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Globally, water resources are facing serious threat owing to the increasing concentration of various emerging contaminants. Indiscriminately discarded and/or excreted antibiotics and their residues are one such emerging contaminants. Since long-term persistence of these residues in environment is responsible for developing antimicrobial (antibacterial) resistance in the organisms, their removal from water / wastewater is essential. Hence, scientists are attempting to evolve novel methods to encounter antibiotics and their residues in water. One such method is the adsorption of antibiotics onto a suitable matrix thereby reducing their concentration in water. Biochar has been proven to act as a suitable adsorbent for various contaminants; however, their removal efficiency remains a concern. Therefore, functionalization of biochar using various physical and chemical modifications, was developed as a technique that can help in efficient removal of antibiotics. Functionalization has been seen to improve the physical and chemical properties of biochar; such as, pore volume, pore diameter, surface morphology, surface functional groups, polarity, porosity etc. In this review, functionalized biochars have been explored to understand their efficacy and mechanism for the removal of antibiotics and their residues. The discussion includes biochar functionalization methods, impact of property modifications on the removal of antibiotic residues, and their removal mechanism. In addition, cost-effectiveness, economy of the adsorption process, and its environmental effects have also been dealt with.

This study evaluates the effectiveness of iron-modified biochar (Fe-BC) in fixed-bed heterogeneous Fenton processes for levofloxacin (LFX) removal, a widely-used fluoroquinolone antibiotic. The objective is to optimize parameters such as pH, oxidants (H2O2 and S2O82−), and biochar forms (functionalized and raw) using factorial analysis of mixed data (FAMD) and response surface methodology (RSM). These optimizations identified the ideal conditions for maximal LFX removal. The most effective removal with Fe-BC occurred at 2.5 mM H2O2 and pH 7.5, while the optimal S2O82− conditions were 1.6 mM at pH 2.8. Both Fe-BC and raw biochar (RBC) showed the highest adsorption at pH 5.8. In adsorption-only, RBC and Fe-BC reduced LFX to 530 μg/L and 335 μg/L, respectively, in 60 min. The oxidation process further decreased LFX levels to between 8.9 μg/L and 0.1 μg/L using S2O82− and H2O2, respectively. The research expanded upon a kinetic model, incorporating the calculation of kinetic constants for both adsorption and oxidation processes, to deepen our understanding of the intricate degradation dynamics at play. Identifying by-products was crucial in elucidating degradation pathways. These findings are vital for environmental remediation, demonstrating the efficiency of Fe-BC in removing harmful antibiotics from water. This research highlights the potential of modified biochar in environmental clean-up, especially for water contaminated with antibiotics. The results emphasize the importance of optimizing treatment conditions for effective antibiotic removal, contributing valuable insights to the field of environmental remediation.

Licorice processing waste was pyrolyzed at different temperatures (500 and 700 °C) to obtain biochar (BC500 and BC700) for use as a slow-release fertilizer on Solanum lycopersicum. The materials were characterized through BET analysis, SEM, elemental analysis, pHzc, and pyrolysis temperature effect was evaluated. The biochars were functionalized by the impregnation method to enrich them with nitrogen, phosphorus, and potassium (NPK), and desorption tests were performed in aqueous solution at different pHs (5 and 7). The pseudo-second-order model described well the release of all 3 macronutrients tested, BC500 was found to have slower release kinetics due to smaller pore size, reaching adsorption/desorption equilibrium after 14 days, compared with 10 for BC700, Kdes were lower in all 3 cases and NPK content was higher, initial pH did not change the release kinetics. BC500 was selected as an agricultural soil conditioner by testing at both different dosages of BC (0–25 %) and different NPK ratios (3:1:4 and 4:1:3). The treatment significance was evaluated. The best treatment resulted in BC dosage of 25 % nutrient ratio 4:1:3 which increased, compared to the control, total chlorophyll content (+38 %) and carotenoids (+15 %).

