Oxygen activation leading to the generation of reactive oxygen species (ROS) is essential for photocatalytic environmental remediation. The limited efficiency of O2 adsorption and reductive activation significantly limits the production of ROS when employing C3N4 for the degradation of emerging pollutants. Doping with metal single atoms may lead to unsatisfactory efficiency, due to the recombination of photogenerated electron-hole pairs. Here, Mn and S single atoms were introduced into C3N4, resulting in the excellent photocatalytic performances. Mn/S-C3N4 achieved 100% removal of bisphenol A, with a rate constant 11 times that of pristine C3N4. According to the experimental results and theoretical simulations, S-atoms restrict holes, facilitating the photo-generated carriers\' separation. Single-atom Mn acts as the O2 adsorption site, enhancing the adsorption and activation of O2, resulting the generation of ROS. This study presents a novel approach for developing highly effective photocatalysts that follows a new mechanism to eliminate organic pollutants from water.

Biological methods do not effectively remove pharmaceutical products (PPs) and antibiotic resistance genes (ARGs) from wastewater at low temperatures, leading to environmental pollution. Therefore, anaerobic-aerobic-coupled upflow bioelectrochemical reactors (AO-UBERs) were designed to improve the removal of PPs at low temperatures (10 ± 2 °C). The result shows that diclofenac (DIC) and ibuprofen (IBU) removals in the system with aerobic anodic and anaerobic cathodic chambers were 91.7% and 94.7%, higher than that in the control system (12.2 ± 1.5%, 36.5 ± 5.9%), and aerobic zone favors DIC and IBU removal; fluoroquinolone antibiotics (FQs) removals in the system with aerobic cathodic and anaerobic anodic chambers were 17.5-22.4% higher than that in the control system (9.1-22.4%), and anaerobic zone favors FQs removal. Analysis of microbial community structure and ARGs showed that different electrotrophic microbes (Flavobacterium, Acinetobacter, and Delftia) with cold-resistant ability to degrade PPs were enriched in different electrode combinations, and the aerobic cathodic chambers could remove certain ARGs. These results showed that AO-UBERs under intermittent electrical stimulation mode are an alternative method for the effective removal of PPs and ARGs at low temperatures.

Nitrogen-doped biochar as Fenton-like catalysts has been widely used to remove emerging pollutants in wastewater. However, the effect of in-situ and ex-situ nitrogen doping on the Fenton-like catalytic activity of biochar is unclear. In this study, the nitrogen-doped biochar was prepared by in-situ (NBC) and ex-situ (BC-N) nitrogen doping, and the Fenton-like catalytic activity of NBC and BC-N was compared for activating hydrogen peroxide (H2O2), peroxydisulfate (PDS) and peroxymonosulfate (PMS). The results showed that NBC had higher Fenton-like catalytic activity than BC-N, because the formation of carbon quantum dots (CQDs) significantly increased the adsorption capacity to H2O2, PDS and PMS. NBC could activate H2O2, PDS and PMS for degradation of sulfamethoxazole (SMX), but showed different catalytic activity and degradation mechanism. In the systems of NBC/H2O2 and NBC/PDS, CQDs played a key role in the activation of H2O2 and PDS, and surface-bound reactive species were mainly responsible for SMX degradation. In the system of NBC/PMS, NBC acted as both electron mediator and activator, direct electron transfer between PMS and SMX and surface-bound reactive species contributed to SMX degradation. This study provides an insight into the catalytic activity of NBC for H2O2, PDS and PMS.

Chitin is the second most abundant natural biopolymer, which is composed of N-acetyl glucosamine units linked by β-(1 → 4) Chitosan is an N-deacetylated product of chitin. Properties of chitosan and chitin, such as biocompatibility, non-toxic nature, and biodegradability, make them successful alternatives for energy and environmental applications. However, their low mechanical properties, small surface area, reduced thermal properties, and greater pore volume restrict the potential for adsorption applications. Multiple investigations have demonstrated that these flaws can be prevented by fabricating chitosan and chitin with carbon-based composites. This review presents a comprehensive analysis of the fabrication of chitosan/chitin carbon-based materials. Furthermore, this review examines the prevalent technologies of functionalizing chitosan/chitin biopolymers and applications of chitin and chitosan as well as chitosan/chitin carbon-based composites, in various environmental fields (mitigating diverse water contaminants and developing biosensors). Also, the subsequent regeneration and reuse of adsorbents were also discussed. Finally, we summarize a concise overview of the difficulties and potential opportunities associated with the utilization of chitosan/chitin carbon-based composites as adsorbents to remove water contaminants.

