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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 %).

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]

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.)

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]

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]

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]

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]

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]