Antibiotic bioremediation by new generation biochar: Recent updates

Biochar-based composites for removing chlorinated organic pollutants: Applications, mechanisms, and perspectives

Chlorinated organic pollutants constitute a significant category of persistent organic pollutants due to their widespread presence in the environment, which is primarily attributed to the expansion of agricultural and industrial activities. These pollutants are characterized by their persistence, potent toxicity, and capability for long-range dispersion, emphasizing the importance of their eradication to mitigate environmental pollution. While conventional methods for removing chlorinated organic pollutants encompass advanced oxidation, catalytic oxidation, and bioremediation, the utilization of biochar has emerged as a prominent green and efficacious method in recent years. Here we review biochar's role in remediating typical chlorinated organics, including polychlorinated biphenyls (PCBs), triclosan (TCS), trichloroethene (TCE), tetrachloroethylene (PCE), organochlorine pesticides (OCPs), and chlorobenzenes (CBs). We focus on the impact of biochar material properties on the adsorption mechanisms of chlorinated organics. This review highlights the use of biochar as a sustainable and eco-friendly method for removing chlorinated organic pollutants, especially when combined with biological or chemical strategies. Biochar facilitates electron transfer efficiency between microorganisms, promoting the growth of dechlorinating bacteria and mitigating the toxicity of chlorinated organics through adsorption. Furthermore, biochar can activate processes such as advanced oxidation or nano zero-valent iron, generating free radicals to decompose chlorinated organic compounds. We observe a broader application of biochar and bioprocesses for treating chlorinated organic pollutants in soil, reducing environmental impacts. Conversely, for water-based pollutants, integrating biochar with chemical methods proved more effective, leading to superior purification results. This review contributes to the theoretical and practical application of biochar for removing environmental chlorinated organic pollutants.

Preparation of mesoporous biogas residue biochar via a self-template strategy for efficient removal of ciprofloxacin: Effect of pyrolysis temperature

Biochar preparation and application is an anticipated pathway for the resource utilization of biogas residue. In this study, biochars were prepared by the pyrolysis of biogas residue from food waste anaerobic digestion (named as BRBCs) under various pyrolysis temperatures (300, 500, 700, and 900 °C), and the effect of pyrolysis temperatures on the physicochemical characteristics of BRBCs was examined. The adsorption performance toward ciprofloxacin (CIP), a typical antibiotic in waterbodies, was also investigated. The results showed that pyrolysis temperature significantly changed the physicochemical properties of BRBCs. In addition, the minerals in the biogas residue, especially SiO2, were rearranged to form a mesoporous structure in biochar through a self-template strategy (without activator). BRBC prepared at 900 °C exhibited a high specific surface area and pore volume, well-developed mesopore structure, and more carbon structure defects, and exhibited the largest CIP adsorption capacity with 70.29 mg g-1, which was ascribed to the combined interaction of pore diffusion, π-π interactions, hydrogen bonding, complexation, and electrostatic forces. Furthermore, the adsorption of CIP by BRBC900 was well described by two-compartment kinetic and Langmuir isotherm models. BRBC900 showed good adsorption performance toward CIP at pH 7-9. The adsorption of CIP by BRBC is a spontaneous, exothermic, entropy-increasing process. Moreover, BRBC also presented a good recycling potential. Therefore, the preparation of mesoporous biochar based on a self-template strategy not only provides an option for the resource utilization of biogas residue but also offers a new option for the treatment of antibiotic wastewater.

Mechanistic understanding of green synthesized cerium nanoparticles for the photocatalytic degradation of dyes and antibiotics from aqueous media and antimicrobial efficacy: A review

In recent years, extensive research endeavors are being undertaken for synthesis of an efficient, economic and eco-friendly cerium oxide nanoparticles (CeO2 NPs) using plant extract mediated greener approach. A number of medicinal plants and their specific parts (flowers, bark, seeds, fruits, seeds and leaves) have been found to be capable of synthesizing CeO2 NPs. The specific key phytochemical constituents of plants such as alkaloids, terpenoids, phenolic acids, flavones and tannins can play significant role as a reducing, stabilizing and capping agents in the synthesis of CeO2 NPs from their respective precursor solution of metal ions. The CeO2 NPs are frequently using in diverse fields of science and technology including photocatalytic degradation of dyes, antibiotics as well as antimicrobial applications. In this review, the mechanism behind the green synthesis CeO2 NPs using plant entities are summarized along with discussion of analytical results from characterization techniques. An overview of CeO2 NPs for water remediation application via photocatalytic degradation of dyes and antibiotics are discussed. In addition, the mechanisms of antimicrobial efficacy of CeO2 NPs and current challenges for their sustainable application at large scale in real environmental conditions are discussed.

