Search

Activated carbon (AC) has important industrial and environmental applications as it has excellent abilities to sorb contaminants such as per- and polyfluoroalkyl substances (PFAS). Current research aims to develop activated biochars (AB) from renewable biomass to replace AC that is produced from fossil feedstock. Both AC and AB are primarily comprised of condensed aromatic carbon (ConAC), the component that is the focus of this study. ConAC is characterized to determine its relationship with biochar activation conditions and PFAS sorption, which are understudied at present. Benzenepolycarboxylic acid (BPCA) markers for ConAC were quantified in steam-activated biochars (AB-Steam) and carbon dioxide-activated biochars (AB-CO 2) prepared from waste timber at different temperatures (800, 850, 900 °C) and molar ratios of feedstock-carbon:steam (0.50 – 1.25). A non-activated biochar was also included as a reference. ConAC relative to total organic carbon content was higher in AB-Steam than in AB-CO 2 (92 ± 2 % vs. 81 ± 11%). The ratio of benzenehexa- (B6CA) to benzenepentacarboxylic (B5CA) acids revealed that AB-Steam also had larger ConAC clusters than AB-CO 2. These findings provide novel evidence that steam activation is more effective than CO 2 activation in creating ConAC. To assess how ConAC impacts AB sorption abilities, AB-Steam were used to remediate PFAS from contaminated soils. The observed strong correlations between ConAC content and sorption of long-chain PFAS suggest the importance of hydrophobic interactions between PFAS tails and ConAC. Poor correlations for short-chain PFAS, on the other hand, indicated the existence of electrostatic repulsion interactions between PFAS head groups and ConAC. Collectively, these results explain the great ability of AB-Steam to sorb PFAS from contaminated soils (up to 100% remediation). More broadly, this work demonstrates that the BPCA method can be a valuable tool to assess the quality of biochars and other carbonaceous sorbents in relation to their production conditions or contaminant sorption abilities. [Display omitted] • Condensed aromatic carbon (ConAC) content was determined by benzenepolycarboxylic acid (BPCA) markers. • Steam-activated biochars had more ConAC (92 ± 2 %) of larger cluster size than CO 2 -activated biochars (81 ± 11%). • More PFAS sorption (71 ± 25%) was observed at higher ConAC content (> 92%). • Hydrophobic and electrostatic repulsion interactions likely exist between PFAS and ConAC. [ABSTRACT FROM AUTHOR]

Influence of the cosolvent on the sorption of organic acids on biochar has not been well understood. For this purpose, the sorption (log K m , L kg−1) of three aromatic acids (benzoic acid (BA, p K a = 4.20), 1-naphthoic acid (1-NAPA, p K a = 3.70), and 9-anthroic acid (9-ANTA, p K a = 3.65) was evaluated as a function of methanol volume fraction (f c = 0.0, 0.25, and 0.5), liquid pH (2.5 and 7.0), ionic composition (CaCl 2 and KCl) and ionic strength (0.005 M, 0.5 M, and 1 M CaCl 2). A giant Miscanthus -derived biochar (ZPC of 2.86) was used as the sorbent. For all solutes, the sorption coefficients (log K m) measured at pH 2.5 (i.e., pH < p K a) tended to decrease with increasing f c , as expected from the cosolvency model, while the result obtained at pH 7.0 was not fully explained by the same model. The log K m of 1-NAPA in the CaCl 2 system was always greater than in the KCl system (p < 0.05) and the impact became pronounced at high pH (>p K a) with increasing f c. Increasing the Ca2+ concentration at f c = 0.0 (from 0.005 M to 1 M) enhanced the value by 0.32 log unit of K m. These phenomena indicate a significant role of dissolved Ca2+ in the liquid phase, most likely due to the formation of cation bridges between aromatic carboxylates and the biochar surface (i.e., [R-COO--Ca2+]-{Biochar−}). A decrease in the dielectric constant of the methanol mixture could fortify the formation of this bridge. Regardless of the degree of cosolvency power (σ), as the number of aromatic rings of solutes increases, K m decreases in the order BA > 1-NAPA > 9-ANTA, where f c = 0.0. In conclusion, the sorption potential of biochar can be significantly weakened by increasing pH and f c , and in the absence of a divalent cation. [Display omitted] • Sorption of aromatic acids to biochar under various liquid conditions was assessed. • The sorption potential was strongly affected by the cosolvent, pH and cationic composition. • Ca2+ bridging and high pH (>p K a) play a key role in the sorption of aromatic carboxylates. • Sorption was successfully explained by coupling sorption constant of two ionic species. [ABSTRACT FROM AUTHOR]

The presence of pharmaceutical compounds in aqueous environments has become a growing concern due to their potential adverse effects on ecosystems and human health. In this work, synthesis of a novel bio based nanocomposite using a biowaste, palm seed is employed for the preparation of biochar. The bio derived nanocomposite consist of polypyrrole (Ppy), graphene oxide (GO), and biochar, is employed for the Carbamazepine (CBZ) removal. The synthesized nanocomposite, Ppy-GO-Biochar, is characterized using various analytical techniques. The characterization results confirmed the successful synthesis of the Ppy-GO-Biochar nanocomposite with the desired morphology and structural properties. The effect of variables is investigated and the optimum conditions are found as: pH (7.8), adsorbent dosage (1.4 g/L), agitation speed (200 rpm) and temperature (39.5 °C). The results demonstrated that a removal efficiency of over 97.74% and uptake of 45.045 mg/g is achieved for CBZ. Furthermore, the CBZ removal followed pseudo-second-order, indicating chemisorption as the predominant mechanism. The CBZ sorption equilibrium is well represented by Langmuir and Freundlich isotherm. Thermodynamic results show that CBZ sorption is endothermic and spontaneous. Mechanism of CBZ sorption using the synthesized nanocomposite follows π-π interaction and electrostatic attraction. Molecular docking studies were also performed for the sorption of CBZ. [Display omitted] • Synthesis of a novel bio based nanocomposite using a biowaste, palm seeds is employed. • CBZ removal is performed using the novel bio nanocomposite. • A maximum CBZ uptake of 45.0 mg/g and a maximum removal of 97.74% is attained. • Adsorption of CBZ follows Langmuir and Freundlich isotherm. • Mechanism is proposed for CBZ sorption using the bio-derived nanocomposite. [ABSTRACT FROM AUTHOR]

Common isotherm and kinetic models cannot describe the pH-dependent sorption of heavy metal cations by biochar. In this paper, we evaluated a pH-dependent, equilibrium/kinetic model for describing the sorption of cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) by poultry litter-derived biochar (PLB). We performed sorption experiments across a range of solution pH, initial metal concentration, and reaction time. The sorption of all five metals increased with increasing pH. For Cd, Cu, and Pb, kinetics experiments demonstrated that sorption rates were greater at pH 6.5 than at pH 4.5. For each metal, all sorption data were described using single set of four adjustable parameters. Sorption edge and isotherm data were well described with R2 > 0.93 in all cases. Time-dependent sorption was well described (R2 ≥ 0.90) for all metals except Pb (R2 = 0.77). We then used the best-fit model parameters to calculate linear distribution coefficients (K D) and equilibration times as a function of pH and initial solution concentration. These calculations provide a more robust way of characterizing biochar affinity for metal cations than Freundlich distribution coefficients or Langmuir sorption capacity. Because this model can characterize metal cation sorption by biochar across a wider range of reaction conditions than traditional isotherm or kinetic models, it is better suited for estimating metal cation/biochar interactions in engineered or natural systems. [Display omitted] • The sorption of metals by poultry litter biochar increased with increasing pH. • Sorption kinetics were slower at low pH for cadmium, copper, and lead. • A pH-dependent model described equilibrium and time-dependent sorption. • The model is more appropriate for screening biochars than sorption capacity. [ABSTRACT FROM AUTHOR]

Persistent free radicals (PFRs) in biochar have been found to the transformation of organic contaminants in environment. However, there remains insufficient comprehension on the relationship of biochar aging with interfacial reactivity of PFRs to the degradation of phenolic compound in geochemical process. Herein, we studied both sorption and degradation of p -nitrophenol (PNP) on fresh and aged biochars via H 2 O 2 aging under anoxic condition. With increasing aging extent, the enhancive proportion of O-centered radicals was observed progressively as indicated by increased g factors. The aging of PS350 annihilated the presence of PFRs in aged biochars of low-temperature, weakening PFR intensity. But, the aging of PS650 supplied more O-centered radicals for aged biochars of high-temperature, enhancing PFR intensity. This caused the decreased degradation on 5%PS350 and 15%PS350 (37.7–79.6% decline), whereas the increased degradation on 5%PS650 and 15%PS650 (33.3–55.8% increase). At similar intensity and species of PFRs, more adsorbed amount on fresh and aged biochars produced more degradation of PNP. Nevertheless, when PFR intensity of PS650 was much lower than that of PS350, despite high sorption capacity of PS650, the degradation amount of PS350 and PS650 was comparable. The results indicated that the reactivity of C-centered radicals of PS650 was stronger than that of O-centered radicals of PS350 in anoxic system. Overall, the interfacial reactivity of biochars was simultaneously regulated by the sorption capacity of biochars and intensity and species of PFRs. This work provides a deep perspective to the impact of biochar aging on the interfacial reactivity of PRFs to phenolic compound, which will be beneficial to accurately predict the fate of organic contaminant in carbon-rich environment. [Display omitted] • Intensity and species of persistent free radical are affected by biochar aging. • An inverse degradation appears for aged biochars of low- and high-temperatures. • More sorption on fresh and aged biochars can produce more PNP degradation. • The reactivity of biochar is dependent on the intensity and species of PFRs. • The reactivity of C-centered radical is stronger than that of O-centered radical. [ABSTRACT FROM AUTHOR]

