmium at 60 mg/L, XIM and BIM had adsorption capacities of 8.40 ± 0.30 mg/g and 12.23 ± 0.05 mg/g, respectively. BIM demonstrated noticeably greater adsorption capacities than XIM at various cadmium solution concentrations. A combination of isothermal adsorption modeling, kinetic modeling, scanning electron microscopy–energy dispersive X-ray spectroscopy, X-ray diffractometer (XRD), and Fourier-transform infrared spectroscopy (FTIR) analyses showed that cadmium adsorption by XIM primarily involved physical adsorption and pore retention. In contrast, the adsorption mechanism of BIM was mainly attributed to the formation of Cd(CN)2 crystals. [ABSTRACT FROM AUTHOR]

Currently, large amounts of agricultural solid wastes have caused serious environmental problems. Agricultural solid waste is made into biochar by pyrolysis, which is an effective means of its disposal. As the prepared biochar has a good adsorption capacity, it is often used to treat pollutants in water, such as heavy metals and pharmaceuticals. PRO is an emerging contaminant in the environment today. However, there are limited studies on the interaction between biochars with PRO. Thus, in this study, we investigate the adsorption of PRO onto the biochars derived from three different feedstocks. The order of adsorption capacity was corn stalk biochar (CS, 10.97 mg/g) > apple wood biochar (AW, 10.09 mg/g) > rice husk biochar (RH, 8.78 mg/g). When 2 < pH < 9, the adsorption capacity of all the biochars increased as the pH increased, while the adsorption decreased when pH > 9, 10 and 10.33 for AW, CS and RH, respectively. The adsorption of PRO on biochars was reduced with increasing Na+ and Ca2+ concentrations from 0 to 200 mg·L−1. The effects of pH and coexisting ions illustrated that there exist electrostatic interaction and cation exchange in the process. In addition, when HA concentration was less than 20 mg/L, it promoted the adsorption of PRO on the biochars; however, when the concentration was more than 20 mg/L, its promoting effect was weakened and gradually changed into an inhibitory effect. The adsorption isotherm data of PRO by biochars were best fitted with the Freundlich model, indicating that the adsorption process is heterogeneous adsorption. The adsorption kinetics were fitted well with the pseudo-second-order model. All the results can provide new information into the adsorption behavior of PRO and the biochars in the aquatic environment and a theoretical basis for the large-scale application of biochar from agricultural solid wastes. [ABSTRACT FROM AUTHOR]

Combining adsorption with photocatalysis is a strategy to utilize renewable sunlight as for adsorbents regeneration. Herein, a three-dimensional biochar aerogels (CA) was prepared by hydrothermal method using glucose as raw material, and a semiconductor photocatalyst Bi2WO6 (BWO) was loaded on its surface to construct a composite adsorbent CA/BWO. The results showed that when the bed height of the CA/BWO was 6 cm and the flow rate was 1 mL/min, the adsorption efficiency of 10 mg/L phenol (PE) reached 80%. The removal of PE by CA/BWO reached 80% in all five regeneration processes, while CA almost lost its adsorption capacity after three regenerations, indicating the excellent regeneration ability and stability of CA/BWO. It was found that the PE adsorption on CA/BWO conformed to the Langmuir isotherm model and quasi-second-order adsorption kinetics, indicating the adsorption belonged to monolayer chemisorption. Moreover, the presence of natural organic compounds (HA and FA) promoted the adsorption of PE by CA/BWO, which was due to the partial active sites provided by organic compounds adsorbed on CA/BWO. Finally, the penetration test results showed that the synthesized composites have good reusability. These showed that CA/BWO has great potential application value. [ABSTRACT FROM AUTHOR]

Composites are synthesized by combining different materials, resulting in properties suitable for use as adsorbents due to the combination of pores and functional groups within the constituent materials. This study developed a silicabiochar composite to serve as an adsorbent for rhodamine B dye, utilizing silica derived from red mud and biochar obtained from oil palm empty fruit bunches (OPEFB). This research focused on analyzing the characteristics and effectiveness of the composite as an adsorbent by varying its composition. Silica from red mud exhibited a purity of 80.05% and possessed silanol (Si-OH) and siloxane (Si-OSi) functional groups on its surface, whereas biochar from OPEFB had a carbon content of 95.91% and included functional groups such as -OH, C=O, C=C, C-H, and C-O. The combination of silica and biochar yielded a composite surface consisting of -OH, C=O, C=C, C-O, C-H, and Si-O-Si functional groups. The silica-biochar composite demonstrated a greater surface area than its individual components, with silica at 69.824 m²/g and biochar at 95.452 m²/g. The composite with a 1:2 (% w/w) ratio exhibited the largest surface area at 102.371 m²/g, achieving a maximum adsorption capacity of 1.550 mg/g and an efficiency of 88.463%. The adsorption process encompasses physical interactions via pore diffusion and chemical interactions through functional groups. [ABSTRACT FROM AUTHOR]

The emerging pollutant octocrylene is not efficiently removed from effluents by conventional treatment and is recurrently found in rivers. This study evaluated the adsorption of octocrylene using commercial carbon and biochar from spent coffee grounds activated with ZnCl2. The two adsorbents had an efficiency of approximately 100% in pollutant removal throughout the experimental design. The kinetics and equilibrium isotherms showed a good correlation with the experimental data. The kinetics showed adsorption of the contaminant in 40 min for both adsorbents. The model equilibrium isotherms with the best fit and adsorption capacity was Langmuir for biochar, with a capacity of 37.822 ± 0.005 µg∙mg−1 compared to 33.602 ± 0.202 µg∙mg−1 for commercial carbon. Furthermore, a toxicity analysis of a 600 µg∙L−1 octocrylene solution was carried out before and after adsorption with the two charcoals separately, using Allium cepa roots. Before adsorption, the solution was phytotoxic and cytogenotoxic. After adsorption, the solution obtained for each charcoal no longer caused toxicity to the roots. The charcoals tested had high removal efficiency and adsorption capacity, a condition reiterated by the toxicity results. However, biochar better represented the Langmuir model in the adsorption process when removing octocrylene from the aqueous medium. [ABSTRACT FROM AUTHOR]

Sorption is the most important process influencing the amount of herbicide retained in soils. The special properties of biochar could influence the soil retention of pollutants through adsorption. However, the detailed sorption mechanisms as influenced before and after applying biochar to soils with different properties are unclear. This study examined the sorption characteristics of metolachlor using soil samples collected from South China. Sorption experiments were conducted using a batch equilibration method. After comparing the metolachlor sorption constants observed for all soil samples, our results showed that the application of biochar significantly increased the capacity of metolachlor adsorption. Without biochar, sorption capacity (Kf) was positively related to soil organic matter and to a soil particle size of 0.002–0.02 mm in soils developed from granite, of 0.002–0.02 mm in soils developed from delta shockwaves, and of 0.002–0.02 mm, together with complex iron oxide and total iron content, in soils developed from arenaceous shale. Moreover, sorption capacity (Kf) with biochar was positively related to peroxidase in soils developed from granite and to dissociative iron oxide and total iron content in soils developed from arenaceous shale. Our results show that biochar greatly affects metolachlor sorption behavior, probably because of qualitative differences in the structural characteristics of soils with different developmental parent materials and properties. [ABSTRACT FROM AUTHOR]

