Yunshu Zhang

Microplastics (MPs) are widespread environmental pollutants. This study primarily examines the changes in electro distribution of aged MPs in aquatic environments and their subsequent impact on the environment. Under the action of natural and artificial aging, the electron cloud arrangement of MPs will change, thus affecting the relevant properties of MPs. Among them, the free radicals formed by advanced oxidation technology will be enriched on the surface of MPs carrying benzene rings, and react with other pollutants (organic pollutants, heavy metals, etc.) adsorbed by MPs to form environmental persistent free radicals (EPFRs). The electron cloud density of MPs carrying EPFRs increases, and the reactivity will also increase. Additionally, the oxygen-containing functional groups on the surface of aged MPs enhance their selective adsorption, altering their environmental impact. MPs can serve as a source of free radicals in the environment, enhance the oxidation capacity of other substances in the environment, and even affect the expression of antibiotic resistance genes. In addition, MPs have a high mobility, which will have a greater negative impact in the environment. Additionally, the high mobility of MPs amplifies their negative environmental impact. This study examines the changes in electron distribution of aged MPs and highlights their effects on aquatic ecosystems, providing insights into pollution control, toxicity, and degradation mechanisms. Graphical abstract

Ferrate(VI) is a green and efficient water treatment agent for drinking and wastewater. It is widely used in water treatment because it has multi-functional uses such as oxidation, algae removal, disinfection, and adsorption flocculation. It does not cause secondary pollution to the environment. This paper compares ferrate(VI) with other water treatment agents and discusses three methods of preparing ferrate(VI). The removal, adsorption, and control of organic matter, algae, disinfection by-products, and heavy metal ions in water when ferrate(VI) was used as an oxidant, disinfectant, and coagulant were summarized. Ferrate(VI) has some advantages in removing toxic, harmful, and difficult-to-degrade substances from water. Due to the disadvantages of ferrate(VI) such as oxidation selectivity and instability, it is necessary to develop the hyphenated techniques of ferrate(VI). In this review, three hyphenated techniques of ferrate(VI) are summarized: ferrate(VI)–photocatalytic synergistic coupling, ferrate(VI)–PAA synergistic coupling, and ferrate(VI)–PMS synergistic coupling.

Plastic wastes are becoming one of the most serious environmental pollutants because of their high antidegradation properties and the damage they cause to human health. More seriously, plastics can become smaller in size and form microplastics (MPs), attributing to the oxidation, weathering, and fragmentation processes. The influx of MPs into water bodies seriously affects the quality of the aquatic environment. Therefore, it is necessary to summarize the aging process of MPs. In this review, we first provided an overview of the definition and source of MPs. Then we analyzed the potential aging pathways of MPs in the current aquatic environment and elaborated on the changes in the physicochemical properties of MPs during the aging process (e.g., particle size, crystallinity, thermodynamic properties, and surface functional groups). In addition, the possible synergistic contamination of MPs with other pollutants in the environment is illustrated. Finally, the mechanisms of generation and toxicity of environmental persistent free radicals (EPFRs) that may be generated during the photoaging of MPs were described, and the feasibility of using photoaged MPs as photosensitizers to catalyze photoreactive degradation of organic pollutants is proposed. Overall, this review provides a comprehensive and objective evaluation of the behavior of MPs in the aquatic environment.

The misuse of antibiotics causes antibiotic resistance genes (ARGs) in bacteria to be gradually enriched by environmental selection, resulting in increased tolerance and resistance in bacteria to antibiotics. Ballast water is a mobile carrier for the global transfer of bacteria and genes, thus posing a certain risk of ARGs spreading into the global ocean. Therefore, it is important to investigate the current status of ARGs in ballast water, as well as control the abundance of ARGs. Herein, we attempt to comprehensively summarize the distribution and abundance of ARGs in ballast water from different sea areas and analyze the influencing factors (such as physical factors, chemical factors, temperature, pH, etc.) on the distribution of ARGs. Furthermore, we seek to review the changes in ARGs after differential disinfection technology treatment in ballast water (including chlorination, ultraviolet, ozone, and free radical technology), especially the enhancing effect of subinhibitory concentrations of disinfectants on ARGs transfer. Overall, we believe this review can serve as a guide for future researchers to establish a more reasonable standard of ballast water discharge that considers the pollution of ARGs and provide new insight into the risk of vertical and horizontal ARG transfer in ballast water after disinfection.

Antibiotics are highly effective bactericidal drugs that are widely used in human medicine, aquaculture and animal husbandry. Antibiotics enter the aquatic environment through various routes due to low metabolic levels and increased use. Not only are antibiotics inherently toxic, but the spread of potential drug resistance introduced has been identified by the World Health Organization as one of the major threats and risks to global public health security. Therefore, how to efficiently remove antibiotics from water and eliminate the ecological safety hazards caused by antibiotics has been a hot topic in recent years. There are various research methods for decontaminating water with antibiotics. This paper reviews the research and application of various biological, physical, chemical methods and combined processes in antibiotic pollution control. Moreover, this paper describes the degradation mechanism, removal efficiency, influencing factors and technical characteristics of different antibiotics by various methods in detail. Finally, an outlook on future research in antibiotic removal is provided to help promote the development of antibiotic removal technology.

In recent years, the removal of organic pollutants from water and wastewater has attracted more attention to different advanced oxidation processes (AOPs). There has been increasing interest in using peroxyacetic acid (PAA), an emerging oxidant with low or no toxic by-products, yet the promotion and application are limited by unclear activation mechanisms and complex preparation processes. This paper synthesized the related research results reported on the removal of organic pollutants by PAA-based AOPs. Based on the research of others, this paper not only introduced the preparation method and characteristics of PAA but also summarized the mechanism and reactivity of PAA activated by the free radical pathway and discussed the main influencing factors. Furthermore, the principle and application of the newly discovered methods of non-radical activation of PAA in recent years were also reviewed for the first time. Finally, the shortcomings and development of PAA-based AOPs were discussed and prospected. This review provides a reference for the development of activated PAA technology that can be practically applied to the treatment of organic pollutants in water.