The physicochemical properties of biochar determined its sorption of organic contaminations, and the environmental aging process changed the biochar properties. However, the correlation between biochar heterogeneous properties and their sorption characteristics is unclear. In this study, peanut shell biochars were produced at 200–700 °C, and HNO 3 /H 2 SO 4 was used to oxidize 400 °C biochar for 2–10 h to simulate the enhanced aging process of biochar in the environment. Benzene polycarboxylic acid (BPCA) molecular markers, and bulk characterization were analyzed to describe biochar physicochemical properties and to further predict the sorption characteristics to bisphenol A (BPA). For pristine biochars, the mellitic acid/BPCAs (B6CA/BPCAs) increased with the raise of pyrolysis temperature and the H/C atomic ratio was positively correlated with benzenepentacarboxylic acid/B6CA (B5CA/B6CA) (P < 0.01), which indicated the increased aromatic condensation. After HNO 3 /H 2 SO 4 treatment, the aromaticity (H/C ratio) decreased while the highly condensed components in biochars were enriched (increased B6CA/BPCAs values). Multiple regression models were adopted to establish a quantitative relationship between biochar heterogeneous properties and their sorption of BPA. Both nonlinearity coefficient N values (N = 0.08 + 0.103 B5CA/B6CA + 0.721 (O + N)/C, R2 = 0.985) and single-point sorption coefficients log K d (log K d = 1.236 + 0.006 BPCAs + 1.449 (O + N)/C, R2 = 0.936) could be estimated combining molecular markers and polarity parameters for biochars. • The B6CA/BPCAs ratios increase with the pyrolysis temperature. • The polar functional groups formed by oxidation block biochar pore structures. • HNO 3 /H 2 SO 4 oxidation decreases BPCAs contents but increases B6CA/BPCAs. • The nonlinear factors are positively related to B5CA/B6CA for all biochars. • N and log K d could be predicted by combining (O + N)/C and BPCA parameters. [ABSTRACT FROM AUTHOR]

Biochar has recently emerged as a cost-effective solution to combat per- and polyfluoroalkyl substances (PFAS) pollution in water, but mechanistic understanding of which physicochemical properties of biochars dictate PFAS sorptive removal from water remains elusive. Herein, 15 biochars were pyrolyzed from five feedstocks (corn, Douglas fir, eucalyptus, poplar, and switchgrass) at three pyrolysis temperatures (500, 700, and 900 °C) to investigate their removal efficiencies and mechanisms of perfluorooctane sulfonate (PFOS) from water. A commercial biochar was also included for comparison. Biochar physiochemical properties, including elemental composition, pH, specific surface area (SSA), pore structure, hydrophobicity, surface charge, surface functional groups, and crystalline structure were systematically characterized. Batch sorption data showed that the Douglas fir 900 biochar (Douglas fir and 900 are the feedstock type and pyrolysis temperature, respectively; this naming rule applies to other biochars), poplar 900 biochar, and commercial biochar can remove over 95% of PFOS from water. Structural equation model (SEM) was used to elucidate which biochar properties affect PFOS sorption. Interestingly, biochar pore diameter was identified as the most critical factor controlling PFOS removal, but pore diameter/pore volume ratio, SSA, pyrolysis temperature, hydrophobicity, and elemental composition all played variable roles. Hypothetically, biochars with small pore diameters and large pore volumes had a narrow yet deep pore structure that traps PFOS molecules inside once already sorbed, resulting in an enhanced PFOS sorption. Biochars with small pore diameter, low nitrogen content, and high pyrolysis temperature were also favorable for enhanced PFOS sorption. Our findings advance the knowledge of using biochars with optimized properties to remove PFOS and possibly other similar PFAS compounds from water. [Display omitted] • Biochars pyrolyzed from five feedstocks at three pyrolysis temperatures were used to sorb PFOS from water. • Biochars pyrolyzed at the highest temperature (900 °C) exhibited the greatest sorption efficiency for PFOS. • Structural equation model (SEM) analyses identified key physicochemical properties of biochars controlling PFOS sorption. • Biochars were demonstrated as a cost-effective and efficient sorbent for PFOS removal from water. [ABSTRACT FROM AUTHOR]

Abstract In this study, biochar was produced from three differently treated sewage sludge biomasses, in three pyrolytic temperatures, 300 °C, 500 °C and 700 °C, under continuous N 2 supply. The produced samples were physicochemically characterized and their initial metal concentration, along with metal leaching potential, were investigated. Moreover, the application of the biochar samples as adsorbents for the removal of seven emerging organic micro-pollutants from table water and treated wastewater matrices was investigated. The results showed that even though the biochar samples were not especially enriched in terms of physicochemical characterization, they were effective as adsorptive materials in the respective experiments. Pollutant removal was in the range of 67–99% for the table water experiments, while the removal for the wastewater experiments was 35–97%. The results of this study indicate that sewage sludge biochar has the potential to be an effective, low-cost adsorbent, providing, at the same time, a viable and environmentally friendly solution concerning the difficult task of sludge management. Highlights • Sludge pyrolysis could be an efficient method for the valorization of this waste material. • Sludge type affected the physicochemical composition of biochars. • Metal leaching of sewage sludge biochar was more than 70% lower than that of unpyrolyzed sludge. • Pollutant removal from wastewater by sludge biochar ranged from 35 to 97%. [ABSTRACT FROM AUTHOR]

Abstract Within this study different biochars (BC) with widely varying characteristics have been tested as materials for the adsorption of hexachlorocyclohexane's (HCH) isomers (α, β, γ and δ) from water. Three BCs produced from digestate (700 °C), greenhouse tomato waste (550 °C) and durian shell (400 °C) were tested. The BCs demonstrated variable physico-chemical characteristics, especially with respect to surface area, with CO 2 -surface area ranging from 5.4 to 328.6 m2 g−1 and iron content ranging from 0.0733 to 11.17 g kg−1. Isotherm tests were carried out to understand which mechanisms drive HCH uptake to BC, to assess whether stereochemistry affects adsorption and to assess whether competitive sorption occurs. Log K F values ranged from 3.7 to 5.8 (μg kg−1) (μg L−1)−n for the various isomers on the three biochars. No competition (t -test, P < 0.0001) was observed between α-, β-, γ- and δ-HCH. Freundlich adsorption constants of α-, γ- and δ-HCH followed the order: BC digestate > BC greenhouse tomato waste > BC durian shell, in contrast to β-HCH which followed the order: BC durian shell > BC greenhouse tomato waste > BC digestate. In addition to stereochemistry, sorption coefficients were affected most strongly by BC surface area and iron content, in addition to specific HCH/BC matrix interactions. In this study the iron content of a carbonaceous material has been investigated, for the first time, as a factor that can affect the sorption of HCHs. Graphical abstract Image 1 Highlights • Biochars were used for the sorption of α-, β-, γ- and δ-hexachlorocyclohexane. • Isotherms were carried out in single- and multi-component (isomers mixture). • No competition was observed in water batch tests between α-, β-, γ- and δ-HCH. • LogK F ranged from 3.7 to 5.8 (μg kg−1) (μg L−1)−n for all the isomers on biochars. • Sorption is affected by BC surface area, iron content and HCH/BC interactions. [ABSTRACT FROM AUTHOR]

Abstract Nickel-containing wastewater is a serious hazard to water environment, so that it is a burning issue to find an efficient and environment-friendly adsorbent. The conventional biochar could not effectively adsorb nickel (Ni(II)), so our study focuses on exploring the adsorption of chemically modified biochar to Ni(II). In this study, the biochar derived from waste peanut shell was modified by KMnO 4 and KOH (MBC). And a series of experiment were carried out to evaluate the sorption ability and explore adsorption mechanism of modified biochar to Ni(II). The results showed the adsorption ability of MBC to Ni(II) reached 87.15 mg g−1. And the reaction process was spontaneous and endothermic chemisorption. Meanwhile, the analysis of FTIR and XPS visually revealed that the amine groups in the modified biochar could form NH 2 Ni with Ni(II) by complexation, while the hydroxyl could form nickel hydroxide and complexed nickel oxide by co-precipitation and complexation. This research showed this novel MBC is a promising adsorbent and has a fantastic prospect in the application of nickel-containing wastewater. Highlights • Strong adsorption of KMnO 4 and KOH-modified biochar to Ni(II). • The pore structure of modified biochar offered more adsorption sites of Ni(II). • Amine groups and removed Ni(II) by the formation of NH 2 Ni. • Hydroxyl removed Ni(II) by the formation of Ni(OH) 2 and nickel complexes. [ABSTRACT FROM AUTHOR]