Chemical fertilizer (CF) has been widely applied to promote agricultural production in recent years. However, the high solubility of nitrogen (N) and phosphorus (P) in the traditional CF can reduce the nutrient absorption rate of crops, leading to serious environmental issues. Therefore, an alternative fertilizer is required to recover the N and P organic matter from water, in order to promote the sustainable development of agricultural production. Fortunately, biochar can serve as one type of potential cost-effective adsorbent to reclaim the nutrients (e.g., phosphate and ammonium) from wastewater. A win-win strategy can be expected to develop a biochar-based fertilizer for the remediation of wastewater. In this work, the agricultural wastes (such as corn straw and eggshell) were employed to prepare the Ca/Mg-enriched biochar fertilizer (Ca/Mg-BCF) via magnesium salt impregnation, pyrolysis transformation process, and high-efficiency reclaiming of N- and P-containing nutrients from biogas effluent. Then, a series of leaching experiments and kinetics analysis were performed to explore the N and P slow-release behavior of Ca/Mg-BCF. Meanwhile, a systematic investigation was implemented to clarify the effects of environmental factors (pH and temperature) on the N and P slow-release performance. The physical and chemical properties of Ca/Mg-BCF before and after nutrient release were also characterized with X-ray diffraction (XRD) and scanning electron microscope (SEM) equipped with an energy-dispersive X-ray spectrometer (EDX). In addition, a comparison was made to determine the effects of Ca/Mg-BCF on the seed germination and early-stage seedling growth of corn. The results demonstrated that the final accumulative release ratios of N and P from the Ca/Mg-BCF at 48 h were 16, and 9.6 times lower than those of CF, respectively. The leaching experiment indicated that the Ca/Mg-BCF exhibited excellent slow-release performances of the total P and N with sustainable release rates. Moreover, there was no significant effect on the nutrient release from the Ca/MgBCF at temperatures between 10-40 ℃. The N- and P-release were stable between pH 1-7 and pH 3-10, respectively. The SEM characterization showed that the remarkable morphological transformation occurred after Ca/Mg-BCF released nutrients, due to the dissolving of struvite and the formation of CaHPO4 and Ca3 (PO4 )2 . The P-release performance of Ca/Mg-BCF was controlled by the low solubility of Mg-P precipitates that formed on the biochar surface, and then enhanced by the ‘P-trap’ effect of Ca(OH)2 and CaCO3 in the re-precipitation process of 4 3− . Therefore, the N and P-release performance of Ca/Mg-BCF was attributed to the multiple effects, including the dissolution rate of N/P precipitates, re-precipitation of PO4 3− by Ca(OH)2 and CaCO3, electrostatic attraction, hydrogen bonds, pore-filling, and the confinement of biochar. In addition, the Ca/Mg-BCF greatly promoted the seed germination and the growth of corn seedlings, compared with the control and CF. Specifically, the Ca/Mg-BCF-0.8 treatment exhibited a higher seed germination rate of 100%, compared with the control (80%) and CF treatments (40%) in the first five days. This was probably because the fast release rate of N and P from CF caused the salt-stress effect on the seed germination. The height, root length, stem diameter of the corn seedlings, and dry weight of the shoot and root increased by 9.50%, 24.63%, 14.53%, 16.59%, and 38% respectively, after Ca/Mg-BCF-0.8 treatment, compared with the CF. It infers that sufficient nutrients were supplied for the plant growth in a longer period, indicating that the slow-release performance of Ca/Mg-BCF was better matched with the nutrient requirement of plants. In addition, the excellent properties of biochar carriers can be expected to improve the soil environment for a favorable rhizosphere of root growth. Therefore, the Ca/Mg-BCF can be promising potential for sustainable agriculture application with multiple environmental benefits. [ABSTRACT FROM AUTHOR]

Biochar obtained from Moringa seeds husks was functionalized with protein extracted from Moringa kernels powder resulting in a composite biochar (BC-MOP). The functionalization of its surface was characterized by FTIR spectroscopy, which showed the appearance of peaks indicative of protein functions (amines and ketones), confirming the consolidation of the surface. This composite was tested in humic acid (HA) removal from an aqueous solution, and its adsorption capacity was evaluated by comparison with that of biochar (BC). Removal rates favored the composite 81.4 mg g0 for BC-MOP and 41 mg g–1 for BC when the temperature was 25°C which demonstrated the impact of functionalization. The operating parameters pH, contact time, and dose of adsorbent were optimized, and it was found that solution pH played a crucial role in the adsorption process. The adsorption isotherms of the HA fit the Langmuir model better than the Freundlich model, and the adsorption kinetics followed the pseudo-second-order model. The adsorption was chemisorption in nature. The degradation of HA into units of low molecular weight substances was proved by FTIR spectrum and UV absorption after adsorption of HA. This study contributed to the development of new composite biochars with high adsorbent capacity toward organic pollutants. [ABSTRACT FROM AUTHOR]

