Electrons of d-orbital (Mn) and p-orbital (N) enhance the photocatalytic degradation of antibiotics by biochar while maintaining biocompatibility: A combined chemical and biological analysis

Target recognition and selective photocatalytic degradation of trace disinfection By-products by innovative molecular imprinting strategy

Target recognition and selective degradation of trace disinfection by-products (DBPs) in water are crucial for the safety of drinking water and surface water. However, the interference of low concentrations of chlorinated DBPs (Cl-DBPs) and other factors in water remains a major challenge. This study aims to develop a novel catalyst for targeted recognition and removal of target pollutants by constructing specific imprinting cavities (IPC) on the surface of a composite photocatalyst composed of CeO2 and biochar (BC) (CeO2@BC). As an intermediate Cl-DBPs, p-chlorophenol (4-CPs) is highly toxic, prone to bioaccumulation, and difficult to remove. Therefore, 4-CP was chosen as the representative Cl-DBPs, and the 4-CP template molecule was successfully imprinted on BC through non covalent interactions between the functional monomer methyl acrylic acid and the template molecule, which was confirmed by Fourier transform infrared and X-ray photoelectron spectroscopy analysis. The imprinted CeO2@BC (MIP-CeO2@BC) showed highly selective recognition and preferential degradation of 4-CP, with a 38 % increase (from 56 % to 94 %) in the overall removal (adsorption and photodegradation) of 4-CP than the non-imprinted precursor (CeO2@BC). In the presence of competing co-solutes, enrofloxacin (ENR, completely different molecular structure from 4-CP) or 2-chlorophenol (2-CP, has the same chemical formula as 4-CP but different substituent position of Cl), MIP-CeO2@BC removed 2.94 and 2.54 times more 4-CP in the presence of ENR or 2-CP, respectively, than CeO2@BC. This feature also enhanced the ability of the material to resist interference of dissolved organic matter in complex water matrices, with a 4-CP removal of > 60 % in the presence of high concentrations of dextrose, humic acid, or trypsin proteins. Mechanism analysis revealed that molecular imprinting (MIP) can not only selectively uptake 4-CP, but also alter the main degradation pathways, among which photo-generated electrons (e-), holes (h+), and ·OH were identified as the main active substances for degrading 4-CP. Part of the photo-generated e- can be transmitted into the IPC through BC "tunnels", activating the degradation process of 4-CPs trapped in the IPC by the active substances. The combination of MIP and active metals seemed to have the potential to improve the selectivity and effectiveness of photocatalytic degradation of Cl-DBPs in water.

Innovative catalytic approaches in fabricating bimetallic heterostructures for remediation of antibiotic-polluted water: Mechanistic insights and application prospects

The development of photocatalysts with enhanced antibiotic removal efficiency and practical applicability represents a promising avenue. Bimetallic catalysts, as a focal point in photocatalysis research, face challenges in elucidating their operational mechanisms, the absence of straightforward preparation methodologies and comprehensive recycling system when applied to remediation of water bodies. This study innovates by employing an in-situ growth technique to incorporate manganese ferrate nanomaterials onto bismuth oxychloride nanoflowers (MnFe2O4@BiOCl), aiming to construct bimetallic active sites for the photocatalytic degradation of cefalexin (CFX) through a heterojunction structure. The incorporation of MnFe2O4 significantly boosts the adsorption properties, photoelectric response, and CFX removal efficiency (from 5.03 mg/g to 10.27 mg/g) by BiOCl. XPS analysis reveals that the bimetallic structure facilitates photogenerated electron transfer via Mn-O-Bi coordination, delaying the electron-hole recombination, which then acts upon water or hydroxyl groups (-OH) adsorbed onto the surface, generating a multitude of reactive radicals that enhance the photoelectric performance. The study demonstrates that MnFe2O4@BiOCl can continuously photo-catalyze the removal of CFX with a simple and complete recycling strategy, showcasing high recycling efficiency. We posit that bimetallic catalysts prepared via heterojunction structures can achieve efficient CFX antibiotic removal while preserving excellent reusability. The proposed strategy is envisaged to be a promising approach for the photocatalytic removal of antibiotics, offering a sustainable solution for remediation of water.

Enhanced PMS activation efficiency and SMX degradation performance via Fe(II)/Fe(III) cycling with efficient CCF@MoS2@GA-Fe catalyst

Antibiotics, widely used to treat bacterial infections and as agricultural feed additives, pose significant environmental threats due to their persistence, particularly sulfamethoxazole (SMX), which is frequently detected in various ecosystems. Traditional wastewater treatment methods are often ineffective in their removal. This study presents a cost-effective three-dimensional CCF@MoS2@GA-Fe (CMGF) catalyst, with cotton fabric as a support to enhance peroxymonosulfate (PMS) activation in advanced oxidation processes (AOPs). Findings indicates that Mo(IV) active sites in CMGF significantly enhanced electron transfer and redox cycling of Fe(II)/Fe(III), ensuring sustained PMS activation and achieving approximately 3.8 times higher degradation efficiency compared to non-catalytic processes. After five cycles, CMGF retains its high catalytic activity. Key active species during PMS activation include singlet oxygen (1O2), hydroxyl radicals (•OH), and sulfate radicals (SO4-•). This research elucidates the catalytic mechanisms and degradation pathways of the CMGF/PMS system, highlighting its potential for removing organic pollutants from water.

