Super facile one-step synthesis of sugarcane bagasse derived N-doped porous biochar for adsorption of ciprofloxacin

High specific surface area graphene-like biochar for green microbial electrosynthesis of hydrogen peroxide and Bisphenol A oxidation at neutral pH

Green electrosynthesis of hydrogen peroxide (H2O2) is a research hotspot in environmental chemistry, particularly for wastewater and sanitation applications, with microbial fuel cells (MFCs) offering a self-sustaining route for in situ production. This investigation showcases the application of chemically activated bagasse biochar (AcBC), a graphene-like carbon material, as a cathode catalyst in a ceramic membrane-fitted MFC for H2O2 generation and bisphenol A (BPA) degradation. The AcBC had an exceptionally high specific surface area of 1604 m2/g and mimicked the physicochemical characteristic of graphene. The MFC having the AcBC-catalysed cathode attained a maximum H2O2 yield of 248. 9 ± 12.5 mg/L (retention time of 12 h) and peak power density of 125.62 ± 5.62 mW/m2. Moreover, this system was tailored into a bioelectro-Fenton system by doping Zn-Fe over AcBC (Zn-Fe/AcBC) that instigated hydroxyl radical formation, thus responsible for removing 95.46 ± 3.50 % of Bisphenol A (BPA, initial concentration = 10 mg/L) in 300 min. Total organic carbon (initial concentration = 47.1 ± 2.3 mg/L) of BPA-containing real wastewater was reduced by 51.4 ± 3.6 % in 300 min while consistently achieving >90 % removal of BPA over eight continuous cycles. Thus, this research demonstrates the potential of biomass-derived graphene-like carbon in catalyzing green H2O2 synthesis for removal of biorefractory organics while achieving sustainable wastewater treatment.

Preparation of nitrogen-doped biocarbon from sewage sludge and pine sawdust for superior hydrogen sulfide removal: Experimental and DFT studies

Hydrogen sulfide (H2S) is a major air pollutant posing a serious threat to both the environment and public health. In this study, a novel nitrogen-rich biocarbon that effectively removes H2S was produced from a mixture of sewage sludge and pine sawdust using melamine as nitrogen source. Compared with pristine biocarbons, nitrogen (N)-doped biocarbons possessed an adjustable porosity, e.g., higher specific surface area of 786-1547 m2/g, richer nitrogen content of 9.02-10.22%, and larger pore volume of 0.31-0.88 cm3/g. In particular, when H2S flow rate was 100 mL/min at 25 °C under dry conditions, a higher H2S adsorption capacity (376.7 mg/g) was observed on nitrogen-rich biocarbon pyrolyzed at 800 °C (BC800N) due to the larger surface area (1547 m2/g), higher pore volume (0.88 cm3/g), and richer nitrogen content (10.22%). The presence of CO2 in the gas reduced H2S adsorption; however, this was partially overcome by the presence of water vapor. After ten consecutive adsorption/desorption cycles, BC800N retained 96.7% of its adsorption capacity. Scanning electron microscopy, X-ray diffraction analysis, and quasi-in-situ X-ray photoelectron spectroscopy were employed to identify the transformed composites of H2S on the biocarbons. The higher nitrogen content resulting from melamine doping mainly increased the pyridinium N-6 and pyrrole N-5 levels, which serve as nitrogen-containing active sites for H2S adsorption. Density functional theory analysis confirmed that the N-6 atoms affected the adsorption of H2S molecules significantly and play an important role in gas adsorption. This innovative biocarbon material has the potential to facilitate optimized adsorption of H2S and assist in effectively mitigating the environmental impact thereof.

Tailoring a lignocellulosic biomass to simultaneously enhance N-doping and textural properties of porous carbons designed for effective environmental remediation

Transforming lignocellulosic biomass waste into value-added materials like porous carbons offers a sustainable and increasingly important solution for its efficient management within a circular economy framework. Although the heteroatom-doping process enhances oxygen- or nitrogen-containing functionalities on porous carbons, it often leads to losses in structural integrity and other key functionalities. This study presents a novel protocol to produce N-doped porous carbons that efficiently introduces nitrogen groups while improving surface area, microporosity definition and the concentration of oxygen-containing functionalities. This protocol involves modifying the original lignocellulosic biomass by reducing its recalcitrance and remodeling its natural composition, followed by the mixing equivalent mass of chitosan and preceding a chemical activation process Compared to the parent material, the optimized tailored porous carbons exhibited a 15% increase in surface area (1689 m2 g-1) and 13% in microporous volume, along with rises of 22% and 20% in oxygen- and nitrogen-containing functional groups, respectively. Additionally, the anchoring mechanism, modeled using Advanced Statistical Physical Models (ASPM), based on the grand canonical ensemble in statistical physics, validated the surface versatility and heterogeneity of the porous carbons. This versatility is demonstrated by their above-average adsorption capacities for chemically distinct hazardous components in aqueous matrices - methylene blue (876 mg g-1), Pb2+ (44 mg g-1) and acetylsalicylic acid (169 mg g-1) - emphasizing the potential of these N-doped porous carbons for efficient and sustainable applications in aqueous remediation processes.