Mechanisms of adsorption and functionalization of biochar for pesticides: A review

Agricultural production relies heavily on pesticides. However, factors like inefficient application, pesticide resistance, and environmental conditions reduce their effective utilization in agriculture. Subsequently, pesticides transfer into the soil, adversely affecting its physicochemical properties, microbial populations, and enzyme activities. Different pesticides interacting can lead to combined toxicity, posing risks to non-target organisms, biodiversity, and organism-environment interactions. Pesticide exposure may cause both acute and chronic effects on human health. Biochar, with its high specific surface area and porosity, offers numerous adsorption sites. Its stability, eco-friendliness, and superior adsorption capabilities render it an excellent choice. As a versatile material, biochar finds use in agriculture, environmental management, industry, energy, and medicine. Added to soil, biochar helps absorb or degrade pesticides in contaminated areas, enhancing soil microbial activity. Current research primarily focuses on biochar produced via direct pyrolysis for pesticide adsorption. Studies on functionalized biochar for this purpose are relatively scarce. This review examines biochar's pesticide absorption properties, its characteristics, formation mechanisms, environmental impact, and delves into adsorption mechanisms, functionalization methods, and their prospects and limitations.

Performance analysis of hydrochar derived from catalytic hydrothermal carbonization in the multicomponent emerging contaminant systems: Selectivity and modeling studies

In this work, as an alternative to pyrochar, catalytic hydrothermal carbonization has been employed to synthesize hydrochar to eliminate emerging contaminants in multicomponent systems. The hydrochar has been synthesized using a single step catalytic hydrothermal carbonization at low temperature (200 °C) without any secondary activation with high specific surface area and very good adsorption efficiency for the removal of emerging contaminants. The synthesized hydrochar (HC200) was characterized using various analytical techniques and found to have porous structure with 114.84 m2.g-1 of specific surface area and also contained various oxygen-containing functionalities. The maximum adsorption efficiencies of 92.4 %, 85.4 %, and 82 % were obtained for ibuprofen, sulfamethoxazole, and bisphenol A, respectively. Humic acid, a naturally occurring organic compound had a negligible effect on the adsorption of the selected contaminants. The hydrochar's selectivity towards the emerging contaminants in binary and ternary multicomponent systems was in the order of ibuprofen > sulfamethoxazole > bisphenol A.

Small microplastic particles promote tetracycline and aureomycin adsorption by biochar in an aqueous solution

Biochar (BC) has been used to remove antibiotics from wastewater. Microplastics are emerging contaminants of wastewater. The capacities of microplastics for adsorbing antibiotics and the effects of microplastics of different types and particle sizes on antibiotic adsorption by BC have not been studied. Here, adsorption isotherm and kinetics experiments were performed to investigate tetracycline and aureomycin adsorption to polyvinyl chloride particles with diameters of 10, 100, 500, and 2000 μm, polylactic acid particles with diameters of 30, 100, 500, and 2000 μm (PLA30, PLA100, PLA500, and PLA2000, respectively), and wheat straw BC. The highest tetracycline adsorption capacity (25.00 mg g-1) was found for a PLA30 + BC. The tetracycline adsorption capacities of the other microplastic particles were 20.44-24.57 mg g-1. The highest aureomycin adsorption capacity (39.50 mg g-1) was found for 10 μm polyvinyl chloride particles and BC. The aureomycin adsorption capacities of the other microplastic particles were 32.21-38.42 mg g-1. The tetracycline adsorption capacities were 13.69%, 6.28%, 5.49%, and 4.54% higher for PLA30 + BC, PLA100 + BC, PLA500 + BC, and PLA2000 + BC, respectively, than for only BC. This may have been because there were more sites available per unit mass of microplastic for adsorbing tetracycline and dissolved organic carbon on small microplastic particles than large microplastic particles. The results indicated that microplastics can adsorb antibiotics and increase the amounts of antibiotics adsorbed by BC. Therefore, it is essential to consider potential interactions between BC and microplastics when BC is used to remove antibiotics from wastewater.