Effects of cellulase treatment on properties of lignocellulose-based biochar

As the most abundant renewable carbon source, lignocellulose holds potential as a raw material for biofuels and biochar. The components required for biofuel production differ from those for biochar, so combining processes can reduce costs. Biofuel preparation necessitates cellulase treatment of lignocellulose. This study examines the effects of various enzyme treatment conditions (dosage, time, temperature) on lignocellulose, focusing on the properties of biochar derived from it (BC-SR). A mathematical model was constructed to study the relationship between enzyme treatment conditions and BC-SR properties. BC-SR exhibited high adsorption selectivity for bisphenol A and outperformed untreated biochar in fixed-bed column experiments, demonstrating greater removal efficiency and structural integrity. This study provides insights into the impact of enzymatic treatment on biochar and offers a cost-effective method for producing stable, efficient biochar. Additionally, a highly persistent biochar can enter the carbon trading market as a carbon-neutral technology, further realizing economic and environmental benefits.

Based on T.E.S.T toxicity prediction and machine learning to forecast toxicity dynamics in the photocatalytic degradation of tetracycline

The integration of photocatalysis and biological treatment provides an effective strategy for controlling antibiotic contamination, which requires precise monitoring of toxicity changes during the photocatalytic process. In this study, nanoscale TiO2 (P25) was employed to degrade tetracycline (TC) under full-spectrum irradiation, with O2 identified as a crucial reactant for the generation reactive oxygen species (ROS). The toxicity simulation results of the degradation intermediates were closely correlated with the predictions of T.E.S.T software. By analyzing the content of intermediates under different experimental conditions, we developed a machine learning model utilizing the random forest algorithm with a correlation coefficient of R2 = 0.878 and a mean absolute error of MAE = 0.02. The model can track the changes of photocatalytic intermediates, in combination with toxicity simulation, which facilitates the prediction of toxicity at different degradation stages, thus allowing selection of the optimal timing of biological treatment interventions.

Biochar Meets Single-Atom: A Catalyst for Efficient Utilization in Environmental Protection Applications and Energy Conversion

Single-atom catalysts (SACs), combining the advantages of multiphase and homogeneous catalysis, have been increasingly investigated in various catalytic applications. Carbon-based SACs have attracted much attention due to their large specific surface area, high porosity, particular electronic structure, and excellent stability. As a cheap and readily available carbon material, biochar has begun to be used as an alternative to carbon nanotubes, graphene, and other such expensive carbon matrices to prepare SACs. However, a review of biochar-based SACs for environmental pollutant removal and energy conversion and storage is lacking. This review focuses on strategies for synthesizing biochar-based SACs, such as pre-treatment of organisms with metal salts, insertion of metal elements into biochar, or pyrolysis of metal-rich biomass, which are more simplistic ways of synthesizing SACs. Meanwhile, this paper attempts to 1) demonstrate their applications in environmental remediation based on advanced oxidation technology and energy conversion and storage based on electrocatalysis; 2) reveal the catalytic oxidation mechanism in different catalytic systems; 3) discuss the stability of biochar-based SACs; and 4) present the future developments and challenges regarding biochar-based SACs.

DFT and experimental studies of the facet-dependent oxygen vacancies modulated WS2/BiOCl-OV S-scheme structure for enhanced photocatalytic removal of ciprofloxacin from wastewater

The present study explores visible light-assisted photodegradation of ciprofloxacin hydrochloride (CIP) antibiotic as a promising solution to water pollution. The focus is on transforming the optical and electronic properties of BiOCl through the generation of oxygen vacancies (OVs) and the exposure of (110) facets, forming a robust S-scheme heterojunction with WS2. The resultant OVs mediated composite with an optimal ratio of WS2 and BiOCl-OV (4-WS2/BiOCl-OV) demonstrated remarkable efficiency (94.3%) in the visible light-assisted photodegradation of CIP antibiotic within 1.5 h. The CIP degradation using 4-WS2/BiOCl-OV followed pseudo-first-order kinetics with the rate constant of 0.023 min-1, outperforming bare WS2, BiOCl, and BiOCl-OV by 8, 6, and 4 times, respectively. Density functional theory (DFT) analysis aligned well with experimental results, providing insights into the structural arrangement and bandgap analysis of the photocatalysts. Liquid chromatography-mass spectrometry (LC-MS) analysis utilized for identifying potentially degraded products while scavenging experiments and electron paramagnetic resonance (EPR) spin trapping analysis elucidated the S-scheme charge transfer mechanism. This research contributes to advancing the design of oxygen vacancy-mediated S-scheme systems in the realm of photocatalysis, with potential implications for addressing water pollution concerns.