Abstract Currently, the role of amorphous carbon structure (ACS) in sorption of chlorinated hydrocarbons (CHs) to biochars remains little known. Therefore, three CHs (1,1,2,2-tetrachloroethane, 1,3,5-trichlorobenzene and γ-hexachlorocyclohexane) with different molecular properties were selected as model adsorbates to investigate the effect of ACS on sorption of CHs to biochars produced at seven different pyrolysis temperatures (300–900 °C). There were two main mechanisms for ACS controlling the sorption of CHs. First, the polar sites on ACS are hydrophilic, CHs with greater polarity could strongly compete with the water molecule for the hydrophilic sites. Second, ACS of low temperature (300–400 °C) produced biochars possessing the natural organic matter (NOM)-like structure occupied some hydrophobic sites on condensed graphitic structure (CGS) of biochars. CHs with great hydrophobicity possibly seized the hydrophobic sorption sites on CGS from the NOM-like structure. Therefore, ACS of biochar was more benefit for sorption of strong polar CHs (1,1,2,2-tetrachloroethane: π∗ = 0.95; Log K ow = 2.39) or strong hydrophobic CHs (1,3,5-trichlorobenzene: π∗ = 0.70; Log K ow = 4.19) than CHs (γ-hexachlorocyclohexane: π∗ = 0.68; Log K ow = 3.72) with relatively low polarity and hydrophobicity. The result reflects that the interaction between NOM and natural black carbon/biochars in soil and water environment possibly plays the similar role in controlling the environmental behavior of various polar or hydrophobic organic pollutants. Moreover, with increasing concentration of adsorbate (C e), the first mechanism enhanced, while the second mechanism weakened. This study gives a deep insight into the roles of ACS of biochars in controlling the fate and availability of CHs with different molecular properties in environment. Graphical abstract Image 1 Highlights • The role of ACS in sorption of biochars is closely related to the molecular properties of CHs. • CHs with greater polarity compete with water molecular for the hydrophilic sites on ACS. • CHs with stronger hydrophobic compete with NOM-like structure for the hydrophobic sites on CGs. • Sorption behavior of CHs on ACS depends on the concentration of CHs. [ABSTRACT FROM AUTHOR]

Abstract In order to clarify the influence of aromatic structure and COOH substitution of aromatic acids on their sorption to biochars, benzoic acid (BA), phthalic acid (PA), hemimellitic acid (HA), 2-biphenylcarboxylic acid (2-BA), 1-naphthoic acid (1-NA) and naphthalene were selected as model sorbates. Batch experiments on sorption of them to wheat straw-derived biochars at 300 °C (WS300) and 700 °C (WS700) were conducted. Results showed that WS700 with higher specific surface area and pore volume had faster and higher sorption of aromatic acids than WS300. Sorption affinity of aromatic acids decreased with increasing number of aromatic rings (BA > 1-NA > 2-BA), and was weakened by COOH substitution (BA > PA > HA). This was likely due to the π-electron delocalization into additional ring, reduced contact area of nonplanar aromatic structure on biochar surfaces, size exclusion of larger molecules in smaller pores of biochars and decreased hydrophobicity of aromatic acids by COOH substitution that abated the sorption. Dissociation of COOH substitution of aromatic acids also weakened their sorption to biochars due to the lower hydrophobicity of anionic species, and electrostatic repulsion between anionic species and negatively charged surface of biochars. Highlights • Sorption reduction from one to two rings could be due to π-electron delocalization. • Size exclusion of larger molecules in pores of biochars inhibited the sorption. • Planar aromatic structure showed more favorable sorption than nonplanar structure. • Aromatic acids sorption decreased with -COOH substitution number and dissociation. [ABSTRACT FROM AUTHOR]

Metal oxide-Carbon composites have aroused great interesting towards specific anionic contaminants removal from the polluted environment. In this study, aiming at removing toxic chromate ion [Cr(VI)] from aqueous solutions, a novel approach was developed to produce surface-enhanced MgO-coated biochar adsorbent from sugarcane harvest residue (SHR). It was found that sulfuric acid hydrolysis and MgO-coating both facilitated the removal of Cr(VI) by biochars, and the maximum sorption capacities for the pristine biochar (SHR 550 ), MgO-coated biochar (MgSHR 550 ), and acid-assisted MgO-coated biochar (MgASHR 550 ) that derived from the Langmuir isotherm model were 20.79, 54.64, and 62.89 mg g −1 , respectively. Additionally, the Cr(VI) removal was a pseudo-second-order kinetic model controlled process with equilibrium reached within 24 h. The mechanism investigation revealed that Cr(VI) ions was directly sorbed by the MgO-coated biochars via the chemical interaction between MgO and Cr(VI), whereas the sorption-coupled reduction of Cr(VI) to Cr(III) governed the sorption of Cr(VI) on the SHR 550 . Although the increases of solution pH (>2.0) and KNO 3 concentration (>0.05 mol L −1 ) reduced the Cr(VI) removal by biochars, while there were lower secondary pollution risks in MgO-coated biochar treatments due to the suppressed release of Cr(III) in solutions. This work could provide guidance for the production of efficient biochar for the removal of Cr(VI) from wastewater. [ABSTRACT FROM AUTHOR]

This pilot study investigated the affinity of oxidized biochars to sorb lead ions (Pb 2+ ) in aqueous solutions, and its potentiality to serve as bio-filters to detoxify Pb-induced oxidative stress on hydroponically grown chicory. Raw bagasse was slow-pyrolyzed at 600 °C to produce original biochar (O-B), which was further oxidized by HNO 3 and KMnO 4 to generate HNO 3 -B and KMnO 4 -B, respectively. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), digital selected-area electron diffraction (SAED) and Fourier transform infrared spectroscopy (FTIR) analyses were performed to study physicochemical properties of pre-and post-sorption samples. Kinetic and isothermal batch sorption experiments proved the high affinity of oxidized biochar to Pb 2+ ions. Both physisorption and chemisorption mechanisms participated mutually in sorption process. Leaf histochemistry analysis showed various dysfunctions on plants grown under severe Pb-stress including (i) induction of oxidative stress, (ii) deactivation in antioxidant enzymatic and non-enzymatic defense pathways, (iii) defects in plant water status, (iv) disruption in photosynthetic pigments synthesis, and (v) disturbance in the membrane permeability to solute leakage. Biochar filters (particularly KMnO 4 -B) exhibited a scavenging effect against these adverse effects by reducing Pb-bioavailability. Furthermore, the chemical characteristics of biochar and its derivatives (biochar-derived humic acids) provided additional stimulating effect to plant scavenging mechanisms. This ameliorative effect of biochar filters minimized the dramatic reductions in vegetative measurements of plants grown under severe Pb-stress. Hence, this study provides insights regarding the potentiality to functionalize biochar and its derivatives for heavy metal detoxification. [ABSTRACT FROM AUTHOR]

An important pathway for biochar to alter the availability of soil phosphorus (P) is to change P sorption characteristics of the soil. The aim of this study was to understand the mechanisms of biochar effects on P sorption in acid upland red soils in the presence of different concentrations of exogenous P. Rice straw biochar (RSB) was prepared and applied at rates of 0, 1%, 3%, and 5% ( w/w ) to three red soils (MZ 1 , MZ 2 , and QY 1 ) differing in initial pH (pH = 4.31, 4.82, and 5.68, respectively). The P sorption characteristics of these red soils were described using the Langmuir and Temkin equations and their relationships with soil basic physicochemical properties were analyzed. Furthermore, a representative red soil (MZ 2 ) was selected to analyze the zeta potential of soil colloids and the chemical properties of sorption equilibrium solution, in order to understand their relationships with P sorption characteristics. Results showed that within a certain range of P concentration in the equilibrium solution, the amount of P sorbed by the three red soils decreased and the corresponding amount of P desorbed increased with increasing amendment rate of RSB. RSB showed the greatest effect on P desorption characteristics of MZ 2 soil in the presence of higher exogenous P concentration. With increasing RSB amendment rate, the maximum P sorption of MZ 1 soil decreased, while those of MZ 2 and QY 1 soils increased after an initial decrease. Phosphate sorption equilibrium constant and maximum P buffer capacity of each soil first increased and then decreased. However, a single physicochemical property could not interpret complex changes in multi-factors that jointly determine the P sorption characteristics of red soils. In the case of MZ 2 soil, RSB amendment shifted the zeta potential of soil colloids to the negative direction; this decreased the positive charge and increased the negative charge on the soil surface, thus reducing P sorption in the MZ 2 soil. In the presence of the same concentration of exogenous P, RSB amendment altered the pH, dissolved organic C (DOC), humification index (HIX), and maximum fluorescence intensity (F max ) in the sorption equilibrium solution. In most cases, the amount of P sorbed by the MZ 2 soil was negatively correlated with the pH value, DOC concentration, HIX value, and F max value of humic-like dissolved organic matter (DOM), and positively correlated with the F max value of protein-like DOM ( P  < 0.05 or P  < 0.01). The relative fractional distribution of the contents for humic-like and protein-like DOM might determine the difference in the P sorption characteristics of MZ 2 soil. In conclusion, different amendment rates of RSB affected the release of phosphate from soil surfaces into the solution by altering basic physicochemical and electrochemical properties of red soils and chemical properties of sorption equilibrium solution. [ABSTRACT FROM AUTHOR]

A bench scale study was conducted to evaluate the effectiveness of in situ amendments to reduce the bioavailability of pollutants in sediments from a site impacted with polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and cadmium. The amendments tested included fine and coarse coal-based activated carbons (AC), an enhanced pinewood derived biochar (EPB), organoclay, and coke dosed at 5% of sediment dry weight. Strong reductions in total PCB porewater concentrations were observed in sediments amended with the fine AC (94.9–99.5%) and EPB (99.6–99.8%). More modest reductions were observed for the coarse AC, organoclay, and coke. Strong reductions in porewater PCB concentrations were reflected in reductions in total PCB bioaccumulation in fresh water oligochaetes for both the fine AC (91.9–96.0%) and EPB (96.1–96.3%). Total PAH porewater concentrations were also greatly reduced by the fine AC (>96.1%) and EPB (>97.8%) treatments. EPB matched or slightly outperformed the fine AC throughout the study, despite sorption data indicating a much stronger affinity of PCBs for the fine AC. Modeling EPB and fine AC effectiveness on other sediments confirmed the high effectiveness of the EPB was due to the very low final porewater concentrations and differences in the native bioavailability between sediments. However, low bulk density and poor settling characteristics make biochars difficult to apply in an aquatic setting. Neither the EPB nor the fine AC amendments were able to significantly reduce Cd bioavailability. [ABSTRACT FROM AUTHOR]

