Siloxanes are detrimental trace impurities that can severely impair the performance and operational efficiency of biogas combustion systems, making their effective removal essential. Given the relatively high concentration of cyclic siloxanes and their susceptibility to acid-catalyzed ring-opening polymerization, a combined adsorption–polymerization approach on a solid acid adsorbent may offer higher removal efficiency compared to conventional adsorption methods. In this work, we employed activated carbon as a support and fabricated sulfuric acid-supported activated carbon (CSA) via a simple impregnation method. This study represents the first systematic investigation of the synergistic adsorption and acid-catalyzed polymerization of decamethylcyclopentasiloxane (D5) using this material. The activated carbon function as an adsorbent, providing mass transfer channels for D5, whereas the supported sulfuric acid serves as a catalyst to promote its ring-opening polymerization. Dynamic adsorption tests showed that CSA exhibited a high D5 removal capacity, with a theoretical maximum capacity (Qm, th) of 3219.7 mg g−1 at 0 °C. A series of characterizations, kinetic interpretation, mass balance analysis and density functional theory (DFT) calculations were also conducted to elucidate the potential adsorption/polymerization mechanisms responsible for D5 removal. The results confirmed that the formation of highe-molecular-weight polysiloxane structures on the CSA surface imparted a high degree of hydrophobicity to the spent CSA material. These findings highlight the potential of CSA as a cost-effective and practical solution for siloxane removal.

Catalytic methane pyrolysis (CMP) offers a CO2-free route to hydrogen, yet industrial deployment is limited by carbon-induced catalyst deactivation and poor utilization of co-produced carbon. We introduce a “carbon-iron synergy, direct steelmaking” strategy in which a corncob char-supported Fe catalyst (Fe/CC) is engineered to enable efficient methane pyrolysis for H2 generation, while the spent Fe/CC@C composite serves directly as a steelmaking feedstock without carbon separation. After Fe loading, Fe/CC achieves a specific surface area of 261.20 m2/g and an activation energy of 137 kJ/mol, which is well below that of thermal pyrolysis (356-452 kJ/mol). It exhibits uniformly dispersed Fe nanoparticles with nanoscale crystallite sizes anchored on the porous carbon matrix, as confirmed by HRTEM lattice fringe analysis. At 900 °C and 10 mL/min CH4, it exhibits an “induction period”, during which methane conversion initially decreases and then increases, due to dynamic carbon dissolution forming metastable Fe3C and C0.12Fe1.88 phases, as confirmed by XRD and XPS. Over 11 h, methane conversion stabilizes at ∼88%, yielding 12,761.9 mL H2 and 3.08 g of solid carbon. Multiscale characterization shows that deposited carbon evolves from filamentous to spherical, reflecting a shift in the dominant deactivation mechanism from diffusion-limited to encapsulation-driven. Crucially, Fe/CC@C displays superior CO2 gasification reactivity compared with raw corncob char, with an onset temperature of ∼850 °C and a peak gasification rate at ∼970 °C, thereby demonstrating its viability as a ferro-carbon feedstock for low-carbon steelmaking. This work establishes an integrated route that synergistically couples clean hydrogen production with sustainable ironmaking through the concurrent valorization of carbon and iron.

This study delves into the technical strategy of coproducing hydrogen and steelmaking feedstock through catalytic methane pyrolysis, with the aim of converting the the carbon byproduct from a disposal challenge into a value-added resource. A bifunctional catalyst, namely, apricot shell char-supported iron (ASC/Fe), is devised to combine catalytic function with the product value, allowing the spent catalyst-carbon mixture to be directly utilized as a ferrocarbon feedstock for the steel industry. The structure-activity relationship and catalytic performance are comprehensively investigated. The results indicate that the catalyst attains a high specific surface area of 211.6 m2/g subsequent to iron loading, offering abundant active sites and favorable mass transfer channels. At 900 degrees C and a CH4 flow rate of 10 mL/min, the ASC/Fe-40 catalyst demonstrates excellent stability over an 11 h period, sustaining a methane conversion above 86%, with a cumulative hydrogen yield of 12,042.1 mL and a carbon yield of 3.11 g. Mechanistic analysis unveils a two-tier "carbon buffering" deactivation mechanism. Initially, metallic iron absorbs active carbon atoms through bulk carburization, thereby delaying surface graphitic encapsulation. Subsequently, iron carbide (C0.12Fe1.88) forms as an active intermediate phase that maintains catalytic activity, leading to a gradual rather than an abrupt deactivation. The spent solid product (ASC/Fe@C) is characterized as a composite comprising apricot shell char, metallic iron, iron carbide, and graphitic carbon. Its gasification reactivity in CO2 is evaluated with respect to its potential as a steelmaking feedstock. Notably, the ASC/Fe@C demonstrates a gasification onset temperature of approximately 850 degrees C, which is 150 degrees C lower than that of commercial metallurgical coke. At 900 degrees C, it achieves a conversion rate of 70.7%, in contrast to only 6.5% for coke. This superior performance is attributed to the intrinsic high reactivity of the apricot shell char matrix and the catalytic activation of CO2 molecules by the dispersed iron/iron carbide species. In general, this study verifies the feasibility of the "coproduction" concept, providing a new material foundation and technical pathway for coupling clean hydrogen production with low-carbon steelmaking.