Using biochar for dye wastewater treatment is attracting interest due to its excellent adsorption properties and low costs. In this work, a novel biochar derived from oxytetracycline fermentation residue (functionalized OFR biochar, FOBC) was investigated as a efficient adsorbent for typical dyes removal. At 25 °C, the maximum adsorption capacity calculated by Langmuir model of FOBC-3-600 for methylene blue (MB), malachite green (MG), and methyl orange (MO) reached 643.97, 617.89, and 521.03 mg/g, respectively. The kinetics and isotherm model fitting showed that the chemisorption and physisorption both occurred during the adsorption process. Dyes were efficiently adsorbed through pore filling, electrostatic attraction, π-π interactions, and surface complexation. And the cycling experiment and environmental risk assessment indicated that the FOBC-3-600 had excellent recyclability and utilization safety. Overall, this study provides a practical method to simultaneously treat the dyeing wastewater and utilize the antibiotic fermentation residue. [Display omitted] • Oxytetracycline fermentation residue was converted into N-doped porous biochar. • FOBC-3-600 had high specific space area (1269 m2/g) and nitrogen content (5.85 wt%). • FOBC-3-600 showed a superior adsorption capacity for three typical dyes. • Chemisorption played a major role in the adsorption process. • FOBC-3-600 had excellent recyclability and utilization safety. [ABSTRACT FROM AUTHOR]

The impact of functionality of biochar on pressing environmental issue of cadmium (Cd) and lead (Pb) co-contamination in simultaneous soil and water systems has not sufficiently reported. This study investigated the impact of Fe- and Mg-functionalized wheat straw biochar (Fe-WSBC and Mg-WSBC) on Cd and Pb adsorption/immobilization through batch sorption and column leaching trials. Importantly, Fe-WSBC was more effective in adsorbing Cd and Pb (82.84 and 111.24 mg g−1), regeneration ability (removal efficiency 94.32 and 92.365), and competitive ability under competing cations (83.15 and 84.36%) compared to other materials (WSBC and Mg-WSBC). The practical feasibility of Fe-WSBC for spiked river water verified the 92.57% removal of Cd and 85.73% for Pb in 50 mg L−1 and 100 mg L−1 contamination, respectively. Besides, the leaching of Cd and Pb with Fe-WSBC under flow-through conditions was lowered to (0.326 and 17.62 mg L−1), respectively as compared to control (CK) (0.836 and 40.40 mg L−1). In short, this study presents the applicable approach for simultaneous remediation of contaminated water and soil matrices, offering insights into environmentally friendly green remediation strategies for heavy metals co-contaminated matrices. [Display omitted] • The functionalized biochars were deployed under batch adsorption and leaching trial. • Fe-WSBC adsorbed higher Cd and Pb (82.84 and 111.24 mg g−1) than Mg-WSBC and WSBC. • The leachability of Cd and Pb was reduced to 0.326 and 17.62 mg L−1 with Fe-WSBC • Fe-WSBC altered the metals' exchangeable form to residual form, lowering the leaching. [ABSTRACT FROM AUTHOR]

The extraction methods for antimicrobial peptides (AMPs) from plants are varied, but the absence of a standardized and rapid technique remains a challenge. In this study, a functionalized biochar was developed and characterized for the extraction of AMPs from pea protein hydrolysates. The results indicated that the biochar mainly enriched AMPs through electrostatic interaction, hydrogen bonding and pore filling. Then three novel cationic antimicrobial peptides were identified, among which the RDLFK (Arg-Asp-Leu-Phe-Lys) had the greatest inhibitory effect against Staphylococcus aureus and Bacillus subtilis, showcasing IC 50 value of 2.372 and 1.000 mg/mL, respectively. Additionally, it was found that RDLFK could damage bacterial cell membranes and penetrate the cells to inhibit DNA synthesis. These results provided that the biochar-based extraction method presents an efficient and promising avenue for isolating AMPs, addressing a critical gap in the current methodologies for their extraction from plant sources., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. The authors declare no conflicts of interests., (Copyright © 2024. Published by Elsevier Ltd.)