The composite material SBC-Fe-x with sludge and Fe3+ was developed by different calcination temperatures (600, 700, and 800 °C) for the removal of tetracycline (TC). The adsorption rates of SBC-Fe-600, SBC-Fe-700, and SBC-Fe-800 were 77.5%, 89%, and 91%, respectively. Furthermore, the Langmuir model indicated that the maximum adsorption capacity of SBC-Fe-700 (157.93 mg/g) was three times greater than that of SBC-Fe-600. The conclusions were confirmed by a series of characterizations that SBC-Fe-700 showed a larger specific surface area, well-developed pore structure, rich oxygen-containing functional groups and a high degree of graphitization. The results of pH experiments indicated the broad applicability of SBC-Fe-700 for TC adsorption. In addition, SBC-Fe-700 suggested outstanding performance in different water environments. This work produced a feasible adsorbent for the removal of TC, and a new direction for sludge resource utilization was proposed. [ABSTRACT FROM AUTHOR]

The present study assessed the effective use of biochar for the adsorption of two potent HAB toxins namely, Microcystin-LR (MCLR) and Saxitoxin (STX) through a combination of dosage, kinetic, equilibrium, initial pH, and competitive adsorption experiments. The adsorption results suggest that biochar has excellent capabilities for removing MCLR and STX, with STX reporting higher adsorption capacities (622.53–3507.46 µg/g). STX removal required a minimal dosage of 0.02 g/L, while MCLR removal needed 0.4 g/L for > 90%. Similarly, a shorter contact time was required for STX removal compared to MCLR for > 90% of toxin removed from water. Initial pH study revealed that for MCLR acidic conditions favored higher uptake while STX favored basic conditions. Kinetic studies revealed that the Elovich model to be most suitable for both toxins, while STX also showed suitable fittings for Pseudo-First Order and Pseudo-Second Order in individual toxin systems. Similarly, for the Elovich model the most suited kinetic model for both toxins in presence of each other. Isotherm studies confirmed the Langmuir–Freundlich model as the best fit for both toxins. These results suggest adsorption mechanisms including pore filling, hydrogen bonding, π–π interactions, hydrophobic interactions, electrostatic attraction, and dispersive interactions. [ABSTRACT FROM AUTHOR]

In the printing and textile industries, methylene blue (a cationic azo dye) is commonly used. MB is a well-known carcinogen, and another major issue is its high content in industrial discharge. There are numerous removal methodologies that have been employed to remove it from industrial discharge; however, these current modalities have one or more limitations. In this research, a novel magnetized biochar (γ-Fe2O3-LSB) was synthesized using Lagenaria siceraria peels which were further magnetized via the co-precipitation method. The synthesized γ-Fe2O3-LSB was characterized using FTIR, X-ray diffraction, Raman, SEM–EDX, BET, and vibrating sample magnetometry (VSM) for the analysis of magnetic properties. γ-Fe2O3-LSB showed a reversible type IV isotherm, which is a primary characteristic of mesoporous materials. γ-Fe2O3-LSB had a specific surface area (SBET = 135.30 m2/g) which is greater than that of LSB (SBET = 11.54 m2/g). γ-Fe2O3-LSB exhibits a saturation magnetization value (Ms) of 3.72 emu/g which shows its superparamagnetic nature. The batch adsorption process was performed to analyze the adsorptive removal of MB dye using γ-Fe2O3-LSB. The adsorption efficiency of γ-Fe2O3-LSB for MB was analyzed by varying parameters like the initial concentration of adsorbate (MB), γ-Fe2O3-LSB dose, pH effect, contact time, and temperature. Adsorption isotherm, kinetic, and thermodynamics were also studied after optimizing the protocol. The non-linear Langmuir model fitted the best to explain the adsorption isotherm mechanism and resulting adsorption capacity ( q e =54.55 mg/g). The thermodynamics study showed the spontaneous and endothermic nature, and pseudo-second-order rate kinetics was followed during the adsorption process. Regeneration study showed that γ-Fe2O3-LSB can be used up to four cycles. In laboratory setup, the cost of γ-Fe2O3-LSB synthesis comes out to be 162.75 INR/kg which is low as compared to commercially available adsorbents. The results obtained suggest that magnetic Lagenaria siceraria biochar, which is economical and efficient, can be used as a potential biochar material for industrial applications in the treatment of wastewater. [ABSTRACT FROM AUTHOR]

The treatment of produced water (formation water) still represents one of the greatest challenges in the petroleum industry. Among the various pollutants found in produced water, phenol is of particular concern, due to its high toxicity. The aim of this work was to synthesize a Eucalyptus saligna sawdust biochar activated with NiCl2, followed by evaluation of its capacity for the adsorption of phenol. The results confirmed that the chemically activated adsorbent showed higher phenol removal efficiency compared to a non-activated one, possibly due to the interactions involving new and/or intensified functional groups. The adsorbents were characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), Brunauer–Emmett–Teller (BET), and Barrett, Joyner, and Halenda (BJH). Excellent adsorption capacity of the NiCl2-activated biochar was achieved at different pH (2 to 9) of the phenolic solution, with the ideal dosage being 1 g L−1. The adsorption kinetics could be fitted using the Elovich model, indicating that the adsorbent surface was heterogeneous. The adsorption isotherms indicated that multiple layers of the adsorbent were involved in phenol removal, in agreement with the Redlich-Peterson model with βRP trending toward 0. The maximum adsorption capacity of the NiCl2-activated biochar was 76.65 mg g−1. Thermodynamic evaluation indicated that the adsorption was exothermic and physical. Additionally, study of the effect of ionic strength conducted with NaCl, showed no substantial changes for phenol adsorption. Finally, thermal treatment in an inert atmosphere (pyrolysis) enabled effective desorption, with regeneration efficiency maintained at around 70% after three cycles. [ABSTRACT FROM AUTHOR]

One-step carbonization was explored to prepare biochar using the residue of a traditional Chinese herbal medicine, Atropa belladonna L. (ABL), as the raw material. The resulting biochar, known as ABLB4, was evaluated for its potential as a sustainable material for norfloxacin (NOR) adsorption in water. Subsequently, a comprehensive analysis of adsorption isotherms, kinetics, and thermodynamics was conducted through batch adsorption experiments. The maximum calculated NOR adsorption capacity was 252.0 mg/g at 298 K, and the spontaneous and exothermic adsorption of NOR on ABLB4 could be better suited to a pseudo-first-order kinetic model and Langmuir model. The adsorption process observed is influenced by pore diffusion, π–π interaction, electrostatic interaction, and hydrogen bonding between ABLB4 and NOR molecules. Moreover, the utilization of response surface modeling (RSM) facilitated the optimization of the removal efficiency of NOR, yielding a maximum removal rate of 97.4% at a temperature of 304.8 K, an initial concentration of 67.1 mg/L, and a pH of 7.4. Furthermore, the biochar demonstrated favorable economic advantages, with a payback of 852.5 USD/t. More importantly, even after undergoing five cycles, ABLB4 exhibited a consistently high NOR removal rate, indicating its significant potential for application in NOR adsorption. [ABSTRACT FROM AUTHOR]