Advances in oligosaccharides production from brown seaweeds: extraction, characterization, antimetabolic syndrome, and other potential applications

Brown seaweeds are a promising source of bioactive substances, particularly oligosaccharides. This group has recently gained considerable attention due to its diverse cell wall composition, structure, and wide-spectrum bioactivities. This review article provides a comprehensive update on advances in oligosaccharides (OSs) production from brown seaweeds and their potential health applications. It focuses on advances in feedstock pretreatment, extraction, characterization, and purification prior to OS use for potential health applications. Brown seaweed oligosaccharides (BSOSs) are extracted using various methods. Among these, enzymatic hydrolysis is the most preferred, with high specificity, mild reaction conditions, and low energy consumption. However, the enzyme selection and hydrolysis conditions need to be optimized for desirable yield and oligosaccharides composition. Characterization of oligosaccharides is essential to determine their structure and properties related to bioactivities and to predict their most suitable application. This is well covered in this review. Analytical techniques such as high-performance liquid chromatography (HPLC), gas chromatography (GC), and nuclear magnetic resonance (NMR) spectroscopy are commonly applied to analyze oligosaccharides. BSOSs exhibit a range of biological properties, mainly antimicrobial, anti-inflammatory, and prebiotic properties among others. Importantly, BSOSs have been linked to possible health advantages, including metabolic syndrome management. Metabolic syndrome is a cluster of conditions, such as obesity, hypertension, and dyslipidemia, which increase the risk of cardiovascular disease and type 2 diabetes. Furthermore, oligosaccharides have potential applications in the food and pharmaceutical industries. Future research should focus on improving industrial-scale oligosaccharide extraction and purification, as well as researching their potential utility in the treatment of various health disorders.[Figure: see text].

Enhanced copper (II) bioremediation from wastewater using nano magnetite (Fe3O4) modified biochar of Ascophyllum nodosum

Despite the remarkable Cu(II) sorption biochar potential, it is challenging to desorb them for repeated biochar usage. The present study aims to develop engineered biochar by polarizing Ascophyllum nodosum (seaweed) biomass and magnetizing it with Fe3O4 nanoparticles coating. SEM, EDX, XRD, BET, and FT-IR helped to characterize engineered biochar. Unlike conventional, magnetite biochar exhibited a significant Cu(II) removal potential from an aqueous solution at pH 5. The native and magnetic biochar removal efficiency was 75.2 % (36.99 mgg-1) and 90.27% (45.13 mgg-1), respectively. No significant change in temperature effect was observed. Adsorption study showed that magnetic biochar followed the Langmuir isotherm model with Qmax 53.19 mgg-1. Adsorption kinetics study indicates that magnetic biochar chemisorption dominates over physisorption. Thus, this study shows that seaweed-derived modified biochar could be the best alternative bioresource for removing heavy metals from wastewater. It can be reused to reduce the overall treatment cost of the process.

A review on the lignocellulosic derived biochar-based catalyst in wastewater remediation: Advanced treatment technologies and machine learning tools

Wastewater disposal in the ecosystem affects aquatic and human life, which necessitates the removal of the contaminants. Eliminating wastewater contaminants using biochar produced through the thermal decomposition of lignocellulosic biomass (LCB) is sustainable. Due to its high specific surface area, porous structure, oxygen functional groups, and low cost, biochar has emerged as an alternate contender in catalysis. Various innovative advanced technologies were combined with biochar for effective wastewater treatment. This review examines the use of LCB for the synthesis of biochar along with its activation methods. It also elaborates on using advanced biochar-based technologies in wastewater treatment and the mechanism for forming oxidizing species. The research also highlights the use of machine learning in pollutant removal and identifies the obstacles of biochar-based catalysts in both real-time and cutting-edge technologies. Probable and restrictions for further exploration are discussed.

The efficiency and mechanism of excess sludge-based biochar catalyst in catalytic ozonation of landfill leachate

In this study, biochar was produced based on dehydrated excess sludge from the municipal wastewater treatment plant, which was used for catalytic ozonation of pollutants derived from landfill leachate. The necessary catalytic sites in the structure of biochar were originated from the inorganic metals and organic matters in the sludge, which included a large number of functional groups (e.g., C-C, CO, etc.), adsorbed oxygen (Oads accounted for 44.82%) and electron defects (ID/IG=1.01). These active sites could promote the generation of reactive oxygen species (ROS) (e.g., ·OH,·O2-, etc.). The synergistic interaction between the microorganisms in the activated sludge also facilitated the removal rates of pollutants. Proteobacteria, Bacteroidetes, and Deinococcu-Thermus were crucial in the bioreactor. In 16 days of reaction, the removal ratios of NH+4-N and COD were 98.95 ± 0.11% and 90.89 ± 0.47%, respectively. This study not only explains the mechanism of catalytic ozonation of biochar, but also provides a new way of the practical treatment of landfill leachate.