Biogas serves as an alternative energy source to replace traditional fossil fuels and holds significant potential for alleviating environmental issues and the energy crisis. However, it contains trace amounts of siloxanes, which are among the most detrimental components in biogas energy utilization. This review summarizes the properties, sources, hazards, distribution, and purification methods of siloxanes. Adsorption is identified as the most costeffective purification method, offering high efficiency, operational simplicity, and adsorbent reusability, though its performance varies depending on the material type. The study focuses on the adsorption behavior and mechanisms of siloxanes, modification methods for porous materials, and the factors influencing siloxane adsorption capacity on different porous adsorbents. This review aims to provide comprehensive guidelines and a summary of advances in the development of siloxane adsorption materials and their potential industrial applications.

Metronidazole (MNZ) poses a significant environmental challenge due to its high bio-resistance and environmental persistence, resulting in refractory residues that are difficult to eliminate via traditional biochemical methods. Although ZnO-ZnS heterojunctions can facilitate charge separation, the traditional Type-II migration pathway inevitably directs photogenerated carriers toward energy bands with weaker redox potentials. This results in a redox potential compromise that severely limits the intrinsic reaction kinetics of the system, particularly in neutral environments. To address this critical issue, we developed a novel ZnO-ZnS@Biochar (HZSBC) heterojunction using straw biochar as an economical carbon host. The contribution of this work lies in discovering that interface-anchored persistent free radicals (PFRs) function as non-metallic solid-state electron relays. By inducing directional charge shuttling, these PFRs circumvent the aforementioned potential compromise, thereby establishing a Z-scheme charge transfer pathway that preserves exceptional redox capabilities. Via a dual-site anchoring-in situ transformation strategy, high-density oxygen-centered PFRs (spin concentration reaching 20.05 & times;1017 spins/g) were precisely engineered at the HZSBC interface, providing stable electron relay channels for the Z-scheme mechanism. Consequently, HZSBC achieved 90.2% MNZ removal within 110 min under neutral conditions (pH 7.0) with only 8 mM H2O2, exhibiting an apparent rate constant of 1.01 & times; 10_2 min_ 1 and maintaining over 80% removal efficiency after five consecutive cycles. By overcoming the thermodynamic limitations of photocatalysis via PFRs-mediated interfacial band engineering, this work not only offers a new paradigm for the design of high-performance Z-scheme catalysts but also provides an ideal technical pathway for the deep coupling of advanced oxidation processes with downstream biological treatment units.