Biochar(BC)-supported nanoscaled zinc oxide (nZO) was encapsulated either with (nZORc/BC) or with no (nZOR/BC) sodium carboxymethyl cellulose (CMC). The X-ray diffraction and ultraviolet (UV)-visible-near infrared spectrophotometry revealed that nZO of 16, 10, and 20 nm with energy band gaps of 2.79, 3.68 and 2.62 eV were synthesized for nZOR/BC, nZORc/BC and nZO/BC, respectively. The Langmuir isotherm predicted saturated sorption of methylene blue (MB) was 17.01 g kg −1 for nZORc/BC, over 19 times greater than nZOR/BC and nZO/BC. Under UV irradiation, 10.9, 61.6, 83.1, and 41.6% of MB were degraded for nZORc/BC, nZO/BC, nZOR/BC and BC. The scavenging experiment revealed hydroxyl radical dominated CMC degradation. Exogenous CMC (2 g L −1 ) increased MB sorption from 10.6% to 73.1%, but decreased MB degradation from 80.7% to 41.1%, relative to nZOR/BC. Thus, CMC could increase MB sorption by electrostatic attraction and other possible mechanisms. The compromised MB degradation may be ascribed to reduced availability of hydroxyl and superoxide radicals to degrade MB, and increased band gap energy of ZnO. [ABSTRACT FROM AUTHOR]

In the present study, sorption and detoxification of malachite green (MG) dye was executed using biochar resulting after pyrolysis of agro-industrial waste at 400, 600 and 800 °C. Maximum sorption of MG dye (3000 mg/L) was observed on the sugarcane bagasse biochar (SCB) prepared at 800 °C. The interactive effects of different factors like dye concentration, time, pH and temperature on sorption of MG dye were investigated using response surface methodology (RSM). Optimum MG dye concentration, contact time, temperature and pH predicted through Box–Behnken based RSM model were 3000 mg/L MG dye, 51.89 min, 60 °C and 7.5, respectively. ANOVA analysis displayed the non-significant lack of fit value (0.4566), whereas, the predicted correlation coefficient values ( R 2 0.8494) were reasonably in agreement with the adjusted value ( R 2 0.9363) demonstrating highly significant model for MG dye sorption. The applicability of this model was also checked through F – test (30.39) with lower probability (0.0001) value. Furthermore, the characterization of SCB was performed using fourier transform infra-red spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), Brunauer-Emmett-Teller surfaces (BET), total organic carbon (TOC) and atomic absorption spectroscopy (AAS). Phyto-toxicity and cytogenotoxicity studies showed successful removal of MG dye using SCB. In addition, the batch sorption studies for reutilization of SCB revealed that the SCB was effective in removal of MG for five repeated cycles. This technology would be effective for treating the toxic textile effluent released from the textile industries. [ABSTRACT FROM AUTHOR]

Novel sorbent (HBC) is prepared by introducing nano-particles (Maghemite and EDTA functionalized layered double hydroxides) on biochar surface. FTIR, XRD, SEM and EDS are used to characterize the biochar nanocomposites. Pb(II) sorption is highly dependent on solution pH. Sorption kinetics and isotherms indicate that Pb(II) sorption onto the sorbents follows pseudo-second order model and Langmuir isotherm. The maximum sorption capacity of Pb(II) onto HBC is up to146.84 mg g −1 , higher than previously reported sorbents. The magnetic particles enable easy separation of HBC from aqueous solution by external magnetic fields. HBC can be used as effective sorbent for removal of heavy metals from wastewater. [ABSTRACT FROM AUTHOR]

Generally, biochar plays an important role in controlling migration and accumulation of pollutants in soil. In this dissertation, biochars derived from wheat straws at various pyrolysis temperatures are used to investigate how biochar amendment affects adsorption and microbial degradation of atrazine (typical diffuse herbicide) in soils. In order to explore the influence of soil components, soil samples with different organic matter content are collected from typical agricultural sites, which are characterized as black soils in the northeast region of China. The basic sorption characteristics of biochars from wheat straws prepared at diverse pyrolysis temperature are analyzed, along with the comparisons of the sorption difference in the raw soil and soil amended with biochars at four levels of ratio (0.1%, 0.5%, 1.0% and 2.0%). By incubation experiments, atrazine degradation in non-sterile and sterile soils and effects of atrazine degradation rate after biochar amendment are also studied. Atrazine degradation is significantly enhanced in biochar amended soils, which may be because that biochar supplement can promote the growth and metabolism of microorganisms in the soil. Our findings reveal that wheatstraw- derived biochars may be effective remediation reagents for activating degradation of the soil functional microorganism and enhancing sorption of organic matter content, which can be applied to environmental-friendly accelerate the remediation of atrazine contaminated black soils. [ABSTRACT FROM AUTHOR]

In this work, nZVI was immobilized by bamboo derived biochars (nZVI/BB), hydrogen peroxide (H 2 O 2 ) (nZVI/PBB) and nitric acid (HNO 3 ) (nZVI/HBB) modified BB. H 2 O 2 and HNO 3 deceased surface area and pore volume of pristine biochars. Total iron (Fe) contents were 16.50, 24.40, and 13.08% for nZVI/BB, nZVI/PBB and nZVI/HBB, respectively. The X-ray diffraction revealed that nZVI in biochar matrix was dominantly metallic Fe coated with Fe oxides. The transmission electron microscopy indicated nZVI particle sizes were 41.5, 30.5 and 6.1 nm for nZVI/BB, nZVI/HBB and nZVI/PBB, respectively. The removal capacities of arsenate (AsV) and silver ions (Ag + ) by nZVI nanocomposites were compared in a batch experiment. Greater reductive removal of Ag + (1217 g kg −1 nZVI) and sorptive removal of AsV (109.1 g kg −1 nZVI) were achieved in nZVI/PBB, indicating smaller-sized nZVI was more reactive. Thus, particle size of nZVI affected the sorptive and reductive capacities for AsV and Ag + . [ABSTRACT FROM AUTHOR]

Significant concerns have been raised over antibiotics pollution in aquatic environments in recent years. In this study, sorption of sulfamethazine (SMT) by novel graphene oxide-coated biochar nanocomposites (GO-BC) based on graphene oxide (GO) with bamboo sawdust biochar (BC) was investigated. In comparison with the original BC, the sorption capacity of GO-BC for SMT increased by 1.14 times. Sorption of SMT onto GO-BC was proved to be dominantly by chemisorption, and Freundlich isotherm described the sorption adequately. It was found that variation of pH and ionic strength obviously affected the sorption of SMT, and GO-BC had a good sorption effect on SMT at pH 3.0–6.0 and lower ionic strength. Obvious enhancement (by 30%) in sorption of SMT on GO-BC was observed, which might be attributed to the increase of functional groups on the surface of GO-BC. Moreover, the main sorption mechanism for SMT was π-π electron-donor-acceptor interaction, while auxiliary sorption mechanisms were inferred as pore-filling, cation exchange, hydrogen bonding interaction and electrostatic interaction. The results indicated that GO-BC sorption was an efficient way for the removal of SMT. [ABSTRACT FROM AUTHOR]

Bench- and pilot-scale sorption tests were used to probe the performance of several biochars at removing perfluoroalkyl acids (PFAA) from field waters, compared to granular activated carbon (GAC). Screening tests using organic matter-free water resulted in hardwood (HWC) ( K d = 41 L g −1 ) and pinewood (PWC) ( K d = 49 L g −1 ) biochars having the highest perfluorooctanoic acid (PFOA) removal performance that was comparable to bituminous coal GAC ( K d = 41 L g −1 ). PWC and HWC had a stronger affinity for PFOA sorbed in Lake Mead surface water (K F = 11 mg (1−n) L n g −1 ) containing a lower (2 mg L −1 ) dissolved organic carbon (DOC) concentration than in a tertiary-filtered wastewater (K F = 8 mg (1−n) L n g −1 ) with DOC of 4.9 mg L −1 . A pilot-scale study was performed using three parallel adsorbers (GAC, anthracite, and HWC biochar) treating the same tertiary-filtered wastewater. Compared to HWC, and anthracite, GAC was the most effective in mitigating perfluoropentanoic acid (PFPnA), perfluorohexanoic acid (PHxA), PFOA, perfluorooctane sulfonic acid (PFOS), and DOC (45–67% removed at 4354 bed volumes) followed by HWC, and then anthracite. Based on bench- and pilot-scale results, shorter-chain PFAA [perfluorobutanoic acid (PFBA), PFPnA, or PFHxA] were more difficult to remove with both biochar and GAC than the longer-chain, PFOS and PFOA. [ABSTRACT FROM AUTHOR]