Internal electric field-assisted copper ions chelated polydopamine/titanium dioxide nano-thin film heterojunctions activate peroxymonosulfate under visible light to catalyze degradation of gatifloxacin: Theoretical calculations and biotoxicity analysis

The combination of photocatalysis and peroxymonosulfate (PMS) activation is considered effective in treating organic pollutants in water; however, the photocatalysts currently used to activate PMS are primarily in powder form, which cause secondary contamination because they are difficult to recycle. In this study, copper-ion-chelated polydopamine/titanium dioxide (Cu-PDA/TiO₂) nanofilm were prepared for PMS activation on fluorine-doped tin oxide substrates using hydrothermal and in-situ self-polymerization methods. The results showed that Cu-PDA/TiO₂ + PMS + Vis degraded 94.8% of gatifloxacin (GAT) within 60 min, and the reaction rate constant reached 4.928 × 10^-2 min^-1, which was 6.25 and 4.04 folds higher than that of TiO₂ + PMS + Vis (0.789 × 10^-2 min^-1) and PDA/TiO₂ + PMS + Vis (1.219 × 10^-2 min^-1), respectively. The Cu-PDA/TiO₂ nanofilm is easily recyclable and activates PMS to degrade GAT with no inferior performance, unlike the powder-based photocatalysts, and simultaneously maintains outstanding stability, which is highly suitable for applications in real aqueous environments. Biotoxicity experiments were conducted using E. coli, S. aureus, and mung bean sprouts as experimental subjects, and the results showed that the Cu-PDA/TiO₂ + PMS + Vis system had excellent detoxification ability. In addition, a detailed investigation of the formation mechanism of step-scheme (S-scheme) Cu-PDA/TiO₂ nanofilm heterojunctions was conducted by density functional theory (DFT) calculations and in-situ X-ray photoelectron spectroscopy (XPS). Finally, a specific process for activating PMS to degrade GAT was proposed, which provides a novel photocatalysts for practical applications in aqueous pollution.

Adsorption kinetics and mechanism of atrazine on iron-modified algal residue biochar in the presence of soil

Atrazine has been widely used as an herbicide, and its harm has attracted more and more attention. In this study, magnetic algal residue biochar (MARB) was prepared from algae residue, a by-product of aquaculture, by ball milling it with ferric oxide to study the adsorption and removal of the triazine herbicide atrazine in a soil medium. The adsorption kinetics and isotherm results showed that atrazine removal by MARB reached 95.5% within 8 h at a concentration of 10 mg·L^-1, but the removal rate dropped to 78.4% in the soil medium. The pseudo-first- and pseudo-second-order kinetics and Langmuir isotherms best described atrazine adsorption on MARB. It is estimated that the maximum adsorption capacity of MARB can reach 10.63 mg·g^-1. The effects of pH, humic acids, and cations on the adsorption performance of MARB for atrazine were also studied. When pH was 3, the adsorption capacity of MARB was twice that of other pHs. Only in the presence of 50 mg·L^-1 HA and 0.1 mol·L^-1 NH₄⁺, Na, and K, the adsorption capacity of MARB to AT decreased by 8% and 13%, respectively. The results showed that MARB had a stable removal profile over a wide range of conditions. The adsorption mechanisms involved multiple interaction forms, among which the introduction of iron oxide promoted hydrogen bonding formation and π-π interactions by enriching -OH and -COO on the surface of MARB. Overall, the magnetic biochar prepared in this study can be used as an effective adsorbent to remove atrazine in complex environments and is ideal for algal biomass waste treatment and environmental governance.^+.

Impact of antibiotics on microbial community in aquatic environment and biodegradation mechanism: a review and bibliometric analysis

Antibiotic residues in aquatic environments pose a potential hazard, and microbes, which play important roles in aquatic ecosystems, are vulnerable to the impacts of antibiotics. This study aimed to analyze the research progress, trends, and hot topics of the impact of antibiotics on microbial community and biodegradation mechanism using bibliometric analysis. An in-depth analysis of the publication characteristics of 6143 articles published between 1990 and 2021 revealed that the number of articles published increased exponentially. The research sites have been mainly concentrated in the Yamuna River, Pearl River, Lake Taihu, Lake Michigan, Danjiangkou Reservoir, etc., illustrating that research around the world is not even. Antibiotics could change the diversity, structure, and ecological functions of bacterial communities, stimulate a widespread abundance of antibiotic-resistant bacteria and antibiotic-resistant genes, and increase the diversity of eukaryotes, thus triggering the shift of food web structure to predatory and pathogenic. Latent Dirichlet allocation theme model analysis showed three clusters, and the research hotspots mainly included the effect of antibiotics on the denitrification process, microplastics combined with antibiotics, and methods for removing antibiotics. Furthermore, the mechanisms of microbe-mediated antibiotic degradation were unraveled, and importantly, we provided bottlenecks and future research perspectives on antibiotics and microbial diversity research.