Water pollution has become increasingly severe worldwide, with the discharge of dye-containing wastewater posing significant threats to water quality and aquatic ecosystems globally. Adsorption has been recognized as an essential method for dye wastewater treatment due to its simplicity, low cost, and high efficiency. Almond shell (Prunus dulcis) biochar, a renewable material with porous structures, has attracted substantial research attention due to its economic and environmental advantages. However, traditional biochar suffers from small surface area and insufficient adsorption active sites, necessitating physical or chemical modifications to enhance its adsorption performance. The unmodified almond shell biochar exhibited a specific surface area of only 2.94-144.12 m2/g and methylene blue(MB)removal rates of 22.40-38.75 %. In this study, phenolic resin, potassium humate, and polyimide were employed as modifiers to prepare modified biochar materials (PRC@HB, PHC@HB, and PIC@HB) using a coating-CO2 activation carbonization method. Results showed significant differences in the adsorption performance of these materials for methylene blue (MB) in dye wastewater. Under optimal modification conditions, the specific surface areas of PRC@HB, PHC@HB, and PIC@HB reached 346.39 m2/g, 498.94 m2/g, and 418.86 m2/g, respectively, representing increases of 32.6-fold, 169.7-fold, and 2.9-fold compared to their unmodified counterparts. Correspondingly, MB removal rates improved dramatically to 94.21 %, 96.91 %, and 23.43 %, respectively. Notably, although PIC@HB exhibits a high specific surface area (418.86 m2 g-1), its MB removal efficiency remains low (23.43 %), which is attributed to less-favourable surface chemistry and the dominance of weak pi-pi interactions rather than electrostatic attraction. The adsorption isotherms followed the Langmuir model, and the adsorption kinetics conformed to the pseudo-second-order kinetic model. This study highlights the potential of modified almond shell biochar as a promising adsorbent in water pollution treatment.

Deep eutectic solvents (DES) serve as green media for biomass pretreatment. However, the role of each DES component in biochar structure remains unclear. We demonstrate that choline chloride (ChCl) transforms pine sawdust-derived biochar from a homogeneous microporous carbon into a heterogeneous hierarchical porous material featuring sulfonic acid functionalities. Control experiments using methanesulfonic acid (MSA) alone produced microporous biochar (MPC, SBET = 473 m2/g, Vmeso = 0.01 cm3/g) that lacked sulfonic groups. In contrast, the pretreatment with ChCl–MSA DES yielded CMPC with a comparable SBET (464 m2/g) but substantially enhanced mesoporosity (Vmeso = 0.51 cm3/g) and covalent sulfonic acid grafting, as demonstrated by FTIR (1384, 1314, 776 cm−1) and XPS S 2p (–SO3H at 168.0 eV, CS at 164.1 eV). Remarkably, metronidazole adsorption shifted from Langmuir-type on MPC (homogeneous, R2 = 0.9867) to Freundlich-type on CMPC (heterogeneous, R2 = 0.9894), with adsorption capacity increasing from 25.5 to 40.5 mg/g. Therefore, ChCl triggers the homogeneity-to-heterogeneity transition of biochar, offering a design principle for functional carbon materials.

Catalytic pyrolysis of hydrocarbons presents a promising approach for the remediation of volatile organic compounds (VOCs), facilitating the concurrent generation of COx-free hydrogen and high-value carbon nano-materials. Nevertheless, the advancement of catalysts with improved activity and stability persists as a crucial challenge in the progression of this technology. Furthermore, the impact of commonly utilized preparation methods on catalytic performance has not been fully elucidated. In this study, three iron-based catalysts supported on magnesium oxides, prepared through co-precipitation (Fe/MgO-C), impregnation (Fe/MgO-I), and sol-gel (Fe/MgO-S) techniques, were assessed for their performance in the catalytic pyrolysis of toluene. Thorough characterization was carried out on both the fresh and spent catalysts. The findings suggested that the catalytic activity, stability, and morphology of the resultant carbon deposits were closely associated with the preparation methods, which influenced the crystallinity of the active iron species and the strength of the metal-support interactions. Among the three catalysts, Fe/MgO-C displayed the highest iron crystallinity and the strongest metal-support interaction, thus exhibiting the optimal catalytic performance. Specifically, it accomplished complete conversion of 427 mg of toluene within 2 h at 1000 degrees C, while concurrently generating 372 mL of hydrogen and 363 mg of carbon. The carbon deposited on the spent Fe/MgO-C catalyst was predominantly comp.osed of high-crystallinity carbon fibers, whereas the carbon products formed on the Fe/MgO-I and Fe/ MgO-S catalysts were primarily irregular carbon flakes and amorphous encapsulating carbon layers, respectively. This study offers a scientific foundation for the development of novel, efficient, and sustainable technologies for the resourceful treatment of hydrocarbon-based VOCs.