In this study, an acidic biochar and a neutral biochar were applied at 5 wt% into two soils for an 11-month incubation experiment. One Ferrosol soil (Ba) was slightly acidic with low organic matter and the other Dermosol soil (Mt) was slightly alkaline with high organic matter. The acidic (pH = 3.25) wood shaving (WS) biochar had no marked impact on nutrient levels, cation exchange capacity (CEC), pH and acid neutralization capacity (ANC) of either soil. By contrast, the neutral (pH = 7.00) chicken litter (CL) biochar significantly increased major soluble nutrients, pH, ANC of soil Ba. In terms of C storage, 87.9% and 69.5% WS biochar-C can be sequestrated as TOC by soil Ba and Mt, respectively, whereas only 24.0% of CL biochar-C stored in soil Ba and negligible amount in Mt as TOC. Biochars did not have significant effects on soil sorption capacity and sorption reversibility except that CL biochar increased sorption of soil Ba by around 25.4% and decreased desorption by around 50.0%. Overall, the studied acidic C rich WS biochar held little agricultural or remedial values but was favourable for C sequestration. The neutral mineral rich CL biochar may provide short-term agricultural benefit and certain sorption capacities of lower sorption capacity soils, but may be unlikely to result in heightened C sequestration in soils. This is the first study comprehensively examining functions of acidic and neutral biochars for their benefits as a soil amendment and suggests the importance of pre-testing biochars for target purposes prior to their large scale production. [ABSTRACT FROM AUTHOR]

Biochar produced by thermal decomposition of biomass under oxygen-limited conditions has received increasing attention as a cost-effective sorbent to treat metal-contaminated waters. However, there is a lack of information on the roles of different sorption mechanisms for different metals and recent development of biochar modification to enhance metal sorption capacity, which is critical for biochar field application. This review summarizes the characteristics of biochar (e.g., surface area, porosity, pH, surface charge, functional groups, and mineral components) and main mechanisms governing sorption of As, Cr, Cd, Pb, and Hg by biochar. Biochar properties vary considerably with feedstock material and pyrolysis temperature, with high temperature producing biochars with higher surface area, porosity, pH, and mineral contents, but less functional groups. Different mechanisms dominate sorption of As (complexation and electrostatic interactions), Cr (electrostatic interactions, reduction, and complexation), Cd and Pb (complexation, cation exchange, and precipitation), and Hg (complexation and reduction). Besides sorption mechanisms, recent advance in modifying biochar by loading with minerals, reductants, organic functional groups, and nanoparticles, and activation with alkali solution to enhance metal sorption capacity is discussed. Future research needs for field application of biochar include competitive sorption mechanisms of co-existing metals, biochar reuse, and cost reduction of biochar production. [ABSTRACT FROM AUTHOR]

Inorganic minerals are important compositions in biochars, but their roles in biochar functions are investigated limitedly, which restricted our understanding on biochar applications. This study applied different biomasses to produce biochars. Their properties as well as sorption to bisphenol A (BPA) were studied, with a major focus on the role of inorganic compositions. Oxalates, carbonates, as well as KCl crystals were observed in the produced biochars depending on the feedstocks and temperatures. Oxalates and KCl formed at relatively low temperature (200–300 °C), while carbonates generally formed at pyrolysis temperature above 400 °C. The separated insoluble crystal particles and the dissolved salts have limited contribution to the apparent BPA sorption, but ash content removal altered BPA sorption. The potential impact of inorganic composition to BPA sorption should be resulted from biochar properties. Based on biochar characterization and sorption comparison before and after ash removal, we proposed that the formation of inorganic mineral compositions in biochar particles may have blocked the inner pores, which limited the significance of these sorption sites. As a result, the interactions of BPA and biochars were mostly determined by biochar surface functional groups. The acid treatment removed most of the inorganic compositions, and exposed more sorption sites, which consequently increased BPA sorption. Biochar sorption capacity may be further increased if the accessibility of the inner pores could be enhanced. [ABSTRACT FROM AUTHOR]

In order to investigate contributions of cellulose (CEL), hemicellulose (HEM), lignin (LIG) to the sorption capacity of biochar derived from lignocellulose, the individual component and their artificially modeled biomass mixture (C-H-L) were pyrolyzed under oxygen-limited condition at various pyrolytic temperatures (i.e. 250, 350, 500, 700 °C). The characterization analysis of biochars and sorption batch experiments were carried out. Variations in physiochemical property of different component biochars resulted in discrepancies in their ability to function as sorbents to 1,2,4-trichlorobenzene (1,2,4-TCB). The maximum mass sorption capacity (Q fm ) of 1,2,4-TCB was the greatest on CEL biochars ranging from 58.31 to 601.20 mg g −1 , and can be best explained by their huge surface area and micropore volume. Hydrophobic partitioning-sorption into ‘soft’ amorphous alkyl carbon may account for the second greatest Q fm (45.09–56.57 mg g −1 ) on HEM biochars under low pyrolytic temperatures (250–350 °C) with the lowest surface area. LIG biochars with more compact and smooth aromatic structure surface may undergo a surface monolayer specific adsorption. The Q fm (87.86–196.53 mg g −1 ) on C-H-L biochars were largely dependent on CEL and HEM components for their outstanding sorption capacity and higher content in biomass. Therefore, the results highlighted the importance of CEL and HEM components for 1,2,4-TCB sorption to biochar. [ABSTRACT FROM AUTHOR]

Per- and poly-fluoroalkyl substances (PFAS) can cause deleterious effects at low concentrations (70 ng/L). Their remediation is challenging. Aqueous μg/L levels of PFOS, PFOS, PFOSA, PFBS, GenX, PFHxS, PFPeA, PFHxA, and PFHpA (abbreviations defined in Table 1) multi-component adsorption (pH dependence, kinetics, isotherms, fixed-bed adsorption, regeneration, complex matrix) was studied on commercial Douglas fir biochar (BC) and its Fe 3 O 4 -containing BC. BC is a waste product when syn-gas is produced in a large scale from wet Douglas fir wood fed to gasification at 900–1000 °C and held for 1–20 s. This generates a relatively high surface area (∼700 m2/g) and large pore volume (∼0.25 cm3/g) biochar. Treatment of BC with FeCl 3 /FeSO 4 and NaOH to chemically precipitate Fe 3 O 4 onto BC. BC and its magnetic Fe 3 O 4 /BC analogue rapidly adsorbed (20–45 min equilibrium time) significant amounts of PFOS (∼14.6 mg/g) and PFOA (∼652 mg/g) at natural waters' pH range (6–8). Adsorption from μg/L concentrations has produced remediated aqueous PFAS concentrations of ∼50 ng/L or below the detection limits, which is closing in on EPA advisory limits. Column capacities of PFOS were 215.3 mg/g on BC and 51.9 mg/g Fe 3 O 4 /BC vs 53.0 mg/g and 21.8 mg/g, respectively, for PFOA. Hydrophobic and electrostatic interactions are thought to drive this sorption. Successful stripping regeneration by methanol was achieved. Thus, hydrophobic Douglas fir biochar produced by fast high temperature pyrolysis and its Fe 3 O 4 /BC analogue are adsorbent candidates for PFAS remediation from the dilute PFAS concentrations often found in polluted environments. Small Fe 3 O 4 /BC particles can be magnetically removed from batch treatments avoiding filtration. [Display omitted] • Trace PFOS and PFOA were remediated using commercial Douglas fir biochar variants. • PFOS column capacities were 48–210 mg/g and PFOA capacities were 17–48 mg/g. • Post sorption mixtures gave PFAS levels of ∼50 ppt or below the detection limits. • Micelle driven hydrophobic sorption interactions were sought to be predominant. [ABSTRACT FROM AUTHOR]

Sorption is considered a cost-effective technique for cadmium (Cd) removal from water, while the exhausted Cd-enriched sorbent should be properly disposed of. In this study, pyrolysis of exhausted hydrochar sorbent was conducted at 300–900 °C, and the behavior of Cd and the physicochemical properties and environmental applications of the regenerated biochar were investigated. The vaporization of adsorbed Cd in hydrochar was greatly enhanced by elevating pyrolysis temperature, and almost no Cd was observed in the regenerated biochars obtained at 700–900 °C. In comparison with the raw hydrochar, the regenerated biochars showed higher pH, ash content, and carbon content, while the contents of hydrogen and oxygen decreased. According to the toxicity characteristic leaching procedure result, the toxicity and mobility of Cd in hydrochar were greatly reduced after pyrolysis. Notably, the regenerated biochar showed much higher Cd sorption capacity (26.05–30.24 mg/g) than the raw hydrochar (6.70 mg/g). Surface complexation with oxygen-containing functional groups was the dominant Cd sorption mechanism for hydrochar, and precipitation between Cd2+ and carbonates dominated the Cd removal by the regenerated biochars. These results illuminated that pyrolysis can be an effective technique for the harmless disposal of exhausted hydrochar sorbent and the regeneration of valuable biochar. [Display omitted] • Vaporization of Cd in hydrochar was enhanced by elevating pyrolysis temperature. • The regenerated biochars showed different properties compared with hydrochar. • The toxicity and mobility of Cd in hydrochar were greatly reduced after pyrolysis. • The regenerated biochar showed much higher Cd sorption capacity than hydrochar. • Different mechanisms dominated the Cd sorption by hydrochar and biochar. [ABSTRACT FROM AUTHOR]