Using Euryale ferox husk as raw material, pristine biochar (EBC), Bi2MoO6-modified biochar (BM-EBC), and BiFeO3-modified biochar (BF-EBC) were prepared and employed for decontaminating Congo red (CR) from wastewater. Compared with EBC (217.59 mg/g) and BF-EBC (359.49 mg/g), a superior adsorption capacity of 460.77 mg/g was achieved by BM-EBC. Based on the evaluation results of the Freundlich and pseudo-second-order models, multilayer chemisorption was suggested as the adsorption mechanism. The adsorption process of BM-EBC was spontaneous and endothermic, and the rate-limiting step pertained to liquid film diffusion and intraparticle diffusion. The underlying removal mechanism was explored via SEM, BET, FTIR, XPS, Raman spectra, and Zeta potential analyses. The introduction of bismuth oxymetallates with their high number of M–O (M: Bi, Mo, Fe) structural elements provided the adsorbent with enlarged surface areas and reinforced oxygen functional groups, thereby promoting pore filling, π-π interactions, hydrogen bonding, and complexation, leading to enhanced adsorption capacity. These results demonstrate that Euryale ferox husk biochar modified by bismuth oxymetallates has high prospects for valorizing biomass waste and removing CR from wastewater. [ABSTRACT FROM AUTHOR]

The production of sludge-based biochar to recover phosphorus (P) from wastewater and reuse the recovered phosphorus as agricultural fertilizer is a preferred process. This article mainly studied the removal of phosphate (PO4-P) from aqueous solution by synthesizing sludge-based biochar (MgSBC-0.1) from anaerobic fermentation sludge treated with magnesium (Mg)-loading-modification, and compared it with unmodified sludge-based biochar (SBC). The physicochemical properties, adsorption efficiency, and adsorption mechanism of MgSBC-0.1 were studied. The results showed that the surface area of MgSBC-0.1 synthesized increased by 5.57 times. The material surface contained MgO, Mg(OH)2, and CaO nanoparticles. MgSBC-0.1 can effectively remove phosphate in the initial solution pH range of 3.00–7.00, with a fitted maximum phosphorus adsorption capacity of 379.52 mg·g-1. The adsorption conforms to the pseudo second-order kinetics model and Langmuir isotherm adsorption curve. The characterization of the adsorbed composite material revealed the contribution of phosphorus crystal deposition and electrostatic attraction to phosphorus absorption. [ABSTRACT FROM AUTHOR]

Biochars have received much attention as efficient adsorbents for water pollutants. Besides, the chemical treatment of biochars performed to increase the adsorption capacity usually causes secondary chemical pollution and increases the cost of the process. The biomass feedstock utilised in biochar preparation impacts significantly the surface properties and adsorption capacity. Thus, the need to prepare new biochars from new feedstock with potentially high uptake capacities. Herein, we prepared new biochar (POBC) from Platanus occidentalis waste leaves (POL), which was utilised for the ultrasonic-aided adsorption of bromophenol blue (BRB) and thiazolyl blue tetrazolium bromide (TTB). The FTIR, SEM, EDX, TGA, BET, pHpzc, and elemental characterisations of POBC revealed potent surface characteristics desirable for efficient dye adsorption. An increase in the surface area from 14.31 m2/g to 31.94 m2/g and the pore volume from 0.0214 cm3/g to 0.0326 cm3/g was obtained after the conversion of the POL to POBC. Besides, the SEM images of POBC revealed a highly porous surface structure of the adsorbent. The Freundlich and pseudo-second-order model presented the best fit to the isotherm and kinetics based on the high coefficient of determination (R2 > 0.9) and low sum square errors (SSE < 0.31). The heterogeneous surface nature of POBC was inferred from the independent-oriented site model. The monolayer adsorption capacity of 45.03 mg/g and 48.8 mg/g were obtained for BRB and TTB, respectively. Thermodynamics showed an endothermic, feasible, and random uptake, and POBC displayed efficient potentials to be reused. The obtained results revealed that novel POBC is an efficient low-cost biochar with high adsorption capacity for dyes. [ABSTRACT FROM AUTHOR]

To enhance the adsorption performance of municipal sludge biochar on Cd(II), modified sludge biochar was prepared by sodium hydroxide/magnesium chloride (NaOH/MgCl2) graded activation, and the Cd(II) adsorption performance on sludge biochar (BC), NaOH-activated sludge biochar (NBC) and NaOH/MgCl2 activated sludge biochar (NBC-Mg) was investigated. The results showed that NaOH/MgCl2 graded activation upgraded the surface structure and enhanced the graphitization of sludge biochar. The adsorption experiments indicated that the adsorption kinetic and adsorption isotherm for Cd(II) were in accordance with the pseudo second-order kinetic and Langmuir model. The adsorption capacity of NBC-Mg (143.49 mg/g) for Cd(II) was higher than that of BC (50.40 mg/g) and NBC (85.20 mg/g). The mechanism of Cd(II) adsorption included ion exchange, complexation, cation-π interaction, and mineral precipitation. After five regeneration, the removal efficiency of Cd(II) by NBC-Mg remained above 90%. This work indicated that sludge biochar prepared by multistage activation could be an effective material for Cd-containing wastewater treatment. [ABSTRACT FROM AUTHOR]

The accumulation of non-biomass wastes, including anthracite, asphalt/asphaltene, synthetic polymers, petroleum coke, and tire wastes, contributes to environmental pollution. Utilizing these waste resources as precursors for activated carbon production emerges as an economical and sustainable strategy for energy storage and environmental remediation. This review (explicitly from 2010 to 31 December 2022) comprehensively explores recent advancements in employing these waste materials for activated carbon synthesis. The study highlighted textural characteristics such as surface chemistry, surface area, microstructures, and mesostructures and their impact on the functionality of activated carbon. Examining various precursors, asphalt-based activated carbons exhibited superior mean specific surface area (2715.73 m2g─1) and pore volume (1.6078 cm3g─1), surpassing other reported sources. Anthracite-based activated carbon stood out with a specific capacitance of 433 Fg─1, demonstrating excellent energy storage potential. In wastewater treatment, asphalt-based activated carbons display a remarkable qmax of 1113 mgg─1, while waste tire-based activated carbon exhibited a strong gaseous compound removal capacity of 475 mgg─1. Despite widespread application in wastewater treatment, the investigation notes a gap in utilizing these activated carbons for energy storage. The activated carbon derived from these non-biomass sources emerges as a promising material with commendable properties in volume and pore sizes, surface area, surface behavior, and functional groups. The review guides researchers toward an economical approach for producing non-biomass-derived activated carbons with exceptional physicochemical characteristics and adsorption capacity. It concludes by critically evaluating current knowledge gaps, synthesizing challenges, and offering recommendations for future research endeavors. [ABSTRACT FROM AUTHOR]