Emerging pollutants (EPs) are prevalent in aquatic environments globally. Researchers strive to understand their occurrence and behavior prior to their release into the environment. In this study, we examined five wastewater treatment plants (WWTPs), collected 50 wastewater samples and 10 sludge samples. We explored the sources and destinations of phthalic acid esters (PAEs) within these WWTPs using mass balance equations. Wastewater treatment diminished the frequency and concentration of PAEs, and decreased the fraction of short-chain PAEs. We confirmed the increased concentration of PAEs post-primary treatment and modified the mass balance equation. Calculations suggest that weaker \"the mix\" in winter than in summer and stronger sedimentation in winter than in summer resulted in high efficiency of PAEs removal by winter wastewater treatment. The mass flux of biodegradation was influenced by the combination of biodegradation efficiency and the strength of the particular type of PAEs collected, with no seasonal differences. Mass fluxes for sludge sedimentation were mainly influenced by season and were higher in winter than in summer. This study enhances our understanding of emerging pollutants in manual treatment facilities and offers insights for optimizing wastewater treatment methods for water professionals.

The coexistence of multiple emerging contaminants imposes a substantial burden on the ecophysiological functions in organisms. The combined toxicity and underlying mechanism requires in-depth understanding. Here, marine blue mussel (Mytilus galloprovincialis L.) was selected and exposed to 2,2\',4,4\'-tetrabromodiphenyl ether (BDE-47) and perfluorooctanoic acid (PFOA) individually and in combination at environmental related concentrations to elucidate differences in stress responses and potential toxicological mechanisms. Characterization and comparison of accumulation, biomarkers, histopathology, transcriptomics and metabolomics were performed. Co-exposure resulted in differential accumulation patterns, exacerbated histopathological alterations, and different responses in oxidative stress and biomarkers for xenobiotic transportation. Moreover, the identified differentially expressed genes (DEGs) and differential metabolites (DEMs) in mussels were found to be annotated to different metabolic pathways. Correlation analyses further indicated that DEGs and DEMs were significantly correlated with the above biomarkers. BDE-47 and PFOA altered the genes and metabolites related to amino acid metabolism, energy and purine metabolism, ABC transporters, and glutathione metabolism to varying degrees, subsequently inducing accumulation differences and combined toxicity. Furthermore, the present work highlighted the pivotal role of Nrf2-keap1 detoxification pathway in the acclimation of M. galloprovincialis to reactive oxygen species (ROS) stress induced by BDE-47 and PFOA. This study enabled more comprehensive understanding of combined toxic mechanism of multi emerging contaminants pollution.

A massive amount of toxic substances and harmful chemicals are released every day into the outer environment, imposing serious environmental impacts on both land and aquatic animals. To date, research is constantly in progress to determine the best catalytic material for the effective remediation of these harmful pollutants. Hybrid nanomaterials prepared by combining functional polymers with inorganic nanostructures got attention as a promising area of research owing to their remarkable multifunctional properties deriving from their entire nanocomposite structure. The versatility of the existing nanomaterials\' design in polymer-inorganic hybrids, with respect to their structure, composition, and architecture, opens new prospects for catalytic applications in environmental remediation. This review article provides comprehensive detail on catalytic polymer nanocomposites and highlights how they might act as a catalyst in the remediation of toxic pollutants. Additionally, it provides a detailed clarification of the processing of design and synthetic ways for manufacturing polymer nanocomposites and explores further into the concepts of precise design methodologies. Polymer nanocomposites are used for treating pollutants (electrocatalytic, biocatalytic, catalytic, and redox degradation). The three catalytic techniques that are frequently used are thoroughly illustrated. Furthermore, significant improvements in the method through which the aforementioned catalytic process and pollutants are extensively discussed. The final section summarizes challenges in research and the potential of catalytic polymer nanocomposites for environmental remediation.

