Prehydrated Electrons Activated by Continuous Electron Transfer Stemmed from Peracetic Acid Homolysis Mediated by Diamond Surface Defects for Enhanced PFOA Destruction.

Research on the use of peracetic acid (PAA) activated by nonmetal solid catalysts for the removal of dissolved refractory organic compounds has gained attention recently due to its improved efficiency and suitability for advanced water treatment (AWT). Among these catalysts, nanocarbon (NC) stands out as an exceptional example. In the NC-based peroxide AWT studies, the focus on the mechanism involving multimedia coordination on the NC surface (reactive species (RS) path, electron reduction non-RS pathway, and singlet oxygen non-RS path) has been confined to the one-step electron reaction, leaving the mechanisms of multichannel or continuous electron transfer paths unexplored. Moreover, there are very few studies that have identified the nonfree radical pathway initiated by electron transfer within PAA AWT. In this study, the complete decomposition (kobs = 0.1995) and significant defluorination of perfluorooctanoic acid (PFOA, deF% = 72%) through PAA/NC has been confirmed. Through the use of multiple electrochemical monitors and the exploration of current diffusion effects, the process of electron reception and conduction stimulated by PAA activation was examined, leading to the discovery of the dynamic process from the PAA molecule → NC solid surface → target object. The vital role of prehydrated electrons (epre-) before the entry of resolvable electrons into the aqueous phase was also detailed. To the best of our knowledge, this is the first instance of identifying the nonradical mechanism of continuous electron transfer in PAA-based AWT, which deviates from the previously identified mechanisms of singlet oxygen, single-electron, or double-electron single-path transfer. The pathway, along with the strong reducibility of epre- initiated by this pathway, has been proven to be essential in reducing the need for catalysts and chemicals in AWT.

Ultraviolet technology application in urban water supply and wastewater treatment in China: Issues, challenges and future directions.

This study thoroughly explores the application of Ultraviolet (UV) water treatment technology in urban wastewater treatment and water supply in China, highlighting its crucial role in enhancing water quality safety. UV technology, with its environmentally friendly and low-carbon characteristics, is deemed more in line with the demands of sustainable development compared to traditional chemical disinfection methods. The widespread application of UV technology in urban wastewater treatment in China, particularly in the context of urban sewage treatment, is examined. However, to better promote and apply UV technology, there is a need to deepen the understanding of this technology and its application among a broad base of users and design units. The importance of gaining in-depth knowledge about the performance of UV water treatment equipment, the design calculation basis, and operational considerations, as well as the ongoing development of relevant standards, is underscored to ensure that the equipment used in projects complies with engineering design and production requirements. Furthermore, the positive trend of UV technology in the field of advanced oxidation, indicating a promising trajectory for engineering applications, is pointed out. Regarding the prospects of industrial development, a thorough analysis is conducted in the article, emphasizing the necessity for all stakeholders to collaborate and adopt a multi-level approach to promote the sustainable development and application of UV water treatment technology. This collaborative effort is crucial for providing effective safeguards for China's environment, ecology, and human health.

Effects of treatments and distribution on microbiome and antibiotic resistome from source to tap water in three Chinese geographical regions based on metagenome assembly.

Antibiotic resistance genes (ARGs) represent emerging environmental pollutants that present health risks. Drinking water supply systems (DWSSs), including sources to tap water, play crucial roles in the dissemination and propagation of ARGs. However, there was a paucity of knowledge on the relative abundance, diversity, mobility, and pathogenic hosts of ARGs in DWSSs from source to tap. Therefore, the effects of treatments and distributions on the microbial community and ARGs from three geographical regions (downstream areas of the Yellow, Yangtze, and Pearl Rivers) were elucidated in the present study. Treatment processes lowered the complexity of the microbial community network, whereas transportation increased it. The assembly mechanisms of the microbial community and antibiotic resistome were primarily driven by stochastic processes. Distribution greatly increased the contribution of stochastic processes. Multidrug ARGs (for example, multidrug transporter and adeJ) and bacitracin ARG (bacA) were the primary mobile ARGs in drinking water, as identified by the metagenomic assembly. Achromobacter xylosoxidans, Acinetobacter calcoaceticus, and Acinetobacter junii harbored diverse multidrug ARGs and mobile genetic elements (MGEs) (recombinases, integrases, and transposases) as potential pathogens and were abundant in the disinfected water. Environmental factors, including pH, chlorine, latitude, longitude, and temperature, influenced the ARG abundance by directly regulating the MGEs and microbial community diversity. This study provides critical information on the fate, mobility, host pathogenicity, and driving factors of ARGs in drinking water, which is conducive to ARG risk assessment and management to provide high-quality drinking water to consumers.

Tailoring S-vacancy concentration changes the type of the defect and photocatalytic activity in ZFS.