In the last decade, there has been increasing scrutiny of using biochar to remove pollutants from the waste water. However, due to particle size of biochar and the difficulty of its separation after the adsorption process, the use of these adsorbents has always been a challenge, until magnetic biochar (MB) was proposed by researchers. The production of MB is divided into pre-pyrolysis and post- pyrolysis methods. The MB activation/modification methods included physical and chemical activation/ammonization, sulfurization, oxidation, polymerization and MB production without modification/activation was investigated. In this research, studies that produced MB as a one-step heating and post-pyrolysis method reviewed. The results showed that the capacity of different MB to remove lead, cadmium, chromium, copper, and arsenic was calculated to be 96.9, 91.2, 90.5, 97.6 and 55.42%, respectively. In these studies, the weight ratio of the magnetic fraction to biochar, temperature, and carbonization time were 1.2 (g/g), 575 °C, and 130 min, respectively. During the absorption process, the adsorption capacity of magnetic biochar increased and then reached a constant value. Therefore, the magnetic biochar has good ability to hold the adsorbed pollutants to the end of process. Also, as the initial pollutant concentration increased, the adsorption capacity unexpectedly increased and eventually reached its maximum, indicating a high affinity of the magnetic biochar with the pollutants. [ABSTRACT FROM AUTHOR]

The present study reports the effective removal of benzene in aqueous phase onto biochar. The adsorption capacity of benzene onto biochars made at different pyrolytic temperatures (e.g., 350, 550, and 750 °C) and from various feedstocks (e.g., grape pomace, rice husk, and Kentucky bluegrass) were investigated. The adsorption capacity of Kentucky bluegrass-derived biochar (KB-BC) prepared at 550 °C for benzene was better than other biochars, owing to the higher surface area and functional groups. The adsorption isotherms and kinetics model for benzene by KB-BC550 fitted the Freundlich and pseudo-first order, respectively. In addition, the results of response surface methodology (RSM) designed with biochar dose, reaction time, and benzene concentration showed the maximum adsorption capacity (ca. 136 mg BZ/g BC) similar to that from kinetic study. KB-BCs obtained as waste grass biomass may be a valuable adsorbent, and RSM may be a useful tool for the investigation of optimal conditions and results. [ABSTRACT FROM AUTHOR]

BACKGROUND: In this study, a defective biochar with honeycomb‐like porous structure (BC‐PH) was successfully prepared by the activation of pristine biochar derived from bamboo shoot shell with the chemical reagent KOH, and was applied to selectively separate ReO4− (a chemical analogue for radioactive TcO4−) from acidic solutions. RESULTS: The diffusion, mass transfer and recovery for ReO4− could be significantly improved by the large specific surface area (SBET, 2412 m2 g−1) and high total volume (Vtot, 1.26 cm3 g−1) of BC‐PH. The influence of adsorbent dosage, system pH and coexisting ions with different valence states on the adsorption capability and selectivity of BC‐PH toward ReO4− was systematically investigated. BC‐PH exhibited high adsorption capacity and selectivity for ReO4− with a maximal sorption capacity (qm) of 73.11 mg g−1 at initial pH 2. By applying an analysis of kinetics and isotherm adsorption studies, the liquid film diffusion was verified to be the primary rate‐controlling step for the sorption of ReO4− and the multilayer adsorption process occurred on the heterogeneous surface of BC‐PH. Besides, the recovery of ReO4− using BC‐PH occurred in an exothermic and spontaneous manner according to thermodynamic analysis. Furthermore, an investigation of the adsorption mechanism suggested that pore filling and electron donor–acceptor interaction were mainly related to the removal of ReO4−. CONCLUSION: These results suggest that BC‐PH has great potential for the application of TcO4− separation in consideration of its high adsorption capacity and selectivity. © 2024 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

In order to treat phosphorus-containing wastewater and realize the resource utilization of wetland plant residues, biochar was prepared by the pyrolysis of canna aquatic plant waste at 700 °C, and the adsorption characteristics of phosphorus by MgO-modified biochar (MBC) were explored. The main results are as follows: the adsorption capacity of the MBC was eight times that of unmodified biochar (BC), and the adsorption capacity was up to 244 mg/g. The isothermal adsorption data were consistent with the Langmuir equation, which indicates monolayer adsorption. The functional groups changed little before and after the modification, but a new diffraction peak appeared after the modification. Compared with the standard card, it was suggested that there were MgO crystals with a higher purity. SEM images showed that the BC had a smooth surface, an obvious pore structure, and a thin pore wall, while the MBC had a rough surface and a layered structure, which can provide more adsorption sites for phosphate adsorption. In addition, an XPS analysis showed that Mg3(PO4)2 crystals appeared on the surface of the MBC after adsorption. The mechanism analysis showed that MgO is an important substance for MBC to adsorb phosphorus, and electrostatic adsorption and complex precipitation play key roles. In the test to verify the removal of actual phosphorus-containing wastewater by MBC, it was found that the removal rates for wastewater with 2.06 mg/L and 199.8 mg/L of phosphorus by MBC were as high as 93.4–93.9% and 99.2–99.3%, respectively. MBC can be used as an efficient adsorbent for phosphorus removal. [ABSTRACT FROM AUTHOR]

In this work, the adsorption of nickel ions from a real effluent from a metal-mechanic industry was investigated in a fixed-bed column using biochar. Biochar was prepared from winemaking residues originating from the Beifiur® composting process. The use of wine industry residues as precursor materials for biochar production is established in biomass residue valorization using the existing logistics and the lowest possible number of manipulations and pre-treatments. The results found in the work showed that the optimal conditions for nickel adsorption in fixed-bed columns were bed height (Z) of 7 cm, initial nickel concentration (C0) of 1.5 mg L−1, and flow rate (Q) of 18 mL min−1. In this condition, the maximum adsorption capacity of the column was 0.452 mg g−1, the mass transfer zone (Zm) was 3.3 cm, the treated effluent volume (Veff) was 9.72 L, and the nickel removal (R) was 92.71%. The Yoon-Nelson and BDST dynamic models were suitable to represent the breakthrough curves of nickel adsorption. Finally, the fixed-bed column adsorption using biochar from winemaking residues proved to be a promising alternative for nickel removal from real industrial effluents. [ABSTRACT FROM AUTHOR]

In this study, an experimental strategy to obtain biochar and activated carbon from torrefied palm kernel shell as an efficient material for CO2 removal was evaluated. Biochar was obtained by slow pyrolysis of palm kernel shell at different temperatures (350 °C, 550 °C, and 700 °C) and previously torrefied palm kernel shell at different temperatures (220 °C, 250 °C, and 280 °C). Subsequently, activated carbons were prepared by physical activation with CO2 from previously obtained biochar samples. The CO2 adsorption capacity was measured using TGA. The experimental results showed that there is a correlation between the change in the O/C and H/C ratios and the functional groups –OH and C=O observed via FTIR in the obtained char, indicating that both dehydration and deoxygenation reactions occur during torrefaction; this favors the deoxygenation reactions and makes them faster through CO2 liberation during the pyrolysis process. The microporous surface area shows a significant increase with higher pyrolysis temperatures, as a product of the continuous carbonization reactions, allowing more active sites for CO2 removal. Pyrolysis temperature is a key factor in CO2 adsorption capacity, leading to a CO2 adsorption capacity of up to 75 mg/gCO2 for biochar obtained at 700 °C from non-torrefied palm kernel shell (Char700). Activated carbon obtained from torrefied palm kernel shell at 280 °C (T280-CHAR700-AC) exhibited the highest CO2 adsorption capacity (101.9 mg/gCO2). Oxygen-containing functional groups have a direct impact on CO2 adsorption performance due to electron interactions between CO2 and these functional groups. These findings could provide a new experimental approach for obtaining optimal adsorbent materials exclusively derived from thermochemical conversion processes. [ABSTRACT FROM AUTHOR]