Environmental distresses linked to heavy metal (HM) impurity in the water received significant attention among research communities. Recently, advancements in industrial sectors like paper industries, mining, non-ferrous metallurgy, electroplating, mineral paint production, etc. have resulted in massive heavy metals in wastewater. In contrast to organic pollutants, HMs are not recyclable and can be simply engrossed by living organisms. Recently, different solutions have been employed for removing HMs from water and wastewater, like membrane filtration, chemical precipitation, adsorption, ion-exchange, flotation, flocculation, etc. Sorption can be considered one of the efficient solutions for eradicating HMs from waste water. With this motivation, this article concentrates on the design of Remora Optimization with Deep Learning Enabled Heavy Metal Sorption Efficiency Prediction (RODL-HMSEP) model onto Biochar. The proposed RODL-HMSEP technique intends to determine the sorption performance of HMs of various biochar features. Initially, the density based clustering (DBSCAN) technique is applied to simulating the features of metal adsorption data and splitting them into clusters of identical features. Besides, deep belief network (DBN) model was employed for prediction and the efficiency of the DBN model is optimally adjusted with utilize of RO technique. The experimental validation of the RODL-HMSEP technique ensured the promising performance of the RODL-HMSEP technique on the prediction of sorption efficiency onto biochar over other methods The experimental validation of the RODL-HMSEP technique ensured the promising performance of the RODL-HMSEP technique on the prediction of sorption efficiency onto biochar over other methods. [Display omitted] • Remora Optimization with Deep Learning Enabled Heavy Metal Sorption Efficiency Prediction (RODL-HMSEP) model onto Biochar. • RODL-HMSEP technique aims for predicting the sorption performance of HMs of various biochar features. • The RODL-HMSEP model uses density-based clustering (DBSCAN) technique for simulating the features of metal adsorption data. • Deep belief network (DBN) model performs the next phase of data clustering. • RODL-HMSEP technique ensured promising performance on the prediction of sorption efficiency onto biochar over other methods. [ABSTRACT FROM AUTHOR]

Chromium (Cr) contamination in soil and water poses high toxicity risks to organisms and threatens food and water security worldwide. Biochar has emerged as a promising material for cleaning up Cr contamination owing to biochar's strong capacity to immobilize Cr. This paper synthesizes information on biochar modification for the efficient remediation of Cr contamination in soil and water, and critically reviews mechanisms of Cr adsorption on pristine and modified biochars. Biochar modification methods include physical activation via ball milling or ultraviolet irradiation, chemical activation via magnetization, alkali/acid treatment, nano-fabrication or loading of reductive agents, and biological activation via integrating biochars with microorganisms and their metabolites. Modified biochars often have multi-fold enhancement in Cr adsorption/reduction capacity than pristine biochars. Iron (Fe)-supported magnetic biochars have the most promising Cr removal abilities with high reusability of the biochars. Pre-pyrolysis modification with Fe could load Fe 3 O 4 micro-/nanoparticles on biochars, and increase the surface area and electrostatic attraction between chromate anions and biochar surfaces, and reduce Cr(VI) to Cr(III). Post-pyrolysis modification could enrich oxygen-containing functional groups such as C O and –OH on biochar surfaces and promote Cr reduction and adsorption. Future research directions for Cr mitigation using advanced biochar products are discussed in this review. [Display omitted] • Chromium (Cr) biogeochemistry and its remediation using pristine/modified biochars. • Negatively charged O-containing groups on biochar surfaces act as electron donors. • Iron-modified biochars exhibit high Cr removal ability and reusability. • Post-pyrolysis modification enriches O-containing functional groups on biochar. • Biochar-based nanocomposites are effective reductants and adsorbents for Cr(VI). [ABSTRACT FROM AUTHOR]

Soil amendment with biochar may trigger a series of positive and negative biological effects, partly because it interferes quorum sensing (QS) signals synthesized by microorganisms for communication. However, the mechanisms through which biochar interacts with these QS signals remain elusive. This study explored the mechanisms of interactions between N -acyl homoserine lactones (AHLs) and two maize straw-derived biochars (MBs) with different pyrolysis temperature. Pseudo-second-order equation model best depicted AHLs sorption kinetics on MBs. The intra-particle diffusion model revealed that AHLs sorption onto MBs consists of several stages. The sorption isotherms data of AHLs on MBs were in well agreement with both Langmuir and Freundlich models, indicating the occurrence of energetic distribution of active sites on the heterogeneous biochar with multilayer sorption. However, the AHLs sorption capacity on MBs varied, with biochar pyrolyzed at 600 °C displaying a higher AHLs sorption capacity compared with biochar pyrolyzed at 300 °C. It may be attributed to a variety of physiochemical interactions such as pore filling, functional groups complexation, hydrogen bond, and hydrophobic action. The adsorption/partitioning model results and thermodynamic parameters of Gibbs free energy (ΔG) confirmed that physical and chemical sorption occurred concurrently throughout the whole AHLs sorption process, with physical partitioning playing a greater role than surface sorption. The findings suggest that soil amendment with biochar may have a variety of effects on intra/inter-cellular communication, further implying biochar can be specially prepared to mediate soil processes related to microbial communication, like pollutant biodegradation, and carbon/nitrogen cycling. [Display omitted] • Maize biochars (MBs) exhibited superior N -acyl homoserine lactone (AHL) sorption capacity. • Physical sorption dominated the sorption of AHLs onto MBs. • Sorption characteristics of AHLs on MBs are attributed to the physicochemical properties of MBs and AHLs. [ABSTRACT FROM AUTHOR]

The potential for rice husk (RH) and wood chip (WC) biochars to remove levofloxacin (LEV) from aqueous solution was evaluated. The physical and chemical properties of the biochars were characterized using various tools and techniques. Furthermore, batch sorption experiments were conducted to determine the sorption ability of the biochars to LEV. The pseudo-second order kinetic model described the sorption kinetic data better than the pseudo-first order kinetic model and the Elovich equation because the process involved both surface adsorption and pore diffusion. For the isotherms, the Langmuir equation fitted the data better than the Freundlich equation. The maximum Langmuir sorption capacities of the biochars to LEV ranged from 1.49 to 7.72 mg g −1 . Thermodynamic parameters obtained from the experiments showed that the adsorption of LEV onto the WC biochar was spontaneous and exothermic, while its adsorption onto the RH biochar was spontaneous and endothermic under tested conditions. A mixture of 0.025 M phosphate buffer (80%, pH 3.0) and acetonitrile (20%) effectively desorbed the LEV from the biochars with a recovery rate up to 80%. Findings from this work indicate that biochars can be used as an alternative adsorbent to effectively remove emerging contaminants including LEV from aqueous solutions. [ABSTRACT FROM AUTHOR]

The use of biochar has been suggested as a means of remediating contaminated soil and water. The practical applications of conventional biochar for contaminant immobilization and removal however need further improvements. Hence, recent attention has focused on modification of biochar with novel structures and surface properties in order to improve its remediation efficacy and environmental benefits. Engineered/designer biochars are commonly used terms to indicate application-oriented, outcome-based biochar modification or synthesis. In recent years, biochar modifications involving various methods such as, acid treatment, base treatment, amination, surfactant modification, impregnation of mineral sorbents, steam activation and magnetic modification have been widely studied. This review summarizes and evaluates biochar modification methods, corresponding mechanisms, and their benefits for contaminant management in soil and water. Applicability and performance of modification methods depend on the type of contaminants (i.e., inorganic/organic, anionic/cationic, hydrophilic/hydrophobic, polar/non-polar), environmental conditions, remediation goals, and land use purpose. In general, modification to produce engineered/designer biochar is likely to enhance the sorption capacity of biochar and its potential applications for environmental remediation. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are organic micro pollutants which are persistent compounds in the environment due to their hydrophobic nature. Concerns over their adverse effects in human health and environment have resulted in extensive studies on various types of PAHs removal methods. Sorption is one of the widely used methods as PAHs possess a great sorptive ability into the solid media and their low aqueous solubility property. Several adsorbent media such as activated carbon, biochar, modified clay minerals have been largely used to remove PAHs from aqueous solution and to immobilise PAHs in the contaminated soils. According to the past studies, very high removal efficiency could be achieved using the adsorbents such as removal efficiency of activated carbon, biochar and modified clay mineral were 100%, 98.6% and >99%, respectively. PAHs removal efficiency or adsorption/absorption capacity largely depends on several parameters such as particle size of the adsorbent, pH, temperature, solubility, salinity including the production process of adsorbents. Although many studies have been carried out to remove PAHs using the sorption process, the findings have not been consolidated which potentially hinder to get the correct information for future study and to design the sorption method to remove PAHs. Therefore, this paper summarized the adsorbent media which have been used to remove PAHs especially from aqueous solutions including the factor affecting the sorption process reported in 142 literature published between 1934 and 2015. [ABSTRACT FROM AUTHOR]

Heavy metals such as chromium (Cr) and arsenic (As) occur in ionic form in soil, with chromate [Cr(VI)] and arsenate As(V) being the most pre-dominant forms. The application of biochar to Cr(VI) and As(V) spiked and field contaminated soils was evaluated on the reduction processes [(Cr(VI) to Cr(III)] and [As(V) to As(III))], and subsequent mobility and bioavailability of both As(V) and Cr(VI). The assays used in this study included leaching, soil microbial activity and XPS techniques. The reduction rate of As(V) was lower than that of Cr(VI) with and without biochar addition, however, supplementation with biochar enhanced the reduction process of As(V). Leaching experiments indicated Cr(VI) was more mobile than As(V). Addition of biochar reversed the effect by reducing the mobility of Cr and increasing that of As. The presence of Cr and As in both spiked and contaminated soils reduced microbial activity, but with the addition of biochar to these soils, the microbial activity increased in the Cr(VI) contaminated soils, while it was further decreased with As(V) contaminated soils. The addition of biochar was effective in mitigating Cr toxicity by reducing Cr(VI) to Cr(III). In contrast, the conversion process of As(V) to As(III) hastened by biochar was not favourable, as As(III) is more toxic in soils. Overall, the presence of functional groups on biochar promotes reduction by providing the electrons required for reduction processes to occur as determined by XPS data. [ABSTRACT FROM AUTHOR]