Volatile aromatic hydrocarbons released during industrial activities pose substantial environmental and health risks because of their toxic nature and role in generating secondary pollutants. This research explores the effectiveness of catalytic pyrolysis as a novel approach for the efficient removal and transformation of aromatic hydrocarbon contaminants. Specifically, an Fe/Al2O3 catalyst was designed and assessed for its capability to break down toluene-a model aromatic hydrocarbon-into hydrogen and solid carbon product. The Al2O3 support material, Fe2O3/Al2O3 precursor, Fe/Al2O3 catalyst, and solid carbon product underwent detailed analysis via multiple characterization methods such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, and nitrogen adsorption-desorption measurements. The findings indicated that alpha-Fe was primarily dispersed across the Al2O3 pore network, creating particles ranging from nano-to micro-scale and inducing additional interstitial voids due to particle clustering. When operating under ideal parameters (T = 800 degrees C, Cin = 48.89 mg/L, Vg = 0.205 L/min, mcat = 2.0 g), the system exhibited exceptional performance, eliminating 1368 mg/g of gaseous toluene and yielding 1188 mg/g of carbon-based products, chiefly carbon nanofibers, alongside 1301 mL/g of hydrogen. The generated carbon nanofibers could be easily separated from the spent catalyst, which exhibited only a slight decrease (6.8 %) in its capacity for toluene removal after five times of recovery and reutilization. This integrated approach combining decontamination with efficient utilization offers a promising pathway towards environmentally friendly mitigation of volatile organic compound pollution.

A group of silica-based supports with varying Al/Si ratios (S−x) was synthesized using the sol–gel method, followed by a chlorosulfonic acid modification to produce supported sulfonic acids (SA−x). The S−x and SA−x materials, along with their adsorption products, were characterized via techniques such as FTIR, BET, and HPLC-MS. The analysis revealed that the sulfonic acid groups in the SA−x materials existed in two anchoring states: the covalently bonded (CB) state [SiOx–O]ɗ−–SO3Hɗ+ and the ion-paired (IP) state AlOy+:OSO3H−. The sulfonation reactivity of the CB-state sulfonic acid was enhanced, whereas that of the IP-state counterpart was diminished. The incorporation of a minor quantity of aluminum ions (x = 0.1) markedly enhanced the adsorption efficiency of SAs for o-xylene, extending the reaction temperature range to 110–190 °C and increasing the breakthrough adsorption capacity (QB) to 946.1 mg g−1. However, excessive aluminum ion incorporation was detrimental to the adsorption performance of SAs for o-xylene. SA−0.1 showed superior adsorptive capabilities and excellent recyclability, maintaining its performance over four consecutive adsorption/regeneration cycles with only a minor decrease of 4.5%. These findings suggest that SAs prepared with a minor amount of aluminum ions have significant potential for application as adsorbents for the removal of benzene series pollutants.

The application of carbon composite materials (CCMs) spans across various fields, and their preparation primarily involves the non-oxygen pyrolysis of non-volatile macromolecular precursors, which poses challenges in tailoring their composition and microstructure. Here, we propose a binary co-pyrolysis approach for the synthesis of CCMs, utilizing small organic molecules such as Phenanthroline (Phen), o-Phenylenediamine (oPD), and Melamine (Mel) as precursors, along with Co(II) salt as a catalyst. We conducted a thermogravimetric analysis of these three binary systems, aiming to synthesize CCMs at moderate temperatures (330 - 460 degrees C). Subsequently, we characterized the CCMs in terms of their bulk structure, composition, and surface properties. Finally, we assessed their decontamination performance through catalytic H2O2 degradation of methylene blue and adsorption of Pb(II)/phosphate. The results revealed that Co(II) can promote the preferential formation of thermally stable intermediate polymeric structures and inhibit the direct evaporation of the precursors. The prepared CCM-Phen-Co, CCM-oPD-Co, and CCM-Mel-Co exhibit a lamellar and (N, O, Co)-co-doped amorphous structure. Furthermore, both CCM-Phen-Co and CCM-oPD-Co demonstrate complete removal efficiency for methylene blue at a concentration of 10 mg/L, while the maximum adsorption capacity of CCM-oPD-Co for Pb(II) and CCM-Phen-Co for phosphate are 58.0 mg/g and 13.6 mg/g respectively. The CCMs demonstrate promising efficacy in environmental catalysis and adsorption for decontamination purposes.