Licorice processing waste was pyrolyzed at different temperatures (500 and 700 °C) to obtain biochar (BC500 and BC700) for use as a slow-release fertilizer on Solanum lycopersicum . The materials were characterized through BET analysis, SEM, elemental analysis, pH zc , and pyrolysis temperature effect was evaluated. The biochars were functionalized by the impregnation method to enrich them with nitrogen, phosphorus, and potassium (NPK), and desorption tests were performed in aqueous solution at different pHs (5 and 7). The pseudo-second-order model described well the release of all 3 macronutrients tested, BC500 was found to have slower release kinetics due to smaller pore size, reaching adsorption/desorption equilibrium after 14 days, compared with 10 for BC700, K des were lower in all 3 cases and NPK content was higher, initial pH did not change the release kinetics. BC500 was selected as an agricultural soil conditioner by testing at both different dosages of BC (0-25 %) and different NPK ratios (3:1:4 and 4:1:3). The treatment significance was evaluated. The best treatment resulted in BC dosage of 25 % nutrient ratio 4:1:3 which increased, compared to the control, total chlorophyll content (+38 %) and carotenoids (+15 %)., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Although biochar (BC) has been widely used to adsorb pollutants in environment due to its natural and green characteristics, the structural defects of BC limit the ability to remove various environmental pollutants in aqueous solution. In this study, oxidized biochar (OBC) and sulfhydryl biochar (SBC) derived from pomelo peel (PP) were prepared through an oxidation and esterification reaction. BC and modified BC were used for the removal of methylene blue (MB), Cd2+, and phenanthrene (PHE) in aqueous solution. The adsorption behavior and efficiency toward different types of pollutants were studied by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), Raman, X-ray photoelectron spectroscopy (XPS), kinetics, and isotherm model fitting. The results showed that the change of pH had great effect on MB and Cd2+ adsorption, but not on PHE. SBC not only possessed the newly formed sp2-hybridized domains with easy access to aromatic pollutants but also had multiple functional groups (-COOH, -OH, -SH, -NH2) that provided adsorption sites for positively charged pollutants. SBC was more flexible and efficient in purifying pollutants compared to BC and OBC, with the saturated adsorption capacities of MB (209.16 mg/g), Cd2+ (786.19 mg/g), and PHE (521.58 mg/g). Moreover, the adsorption kinetic and isotherms fitting showed that the adsorption mechanisms were closely related to the structure of biochar and the properties of pollutants, including π-π interaction, surface charge, electrostatic interaction, surface functional groups, and Van der Waals force. In addition, the analysis of structure-function relationship demonstrated the enhanced hydrophilicity and the easy exposure of the binding sites on OBC and SBC. Hence, it was significantly effective to regulate microstructure and interfacial properties to promote its adsorption behaviors of biochar. [ABSTRACT FROM AUTHOR]

The functionalized biochar was assembled on modified zeolite to synthesize a novel modified composite adsorbent. The latter was applied to simultaneous adsorption of ammonium and nitrate. The Box–Behnken design (BBD) in response surface methodology (RSM) was applied to optimize the parameters, which included ratio of raw materials, adsorbent dose, pH, and temperature. The chemical functional groups were determined by Fourier transform infrared adsorption (FT-IR). Stronger absorption peaks of amine groups indicated that the functionalized adsorbent could enhance the adsorption of contaminants. The composite adsorbent effectively increased NH4+ and NO3− adsorption capacity by porous structure recombination, change of surface morphology and further exposure of surface functional groups. The kinetic results indicate that the adsorption of both NH4+ and NO3− follows a pseudo-second-order nonlinear model. The Langmuir isotherm model fitted well the experimental data with a maximum adsorption capacity of 24.45 mg/g for nitrate and 24.63 mg/g for ammonium at 25°C. Nitrate was absorbed by electrostatic interactions with grafted amine groups and, in contrast, the ammonium adsorption was mainly related to ion exchange with Na+. The adsorption process of both nitrate and ammonium were spontaneous and exothermic. The adsorbents can be regenerated effectively in NaCl and NaOH mixed solutions, and the desorbed adsorbents are of high reusability and can be applied effectively at least for five cycles. Therefore, it has a great potential for nitrate and ammonium simultaneous removal from water environment. [ABSTRACT FROM AUTHOR]

Biochar (BC) has been widely used to remove heavy metals from wastewater. However, due to the hydrophobicity of BC and the lack of its surface functional groups, the effect of metal ions adsorption onto BC is limited. In order to improve the adsorption efficiency, l-cysteine was used to modify biochar derived from pomelo peel (PP) to regulate surface structure. The characteristics of BC and cysteine/biochar composite (cys/BC) were analyzed by various characterization methods. Results showed that the hydrophilicity of biochar was enhanced, and the number of surface functional groups was increased, resulting to strong adsorption ability of Ag(I) (618.9 mg/g), Pb(II) (274.5 mg/g), and As(V) (34.7 mg/g) for cys/BC, which increased approximately by 15%, 35%, and 29% compared with that of BC, respectively. The adsorption process of Pb(II) onto cys/BC was fitted better by the Freundlich isotherm model and for Ag(I) and As(V) by the Langmuir isotherm model. Moreover, the adsorption kinetics followed pseudo-second-order equation and the adsorption process was controlled by the intraparticle diffusion for Ag(I), Pb(II), and As(V) adsorption onto cys/BC. In addition, the adsorption capacities of cys/BC for Ag(I), Pb(II), and As(V) decreased slightly after five adsorption/desorption cycles. Finally, the multiple adsorption mechanisms including functional groups, pore adsorption, surface complexation, and cations-π were analyzed. The paper demonstrated that the cys/BC composite could be reused as effective adsorbents for removing contaminants in the environment. [ABSTRACT FROM AUTHOR]