Biochars that were produced from pig manure at three different temperatures were amended to sand and cropped with wheat to examine the effect of wheat roots on biochar properties and its sorption capacity. After being aged with wheat roots for three months, the biochar samples showed significant changes in their physicochemical properties, which depended on biochar types and their distances from the roots. In general, the ash content and micropores decreased and the polarity increased after root aging. The changes in the biochar properties in turn affected biochar sorption capacities. The sorption of atrazine and phenanthrene by the biochar that was produced at 300 °C (BC300) both increased by different extents after aging, significantly decreased for BC700, and there were little changes for BC500. The complex changes were due to the different dominant sorption mechanisms for different biochars and different chemicals. For BC700, hydrophobic partition and pore-filling were the main processes, especially for phenanthrene, whereas for BC300, polar interactions dominated. [ABSTRACT FROM AUTHOR]

Sorption behavior of acetochlor (ACE), dibutyl phthalate (DBP), 17α-Ethynyl estradiol (EE2) and phenanthrene (PHE) with biochars produced from three feedstocks (maize straw (MABs), pine wood dust (WDBs) and swine manure (SWBs)) at seven heat treatment temperatures (HTTs) was evaluated. The bulk polarity of these biochars declined with increasing HTT while the aromaticity and CO 2 -surface area (CO 2 -SA) rose. The surface OC contents of biochars were generally higher than bulk OC contents. The organic carbon (OC)-normalized CO 2 -SA (CO 2 -SA/OC) of biochars significantly correlated with the sorption coefficients ( n and log K oc ), suggesting that pore filling could dominate the sorption of tested sorbates. SWBs had higher log K oc values compared to MABs and WDBs, due to their higher ash contents. Additionally, the log K oc values for MABs was relatively greater than that for WDBs at low HTTs (≤400 °C), probably resulting from the higher CO 2 -SA/OC, ash contents and aromaticity of MABs. Surface polarity and the aliphatic C may dominate the sorption of WDBs obtained at relatively low HTTs (≤400 °C), while aromatic C affects the sorption of biochars at high HTTs. Results of this work aid to deepen our understanding of the sorption mechanisms, which is pivotal to wise utilization of biochars as sorbents for hazardous organic compounds. [ABSTRACT FROM AUTHOR]

Carbonaceous materials like biochars are increasingly recognized as effective sorbent materials for sequestering organic pollutants. Here, we study sorption behavior of two common hydrophobic organic contaminants 2,2′,5,5′-tetrachlorobiphenyl (CB52) and phenanthrene (PHE), on biochars and other carbonaceous materials (CM) produced at a wide range of conditions and temperatures from various feedstocks. The primary aim was to establish structure–reactivity relationships responsible for the observed variation in CM and biochar sorption characteristics. CM were characterized for their elemental composition, surface area, pore size distribution, aromaticity and thermal stability. Freundlich sorption coefficients for CB52 and PHE (i.e. Log K F,CB52 and K F,PHE , respectively) to CM showed a variation of two to three orders of magnitude, with Log K F,CB52 ranging from 5.12 ± 0.38 to 8.01 ± 0.18 and Log K F,PHE from 5.18 ± 0.09 to 7.42 ± 1.09. The highest Log K F values were observed for the activated CM, however, non-activated biochars produced at high temperatures (>700 °C) sorbed almost as strongly (within 0.2–0.5 Log units) as the activated ones. Sorption coefficients significantly increased with pyrolysis temperature, CM surface area and pore volume, aromaticity, and thermal stability, and decreased with H/C, O/C, (O + N)/C content. The results of our study contribute to the understanding of processes underlying HOC sorption to CM and explore the potential of CM as engineered sorbents for environmental applications. [ABSTRACT FROM AUTHOR]

The sorption strength of neutral organic compounds to charcoal, also called biochar was reviewed and related to charcoal and compound properties. From 29 studies, 507 individual Freundlich sorption coefficients were compiled that covered the sorption strength of 107 organic contaminants. These sorption coefficients were converted into charcoal-water distribution coefficients (K D ) at aqueous concentrations of 1 ng/L, 1 µg/L and 1 mg/L. Reported log K D values at 1 µg/L varied from 0.38 to 8.25 across all data. Variation was also observed within the compound classes; pesticides, herbicides and insecticides, PAHs, phthalates, halogenated organics, small organics, alcohols and PCBs. Five commonly reported variables; charcoal production temperature T, surface area SA, H/C and O/C ratios and organic compound octanol–water partitioning coefficient, were correlated with K D values using single and multiple-parameter linear regressions. The sorption strength of organic compounds to charcoals increased with increasing charcoal production temperature T, charcoal SA and organic pollutant octanol–water partitioning coefficient and decreased with increasing charcoal O/C ratio and charcoal H/C ratio. T was found to be correlated with SA (r 2 = 0.66) and O/C (r 2 = 0.50), particularly for charcoals produced from wood feedstocks (r 2 = 0.73 and 0.80, respectively). The resulting regression: log K D = (0.18 ± 0.06) log K ow + (5.74 ± 1.40) log T + (0.85 ± 0.15) log SA + (1.60 ± 0.29) log OC + (−0.89 ± 0.20) log HC + (−13.20 ± 3.69), r 2 = 0.60, root mean squared error = 0.95, n = 151 was obtained for all variables. This information can be used as an initial screening to identify charcoals for contaminated soil and sediment remediation. [ABSTRACT FROM AUTHOR]

Amendments of biochar, a product of pyrolysis of biomass, have been shown to increase fertility of acidic soils by enhancing soil properties such as pH, cation-exchange-capacity and water-holding-capacity. These parameters are important in the context of natural organic matter contained in soils, of which dissolved organic matter (DOM) is the mobile and most bioavailable fraction. The effect of biochar on the content and composition of DOM in soils has received little research attention. This study focuses on the effects of amendments of two different biochars to an acidic acrisol and a pH-neutral brown soil. A batch experiment showed that mixing biochar with the acrisols at a 10 wt.% dose increased the pH from 4.9 to 8.7, and this resulted in a 15-fold increase in the dissolved organic carbon concentration (from 4.5 to 69 mg L −1 ). The pH-increase followed the same trend as the release of DOM in the experiment, causing higher DOM solubility and desorption of DOM from mineral sites. The binding to biochar of several well-characterised reference DOM materials was also investigated and results showed a higher sorption of aliphatic DOM to biochar than aromatic DOM, with DOM-water partitioning coefficients ( K d -values) ranging from 0.2 to 590 L kg −1 . A size exclusion occurring in biochar’s micropores, could result in a higher sorption of smaller aliphatic DOM molecules than larger aromatic ones. These findings indicate that biochar could increase the leaching of DOM from soil, as well as change the DOM composition towards molecules with a larger size and higher aromaticity. [ABSTRACT FROM AUTHOR]

Per- and polyfluorinated compounds (PFCs) have been attracting increasing attention due to their considerable persistence, bioaccumulation, and toxicity. Here, we studied the sorption behavior of three PFCs, viz. perfluorooctanesulfonic acid (PFOS), perfluorooctanecarboxylic acid (PFOA), perfluorohexanesulfonic acid (PFHxS), on one activated carbon (AC) and two biochars from different feedstocks, viz. mixed wood (MW) and paper mill waste (PMW). In addition, we explored the potential of remediating three natively PFC contaminated soils by the addition of AC or biochar. The sorption coefficient i.e. Freundlich coefficients Log K F , (μg/kg)/(μg/L) n , for the two biochars were 4.61 ± 0.11 and 4.41 ± 0.05 for PFOS, 3.02 ± 0.04 and 3.01 ± 0.01 for PFOA, and 3.21 ± 0.07 and 3.18 ± 0.03 for PFHxS, respectively. The AC sorbed the PFCs so strongly that aqueous concentrations were reduced to below detection limits, implying that the Log K F values were above 5.60. Sorption capacities decreased in the order: AC > MW > PMW, which was consistent with the material’s surface area and pore size distribution. PFC sorption to MW biochar was near-linear (Freundlich exponent n F of 0.87–0.90), but non-linear for PMW biochar (0.64–0.73). Addition of the AC to contaminated soils resulted in almost complete removal of PFCs from the water phase and a significant (i.e. 1–3 Log unit) increase in soil–water distribution coefficient Log K d . However, small to no reduction in pore water concentration, and no effect on Log K d was found for the biochars. We conclude that amendment with AC but not biochar can be a useful method for in situ remediation of PFC-contaminated soils. [ABSTRACT FROM AUTHOR]

Two experiments were conducted where three biochars, made from macadamia nutshell (MS), hardwood shaving (WS) and chicken litter (CL), were co-composted with chicken manure and sawdust, and also incubated with a chicken litter based commercial compost. Biochars were added at the rates of 5% and 10% in the co-composting and 10% and 20% in the incubation experiment. The rates of biochar had no consistent effect on the change in element contents of composted- or incubated-biochars. The biochar C demonstrated recalcitrance in both composting and incubation systems. Composting increased the CEC of biochars probably due to thermophilic oxidation. The increases in CEC of WS and CL were 6.5 and 2.2 times, respectively, for composting. Translocation of elements, between biochar and compost medium, occurred in both directions. In most cases, biochars gained elements under the influence of positive difference of concentrations (i.e., when compost medium had higher concentration of elements than biochar), while in some cases they lost elements despite a positive difference. Biochar lost some elements (WS: B; CL: B, Mg and S) under the influence of negative difference of concentrations. Some biochars showed strong affinity for B, C, N and S: the concentration of these elements gained by biochars surpassed the concentration in the respective composting medium. The material difference in the biochars did not have influence on N retention: all three netbag-biochars increased their N content. The cost of production of biochar-compost will be lower in co-composting than incubation, which involves two separate processes, i.e., composting and subsequent incubation. [ABSTRACT FROM AUTHOR]