Excess existence of ammonium in water bodies is a hazard to aquatic health. Recent studies demonstrated the use of pig manure biochar (PBC) as a potential adsorbent for ammonium removal. This study investigates alteration in the adsorption capability of modified PBCs to ammonium. Modifications were done by immersing PBC in different acid/alkaline mediums such as H2SO4 HCl, NaOH, KOH, and FeSO4. Adsorption kinetics of modified PBC to ammonium was studied and compared. Also, physical characteristics of these modified biochars were analyzed using BET, SEM, XRD, and FTIR to explore the ammonium adsorption mechanism. The adsorption capacity of ammonia nitrogen was improved for PBCKOH and PBCHCl, whereas it was found to decrease for other modified biochars. The improvement is likely due to an increase in specific surface area and pore size as well as formation of active functional groups and ions during the modification process. While both pseudo-first-order kinetics (R2 > 0. 9) and pseudo-second-order (R2 > 0.9) kinetics could fit the adsorption kinetic data well, among modified biochars, PBCFeSO4 and PBCH2S04 fit better with pseudo-first-order model, while others fit pseudo-second-order model better. Both Langmuir and Freundlich model were in good agreement with the adsorption isotherm data for raw and modified biochars (R2 > 0.9). Variation in the adsorption capacity of ammonia nitrogen by different modified PBC might be due to synthesis of both physical and chemical factors. This study will lay a theoretical foundation for the future exploration of modification treatments of pig manure biochar for adsorption of ammonia nitrogen from wastewater. [ABSTRACT FROM AUTHOR]

To boost the adsorption‐photocatalytic performances of biochar in wastewater treatment, biochar was modified with ternary metal oxides ZnO, Sm2O3, and MgO (ZnSm/Mg‐biochar) via the one‐step pyrolysis method. The optimal 2b‐ZnSm/Mg‐biochar with a Zn/Sm molar ratio of 1:1 exhibited the better removal activity of RhB in comparison with biochar, 2‐Mg/biochar, and b‐ZnSm/biochar. The removal efficiency and adsorption capacity of 2b‐ZnSm/Mg‐biochar was 99.46% and 979.22 mg g−1 for RhB solution of 410 mg g−1, respectively. The adsorption kinetics and isotherms of ZnSm/Mg‐biochar composites were as described by second‐order and Langmuir models, respectively. The abundant vacant sites at the junction interface of ZnO, Sm2O3, MgO, and biochar were favorable for the adsorption and photon capturing, achieving the efficient photo‐conversion of RhB under the stimulated solar‐light irradiation. [ABSTRACT FROM AUTHOR]

Diesel oil contamination is a threat to environment and human health. Many technologies have been developed to address this issue; however, they are costly to be deployed in real-world oil remediation. Adsorption remains to be one of the most economical methods to remove oil from water. Here, we used banana peel biochar (BPBC) immobilized in teabags as an adsorbent for the removal of diesel oil in water. We investigated the adsorption behavior of BPBC under different conditions, examining the influence of adsorbent loading, pH, salinity, and contact time on its efficiency for removing diesel oil in water. Our results show that the sorption capacity of BPBC is significantly affected by the amount of adsorbent used. Lower biochar loadings enhance the sorption capacity due to greater surface area accessibility, while higher loadings lead to decreased efficiency due to pore blockage and reduced surface exposure. Interestingly, the pH of the solution was found to have minimal impact on the sorption process. This is attributed to diesel oil's hydrophobic and non-polar nature, which leads to its interaction with BPBC being predominantly governed by hydrophobic forces instead of pH-sensitive electrostatic interactions. Salinity emerged as a crucial factor in the adsorption process. An increase in salinity enhances the sorption capacity, likely due to the "salting-out" effect, where higher salt concentrations decrease the solubility of diesel oil, promoting its adsorption onto the biochar surface. Furthermore, the study highlights the importance of contact time, with longer exposure resulting in increased sorption capacity. This trend is explained by the adsorption kinetics, initially characterized by rapid adsorption, followed by a slower, progressive occupation of the biochar's adsorption sites. The kinetic analysis of the process suggests that the pseudo-second-order model is more suitable, indicating a chemisorption mechanism. The Harkins–Jura isotherm model was identified as the best fit for explaining the isotherm behavior, owing to its capacity to account for the heterogeneous nature of the biochar surface and the formation of multiple adsorbate layers. The optimum conditions for maximum diesel oil removal are as follows: BPBC loading of 0.50 g, a solution pH of 5.00, a salinity concentration of 12,656.57 mg/L, and a contact time of 240 min. Under these conditions, BPBC exhibited an adsorption capacity of 19.04 g/g. In summary, our research establishes BPBC, particularly when contained within teabags, as an efficient and practical adsorbent for diesel oil removal in water. Its effectiveness, superior to other biochar, is mainly due to its porosity and hydrophobic properties. These findings not only enhance our understanding of BPBC's adsorption capabilities but also underscore its potential for environmental remediation. • Different environmental conditions affect the sorption capacity of banana peel biochar (BPBC) in teabags for diesel oil removal from water: adsorbent loading, pH, salinity, and contact time. • The solution environmental conditions were optimized to achieve maximum oil adsorption efficiency. • Diesel oil adsorption on biochar follows the pseudo-second-order kinetic model and the Harkins-Jura isotherm model. [ABSTRACT FROM AUTHOR]

The study assessed the influence of pyrolysis temperature on the properties of hickory sawdust and peanut shells based biochar, particularly its pore structure, surface functional groups, and adsorption capacity. Results from SEM analysis demonstrated that higher pyrolysis temperatures led to an enhanced pore structure and surface roughness in biochars, providing increased adsorption capacity. Raman spectrum analysis revealed higher levels of disorder and graphitization in biochars pyrolyzed at elevated temperatures. Quantification of surface functional groups using the Boehm method indicated a shift in the abundance of basic and acidic groups under high pyrolysis conditions. Employing the FHH model, fractal characteristics were observed in the pore structure of different biochars, with high-temperature biochars displaying increased disorder. The study also explored the mechanism of SMX adsorption onto biochars, revealing higher adsorption capacity for biochars with richer pore structures and rougher surfaces. The Elovich model proved to be the best fit for describing the chemisorption process of SMX onto the biochars. Moreover, the study demonstrated the impact of urine ions on SMX adsorption onto the biochars. These findings provide valuable insights into the properties and potential applications of biochars in environmental remediation. [ABSTRACT FROM AUTHOR]