This study addresses the challenge of antibiotic wastewater pollution by developing highly efficient adsorbents derived from CO2-activated and polymer-modified almond shell biochar-namely PRC@HB, PHC@HB, and PIC@HB-for the removal of metronidazole (MNZ) from aqueous solutions. These composite materials were synthesized by incorporating phenolic resin, potassium humate, and polyimide, respectively. The maximum MNZ removal efficiencies achieved were 97.44 % for PRC@HB, 92.42 % for PHC@HB, and 28.24 % for PIC@HB. Adsorption kinetics adhered to the pseudo-second-order model, suggesting that chemical adsorption is the dominant mechanism. Thermodynamic analysis indicated that the adsorption process for PRC@HB is exothermic and spontaneous (Delta H =-10.79 kJ/mol), whereas for PHC@HB and PIC@HB, it is endothermic and spontaneous (Delta H = 48.33 kJ/mol and 44.95 kJ/mol, respectively). Characterization via scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and Raman spectroscopy revealed that the modifications significantly enhanced pore structure and introduced surface functional groups, such as hydroxyl (-OH) and carbonyl (C--O), thereby increasing the availability of adsorption sites. Density functional theory (DFT) calculations elucidated that PRC@HB and PHC@HB achieve superior adsorption through it-it interactions and hydrogen bonding, while PIC@HB exhibits reduced efficiency due to lower hydrophilicity and weaker electron transfer. By integrating experimental and theoretical approaches, this study clarifies the adsorption mechanisms of modified biochar for MNZ removal, providing a scientific foundation for designing efficient, cost-effective materials for antibiotic wastewater treatment.

The recovery and control of volatile organic compounds (VOCs) have gained significant attention. Supported sulfonic acid materials show potential in converting aromatic VOCs into non-volatile sulfonic acid derivatives. However, their effectiveness is closely tied to the anchoring state of the sulfonic acid groups. In this study, two supported sulfonic acids, SSA@CdO and SSA@CaO, were synthesized via the respective reactions of CdO and CaO with chlorosulfonic acid to investigate how the properties of the supports influence sulfonic acid anchoring and reactivity toward o-xylene. Comprehensive characterization and performance tests revealed that sulfonic acid groups on CdO were covalently bonded, forming positively charged sites ([O0.5Cd–O]ɗ−–SO3Hɗ+) with high loading (9.7 mmol/g), enabling excellent o-xylene removal (≥95.6%) and adsorption capacity (51.67–91.59 mg/g) at 130–150 °C. In contrast, ion-paired bonding on CaO formed negatively charged sites ([O0.5Ca]+:OSO3H−), which were inactive in electrophilic sulfonation. This work provides new insights for enhancing supported sulfonic acid materials in VOC treatment.

Carbon slurry-assisted water electrolysis can significantly reduce the energy consumption of hydrogen production, but mass transfer limitations between the carbon source, electrolyte, and electrode hinder its efficiency. This study investigated the use of biochar sacrificial anodes to address the mass transfer issue and examined the hydrogen production efficiency, as well as the effects of oxidation-induced N-doped pinewood on both the persistent free radicals in the sacrificial anode and the free radicals in the electrolyte during water electrolysis. The results reveal that oxidation of nitrogen-doped pinewood char yields the best electrochemical hydrogen production performance and durability. The anode potential was 0.52 VRHE@10 mA/cm2, which is 70 % that of the Pt anode, while the anode only produced 13 % of the anode gas products compared to the Pt anode, maintaining similar hydrogen production efficiency at the cathode. Both pinewood char and directly nitrogendoped pinewood char were rich in carbon-centred aromatic free radicals. The oxidation process increased the oxygen-containing functional groups and generated carbon-oxygen-centred phenoxy free radicals. Oxidationinduced N-doped pinewood char promoted the transformation of phenoxy-type free radicals into oxygencentred benzoquinone free radicals. The alpha-carbon of pyridine-N exhibited the lowest adsorption energy for hydroxyl radicals. The biochar sacrificial anode-assisted water electrolysis relied on alkyl radicals rather than hydroxyl radicals, thereby reducing hydrogen production energy consumption.