Sorption and oxidation are two potential pathways for the decontamination of trivalent antimony (Sb(III))-bearing water, using iron (Fe)-modified biochar (FeBC). Here we investigated the sorption and oxidation behavior of FeBC for Sb(III) in aqueous solutions. Results revealed that Sb(III) removal by FeBC was significantly improved showing the maximum Sb(III) sorption (64.0 mg g−1). Density functional theory (DFT) calculations indicated that magnetite (Fe 3 O 4) in FeBC offered a sorption energy of −0.22 eV, which is 5 times that of non-modified biochar. With the addition of peroxymonosulfate (PMS), the sorption of Sb(III) on FeBC was 7 times higher than that on BC, indicating the sorption capacity of FeBC for Sb(III) could be substantially increased by adding oxidizing agents. Electrochemical analysis showed that Fe modification imparted FeBC higher electron-donating capacity than that of BC (0.045 v. s. 0.023 mmol e− (g biochar)−1), which might be the reason for the strong Sb(III) oxidation (63.6%) on the surface of FeBC. This study provides new information that is key for the development of effective biochar-based composite materials for the removal of Sb(III) from drinking water and wastewater. The findings from this study have important implications for protecting human health and agriculture. [Display omitted] • Fe 3 O 4 loading can increase E ads of Sb(III) over C O on biochar. • Most of the Sb(III) was oxidized by FeBC500 after sorption. • The electron-donating capacities of Fe-modified biochar increased by 195.6%. • A combination of FeBC500 and peroxymonosulfate greatly increased Sb(III) adsorption. [ABSTRACT FROM AUTHOR]

For soil and environmental remediation, biochar/struvite composites are prepared by the crystallization-adsorption method. The recovery rates of N, P, and Mg in the solution increase to 99.02%, 97.23%, and 95.22%, respectively, by forming 10% biochar/struvite composite. X-ray diffraction (XRD) patterns acquired from the 10% biochar/struvite composite show a crystalline structure of MgNH4PO4·6H2O (PDF no. 15-0762) and release of the main nutrient elements (N, P, Mg) from the 10% biochar/struvite composite increases significantly compared to struvite. The solubility of the biochar/struvite composite is the highest in 0.5 mol/L HCl, second in 20 g/L citric acid, and lowest in water. The power function equation describes more precisely the cumulative release of N, P, and Mg from the biochar/struvite composite in distilled water, whereas it follows the simple Elovich equation in 20 g/L critic acid and first-order kinetics equation in 0.5 mol/L HCl. Leaching experiments are performed on the biochar/struvite composite in soil, and the results indicate that the biochar/struvite composite has a longer cycle of release of nutrients than traditional chemical fertilizers and has large potential as a slow-release fertilizer. [ABSTRACT FROM AUTHOR]

Abstract The use of biochars formed by hydrothermal carbonization for the treatment of contaminated water has been greatly limited, due to their poorly developed porosity and low content of surface functional groups. Also, the most common modification routes inevitably require post-treatment processes, which are time-consuming and energy-wasting. Hence, the objective of this research was to produce a cost-effective biochar with improved performance for the treatment of heavy metal pollution through a facile one-step hydrothermal carbonization process coupled with ammonium phosphate, thiocarbamide, ammonium chloride or urea, without any post-treatment. The effects of various operational parameters, including type of modification reagent, time and temperature of hydrothermal treatment, and ratio of modification reagent to precursor during impregnation, on the copper ion adsorption were examined. The adsorption data fit the Langmuir adsorption isotherm model quite well. The maximum adsorption capacities (mg/g) of the biochars towards copper ions followed the order of 40-8h-1.0-APBC (95.24) > 140-8h-0-BC (12.52) > 140-8h-1.0-TUBC (12.08) > 140-8h-1.0-ACBC (7.440) > 140-8h-1.0-URBC (5.277). The results indicated that biochars modified with ammonium phosphate displayed excellent adsorption performance toward copper ions, which was 7.6-fold higher than that of the pristine biochar. EDX and FT-IR analyses before and after adsorption demonstrated that the main removal mechanism involved complexation between the phosphate groups on the surface of the modified biochars and copper ions. Graphical abstract Scheme 1. Preparation pathway of sustainable prolifera-green-tide-based biochars. Unlabelled Image [ABSTRACT FROM AUTHOR]