Novel manganese and nitrogen co-doped biochar based on sodium bicarbonate activation for efficient removal of bisphenol A: Mechanism insight and role analysis of manganese and nitrogen by combination of characterizations, experiments and density functional theory calculations

A novel porous manganese and nitrogen co-doped biochar (Mn-N@SBC) was synthesized via one-step pyrolysis, utilizing loofah agricultural waste as the precursor and NaHCO3 as the activator. The behavior of bisphenol A adsorbed on Mn-N@SBC was evaluated using static batch adsorption experiments. Compared to direct manganese-nitrogen co-doping, co-doping based on NaHCO3 activation significantly increased the specific surface area (231 to 1027 m2·g-1) and adsorption capacity (15 to 351 mg·g-1). Wide pH (2-10) and good resistance to cation/anion, humic acid and actual water demonstrated the robust adaptability of Mn-N@SBC to environmental factors. The significantly reduced specific surface area after adsorption, adverse effects of ethanol and phenanthrene on the removal of bisphenol A, and theoretically predicted interaction sites indicated the primary adsorption mechanisms involved pore filling, hydrophobicity, and π-π-electron-donor-acceptor interaction. This work presented an approach to create high-efficiency adsorbents from agricultural waste, offering theoretical and practical guidance for the removal of pollutants.

Excess sludge-based biochar loaded with manganese enhances catalytic ozonation efficiency for landfill leachate treatment

This study developed an efficient and stable landfill leachate treatment process, which was based on the combination of biochar catalytic ozonation and activated sludge technology for intensive treatment of landfill leachate, aiming to achieve the standard discharge of leachate. The focus is to investigate the effect of manganese loading on the physicochemical properties of biochar and the mechanism of its catalytic ozonation. It was found that more surface functional groups (CO, Mn-O, etc.) and defects (ID/IG = 1.27) were exposed via the change of original carbon structure by loading Mn, which is conducive to the generation of lattice oxygen. Meanwhile, generating different valence states of Mn metal can improve the redox properties and electron migration rate, and encourage the production of reactive oxygen species (ROS) during the reaction process and enhance the catalytic efficiency. The synergistic action of microorganisms, especially denitrifying bacteria, was found to play a key role in the degradation of nitrogenous pollutants during the activated sludge process. The concentration of NH+4-N was reduced from the initial 1087.03 ± 9.56 mg/L to 9.05 ± 1.91 mg/L, while COD was reduced from 2290 ± 14.14 mg/L to 86.5 ± 2.12 mg/L, with corresponding removal rates of 99.17% and 99.20%, respectively. This method offers high efficiency and stability, achieving discharge standards for leachate (GB16889-2008). The synergy between Mn-loaded biochar and microorganisms in the activated sludge is key to effective treatment. This study offers a new approach to solving the challenge of waste leachate treatment.

Zn-Doped MnCO3/CS Composite Photocatalyst for Visible-Light-Driven Decomposition of Organic Pollutants

Zn-doped MnCO3/carbon sphere (Zn-doped MnCO3/CS) composites were synthesized using a simple hydrothermal procedure. Among various samples (ZM-50, ZM-05, and ZMC-0), the ternary Zn-doped MnCO3/CS (ZMC-2) catalyst demonstrated excellent visible light-induced photocatalytic activity. This improvement comes from the Zn addition and the conductive CS, which facilitate electron movement and charge transport. The catalyst exhibited efficient degradation of methylene blue (MB) over a wide pH range, achieving a removal efficiency of 99.6% under visible light. Radical trapping experiments suggested that •OH and •O2- played essential roles in the mechanism of organic pollutant degradation. Moreover, the catalyst maintained good degradation performance after five cycles. This study offers valuable perspectives into the fabrication of carbon-based composites with promising photocatalytic activity.

Enhanced removal efficiency of bensulfuron-methyl by a novel boron doping biochar-based Acinetobacter YH0317 at a lower temperature

Biochar-based bacteria are regarded as an efficient strategy for remediating organic pollutants in aquatic environments. Herein, a strain named Acinetobacter YH0317 that could degrade bensulfuron-methyl (BSM) at a lower temperature (15 °C) was isolated from a paddy rice field with long-term BSM application. Then Acinetobacter YH0317 was loaded on unmodified biochar (BC) and boron doping biochar (BBC). Results showed that BBC-based YH0317 significantly enhanced the removal efficiency of BSM (71.8-99.1%) compared with BC-based YH0317 (41.9-44.0%) and YH0317 alone (18.1-20.7%) in 24 h. BBC promoted the growth of YH0317 and secretion of extracellular secretions by providing a carrier and shelter for YH0317. The electrochemical analysis suggested BBC improved the electron transfer rate, which ultimately facilitated the removal of BSM. Hydroponic experiments indicated that BBC-based YH0317 effectively improved the growth of soybean. This work reports a novel BBC-based Acinetobacter YH0317 that could effectively remediate BSM contamination in the water environment.