Preparation of porous carbon derived from a lignin-based polymer through ZnCl2 activation for effective capture of iodine

Lignin-based porous carbon, a derivative of lignin, is acknowledged for its cost-effectiveness, stability, and environmental sustainability. It exhibits significant adsorption capacity for the removal of heavy metals and in wastewater treatment, rendering it a highly esteemed adsorbent material. However, the potential of lignin-derived porous carbon for the capture of iodine in environmental contexts has yet to be thoroughly investigated. This research aims to examine the iodine capture capabilities of lignin-derived porous carbon in both iodine vapor and iodine/cyclohexane solution. Initially, lignin derivatives (ADL) (Mn = 2.85 × 104, Mw / Mn = 1. 73) were synthesized through the graft copolymerization of lignin (Mn ≈ 2500), 4-acetoxystyrene, and dienopropyl terephthalate in ethylene glycol, utilizing azobisisobutyronitrile (AIBN) as the initiator. Subsequently, ADL was transformed into layered lignin-based porous carbon (ADLC) by one-step carbonization and zinc chloride activation. The iodine adsorption capacity of ADLC was determined to be 2340 mg/g in an iodine vapor environment and 354 mg/g in a 500 mg/L iodine/cyclohexane solution. These findings indicate that the layered porous carbon (ADLC) derived from lignin represents a promising material for iodine capture, providing an economical, stable, and environmentally friendly approach to nuclear waste management.

Pyrolytic conversion of cattle manure and acid mine drainage sludge into biochar for oxidative and adsorptive removal of the antibiotic nitrofurantoin

Antibiotics in aquatic environments can foster the development of antibiotic-resistant bacteria, posing significant risks to both living organisms and ecosystems. This study explored the thermo-chemical conversion of cattle manure (CM) into biochar and assessed its potential as an environmental medium for removing nitrofurantoin (NFT) from water. The biochar was produced through the co-pyrolysis of CM and acid mine drainage sludge (AMDS) in a N2 condition. The gaseous and liquid products generated during pyrolysis were quantified and characterized. The biochar exhibited both catalytic and adsorptive capability in NFT removal. It effectively activated persulfate to drive oxidative degradation of NFT via radical (SO4•- and •OH) and non-radical (1O2) pathways. NFT adsorption on the biochar involved multiple binding mechanisms, including electrostatic, hydrogen bonds, and π-π EDA interactions, as evidenced by XPS analysis before and after the reaction. Furthermore, the biochar's performance stability was demonstrated through five cycles of reuse and leaching tests. These findings present a viable approach to generate energy from waste by co-pyrolyzing of livestock manure and metal-containing industrial waste, while also producing environmental media capable of removing antibiotics from wastewater through diverse mechanisms.

Extraction of antimicrobial peptides from pea protein hydrolysates by sulfonic acid functionalized biochar

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 IC50 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.

Selective phthalate removal by molecularly imprinted biomass carbon modified electro-Fenton cathode

A novel molecularly imprinted biomass carbon (MIP@BC) catalyst functionalized with the virtual template of phthalates was designed as the cathode material which possesses excellent 2-electron oxygen reduction ability and H2O2 production capacity, which is suitable for targeted degradation of phthalates in the electro-Fenton system. Following molecularly imprinted modification, the adsorption capacity of MIP@BC for Dimethyl phthalate (DMP) increased by 40 %, reached 9.26 mg/g. Compared with non-imprinted biomass carbon (NIP@BC), the MIP@BC-mediated electro-Fenton process enhanced the degradation rate of DMP by 72 %. Additionally, the degradation rate of DMP rises by 51 % and 104 % respectively on the basis of river water and domestic sewage. The reactive oxygen species that induced DMP degradation were OH and O2- and targeted adsorption and catalysis exert a synergistic effect. This study provides a new insight into targeted degradation for high-toxicity of emerging contaminants from complex aqueous environment.