Activated zinc biochar (ZnBC) and humic acid (HA) were used as coating agents in a soluble monoammonium phosphate (MAP) to modify phosphorus (P) use efficiency by altering adsorption/desorption kinetics between the granule region and the soil. The coated treatments MAPZnBC and MAPHA were compared with MAP through P diffusivity, kinetics, and agronomic evaluation. Eucalyptus sawdust was used as biomass for biochar synthesis, and a pre-pyrolysis treatment with zinc chloride (ZnCl 2) was applied. The P diffusivity was evaluated in the fertosphere zone. Adsorption and desorption potential of the ZnBC compared with control biochar (BC) was evaluated separately. Desorption kinetics of P from soil was assessed after incubation with MAPZnBC and MAPHA. The shoot dry matter yield (SDM), P uptake, and P use efficiency (PUE) were evaluated with a pot experiment in a clay Oxisol sown with maize and soybeans as successive plant trials, under glasshouse conditions. Surface area values of 940 and 305 m2 g−1 combined with adsorption capacities of 106 and 53 mg P g−1 for ZnBC and BC, respectively, confirm the increased capacity of activated biochar to adsorb P. Both MAPZnBC and MAPHA decreased P diffusivity compared to MAP after 20 days of incubation. Moreover, MAPZnBC and MAPHA presented 20% and 34% more water-soluble phosphorus recovery. MAPZnBC expressed an increase in SDM while MAPHA highlighted P uptake and PUE compared with MAP. Both kinetic studies and agronomic evaluations showed that ZnBC and HA are suitable as coatings for phosphate fertilizers in terms of increasing P efficiency in the fertosphere on high P-fixing soils. [Display omitted] • Technologies for coating fertilizer granules have the potential to increase P use efficiency. • Zinc-biochar was an effective acting as buffering matrix between soil-phosphorus adsorption. • Humic acid and activated zinc-biochar as coating agents increased soil-phosphorus availability. • An increase of phosphorus content in plants occurred only by using humid acid as an additive. [ABSTRACT FROM AUTHOR]

[Display omitted] • β-CD, Fe 3 O 4 and sodium alginate are combined to modify biochar. • β-CD@MBC P possesses good uptake for Pb (II) and MB under a wide pH scope. • Host-guest interaction, H-bonding and π-π stacking are responsible for MB removal. • Complexation and active sites supplied by adsorbed MB promote Pb (II) binding. • β-CD@MBC P pellet was easily separated from water with high desorption efficiency. Due to the high biological toxicity, the concurrent elimination of lead (Pb (II)) and methylene blue (MB) has become a challenging problem. Therefore, a newly β-cyclodextrin (β-CD) modified magnetic alginate/biochar (β-CD@MBC P) material was developed. Comprehensive characterizations proved the successful coating of β-CD onto MBC P surface by microwave-aided fabrication. The β-CD@MBC P achieved high-efficiency uptake for contaminants under a wide pH scope. In the dual system, Pb (II) elimination was facilitated with the presence of MB, due to the active sites provided by MB. In the presence of Pb (II), MB uptake was inhibited due to the electrostatic repulsion between positively charged MB and Pb (II). Electrostatic attraction and complexation contributed to capturing Pb (II), while π-π interactions, host–guest effect, and H-bonding were important in MB elimination. After four cycles, β-CD@MBC P maintained comparatively good renewability. Findings demonstrated that β-CD@MBC P could be an effective remediation material for Pb (II)/MB adsorption from aqueous environments. [ABSTRACT FROM AUTHOR]

Sorptive removal of six phenolic endocrine disrupting chemicals (EDCs) estrone (E1), 17β-estradiol (E2), estriol (E3), 17α-ethynylestradiol (EE2), bisphenol A (BPA) and 4- tert -butylphenol (4 t BP) by functionalized biochar (fBC) through competitive interactions was investigated. EDC sorption was pH dependent with the maximum sorption at pH 3.0–3.5 due to hydrogen bonds and π-π interactions as the principal sorptive mechanism. Sorption isotherm of the EDCs was fitted to the Langmuir model. Sorption capacities and distribution coefficient values followed the order E1 > E2 ≥ EE2 > BPA > 4 t BP > E3. The findings suggested that EDC sorption occurred mainly through pseudo-second order and external mass transfer diffusion processes, by forming H-bonds along with π-π electron-donor–acceptor (EDA) interactions at different pH. The complete removal of ∼500 μg L −1 of each EDC from different water decreased in the order: deionised water > membrane bioreactor (MBR) sewage effluent > synthetic wastewater. The presence of sodium lauryl sulphonate and acacia gum in synthetic wastewater significantly suppressed sorption affinity of EDCs by 38–50%, hence requiring more fBC to maintain removal efficacy. [ABSTRACT FROM AUTHOR]

