Efficient Catalytic Elimination of Toxic Volatile Organic Compounds via Advanced Oxidation Process Wet Scrubbing with Bifunctional Cobalt Sulfide/Activated Carbon Catalysts

Enhancing xylene degradation by core-shell TS-1@TiO2 in a bubble reactor with ultraviolet/H2O2

Volatile organic compounds (VOCs) in the atmosphere pose a critical global challenge due to their detrimental health effects. The ultraviolet (UV)/Fenton-like system has shown promise for VOC degradation. However, maintaining long-term catalytic efficiency by minimizing intermediate byproduct accumulation remains key challenges. In this study, a novel core-shell catalyst is developed which composed of anatase-phase titanium dioxide (TiO2) nanoparticles deposited on titanium silicalite-1 (TS-1) via a Stöber method in an ethanol/ammonia mixture. The TS-1@TiO2 structure promotes efficient spatial separation of photogenerated electrons and holes under UV irradiation, enhancing the activation of H2O2 to yield highly reactive free radicals (OH, OOH and O2-) for effective xylene degradation. In a UV/H2O2 bubble reactor, the TS-1@TiO2 catalyst demonstrates stable xylene degradation efficiency (75 % over 200 min), surpassing the performance of standalone TS-1 (53.2 %) and TiO2 (57.1 %). This design addresses critical challenges in sustained radical generation and intermediate suppression, offering a robust strategy to improve the longevity and efficiency of UV/H2O2 systems for environmental remediation.

Rapid charge transfer and enhanced internal electric field in core-shell Schottky junction for photocatalyzed Fenton reaction: Performance and mechanism

The challenge of achieving fast and efficient separation of photogenerated carriers lies in the kinetics of photocatalytic reactions. In the present study, we employed solvothermal and surfactant-induced methods to uniformly grow BiOCl on the surface of CoS Nano-flower balls, thereby forming core-shell Schottky heterojunctions. X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations demonstrated the directional transfer of electrons and the establishment of an enhanced built-in electric field during the formation of these heterojunctions. This rapid separation of photogenerated carriers effectively activates the photo-Fenton system and enhances its synergistic effect. After 60 min of light exposure and the addition of Peroxymonosulfate (PMS), 100C-PBOC effectively degraded 95.6 % of ciprofloxacin, exhibiting a degradation rate k-value that is 1.97 times higher than that of photocatalytic degradation alone. Considering the insufficiency of mineralization, we conducted liquid chromatography-mass spectrometry (LC-MS) tests in conjunction with DFT calculations to elucidate the complete degradation mechanism and assess the toxicity of the degraded intermediates, most of which exhibited significantly reduced toxicity. This study addresses the gap in the application of CoS co-catalysts in photocatalytic wastewater treatment and offers a novel approach to the design of core-shell heterojunctions.

Sp-hybridized carbon- facilitated peroxymonosulfate activation for superior phenolic pollutant removal

Carbocatalysts, widely regarded as eco-friendly catalysts in the field of peroxymonosulfate (PMS) activation for pollutant removal, exhibit significant variations in performance depending on the type of carbon atom hybridization. Notably, the novel graphdiyne (GDY), characterized by its sp-hybridized carbon (sp-C), has recently garnered significant attention. However, the precise mechanistic role of sp-C on PMS activation remains unclear. Herein, we elucidate the role of sp-C on PMS activation and the corresponding mechanism behind enhanced phenolic pollutant degradation over the GDY catalyst. GDY demonstrates exceptional phenolic removal efficiency (97 %), which far exceeds that of traditional sp2-hybridized graphene (2 %). The GDY facilitates pollutant oxidation via a catalyst-mediated electron transfer mechanism. The sp-C provides additional sites for PMS adsorption and donates significantly more electrons from GDY to PMS (0.51 e more than graphene), effectively facilitating PMS activation, intermediate species conversion, and reaction kinetics during phenolic pollutant degradation. By integrating the monolithic GDY catalyst into a flow-through device for continuous phenolic pollutant removal, long-lasting phenolic removal was maintained for over 80 hours, with a removal rate exceeding 85 %. This work highlights that sp-C in GDY effectively enhances PMS activation, providing a pathway for efficient organic pollutant degradation in advanced oxidation processes.

Electron-rich CuOx@Al2O3 Catalyst for Sustainable O2 Activation in Fenton-Like Reactions

Molecular oxygen (O2) activation is pivotal in advancing green chemistry and catalysis, addressing processes such as energy conversion and environmental remediation. However, the inherent inertness of the O2 necessitates highly efficient catalysts. In this study, an electron-rich CuOx@Al2O3 catalyst with high metal loading and dispersion was synthesized via the ion-exchange inverse-loading method. The novel CuOx@Al2O3 significantly enhanced O2 activation due to the accelerated Cu0 → Cu+ → Cu2+ redox cycle, achieving the 85% chlorobenzene removal in Fenton-like reaction. This is substantially higher than the chlorobenzene removal observed with conventional CuOx/Al2O3 (45%). Experiments and density functional theory (DFT) calculations revealed that Cu-Cu sites over CuOx@Al2O3 greatly facilitated charge transfer, weakened O-O bonds, and promoted synergistic O2 and H2O2 activation to produce •OH and O2•-, thereby enhancing oxidants utilization efficiency. This study provides a sustainable pathway for pollutant degradation by achieving O2 activation and offers valuable insights for designing advanced Cu-based catalysts in green oxidation processes and environmental remediation.