Novel magnetic graphoxide/biochar composite derived from tea for multiple SAs and QNs antibiotics removal in water

Antibiotics pollution is an urgent public health issue. Biochar is a kind of promising composite for removal antibiotic in aqueous environment. In this study, a novel magnetic graphoxide/biochar composite (mGO/TBC) was synthesized by simple impregnation method and used as an efficient and recyclable persulfate (PS) activator for degradation and removal of sulfonamides (SAs) and quinolones (QNs) antibiotics. Based on the synergism pre-adsorption and degradation between graphoxide and biochar, the removal rates of mGO/TBC on sarafloxacin hydrochloride, sulfadimethoxine, sulfapyridine, sulfadoxine, sulfamonomethoxine, sulfachloropyridazine, enrofloxacin, and ciprofloxacin were increased above 95%. Moreover, the mGO/TBC could be reused at least seven times after degradation-recovery cycles. Quenching experiment and ESR analysis proved that ¹O₂, ^•OH, and SO₄^•- from mGO/TBC/PS system were the primary oxidation active species to degrade SAs and QNs. It is a promising substrate for antibiotic bioremediation with good application prospects.

Advancement in algal bioremediation for organic, inorganic, and emerging pollutants

Rapidly changing bioremediation prospects are key drive to develop sustainable options that can offer extra benefits rather than only environmental remediation. Algal remediating is gaining utmost attention due to its mesmerising sustainable features, removing odour and toxicity, co-remediating numerous common and emerging inorganic and organic pollutants from gaseous and aqueous environments, and yielding biomass for a range of valuable products refining. Moreover, it also improves carbon footprint via carbon-capturing offers a better option than any other non-algal process for several high CO₂-emitting industries. Bio-uptake, bioadsorption, photodegradation, and biodegradation are the main mechanisms to remediate a range of common and emerging pollutants by various algae species. Bioadsorption was a dominant remediation mechanism among others implicating surface properties of pollutants and algal cell walls. Photodegradable pollutants were photodegraded by microalgae by adsorbing photons on the surface and intracellularly via stepwise photodissociation and breakdown. Biodegradation involves the transportation of selective pollutants intracellularly, and enzymes help to convert them into simpler non-toxic forms. Robust models are from the green microalgae group and are dominated by Chlorella species. This article compiles the advancements in microalgae-assisted pollutants remediation and value-addition under sustainable biorefinery prospects. Moreover, filling the knowledge gaps, and recommendations for developing an effective platform for emerging pollutants remediation and realization of commercial-scale algal bioremediation.

Efficient Adsorption of a Sulfonamide Antibiotic in Aqueous Solutions with N-doped Magnetic Biochar: Performance, Mechanism, and Reusability

Conventional biochar has limited effectiveness in the adsorption of sulfonamide antibiotics, while modified biochar exhibits greater adsorption potential. Residues of sulfamethoxazole (SMX) in the aquatic environment can threaten the safety of microbial populations as well as humans. In this study, iron-nitrogen co-doped modified biochar (Fe-N-BC) was prepared from palm fibers and doped with Fe and urea via synthesis at 500 °C. Fe-N-BC has a richer surface functional group based on elemental content, X-ray photoelectron spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The Brunauer-Emmett-Teller (BET) specific surface area test exhibited Fe-N-BC, which possessed a greater surface area (318.203 m²/g) and a better developed pore structure (0.149 cm³/g). The results of the hysteresis loop and the Raman spectrum show that Fe-N-BC has a higher degree of magnetization and graphitization. Fe-N-BC showed a remarkable adsorption capacity for SMX (42.9 mg/g), which could maintain 93.4% adsorption effect after four cycles, and 82.8% adsorption capacity in simulated piggery wastewater. The adsorption mechanism involves pore filling, surface complexation, electrostatic interactions, hydrogen bonding, and π-π EDA interactions. The results of this study show that Fe-N-BC prepared from palm fibers can be a stable, excellent adsorbent for SMX removal from wastewater and has promise in terms of practical applications.