Moringa oleifera seeds, in particular, have been used for water and wastewater treatment due to their ability to remove many pollutants. Therefore, the present work aims to produce bioadsorbent materials by pyrolysis using biomass from the seed shell of Moringa oleifera to remove the drug Metronidazole present in an aqueous medium. The biochars produced were activated with phosphoric acid (H3PO4) and potassium hydroxide (KOH) to compare the material's modifications and adsorption mechanisms with the biochar in nature (BCM). The biochars were characterized by Point-of-zero charges (pHpzc), Scanning Electron Microscopy (SEM), X-ray Diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. The studies showed that the adsorption behavior varied with the pH of the solution. The adsorption study verified that the activated biochars presented better results, so in the kinetic study, the adsorption behavior occurred rapidly in the initial minutes until stabilizing within 3–4 h, better fitting the Elovich model. Isotherm models were tested, where the experimental data were adjusted to the Sips model, with an adsorption capacity of 18 mg g−1 for acid-activated biochar (BCH3PO4) and KOH-activated biochar (BCKOH) with 366.49 mg g−1. The results showed that biochars, especially BCKOH, become viable for production because they are a low-cost material and highly effective in removing drugs. [ABSTRACT FROM AUTHOR]

Biochar, a carbon-dense material known for its substantial specific surface area, remarkable porosity, diversity of functional groups, and cost-effective production, has garnered widespread acclaim as a premier adsorbent for the elimination of heavy metal ions and organic contaminants. Nevertheless, the application of powdered biochar is hindered by the challenges associated with its separation from aqueous solutions, and without appropriate management, it risks becoming hazardous waste. To facilitate its use as an immobilization medium, biochar necessitates modification. In this investigation, sodium alginate, celebrated for its superior gelation capabilities, was amalgamated with polyvinyl alcohol to bolster mechanical robustness, thereby embedding biochar to formulate sodium alginate biochar microspheres (PVA/SA-FMB). A meticulously designed response surface methodology experiment was employed to ascertain the optimal synthesis conditions for PVA/SA-FMB. Characterization outcomes unveiled a highly developed surface abundant in functional groups and confirmed the successful incorporation of iron ions. Adsorption trials revealed that at a temperature of 25 °C and a pH of 2, the adsorption capacity of PVA/SA-FMB for Cr(VI) was 13.7 mg/g within the initial 30 min, reaching an equilibrium capacity of 26.03 mg/g after 1440 min. Notably, the material sustained a Cr(VI) removal efficiency exceeding 90% across five cycles, underscoring its rapid and effective Cr(VI) eradication performance. Kinetic and isothermal adsorption analyses suggested that the adsorption of Cr(VI) adheres to a pseudo-second-order kinetic model and the Freundlich isotherm, indicative of monolayer adsorption dominated by reaction mechanisms. X-ray photoelectron spectroscopy (XPS) analysis inferred that the adsorption mechanism predominantly encompasses electrostatic attraction, redox processes, and complex formation. [ABSTRACT FROM AUTHOR]

The resource utilization of agricultural and forestry waste, especially the high-value transformation of low-grade phosphate rock and derivatives, is an important way to achieve sustainable development. This study focuses on the impregnation and co-pyrolysis of rice straw (RS) with fused calcium magnesium phosphate (FMP), FMP modified with citric acid (CA-FMP), and calcium dihydrogen phosphate (MCP) to produce three phosphorous-enriched biochars (PBC). The Cd(II) removal efficiency of biochars before and after phosphorus modification was investigated, along with the adsorption mechanism and contribution of biochars modified with different phosphorus sources to Cd(II) adsorption. The result indicated that CA-FMP and MCP could be more uniformly loaded onto biochar, effectively increasing the specific surface area (SSA) and total pore volume. The adsorption of Cd(II) onto PBC followed a mono-layer chemisorption process accompanied by intraparticle diffusion. The adsorption of Cd(II) by PBC involved ion exchange, mineral precipitation, complexation with oxygen-containing functional groups (OFGs), cation-π interaction, electrostatic interaction, and physical adsorption. Ion exchange was identified as the primary adsorption mechanism for Cd(II) by BC and FBC (51.53% and 53.15% respectively), while mineral precipitation played a major role in the adsorption of Cd(II) by CBC and MBC (51.10% and 47.98% respectively). Moreover, CBC and MBC significantly enhanced the adsorption capacity of Cd(II), with maximum adsorption amounts of 128.1 and 111.5 mg g−1 respectively. [ABSTRACT FROM AUTHOR]

Climate change caused by the greenhouse gases CO2 remains a topic of global concern. To mitigate the excessive levels of anthrophonic CO2 in the atmosphere, CO2 capture methods have been developed and among these, adsorption is an especially promising method. This paper presents a series of amine functionalized biochar obtained from desiccated coconut waste (amine-biochar@DCW) for use as CO2 adsorbent. They are ethylenediamine-functionalized biochar@DCW (EDA-biochar@DCW), diethylenetriamine-functionalized biochar@DCW (DETA-biochar@DCW), triethylenetetramine-functionalized biochar@DCW (TETA-biochar@DCW), tetraethylenepentamine-functionalized biochar@DCW (TEPA-biochar@DCW), and pentaethylenehexamine-functionalized biochar@DCW (PEHA-biochar@DCW). The adsorbents were obtained through amine functionalization of biochar and they are characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, Brunauer–Emmett–Teller (BET), and thermogravimetric analysis (TGA). The CO2 adsorption study was conducted isothermally and using a thermogravimetric analyzer. From the results of the characterization analyses, a series of amine-biochar@DCW adsorbents had larger specific surface area in the range of 16.2 m2/g–37.1 m2/g as compare to surface area of pristine DCW (1.34 m2/g). Furthermore, the results showed an increase in C and N contents as well as the appearance of NH stretching, NH bending, CN stretching, and CN bending, suggesting the presence of amine on the surface of biochar@DCW. The CO2 adsorption experiment shows that among the amine modified biochar adsorbents, TETA-biochar@DCW has the highest CO2 adsorption capacity (61.78 mg/g) when using a mass ratio (m:m) of biochar@DCW:TETA (1:2). The adsorption kinetics on the TETA-biochar@DCW was best fitted by the pseudo-second model (R2 = 0.9998), suggesting the adsorption process occurs through chemisorption. Additionally, TETA-biochar@DCW was found to have high selectivity toward CO2 gas and good reusability even after five CO2 adsorption–desorption cycles. The results demonstrate the potential of novel CO2 adsorbents based on amine functionalized on desiccated coconut waste biochar. [ABSTRACT FROM AUTHOR]

Biochar adsorbs contaminants from wastewater. However, biochar's modification, its application in nutrient removal from wastewater, and its mechanism of nutrient removal need to be explored. In this study, nitrate and phosphate were recovered from secondary treated domestic wastewater using microalgal biochar (Spirulina sp.). The biochar was obtained by microwave pyrolysis of algae at 400 W power for 10 min. The biochar was modified using Mg(OH)2 under different conditions. Three pre‐and post‐treated biochars with varied Mg(OH)2 percentages (2%, 4%, and 6% by weight) were produced. All the modifications in biochar improved its specific surface area. Highest specific surface area of the modified biochar reached 33 m2/g compared to 12 m2/g of the unmodified biochar. SEM analysis showed improvement in the porosity of the modified biochars. Modification also introduced ‒OH, ‒C=C‒ and ‒C‒O‒C‒ functional groups on the biochar surface. All these modifications improved the nutrient adsorption capability of the biochar. Adsorption studies indicated that 4% post‐treated biochar (Po4) was the best. The adsorption data fit the pseudo second order kinetic model with R2 being 0.99 and 0.96 for phosphate and nitrate respectively. Among different isotherm models, the Freundlich isotherm model showed the best fit for phosphate and nitrate, with their respective R2 being 0.96 and 0.97, indicating multi‐layer physical‐chemical adsorption, including the intra‐particle diffusion. The equilibrium time for adsorption for nitrate and phosphate was 7 and 6 h, respectively. The optimum pH was 5 and 6 for nitrate and phosphate, respectively, and the optimum dosage was 2 g/L. The maximum adsorption capacity for nitrate and phosphate was 7.9 and 8.9 mg/g, respectively. Po4 showed potential as a fertilizer as it had 5.84 and 3.02 g of extractable phosphate and nitrate per kg of biochar. [ABSTRACT FROM AUTHOR]