Defect engineering is crucial in the development of semiconductor catalyst activity. However, the influence of defect/vacancy density and states on catalysis remains vague. Thus, the optimized sulfur vacancy (SV) state is achieved among Fe-ZnS models (ZFS) via a chemical etching strategy for photocatalytic degradation (PD). As the SV concentration (ρSV) increases, the predominant state of vacancies changes from isolated defects－a state to a combination of a state and vacancy clusters－e state, as verified by positron annihilation and X-ray absorption fine structure spectra. However, the two types of defect states activated the intrinsic activity of the crystal via radically different mechanisms and exerted different degrees of influence on PD activity, as revealed by first-principles calculations and quantitative structure-activity relationship. Our results suggest that the SV activity is strongly influenced by its concentration in the ZFS crystal, while the vacancy concentration is not a control parameter for the PD activity, but a defect form. The underlying essence of atomic defects behavior affecting crystal catalytic activity at the atomic level is also revealed in this paper. Uncovering these structural relationships provide a theoretical basis for designing effective catalysts.

Activating the Basal Plane of 2H-MoS2 by Doping Phosphor for Enhancement in the Photocatalytic Degradation of Organic Contaminants.

The 2H phases of MoS2 (2H-MoS2) monolayers present a wealth of new opportunities in photocatalysis owing to their photoinduced catalyzing ability and excellent charge carrier mobility. However, the complete release of their catalytic activities is restricted by their inert basal planes. Although the inert base planes of 2H-MoS2 are known to be activated by atomic doping, the operational principle of the exotic atoms remains vague. In this study, the unutilized inert base sites of MoS2 were activated via an oxygen-aided P-substituted method (denoted as POMS). Molecular structural tests and analyses of POMS indicated that the inert MoS2 substrate is activated when the inerratic crystal phases transform to amorphous phases in the P-doping process. The fully activated inert base planes provide sufficient reaction sites for photo-oxidized water contaminants. The designed POMS presented superior activity in organic degradation and completely removed sulfamethoxazole within 20 min. Uncovering these operational principles provides a theoretical basis for designing effective catalysts.

Photocatalytic oxidation of norfloxacin by Zn0.9Fe0.1S supported on Ni-foam under visible light irradiation.

Norfloxacin (NOR) is an emerging antibiotics contaminant due to its high resistance to microbial degradation and natural weathering. In this study, Fe-doped ZnS photocatalyst (Zn0.9Fe0.1S) was deposited on nickel foam (Ni-foam) to improve photocatalytic activity under visible light irradiation. The mass ratio of Zn0.9Fe0.1S and Ni-foam was optimized to be 0.03 g catalyst versus per g Ni-foam (0.03 Zn0.9Fe0.1S/Ni-foam), which led to the highest removal rate of 95%. The optimal degradation condition for NOR over 0.03 Zn0.9Fe0.1S/Ni-foam was pH at 7.0, initial NOR concentration of 5 mg L-1, and initial photocatalyst concentration of 11.7 g L-1, with the highest first-order reaction rate constant of 0.025 min-1 and mineralization rate of 63.1%. The NOR removal rate on 0.03 Zn0.9Fe0.1S/Ni-foam photocatalyst (95%) was approximately four times of that obtained on Zn0.9Fe0.1S photocatalyst (25%). The increased photocatalytic performance could be attributed to the function of Ni-foam as excellent electron collectors that provided efficient photoinduced charge separation from Zn0.9Fe0.1S. The reactive species responsible for the degradation of NOR were photo-generated holes, hydroxyl radical, and superoxide radicals. Nearly 90% of the photocatalytic efficiency was retained over seven cycles and the released metal ion concentrations were <0.3% of the total mass of photocatalyst, suggesting high stability of the photocatalyst during the photocatalytic reactions. The aqueous/solid mass transfer and intraparticle mass transfer for Zn0.9Fe0.1S/Ni-foam were not limiting factors for the degradation of NOR. Therefore the Zn0.9Fe0.1S/Ni-foam photocatalyst could be applied in the degradation of hazardous pollutants.

Optimization and Degradation Mechanism of Photocatalytic Removal of Bisphenol A Using Zn0.9 Fe0.1 S Synthesized by Microwave-assisted Method.

The sulfide photocatalyst of Zn0.9 Fe0.1 S was successfully synthesized by a facile microwave-assisted method, and Zn0.9 Fe0.1 S photocatalysts were characterized using SEM, EDX, XRD and BET. The specific surface area of synthesized Zn0.9 Fe0.1 S is 78.1 m2 g-1 , and total pore volume is 0.4 cm3 g-1 . With bisphenol A (BPA) as a target pollutant, photocatalytic system of UV + Zn0.9 Fe0.1 S + H2 O2 was set up. Some influencing parameters, including H2 O2 dosage, initial pH value, initial concentration of BPA and Zn0.9 Fe0.1 S dosage, were investigated, and the stability of the Zn0.9 Fe0.1 S was also studied during the photocatalysis. The optimum values of operating parameters were found at an initial pH value of 5.0, a H2 O2 dosage of 0.15 mmol L-1 and a Zn0.9 Fe0.1 S dosage of 0.08 g when the initial concentration of BPA was 10 mg L-1 . Under the optimal conditions, the highest removal rate of BPA achieved 95%. After seven consecutive reaction cycles, the degradation efficiency of BPA could still reach 85% and there was only a little dissolution of Zn2+ and Fe2+ . Compared with the traditional photo-Fenton system, the UV + Zn0.9 Fe0.1 S + H2 O2 system can not only improve the degradation efficiency of BPA, but also reduce the dosage of H2 O2 and thus reduce the processing cost.