Selective adsorption of antibiotics on manganese oxide-loaded biochar and mechanism based on quantitative structure-property relationship model

In this study, MnCl₂-impregnated biomass was oxygen-limited pyrolyzed to produce manganese oxide-loaded biochar (MBC), its adsorption behaviors and influencing factors on tetracycline (TTC), norfloxacin (NOR), and sulfamethoxazole (SMX) were systematically investigated. Three antibiotics exhibited enhanced adsorption behavior on MBC, with maximum adsorption capacity as accurately described by Sips isotherm: TTC (534 mg/g) > NOR (67 mg/g) > SMX (28 mg/g). Hydrogen bonding, n/π-π interactions, electrostatic interaction, surface coordination, and hydrophobic interaction are the major mechanisms for the improved adsorption. Manganese oxide particles on MBC promoted surface coordination and hydrogen bonding. Antibiotic molecules with more hydroxyl oxygen-containing functional groups are more susceptible to migrate to biochar surfaces and to be adhered. Moreover, the quantitative structure-property relationship (QSPR) model was constructed and revealed that hydrogen bonding and π-π interactions were crucial for tetracycline antibiotics selective adsorption. Hence, MBC was a prospective adsorbent with promising applications for antibiotic removal in sewage processing.

N, S Co-Doped Carbons Derived from Enteromorpha prolifera by a Molten Salt Approach: Antibiotics Removal Performance and Techno-Economic Analysis

N, S co-doped bio-carbons with a hierarchical porous structure and high surface area were prepared using a molten salt method and by adopting Entermorpha prolifera (EP) as a precursor. The structure and composition of the bio-carbons could be manipulated by the salt types adopted in the molten salt assisted pyrolysis. When the carbons were used as an activating agent for peroxydisulfate (PDS) in SMX degradation in the advanced oxidation process (AOP), the removal performance in the case of KCl derived bio-carbon (EPB-K) was significantly enhanced compared with that derived from NaCl (EPB-Na). In addition, the optimized EPB-K also demonstrated a high removal rate of 99.6% in the system that used local running water in the background, which proved its excellent application potential in real water treatment. The degradation mechanism study indicated that the N, S doping sites could enhance the surface affinity with the PDS, which could then facilitate ¹O₂ generation and the oxidation of the SMX. Moreover, a detailed techno-economic assessment suggested that the price of the salt reaction medium was of great significance as it influenced the cost of the bio-carbons. In addition, although the cost of EPB-K was higher (USD 2.34 kg^-1) compared with that of EPB-Na (USD 1.72 kg^-1), it was still economically competitive with the commercial active carbons for AOP water treatment.

Influence of pyrolysis temperature on biochar properties and Cr(VI) adsorption from water with groundnut shell biochars: Mechanistic approach

This study was envisaged to understand the effect of increasing pyrolysis temperature on the Cr(VI) removal potential of the groundnut shells derived biochars. The biochars were prepared at four different pyrolysis temperatures (350 °C, 450 °C, 550 °C, 650 °C) and were used unmodified to examine the adsorption potential for Cr(VI). Influence of biochar dose (1-10 g/L), pH_initial (2-10), Cr(VI)_initial (10-500 mg/L) on Cr(VI) adsorptions; adsorption kinetics and isotherms were investigated. The observations suggested that the pyrolysis temperature is the key player in deciding the physicochemical properties as well the adsorption potential of the biochars. SEM and FTIR analysis suggested significant morphological and functional transformations in biochars with increasing pyrolysis temperature. The pH_initial was found to be the most profound adsorption parameter determining the adsorption potential of the biochars. The Cr(VI) adsorption capacity of the biochars decreased with the increase of the pyrolysis temperature (142.87-31.25 mg/L) as well as the solution pH_initial. All the biochars attained 100% removal efficiency with 50 mg/L of Cr(VI)_initial and GNSB/350 achieved it in the minimum time (10 h) among all the biochars. GNSB/350 showed promising Langmuir adsorption capacity of 142.87 mg/L (pH 2, T_adsorption 30 °C, Cr(VI)_initial 10-500 mg/L). In addition, the adsorption mechanism was found to be a synergistic action of chemi/physi-sorption with monolayer adsorption. Hence, the pyrolysis temperature significantly altered the physicochemical properties of the biochars, which highly influenced the adsorption performance of biochars.