The combustion of biogas results in the formation of glassy SiO2 deposits due to the presence of volatile methylsiloxane (VMS) impurities, necessitating their removal from the biogas. As critical components of VMS, cyclic siloxanes can undergo ring-opening polymerization. Given the minimal catalyst consumption required, concentrating cyclic siloxanes from biogas on a support surface through polymerization could be more effective than traditional adsorption methods. In this study, a silica gel-supported sulfuric acid (SSA/SG) material was developed for biogas cleanup. The silica gel's adsorption properties were utilized to capture D4 on its surface, where it underwent ring-opening polymerization catalyzed by the anchored sulfuric acid. Dynamic adsorption tests showed that SSA/SG3 had an impressive D4 removal efficiency (Qm, th = 2459.1 mg g-1 at 20 degrees C), surpassing most materials used for D4 adsorption. Optimization of process conditions revealed that higher intake concentrations, moderate gas flow rates, increased adsorbent mass, and lower relative humidity significantly enhanced the D4 removal efficiency. Potential adsorption/polymerization mechanisms were also systematically explored through density functional theory calculations. These findings confirmed the formation of higher molecular weight polysiloxane structures on the sulfuric acid-supported silica gel, underscoring the costeffectiveness and practical potential of this method for VMS removal.

Siloxane components in biogas combustion produce silicon dioxide, which damages equipment and hinders biogas utilization. Conventional siloxane removal via physical adsorption is limited by the pore structure of the adsorbent material, necessitating precise material synthesis. Improvement in siloxane removal efficiency remains possible. By using a simple sulfuric acid impregnation, an activated biochar-supported sulfuric acid (ABSA) was here successfully synthesized. An efficient removal of octamethylcyclotetrasiloxane (D4; a model of siloxane) could be achieved by using the synthesized ABSA and a combination of adsorption and acid-induced siloxane polymerization, even under ambient conditions. This approach achieved maximum values for theoretical breakthrough adsorption capacity and saturation adsorption capacity at 3598.7 mg g- 1 and 5637.5 mg g- 1 respectively. Furthermore, dynamic adsorption experiments revealed that varying inlet concentrations, gas flow rate, adsorbent quantities, relative humidities, and loaded H2SO4 amounts played crucial roles in determining D4 removal effectiveness. According to the characterization results, the adsorption mechanism revealed that when that D4 was adsorbed, a ring-opening reaction occurred in the acidic environment of the supported sulfuric acid, which subsequently led to polymerization. These discoveries laid a pivotal groundwork for the development of an advanced biogas purification technique.

Carbon-assisted water electrolysis (CAEW), leveraging the carbon oxidation reaction (COR) in place of the oxygen evolution reaction (OER), substantially reduces the energy demand for H2 production. However, CO2 is the primary anode product in conventional CAEW, limiting its practical value. Additionally, mass transfer constraints significantly impact the efficiency of COR in substituting for OER in traditional CAEW systems. This study proposes an advanced CAEW process for syngas production, utilizing Aspen Plus simulations to generate H2 at the cathode and CO at the anode. A self-supporting corncob biomass char sacrificial anode was synthesized via hydrothermal-molding-pyrolysis. Simulation outcomes demonstrate that energy consumption for syngas production decreases as the H2/CO ratio increases within the 1 to 5 range, reaching minimum values of 1.14 kWh/ m3-H2 and 1.45 kWh/m3-syngas theoretically at an H2/CO ratio of 3. Electrochemical testing reveals that the corncob biomass char anode operates at a potential approximately 1/3 lower than that of a Pt anode while maintaining cathodic H2 production efficiency. The corncob sacrificial anode produces reduced gas and O2, confirming the replacement of OER by COR. Additionally, the anode gas contains around 10 % CO, validating CAEW's feasibility for syngas production.