Sorption behavior of propiconazole (PROPI) by plant-residue derived biochars (PLABs) and animal waste-derived biochars (ANIBs) obtained at three heating treatment temperatures (HTTs) (300, 450 and 600 °C) (e.g., BCs300, BCs450, and BCs600) and their corresponding de-ashed BCs450 was investigated. PLABs belonged to high- or medium-C biochars and ANIBs were low-C biochars. Surface C concentrations of the tested biochars were generally higher than their corresponding bulk C. Surface polar groups were mainly composed of O-containing groups of minerals within biochars. The nonlinearity coefficients ( n ) of propiconazole (PROPI) sorption isotherms ranged from 0.23 to 0.64, which was significantly and negatively related to organic carbon (OC)–normalized CO 2 -surface area (CO 2 -SA/OC) of biochars. This correlation along with the positive relationship between CO 2 -SA/OC and aromaticity indicates that pore-filling in nanopores within aromatic C dominate nonlinear PROPI sorption. HTTs or C contents do not necessarily regulate PROPI sorption. Removal of minerals from BCs450 elevated PROPI sorption because minerals may exert certain influence on sorption via impacting spatial arrangement of polar groups and/or organic matter (OM)–mineral interactions. This study helps to better understand sorption behavior of PROPI to biochars and evaluate the potential role of biochar in water treatment systems. [ABSTRACT FROM AUTHOR]

Various sorbent materials were evaluated for the fractionation of naphthenic acid fraction components (NAFCs) from oil sand process-affected water (OSPW). The solid phase materials include activated carbon (AC), cellulose, iron oxides (magnetite and goethite), polyaniline (PANI) and three types of biochar derived from biomass (BC-1; rice husks, BC-2; acacia low temperature and BC-3; acacia high temperature). NAFCs were semi-quantified using electrospray ionization high resolution Orbitrap mass spectrometry (ESI-MS) and the metals were assessed by inductively coupled plasma optical emission spectrometry (ICP-OES). The average removal efficacy of NAFCs by AC was 95%. The removal efficacy decreased in the following order: AC, BC-1 > BC-2, BC-3, goethite > PANI > cellulose, magnetite. The removal of metals did not follow a clear trend; however, there was notable leaching of potassium by AC and biochar samples. The bound NAFCs by AC were desorbed efficiently with methanol. Methanol regeneration and recycling of AC revealed 88% removal on the fourth cycle; a 4.4% decrease from the first cycle. This fractionation method represents a rapid, cost-effective, efficient, and green strategy for NAFCs from OSPW, as compared with conventional solvent extraction. [ABSTRACT FROM AUTHOR]

Carbon (C)-rich, solid products from pyrolysis (pyrochars) and hydrothermal carbonization (HTC, hydrochars) are expected to reduce the bioavailability and bioaccessibility of pesticides as side effect of soil addition. To compare effects of different feedstocks (digestate, miscanthus, woodchips) and production processes (pyrolysis at 750 °C, HTC at 200 °C and 250 °C), 14 C-labeled isoproturon (IPU) was applied at 0.75 kg ha − 1 to loamy sand amended either with 0.5% or 5% pyrochars or hydrochars, which was then incubated for 50 d. Mineralization of IPU was measured as 14 C–CO 2 released from soil-char composites. Pore-water and methanol extractable 14 C-IPU was quantified as well as non-extractable 14 C-residues (NER). Furthermore, C mineralization of pyrochars, hydrochars and feedstocks was studied to assess the relationship between IPU bioaccessibility and char decomposability. In pure soil, 8.1% of applied IPU was mineralized after 50 d. This was reduced more strongly in pyrochar treatments (81 ± 6% reduction) than in hydrochar treatments (56 ± 25% reduction). Different feedstocks had no significantly different effect when 5% char was added, but their effect was significant and dependent on the production process in 0.5% amendments. Pesticide binding can occur by surface sorption as well as by diffusion and subsequent occlusion in micropores. The latter can be expected to result in high amounts of NER, as it was observed in the pyrochar treatments. Hydrochars were less stable than pyrochars and contained lower amounts of NER. Thus, in hydrochar amended soils, better accessibility of IPU to microbial degradation may be a result of full char decomposition within decades ensuring controlled pesticide degradation. [ABSTRACT FROM AUTHOR]

Sludge derived biochars (SDBCs) may have the potential to simultaneously remove heavy metals and organic contaminants in relation to their various active sorption sites for both metal ions and organic compounds. SDBCs have been proven to provide a considerable capacity for immobilizing Pb(II) and Cr(VI) ions in solution, and in this study their ability to sorb atrazine, in addition to their corresponding interactive influences with coexisting metal ions, is extensively investigated. The results indicate that all atrazine adsorption isotherms fit well with the Freundlich equation, and the greatest value of 16.8 mg g −1 sorption capacity occurred with SDBCs pyrolyzed at 400 °C for 2 h. The slow sorption kinetics fit well with the Lagergren’s 2nd order reaction, and depend upon the initial atrazine concentration, indicating the significance of a site-specific process. The ionic strength-dependence of the atrazine adsorption behavior further consolidates the involvement of the mechanism of the H-bond with hydroxyl groups on SDBC. However, when Pb(II)/Cr(VI) metal ions coexist in solution, they substantially suppress atrazine adsorption, probably because the inner complex between the hydroxyl groups on SDBCs and Pb(II)/Cr(III) ions intrude the weak H-bond with atrazine. As a result, metal adsorption was found to be unaffected by the coexisting atrazine. Therefore, although SDBC is applicable for atrazine removal/immobilization in most of environmentally relevant conditions, a two-step process may be required if heavy metal ions coexist. [ABSTRACT FROM AUTHOR]

The sorption of two monoterpenes, α pinene and limonene to the carbonaceous geosorbents graphite, bituminous coal, lignite coke, biochar and Pahokee peat was quantified. Polyethylene (PE) passive samplers were calibrated for the first time for these compounds by determining the PE-water partitioning coefficients and used as a tool to determine sorption to the carbonaceous geosorbents. Log K PE-water values were 3.49 ± 0.58 for α pinene and 4.08 ± 0.27 for limonene. The sorption of limonene to all materials was stronger than that for α pinene (differences of 0.2–1.3 log units between distribution coefficients for the monoterpenes). Placing K d values in increasing order for α pinene gave biochar ≈ Pahokee peat ≈ bituminous coal ≈ lignite coke < graphite. For limonene the order was: Pahokee peat ≈ biochar ≈ bituminous coal < graphite ≈ lignite coke. Micropore (defined as pores <1.5 nm) and nanopore surface area (defined as pores 1.5 nm to 50 nm) normalised carbonaceous geosorbent-water distribution coefficients were also calculated. There was no clear correlation of these distribution coefficients with SA. Elemental composition was used to assess the degree of condensation (or alteration) of the carbonaceous geosorbents. The degree of carbonisation increased in the order; Pahokee peat < lignite coke < bituminous coal < biochar < graphite, however this was not correlated with an increase in the experimental distribution coefficients. [ABSTRACT FROM AUTHOR]

Highlights: [•] No effect of biochar on the sorption of three out of four tested compounds. [•] Sorption of a chloridazon metabolite enhanced due to higher organic matter content. [•] No significant effect of the biochar amendment on desorption. [•] Biochar has limited potential to mitigate the leaching of polar pollutants in soil. [Copyright &y& Elsevier]

Freshwater sludge (FS) produced from drinking water treatment plants is generally filter pressed and disposed in the landfill. However, FS could be potentially reused. In this study, FS were processed into biochar and hydrochar via pyrolysis and hydrothermal carbonization, respectively. The sorption characteristics/mechanisms of FS and its derivatives (biochar-B300, B500 and B700 and hydrochar-H140, H160, H180 and H200) for the removal of three typical pollutants (i.e., lead (Pb), phosphorus (P) and enrofloxacin (ENR)) found in swine wastewater were investigated using batch adsorption tests and microstructural analyses. It was found that Pb sorption was relatively enhanced due to the increased electrostatic attraction and surface precipitation of Pb(OH) 2 while the anionic phosphate adsorption relatively decreased as a result of enhanced electrostatic repulsion at higher solution pHs. Comparatively, ENR adsorption was less affected by solution pH probably due to dominance of physical adsorption evidenced by the good fitting of the BET isotherm model (R2 = 0.95). The maximum sorption capacities of Pb were in the order of B700≈B500 (71 mg/g)>B300 ~ FS(37 mg/g)>H140 ~ H160 (13 mg/g)>H180 ~ H200 (6 mg/g). The adsorption capacities for P were relatively lower: FS (47 mg/g)>B300 (38 mg/g)>H140 (27 mg/g)>B700 (37 mg/g)≈B500 (24 mg/g)≈H160 (23 mg/g)>H180 (16 mg/g)>H200 (14 mg/g). This study provides an understanding of the sorption characteristics and mechanisms of FS and its carbonaceous products for common cationic, anionic and organic pollutants and elucidates new insights into the reuse of FS for pollutant removal to achieve the waste-to-resource concept and enhance water quality, soil health and food safety. [Display omitted] • Remove Pb, P and ENR with FS and derived biochar and hydrochar. • Adsorption capacity for Pb follows order of biochar > FS > hydrochar. • Adsorption capacity for P follows order of FS > biochar > hydrochar. • ENR adsorption follows BET isotherm model, dominated by physical adsorption. • Adsorption on all adsorbents was affected by solution pH. [ABSTRACT FROM AUTHOR]