Application of Biochar-Based Materials for Effective Pollutant Removal in Wastewater Treatment

With the growth of the global population and the acceleration of industrialization, the problem of water pollution has become increasingly serious, posing a major threat to the ecosystem and human health. Traditional water treatment technologies make it difficult to cope with complex pollution, so the scientific community is actively exploring new and efficient treatment methods. Biochar (BC), as a low-cost, green carbon-based material, exhibits good adsorption and catalytic properties in water treatment due to its porous structure and abundant active functional groups. However, BC's pure adsorption or catalytic capacity is limited, and researchers have dramatically enhanced its performance through modification means, such as loading metals or heteroatoms. In this paper, we systematically review the recent applications of BC and its modified materials for water treatment in adsorption, Fenton-like, electrocatalytic, photocatalytic, and sonocatalytic systems, and discuss their adsorption/catalytic mechanisms. However, most of the research in this field is at the laboratory simulation stage and still needs much improvement before it can be applied in large-scale wastewater treatment. This review improves the understanding of the pollutant adsorption/catalytic properties and mechanisms of BC-based materials, analyzes the limitations of the current studies, and investigates future directions.

Heteroatom doped biochar-aluminosilicate composite as a green alternative for the removal of hazardous dyes: Functional characterization and modeling studies

In this work, a novel nitrogen-doped biochar bentonite composite was synthesized by a single-pot co-pyrolysis method. Batch studies were conducted to evaluate the performance of the developed composite in eliminating synthetic dyes from the aqueous matrix. Energy dispersive X-ray spectroscopy analysis and field emission scanning electron microscopy imaging confirmed the N doping and bentonite impregnation into biochar. X-ray photoelectron spectroscopy analysis revealed that the N atoms were doped interstitially into the carbon matrix of biochar in the form of pyridinic and pyrrolic nitrogen. Simultaneous heteroatom doping and bentonite impregnation reduced the specific surface area to 41.721 m2 g-1 but improved the adsorption capacity of biochar for dye adsorption. Further experimental studies depicted that simultaneous bentonite impregnation and N doping into the biochar matrix is beneficial for direct blue-6 (DB-6) and methylene blue (MB) removal and maximum adsorption capacities of 53.17 mg. g-1 and 41.33 mg. g-1 were obtained for MB and DB-6, respectively, at varying conditions. Adsorption energetics of the dyes with the developed composite portrayed the spontaneity of the process through negative ΔG values. The Langmuir and Freundlich isotherm models fitted the best for MB and DB-6 adsorption. The monolayer adsorption capacity and favourability factor for MB and DB-6 adsorption were calculated to be 54.15 mg. g-1 and 0.217, respectively from the best-fitted isotherms. Based on density functional theory calculations and spectroscopic studies, major interactions governing the adsorption were predicted to be charge-based interactions, π-π interactions, H-bonding, and Lewis acid-base interactions.

Boron Removal in Aqueous Solutions Using Adsorption with Sugarcane Bagasse Biochar and Ammonia Nanobubbles

Boron is a naturally occurring trace chemical element. High concentrations of boron in nature can adversely affect biological systems and cause severe pollution to the ecological environment. We examined a method to effectively remove boron ions from water systems using sugarcane bagasse biochar from agricultural waste with NH3 nanobubbles (10% NH3 and 90% N2). We studied the effects of the boron solution concentration, pH, and adsorption time on the adsorption of boron by the modified biochar. At the same time, the possibility of using magnesium chloride and NH3 nanobubbles to enhance the adsorption capacity of the biochar was explored. The carbonization temperature of sugarcane bagasse was investigated using thermogravimetric analysis. It was characterized using XRD, SEM, and BET analysis. The boron adsorption results showed that, under alkaline conditions above pH 9, the adsorption capacity of the positively charged modified biochar was improved under the double-layer effect of magnesium ions and NH3 nanobubbles, because the boron existed in the form of negatively charged borate B(OH)4- anion groups. Moreover, cations on the NH3 nanobubble could adsorb the boron. When the NH3 nanobubbles with boron and the modified biochar with boron could coagulate each other, the boron was removed to a significant extent. Extended DLVO theory was adopted to model the interaction between the NH3 nanobubble and modified biochar. The boron adsorption capacity was 36 mg/g at room temperature according to a Langmuir adsorption isotherm. The adsorbed boron was investigated using FT-IR and XPS analysis. The ammonia could be removed using zeolite molecular sieves and heating. Boron in an aqueous solution can be removed via adsorption with modified biochar with NH3 nanobubbles and MgCl2 addition.