Biochar and functionalized biochar (fBC-1 and fBC-2) were prepared and applied to remove antibiotic chloramphenicol from deionized water, lake water and synthetic wastewater. Results showed that chloramphenicol removal on biochar was pH dependent and maximum sorption occurred at pH 4.0–4.5. The sorption data of chloramphenicol fitted better with the Langmuir isotherm model than the Freundlich isotherm model with the maximum Langmuir sorption capacity of 233 μM g − 1 using fBC-2. Chloramphenicol sorption on fBC-2 followed the trend: deionized water > lake water > synthetic wastewater. The presence of humic acid decreased the sorption distribution coefficient ( K d ) while the presence of low ionic strength and soil in solution increased K d value significantly. The mechanism of sorption on fBC mainly involved electron-donor-acceptor (EDA) interactions at pH < 2.0; formation of charge assisted hydrogen bond (CAHB) and hydrogen bonds in addition to EDA in the pH 4.0–4.5; and CAHB and EDA interactions at pH > 7.0. Additionally, solvent and thermal regeneration of fBC-2 for repeatable applications showed excellent sorption of chloramphenicol under the same condition, due to the creation of a molecular imprinting effect in fBC-2. Consequently, fBC-2 can be applied with excellent reusability properties to remove chloramphenicol and other similar organic contaminants. [ABSTRACT FROM AUTHOR]

In this study, nano-cerium oxide functionalized maize straw biochar (Ce-MSB) was prepared and utilized to remove P from agricultural wastewater. Response Surface Model was applied to optimize the operating conditions. Moreover, Ce-MSB was applied to actual rice paddy column for the first time. Response Surface Model (RSM) showed higher materials ratio had positive effect on PO 4 3− adsorption capacity, while higher pyrolysis temperature had negative effect. The maximum adsorption capacity of Ce-MSB for PO 4 3− was 78 mg g −1 , implying that Ce-MSB was an effective functionalized adsorbent for P removal. Paddy soil column experiment showed that application of Ce-MSB decreased total phosphorus concentration of surface water by 27.33% and increased total phosphors (TP) content of top soil by 7.22%. Further, Ce-MSB tends to increase rice plant height and leaf area. Therefore, Ce-MSB can be used as a promising functionalized biochar to reduce the risk of phosphorus loss from paddy field surface running water. [ABSTRACT FROM AUTHOR]

[Display omitted] • High efficiency biochar was prepared from banana peel by MWP. • The BPB had high adsorption capacity of 2297.83 mg·g−1 for MG. • Ion exchange plays an essential role in the adsorption process. • Banana peel biochar has great potential for practical applications. In this study, functionalized banana peel biochar (BPB) was prepared by microwave-assisted pyrolysis for the first time to investigate its adsorption to malachite green (MG) dye. Adsorption experiments showed that the maximum adsorption capacity of BPB500 and BPB900 to malachite green reached 1790.30 and 2297.83 mg·g−1 within 120 min. The adsorption behaviour was well-fitted by the pseudo-second-order kinetic model and Langmuir isotherm model, and ΔG0 < 0, ΔH0 > 0, indicated that the adsorption process was endothermic and spontaneous, dominated by chemisorption. The adsorption mechanism of MG dye on BPB included hydrophobic interaction, hydrogen bonding, π-π interaction, n-π interaction, and ion exchange. Meanwhile, through regeneration tests, simulated wastewater treatment experiments, and cost calculations, it was found that BPB has great potential for practical applications. This work demonstrated that microwave-assisted pyrolysis is a viable low-cost approach for producing excellent sorbents from biomass, and banana peel is a promising feedstock to prepare biochar for dye removal. [ABSTRACT FROM AUTHOR]

The widely used nanosized zero-valent iron (nZVI or nFe 0 ) particles and their composite material lose reductive nature during application, and the stability of transformed composite material for repeatable application is not addressed to date. To shed light on this, nZVI was synthesized from scrap material and immobilized on functionalized biochar (fBC) to prepare nZVI-fBC composite. Comparative study between nZVI and nZVI-fBC composite on the removal of chlorinated antibiotic chloramphenicol from different water types was conducted. The results suggested that nZVI was solely responsible for reduction of chloramphenicol. Whereas nZVI-fBC could be applied once, within a few hours, for the reduction of chloramphenico (29–32.5%) and subsequently sorption (67.5–70.5%) by transforming to a fully magnetic composite (nFe 3 O 4 -fBC) gaining stability with synergistic sorption performance. In both cases, two reduction by-products were identified namely 2-chloro-N-[1,3-dihydroxy-1-(4-aminophenyl)propan-2-yl]acetamide ( m / z 257) and dechlorinated N-[1,3-dihydroxy-1-(4-aminophenyl)propan-2-yl]acetamide ( m / z 223). The complete removal of 3.1 µM L −1 of chloramphenicol in different water was faster by nZVI-fBC (∼12–15 h) than by stable nFe 3 O 4 -fBC composite (∼18 h). Both nZVI-fBC and nFe 3 O 4 -fBC composites removed chloramphenicol in the order: deionized water > lake water > synthetic wastewater. nFe 3 O 4 -fBC showed excellent reusability after regeneration, with the regenerated nFe 3 O 4 -fBC composite (after 6 cycles of application) showing significant performance for methylene blue removal (∼287 mg g −1 ). Therefore, the transformed nFe 3 O 4 -fBC composite is a promising and reusable sorbent for the efficient removal of organic contaminants. [ABSTRACT FROM AUTHOR]