Emergent plants have been remarkably effective in reducing phosphorus (P) discharge from ecological ditches; however, the treatment and recycling of these residues is a great challenge. In this study, magnetic biochars (MBs, i.e., MB-A, MB-C, and MB-T) were fabricated from three emergent plant residues (Acorus calamus L., Canna indica L., and Thalia dealbata Fraser, respectively) and modified with Fe(II)/Fe(III). Scanning electron microscopy-energy dispersive spectroscopy and X-ray diffraction spectra confirmed the successful loading of Fe3O4 and FeO(OH) onto the surfaces of the MBs. Batch adsorption experiments showed that MBs exhibited a higher P adsorption capacity than that of the raw biochars. Within the range of 0.8–43.0 mg L−1 in solution, the adsorption capacities of P by MB-A, MB-C, and MB-T were 304.6–5658.8, 314.9–6845.6, and 292.8–5590.0 mg kg−1, with adsorption efficiencies of 95.2–32.9%, 98.4–39.8%, and 91.5–32.5%, respectively. The primary mechanisms that caused P to adsorb onto the MBs were inner-sphere complexation and electrostatic attraction. Low pH conditions were more beneficial for the P adsorption of the MBs, while co-existing anions had a negative impact with the following order: HCO3− > SO42− > Cl−≈NO3−. The P-31 nuclear magnetic resonance results further demonstrated that the main adsorbed P species on the MBs was orthophosphate, followed by orthophosphate monoesters and DNA. Overall, MBs offer a resource utilization strategy for emergent plant residues and P-laden MBs are promising alternative P fertilizers. Highlights: Emergent plant biochar modified with Fe(II)/Fe(III) enhanced P adsorption capacity. Canna indica residue-derived MB exhibited the best P adsorption efficiency. MBs promoted P adsorption mainly via inner-sphere complexation and electrostatic attraction. P species adsorbed by MBs were mainly orthophosphate followed by orthophosphate monoesters and DNA. [ABSTRACT FROM AUTHOR]

Layered double hydroxide (LDH) is frequently used for phosphate removal in water, while a desirable LDH adsorbent should have sufficiently high adsorption capacity and selectivity. To enhance the removal performance and selectivity of phosphate by LDH, La-doped layered double hydroxide/biochar (La–MgAl–LDH/BC) was synthesized by using a co-precipitation method. Investigation results showed that lanthanum (La) metal loading can significantly enhance the phosphate adsorption performance of La–MgAl–LDH. Then, the introduction of La–MgAl–LDH into BC improved the adsorption capacity of phosphate by the adsorbent, which is 1.8 times that of pure La–MgAl–LDH. The optimum La to Al molar ratio was 0.2 : 0.8 in La–MgAl–LDH materials, and the La–MgAl–LDH to BC mass ratio was 9.3 : 10. Furthermore, both La–MgAl–LDH and La–MgAl–LDH/BC exhibited an enhanced ability to resist interference from co-existing anions (Cl−, SO42−, NO3− and CO32−) compared to LDH. For batch experiments, the kinetic results indicated that the adsorption process of phosphate by La–MgAl–LDH/BC follows a pseudo-second-order kinetics model, reaching equilibrium quickly within 1 h. Furthermore, film diffusion and intra-particle diffusion simultaneously took place. The maximum monolayer phosphate adsorption capacity of La–MgAl–LDH/BC could reach 249.3 mg PO43− g−1 (513.6 mg PO43− g−1, converting to an equivalent La–MgAl–LDH). After four cycles, La–MgAl–LDH/BC showed good reusability, and over 63.5% of phosphate uptake was retained with minimal metal leaching. Additionally, phosphate could be rapidly removed from actual water and simulated water at low concentrations. The electrostatic attraction, ligand exchange, ion exchange and Lewis acid action jointly facilitate the adsorption of phosphate. [ABSTRACT FROM AUTHOR]

Large quantities of livestock manure not only occupy farmland but also serve as the primary source of antibiotics and antibiotic resistance genes (ARGs) in agricultural soil. To enhance the resource utilization of animal manure and mitigate ecological risks associated with antibiotics in agroecosystems, chicken manure was used as a raw material for biochar production. The manure derived biochar (MB) was modified with an alkali–acid two‐step modification process. The results showed that the total pore volume and surface area of alkali–acid modified MB (AMMB) was significantly increased about three and five times, respectively after modification. The SEM images showed that the surface of AMMB had a more regular and clearer structure with fewer impurities. The improvement of surface properties of AMMB significantly increased its adsorbing capacity of tetracycline in the soil. The adsorption kinetics of tetracycline by AMMB were better fitted by the pseudo‐second‐order kinetic model, suggesting that the adsorption of tetracycline on biochar followed the process of chemisorption. The adsorption mechanisms mainly involved the pore filling, hydrophobic effect, and π–π EDA interaction. Moreover, after a 60 days amendment of AMMB, the total relative abundances (RAs) of tested tetracycline resistance genes (TRGs) in soil decreased significantly, which suggested that AMMB can be a potential material to reduce risks of antibiotics and its resistance genes. [ABSTRACT FROM AUTHOR]

Landfill leachate (LLCH) disposal poses challenges due to high pollutant concentrations. This study investigates the use of biochar (BC) derived from wheat straw for nitrogen content reduction. Laboratory experiments evaluated BC's adsorption capacity (qm) for nitrogen removal from ammonium chloride solution (NH4Cl) and LLCH, along with testing isotherm models. The results demonstrated that BC was more efficient (95.08%) than commercial activated carbon AC (93.11%), the blank, in adsorbing nitrogen from NH4Cl. This superior performance of BC may be attributed to its higher carbon content (57.74%) observed through elemental analysis. Lower results for BC/LLCH may be due to LLCH's complex chemical matrix. The Langmuir isotherm model best described BC/NH4Cl adsorption (qm = 0.5738 mg/g). The AC/NH4Cl data also fitted into the Langmuir (R2 ˃ 0.9) with a qm of 0.9469 mg/g, and 26.667 mg/g (R2 ˂ 0.9) was obtained for BC/LLCH; the BC/LLCH also gave higher qm (R2 ˃ 0.9) using the Jovanovich model (which also follows Langmuir's assumptions). The mean energy of the adsorption values estimated for the AC/NH4Cl, BC/NH4Cl, and BC/LLCH processes were 353.55, 353.55, and 223.61 kJ/mol, respectively, suggesting that they are all chemisorption processes and ion exchange influenced their adsorption processes. The Freundlich constant (1/n) value suggests average adsorption for BC/LLCH. The BC/LLCH data followed the Harkins–Jura model (R2: 0.9992), suggesting multilayered adsorption (or mesopore filling). In conclusion, biochar derived from wheat straw shows promising potential for landfill leachate remediation, offering efficient nitrogen removal capabilities and demonstrating compatibility with various adsorption models. This research also lays the groundwork for further exploration of other biochar-based materials in addressing environmental challenges associated with landfill leachate contamination. [ABSTRACT FROM AUTHOR]