In this study, ionizing radiation was used to induce the in-situ formation of highly dispersed nanosized cobalt oxide on the surface of graphene oxide (R-Co-GO), which was highly effective for activating PMS to degrade sulfamethoxazole (SMX). R-Co-GO had the highest catalytic activity when 150 μL cobalt chloride hexahydrate solution was used in the precursor, and the pseudo first-order kinetic constant of SMX degradation was 0.07 min-1 with high mineralization efficiency (63.1 %) and high PMS utilization efficiency. The sulfate radicals and high-valent cobalt oxo were mainly responsible for SMX degradation. Mechanism analysis showed that cobalt active site dominated in PMS activation, which was responsible for the formation of sulfate radicals and high-valent cobalt oxo; while the carbon framework contributed to the formation of singlet oxygen. The R-Co-GO-150 had good catalytic activity and stability in five cycling experiments, in which SMX was completely degraded and the concentration of dissolved Co was below 0.1 mg/L. In addition, the R-Co-GO-150/PMS system could also degrade phenol, bisphenol A, atrazine and nitrobenzene effectively, confirming its wide applicability. This study provided a facile method to uniformly disperse the metal oxides on the surface of carbon materials, and an effective system for the removal of emerging organic pollutants from the actual wastewater.

Biochar has emerged as a versatile and efficient multi-functional material, serving as both an adsorbent and catalyst in removing emerging pollutants (EPs) from aquatic matrices. However, pristine biochar\'s catalytic and adsorption capabilities are hindered by its poor surface functionality and small pore size. Addressing these limitations involves the development of functionalized biochar, a strategic approach aimed at enhancing its physicochemical properties and improving adsorption and catalytic efficiencies. Despite a growing interest in this field, there is a notable gap in existing literature, with no review explicitly concentrating on the efficacy of biochar-based functional materials (BCFMs) for removing EPs in aquatic environments. This comprehensive review aims to fill this void by delving into the engineering considerations essential for designing BCFMs with enhanced physiochemical properties. The focus extends to understanding the treatment efficiency of EPs through mechanisms such as adsorption or catalytic degradation. The review systematically outlines the underlying mechanisms involved in the adsorption and catalytic degradation of EPs by BCFMs. By shedding light on the prospects of BCFMs as a promising multi-functional material, the review underscores the imperative for sustained research efforts. It emphasizes the need for continued exploration into the practical implications of BCFMs, especially under environmentally relevant pollutant concentrations. This holistic approach seeks to contribute to advancing knowledge and applying biochar-based solutions in addressing the challenges posed by emerging pollutants in aquatic ecosystems.

Carbon material modification and defect engineering are indispensable for bolstering the photocatalytic effectiveness of bismuth halide oxide (BiOX). In this study, a novel porous and defect-rich Ar-CB-2 photocatalyst was synthesized for emerging pollutants degradation. Leveraging the interfacial coupling effect of multi-walled carbon nanotubes (MWCNTs), we expanded the absorption spectrum of BiOI nanosheets and significantly suppressed the recombination of charge carriers. Introducing defects via Argon (Ar) plasma-etching further bolstered the adsorption efficacy and electron transfer properties of photocatalyst. In comparison to the pristine BiOI and CB-2, the Ar-CB-2 photocatalyst demonstrated superior photodegradation efficiency, with the first-order reaction rates for the photodegradation of tetracycline (TC) and bisphenol A (BPA) increasing by 2.83 and 4.53 times, respectively. Further probe experiments revealed that the steady-state concentrations of ·O2- and 1O2 in the Ar-CB-2/light system were enhanced by a factor of 1.67 and 1.28 compared to CB-2/light system. This result confirmed that the porous and defect-rich structure of Ar-CB-2 inhibited electron-hole recombination and boosted photocatalyst-oxygen interaction, swiftly transforming O2 into active oxygen species, thus accelerating their production. Furthermore, the possible degradation pathways for TC and BPA in the Ar-CB-2/light system were predicted. Overall, these findings offered a groundbreaking approach to the development of highly effective photocatalysts, capable of swiftly breaking down emerging pollutants.