Coordination Anions Dimensionality-Engineered Dual-Atom Catalysts for Enhanced Fenton-Like Reactions: 3D Coordination Induced Spin-State Transition

Dual-atom catalysts (DACs) have shown significant application potential in Fenton-like reactions. However, effectively modulating their electronic structure and fully understanding the mechanisms driving their high catalytic activity remain challenging. Herein, we propose a coordination anions dimensionality engineering strategy to synthesize biomass-derived dual-atom FeCo-N4O1C catalysts, in which Fe and Co atoms are bridged by two-dimensional planar N atoms and a three-dimensional (3D) axial O atom. Experimental data and theoretical calculations reveal that the 3D coordination structure of FeCo-N4O1C induces the spin state of Fe undergo a transition from a low spin state to an intermediate spin state compared with single-atom Fe-N4O1C, resulting in moderate adsorption and desorption of intermediates, thus reducing the energy barriers for generating more singlet oxygen and high-valent cobalt-oxo species during peroxymonosulfate activation. The electron transfer from Co atoms to neighboring Fe atoms through N atoms and 3D axial O atoms can effectively prevent the poisoning of active species. Benefiting from the 3D coordination structure and the synergistic effects of multiple active sites, the catalyst-dose normalized reaction rate constant reaches 14.5 L min-1 g-1 under low peroxymonosulfate concentrations─an improvement of 1 ∼ 2 orders of magnitude over most reported catalysts. The practical applicability of FeCo-N4O1C is demonstrated through nearly 100% pollutant removal during 7 days of continuous operation in a membrane filtration system. This study provides deep insights into the relationship between electronic structure and catalytic performance through spin-state regulation of DACs, and introduces a promising approach for large-scale synthesis of low-cost, highly efficient DACs for Fenton-like reactions.

Highly selective ethanol gas sensor based on CdS/Ti3C2T x MXene composites

Sensing of hazardous gases has an important role in ensuring safety in a variety of industries as well as environments. Mainly produced by the combustion of fossil fuels and other organic matter, ethanol is a dangerous gas that endangers human health and the environment. Stability and sensing sensitivity are major considerations when designing gas sensors. Here, a superior ethanol sensor with a high response and fast recovery was synthesized by "wrapping" CdS nanoparticles on metallic Ti3C2T x MXene using a simple method. CdS nanoparticles were uniformly covered on the Ti3C2T x MXene surface, forming a "rice crust"-like heterostructure. The sensor displayed good detection of ethanol gas at room temperature. Response signals up to 31% were obtained for ethanol molecules (20 ppm) with quick recovery (41 s). The performance of the ethanol sensor was evaluated across a range of concentrations (5-100 ppm) and relative humidity (60% and 90% RH) at room temperature. Our method could open up a new strategy for the development of ethanol sensors.

Highly efficient synthetic bacterial consortium for biodegradation of aromatic volatile organic compounds: Behavior and mechanism

Aromatic volatile organic compounds (VOCs) are prevalent pollutants in chemically contaminated sites, posing threats to ecological safety and human health. To address the challenge of achieving low-carbon, low-cost, green, and sustainable in-situ remediation at these sites, a highly efficient synthetic bacterial consortium was constructed for biodegradation of selected pollutants (i.e., benzene, toluene, ethyl benzene, m-xylene, chlorobenzene, p-chlorotoluene, and p-chlorotrifluorotoluene). Under optimized conditions, the consortium achieved a total degradation efficiency of 77%. Biodegradation of benzene, toluene, ethyl benzene, and m-xylene followed first-order kinetics, while p-chlorotoluene and p-chlorotrifluorotoluene followed zero-order kinetics. The mechanisms were analyzed using microbiome technology at genetic, protein, and metabolic levels, identifying key enzymes and differences in protein expression and related metabolites. Carbon dioxide measurements and fluorescence spectrum analysis elucidated the transformation pathways. These findings underscore the consortium's significant potential for achieving effective, eco-friendly, and sustainable bioremediation of aromatic VOCs in chemically contaminated environments.

A Critical Review of Deep Oxidation of Gaseous Volatile Organic Compounds via Aqueous Advanced Oxidation Processes

Volatile organic compounds (VOCs) are considered to be the most recalcitrant gaseous pollutants due to their high toxicity, diversity, complexity, and stability. Gas-solid catalytic oxidation methods have been intensively studied for VOC treatment while being greatly hampered by energy consumption, catalyst deactivation, and byproduct formation. Recently, aqueous advanced oxidation processes (AOPs) have attracted increasing interest for the deep oxidation of VOCs at room temperature, owing to the generation of abundant reactive oxygen species (ROS). However, current reviews mainly focus on VOC degradation performance and have not clarified the specific reaction process, degradation products, and paths of VOCs in different AOPs. This study systematically reviews recent advances in the application of aqueous AOPs for gaseous VOC removal. First, the VOC gas-liquid mass transfer and chemical oxidation processes are presented. Second, the latest research progress of VOC removal by various ROS is reviewed to study their degradation performances, pathways, and mechanisms. Finally, the current challenges and future strategies are discussed from the perspectives of synergistic oxidation of VOC mixtures, accurate oxidation, and resource utilization of target VOCs via aqueous AOPs. This perspective provides the latest information and research inspiration for the future industrial application of aqueous AOPs for VOC waste gas treatment.