Plant-derived selenium is an important source of selenium (Se) for humans, which, however, has been restricted by a low content of Se in soil. Traditional Se fertilizers have tended to result in low selenium utilization. Thus, it was necessary to develop a new slow-release material to control Se fertilizer release. In this study, biochar pyrolyzed at 300 °C and 800 °C was cross-linked with polyethyleneimine (PEI) after being treated with HNO3 or NaOH (which were labeled Acid-W300, Acid-W800, Alkali-W300, and Alkali-W800). The results showed that the maximum adsorption capacities of Acid-W300, Alkali-W300, Acid-W800, and Alkali-W800 were 329.16 mg/g, 321.93 mg/g, 315.04 mg/g, and 344.33 mg/g, respectively. Among them, Acid-W800 and Alkali-W800 were mainly imine- and amide-bonded with SO32−, while Acid-W300 and Alkali-W300 were loaded with SO32− by forming the C–Se bonding as well as through imine- and amide-bonding. The release of four biochar-based selenium fertilizers in the red soil and brown soil extracts conformed to the pseudo-second-order kinetic model. The release rate and release amount of four biochar-based selenium fertilizers in the red soil extract were higher than those in the brown soil extract. Alkali-W800-Se had a higher proportion of Se-exchangeable release, accounting for 87.5% of the total loaded selenium, while Acid-W300-Se had the lowest proportion at 62.2%. However, the Se releases of Alkali-W800-Se were more than 42.49% and 37.67% of the total Se-loading capacity during 5 days of continuous red soil extraction and brown soil extraction, respectively. Acid-W300-Se released less than 20% of the total Se-loading capacity. Thus, Acid-W300-Se was the recommended slow-release Se fertilizer in red soil and brown soil. [ABSTRACT FROM AUTHOR]

Here, banana peel biochar (BPBC) generated from discarded saba banana peels powder (SBPP) was utilized as an adsorbent in this study to remove diesel oil from water. The BPBC was synthesized using a slow pyrolysis method and characterized using SEM, EDX, FTIR, DSC, TGA, BET, contact angle analyzer, and XRD. The results showed that BPBC exhibited high porosity, thermal stability, and hydrophobic character, making it a promising adsorbent for oil-water separation and environmental remediation. The adsorption capacity of BPBC for diesel oil removal was examined in terms of adsorbent dose, pH level, salinity, and contact time. Increasing the BPBC dosage, contact time, and salinity significantly enhanced the sorption capacity, however, pH variations had no significant effect on adsorption. Adsorption parameters were correlated using a reduced cubic model, and an adsorbent dose of 2.50 g, pH of 7.00, salinity of 44,999.95 mg/L, and contact duration of 240 minutes were found to be optimal, producing a sorption capacity of 5.3352 g diesel oil/g adsorbent. The adsorption process was characterized by the first-order kinetic model. The creation of multilayer adsorption on the BPBC surface was confirmed by the BET isotherm. Adsorption characterization revealed changes in the surface morphology, elemental analysis, and functional groups of BPBC after adsorption. SEM revealed occupied surface pores, and EDX analysis verified an increase in carbon content. The presence of adsorbed diesel oil molecules on the BPBC surface was detected by FTIR analysis, which exhibited changes in peak appearance and functional group shifts. Overall, this study presents an adsorbent derived from waste material for diesel oil adsorption, which is useful for remediating oil spills and for wastewater treatment. Highlights: • Biochar from saba banana peels was used as an adsorbent to remove diesel oil from water. • The diesel oil solution environmental conditions were optimized to maximize oil adsorption. • Diesel oil adsorption on biochar follows the first-order kinetic model and the BET isotherm model. [ABSTRACT FROM AUTHOR]

In the context of carbon neutrality, promoting resource utilization of industrial alkali lignin addressing heavy metal pollution is crucial for China's pollution alleviation and carbon reduction. Microwave pyrolysis produced functionalized biochar from industrial alkali lignin for Ni(II) adsorption. LB400 achieved 343.15 mg g−1 saturated adsorption capacity in 30 min. Pseudo-second-order kinetic and Temkin isotherm models accurately described the adsorption, which was endothermic and spontaneous (ΔGϴ < 0, ΔHϴ > 0). Quantitative analysis revealed that both dissolved substances and carbon skeleton from biochar contributed to adsorption, with the former predominates (93.76%), including mineral precipitation NiCO3 (Qp) and adsorption of dissolved organic matter (QDOM). Surface complexation (Qc) and ion exchange (Qi) on the carbon skeleton accounted for 6.3%. Higher biochar preparation temperature reduced Ni(II) adsorption by dissolved substances. Overall, biochar which comes from the advantageous disposal of industrial lignin effectively removes Ni(II) contamination, encouraging ecologically sound treatment of heavy metal pollution and sustainable resource utilization. [ABSTRACT FROM AUTHOR]

By expanding the surface area and/or by other chemical reactions, soil additives such as biochar help retain nutrients in the soil. n this work, the effects of biochar on the adsorption and desorption of heavy metals and soil elements necessary for plant growth were investigated. To illustrate the adsorption of nutrients and heavy metals from solution on biochar, the Freundlich isotherm was employed. The rise in mineral nutrients, pH, and EC was linked to an increase in CEC with warmth. Because of its high CEC, biochar improves soil health and increases plant nutrient availability, which can boost agricultural yield when applied to the soil. In manure + biochar at 2.5 + 7.5 t/ha application rate the NH4+-N adsorption capacity was minimum in T7 (15.9 and 117.66) followed by T4 (17.6 and 130.24), T13 (18.7 and 138.38) and maximum in T10 (20.1 and 148.74) at 25 and 200 mg kg-1 level of added NH4+-N, respectively than control T1 (10.3 and 75.3). An increase in the rate of biochar application led to a favourable effect by increasing the NO3–N adsorption capability. The effect on P adsorption was more with biochar than manures. In manure + biochar at 2.5 + 7.5 t/ha application rate the Pb adsorption capacity was minimum in T7 (4.46 and 30.77) followed by T10 (4.71 and 32.49), T13 (5.16 and 35.60) and maximum in T4 (5.48 and 37.81) at 10 and 100 mg kg-1 level of added Pb, respectively than control T1 (1.86 and 12.83). Goat manure, FYM, vermicompost, and poultry manure had the greatest effects on desorption. The desorption of all heavy metals Cd, Pb, Zn, and As decreased as the rate of biochar application increased. Based on excess nutrients and heavy metals, this study supports the use of biochar to mitigate environmental concerns. [ABSTRACT FROM AUTHOR]