Effective utilization and resourcelization of sewage sludge into value-added by-products and insights into its environmental impacts during the fabrication process are urgent tasks to be tackled. Here, we adopt FeCl 3 to activate and functionalize sewage sludge to form FeCl 3 -activated biochars, which exhibited high adsorption capabilities for the treatment of toxic As(III) and Cr(VI) containing wastewaters. Kinetic studies suggested that the adsorption of As(III) and Cr(VI) species onto the biochar surface was attributed to physisorption and chemosorption, respectively. Equilibrium was reached after 3 h for the adsorption of Cr(VI), and slightly slower for that of As(III). Additionally, the structural stability of the adsorbent was maintained even in wastewater with high acidity (pH = 1), as corroborated by microscopic observations. Structural characterization of the adsorbents after adsorption showed that the excellent adsorption performance originated from adsorptive functionalities of the surface functional groups and the active Fe 3 O 4 particles forming Fe-O-As(III)/Fe-O-Cr(VI) complexes with the As(III)/Cr(VI) adsorbates. Evaluation via the green degree method demonstrated that transforming sewage sludge into biochar exerts very low impacts on the environment. Hence, this work offers a green alternative to convert the hazardous sewage sludge into value-added biochar materials, which can be further exploited as supporting frameworks for multifunctional catalysts or expanded to be investigated in reducing carbon footprints and energy conversion areas. [Display omitted] • In-depth understanding of the sorption mechanisms of As(III)/Cr(VI) onto biochar. • Surface functional groups and Fe 3 O 4 played essential roles in adsorption process. • Proof-of-concept studies on utilization and valorization of sewage sludge. • Method to quantify the environmental impact on converting sewage sludge to biochar. [ABSTRACT FROM AUTHOR]

Conventional approaches of making biochars are typically through single sourcing of the feedstock. Here, we hypothesize that multi sourcing can be used to develop tailored functionalized biochar where select functional groups are inherently grafted onto the biochar surface. To test this hypothesis, we used hydrothermal co-liquefaction to produce biochar from various blends of microalgae Cyanidioschyzon merolae (CM) and swine manure (SM). We further characterized each biochar's physicochemical and surface properties to qualify them for applications in construction and manufacturing. In the blended cases, 20–80 CM-SM had the highest biochar yield of 27.06 wt.%, while 80–20 CM-SM had the highest volatile matter, 32.2%. The crystallinity of the biochars ranged from 40–55%. The specific surface area was measured to be in the range of 1.53–5.86 m2/g and average pore size was in the range of 250–360.56 Å. The study results showed presence of functional groups such as alcohols, amides, free fatty acids/esters, cyclic- and straight-chain hydrocarbons on the surface of biochar, which could in turn promote biochar's application as a free-radical scavenger in construction and manufacturing. It should be noted that the use of biochar as a soil amendment is not enough to address the growing piles of biowaste. The outcomes of this study could enable development of non-conventional applications for functionalized biochar. Considering the urgent need for forest management and biowaste valorization, developing viable applications for biochar is significant not only for resource conservation, but also for forest management and environmental sustainability. [Display omitted] [ABSTRACT FROM AUTHOR]

• Novel biochar exhibited a efficient adsorption capacity for Cr(VI) (138.89 mg·g−1). • 28.13% of Cr(VI) was reduced in supernatant and 71.87% was adsorbed on biochar. • Biochar had a good application potential in soil column. A novel functionalized biochar was prepared using corn stalks for efficiently removal and mobility control of Cr(VI). Compared to single modified biochar, iron/zinc biochar (Fe@Zn@HBC) displayed a better removal property and the maximum adsorption capacity of Fe@Zn@HBC reached 138.89 mg·g−1 at pH = 2 and 260 ± 10 Lux illumination. The positive charge on biochar might be the main reason promoting the rapid adsorption of Cr(VI) by electrostatic interaction. Reduction functional groups and photocatalysis (derived from ZnFe 2 O 4 and B-H functional group) provided electrons for Cr(VI) reduction. And the SiO 2 could enhance the reduction process by improving electrons transfer. Finally, FeCr 2 O 4 and ZnFeCrO 4 were formed by coprecipitation and ion exchange. Meanwhile, Fe@Zn@HBC showed a high solid–liquid magnetic separation potential due to the Fe 3 O 4 and ZnFe 2 O 4. In soil column experiment, Fe@Zn@HBC displayed a superior mobility control on biochar particles and Cr(VI) solution under the external magnetic field. [ABSTRACT FROM AUTHOR]