Efficient removal of high concentration dyes from water by functionalized in-situ N-doped porous biochar derived from waste antibiotic fermentation residue

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.

Hydrothermal N-doping, magnetization and ball milling co-functionalized sludge biochar design and its selective adsorption of trace concentration sulfamethoxazole from waters

This study aimed to design an efficient and easily collected/regenerated adsorbent for trace concentration sulfamethoxazole (SMX) removal to eliminate its negative impacts on human health, reduce the risk of adsorbed SMX release and boost the reusability of adsorbent. Various multiple modified sludge-derived biochars (SBC) were synthesized in this work and applied to adsorb trace level SMX. The results demonstrated that hydrothermal N-doping, magnetization coupled with ball milling co-functionalized SBC (BMNSBC) displayed the greater adsorption ability for SMX. The maximum adsorption capacity of BMNSBC for SMX calculated by Langmuir model was 1.02 × 105 μg/g, which was 12.9 times of SBC. Characterization combined with adsorption experiments (e.g., models fitting) and DFT calculation confirmed that π-π conjugation, Lewis acid-base, pore filling and Fe3O4 complexation were the primary forces driving SMX binding to BMNSBC. These diversified physicochemical forces contributed to the fine anti-interference of BMNSBC to background substances (e.g., inorganic compounds and organic matter) and its remarkable adsorption ability for SMX in diverse real waters. The great magnetization strength of BMNSBC was advantage for its collection and efficient regeneration by NaOH desorption. Additionally, BMNSBC exhibited an outstanding security in view of its low leaching levels of iron (Fe) and total nitrogen (TN). The multiple superiority of BMNSBC enable it to be a prospective material for emerging contaminants (e.g., SMX) purification, also offering a feasible disposal approach for municipal waste (e.g., sludge).

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.

Fast and efficient As(III) removal from water by bifunctional nZVI@NBC

As a notable toxic substance, metalloid arsenic (As) widely exists in water body and drinking As-contaminated water for an extended period of time can result in serious health concerns. Here, the performance of nanoscale zero-valent iron (nZVI) modified N-doped biochar (NBC) composites (nZVI@NBC) activated peroxydisulfate (PDS) for As(III) removal was investigated. The removal efficiencies of As(III) with initial concentration ranging from 50 to 1000 μg/L were above 99% (the residual total arsenic below 10 μg/L, satisfying the contaminant limit for arsenic in drinking water) within 10 min by nZVI@NBC (0.2 g/L)/PDS (100 μM). As(III) removal efficiency influenced by reaction time, PDS dosage, initial concentration, pH, co-existing ions, and natural organic matter in nZVI@NBC/PDS system were investigated. The nZVI@NBC composite is magnetic and could be conveniently collected from aqueous solutions. In practical applications, nZVI@NBC/PDS has more than 99% As(III) removal efficiency in various water bodies (such as deionized water, piped water, river water, and lake water) under optimized operation parameters. Radical quenching and EPR analysis revealed that SO4·- and ·OH play important roles in nZVI@NBC/PDS system, and the possible reaction mechanism was further proposed. These results suggest that nZVI@NBC activated peroxydisulfate may be an efficient and fast approach for the removal of water contaminated with As(III).

Enhanced adsorption of Congo red from urea/calcium chloride co-modified biochar: Performance, mechanisms and toxicity assessment

Adsorbents with excellent physicochemical properties and green synthetic routes are desired for efficient removal of Congo red (CR) wastewater. Hence, a novel approach was proposed within this work. Biochar NCBC obtained from Medulla Tetrapanacis was synthesized through co-modification with urea/calcium chloride. NCBC exhibited an enormous surface area (750.09 m2/g) and a micro-mesoporous composite structure. Higher nitrogen content was detected on the surface of NCBC (8.17%) compared to that of urea directly modified biochar (4.63%). Nitrogen observed on the surface of NCBC was presented as graphitic N, pyrrolic N, amine N as well as pyridinic N. Kinetic and isothermal investigations revealed the active sites on NCBC to be homogeneous and bind to CR mainly by chemisorption. Calculated maximum sorption of CR on NCBC was 2512.82 mg/g basing on Langmuir model. Moreover, the practicality of NCBC was further proved by the cultivation of Nelumbo nucifera Gaertn. and Penicillium.