Antibiotic resistance has been recognized as a global threat to human health. Therefore, it is urgent to develop effective strategies to address the contamination of water environments caused by antibiotics. In this study, Fe/Mn bimetallic-modified biochar (FMBC) was synthesized through a one-pot oxidation/reduction-hydrothermal co-precipitation method, demonstrating an exceptional photocatalytic-Fenton degradation performance for oxytetracycline (OTC). Characterization techniques including FTIR, SEM, XRD, VSM, and N2 adsorption–desorption analysis confirmed that the Fe/Mn bimetals were successfully loaded onto the surface of biochar in the form of Fe3O4 and MnFe2O4 mixed crystals and exhibited favorable paramagnetic properties that facilitate magnetic recovery. A key innovation is the utilization of biochar’s inherent phenol/quinone structures as reactive sites and electron transfer mediators, which synergistically interact with the loaded bimetallic oxides to significantly enhance the generation of highly reactive ·OH radicals, thereby boosting catalytic activity. Even after five recycling cycles, the material exhibited minimal changes in degradation efficiency and bimetallic crystal structure, indicating its notable stability and reusability. The photocatalytic degradation experiment conducted in a Fenton-like reaction system demonstrates that, under the conditions of pH 4.0, a H2O2 concentration of 5.16 mmol/L, a catalyst dosage of 0.20 g/L, and an OTC concentration of 100 mg/L, the optimal degradation efficiency of 98.3% can be achieved. Additionally, the pseudo-first-order kinetic rate constant was determined to be 4.88 min−1. Furthermore, this study elucidated the detailed degradation mechanisms, pathways, and the influence of various ions, providing valuable theoretical insights and technical support for the degradation of antibiotics in real wastewater.

The recovery and abatement of volatile organic compounds (VOCs) have received increasing attention due to their significant environmental and health impacts. Supported sulfonic acid materials have shown great potential in converting aromatic VOCs into their non-volatile derivatives through reactive adsorption. However, the anchoring state of sulfonic acid groups, which is closely related to the properties of the support, greatly affects their performance. In this study, two supported sulfonic acid materials, SZO and SMO, were prepared by treating ZrO2 and MgO with chlorosulfonic acid, respectively, to investigate the influence of the support properties on the anchoring state of sulfonic acid groups and their reactive adsorption performance for o-xylene. The supports, adsorbents, and adsorption products were extensively characterized, and the reactivity of SZO and SMO towards o-xylene was systematically compared. The results showed that sulfonic acid groups are anchored on the ZrO2 surface through covalent bonding, forming positively charged sulfonic acid sites ([O1.5Zr-O]δ−-SO3Hδ+) with a loading of 3.6 mmol/g. As a result, SZO exhibited excellent removal efficiency (≥91.3%) and high breakthrough adsorption capacity (ranging from 38.59 to 82.07 mg/g) for o-xylene in the temperature range of 130 –150 °C. In contrast, sulfonic acid groups are anchored on the MgO surface via ion-paired bonding, leading to the formation of negatively charged sulfonic acid sites ([O0.5Mg]+:OSO3H−), which prevents their participation in the electrophilic sulfonation reaction with o-xylene molecules. This work provides new insights into tuning and enhancing the performance of supported sulfonic acid materials for the resource-oriented treatment of aromatic VOCs.

The intimate coupling of photocatalysis and biodegradation (ICPB) technology has received much attraction because of the advantages of both photocatalytic reaction and biological treatment. In this study, ZnO-CoFe2O4@BC (ZCFC) with p-n heterojunction was prepared and used in an ICPB system to degrade metronidazole (MNZ) wastewater. The microstructure, morphology, and optical behavior of heterojunctions in ZCFC were investigated using SEM, XRD, UV-vis, FTIR, and XPS techniques. The results showed that ZCFC inherited the advantages of bamboo biochar's large pore size, and its large pore structure could provide a habitat for bacterial colonization in ICPB, thus shortening the internal mass transfer distance. The degradation of MNZ and chemical oxygen demand (COD) by the ICPB system was 86.8% and 58.5%, respectively, which was superior to single photocatalysis (72.5% for MNZ and 43.8% for COD) and single biodegradation (23.5% for MNZ and 20.1% for COD). In ICPB, photocatalysis and biodegradation showed a synergistic effect in the removal of MNZ, and the order of the major reactive oxygen species (ROS) leading to reduced toxicity of MNZ to the biofilm was center dot OH > h(+) > O-2 center dot(-). High-throughput sequencing analysis showed continuous evolution of biofilm structures in ICPB enriched a variety of functional species, among which the electroactive bacteria Alcaligenes and Brevundimonas played an important role in the degradation of MNZ. In this study, we investigated the possible mechanism of photocatalytic and microbial synergistic degradation of MNZ in the ICPB system and proposed a new technology for degrading antibiotic wastewater that combines the advantages of photocatalysis and biodegradation.