Overview of the environmental risks of microplastics and their controlled degradation from the perspective of free radicals.

Owing to the significant environmental threat posed by microplastics (MPs) of varying properties, MPs research has garnered considerable attention in current academic discourse. Addressing MPs in river-lake water systems, existing studies have seldom systematically revealed the role of free radicals in the aging/degradation process of MPs. Hence, this review aims to first analyze the pollution distribution and environmental risks of MPs in river-lake water systems and to elaborate the crucial role of free radicals in them. After that, the study delves into the advancements in free radical-mediated degradation techniques for MPs, emphasizing the significance of both the generation and elimination of free radicals. Furthermore, a novel approach is proposed to precisely govern the controlled generation of free radicals for MPs' degradation by interfacial modification of the material structure. Hopefully, it will shed valuable insights for the effective control and reduction of MPs in river-lake water systems.

Spatial dynamics and risk assessment of phosphorus in the river sediment continuum (Qinhuai River basin, China).

This study investigated the concentration and fractionation of phosphorus (P) using sequential P extraction and their influencing factors by introducing the PLS-SEM model (partial least squares structural equation model) along this continuum from the Qinhuai River. The results showed that the average concentrations of inorganic P (IP) occurred in the following order: urban sediment (1499.1 mg/kg) > suburban sediment (846.1-911.9 mg/kg) > rural sediment (661.1 mg/kg) > natural sediment (179.9 mg/kg), and makes up to 53.9-87.1% of total P (TP). The same as the pattern of IP, OP nearly increased dramatically with increasing the urbanization gradient. This spatial heterogenicity of P along a river was attributed mainly to land use patterns and environmental factors (relative contribution affecting the P fractions: sediment nutrients > metals > grain size). In addition, the highest values of TP (2876.5 mg/kg), BAP (biologically active P, avg, 675.7 mg/kg), and PPI (P pollution index, ≥ 2.0) were found in urban sediments among four regions, indicating a higher environmental risk of P release, which may increase the risk of eutrophication in overlying water bodies. Collectively, this work improves the understanding of the spatial dynamics of P in the natural-rural-urban river sediment continuum, highlights the need to control P pollution in urban sediments, and provides a scientific basis for the future usage and disposal of P in sediments.

Contribution of 1O2 in the efficient degradation of organic pollutants with Cu0/Cu2O/CuO@N-C activated peroxymonosulfate: A Case study with tetracycline.

Peroxymonosulfate-mediated advanced oxidation processes (PMS-AOPs) degrading organic pollutants (Tetracycline (TC) as an example) in water with singlet oxygen (1O2) as the main reactive oxygen has received more and more attention. However, the generation mechanism of 1O2 is still unclear. Consequently, this study investigates the 1O2 formation mechanism during the activated PMS process using a nitrogen-copper-loaded carbon-based material (Cu0/Cu2O/CuO@N-C), synthesized by thermally decomposing organobase-modified HKUST-1 via a one-pot method. It was discovered that incorporating an organobase (Benzylamine) into the metal organic framework (MOF) precursor directs the MOF's self-assembly process and supplements its nitrogen content. This modification modulates the Nx-Cu-Oy active site formation in the material, selectively producing 1O2. Additionally, 1O2 was identified as the dominant reactive oxygen species in the Cu0/Cu2O/CuO@N-C-PMS system, contributing to TC degradation with a rate of 70.82%. The TC degradation efficiency remained high in the pH range of 3-11 and sustained its efficacy after five consecutive uses. Finally, based on the intermediates of TC degradation, three possible degradation pathways were postulated, and a reduction in the ecotoxicity of the degradation products was predicted. This work presents a novel and general strategy for constructing nitrogen-copper-loaded carbon-based materials for use in PMS-AOPs.

Spinel ferrites materials for sulfate radical-based advanced oxidation process: A review.

In the past decade, the sulfate radical-based advanced oxidation processes (SR-AOPs) have been increasingly investigated because of their excellent performance and ubiquity in the degradation of emerging contaminants. Generally, sulfate radicals can be generated by activating peroxodisulfate (PDS) or peroxymonosulfate (PMS). To date, spinel ferrites (SF) materials have been greatly favored by researchers in activating PMS/PDS for their capability and unique superiorities. This article reviewed the recent advances in various pure SF, modified SF, and SF composites for PDS/PMS activation. In addition, synthesis methods, mechanisms, and potential applications of SF-based SR-AOPs were also examined and discussed in detail. Finally, we present future research directions and challenges for the application of SF materials in SR-AOPs.

A novel polyethersulfone/modified activated carbon fiber composite membrane: potential for removal micropollutants from water under the electric field.

This study aimed to develop a novel composite membrane based on polyethersulfone (PES) and modified activated carbon fibers (ACFs) to remove of sulfamethoxazole (SMZ) from water. The modification of ACFs was conducted by using acid, Fe, and Mn and was confirmed by Fourier transform infrared spectroscopy (FT-IR), energy dispersive X-ray spectroscopy (EDS), and water contact angle measurement. Later on, the composite membranes were prepared using PES (9 wt%), N-N-dimethylacetamide (DMAc) (75 wt%), polyethylene pyrrolidone (PVP) (5 wt%), anhydrous lithium chloride (LiCl) (1 wt%), and various types of modified ACFs (0.8 wt%) as additives. It was found that the contact angle of the membrane decreased by more than 20°, and the zeta potential decreased by more than 10 mV. ACF modified by Fe was used as an admixture, membrane obtained the high comprehensive performance. Especially bovine serum albumin (BSA) rejection rate and flux recovery ratio (FRR) reached 98.8% and 98.4%, respectively. And the removal rates of SMZ increased by 24.6% under the electric field. The degradation products were detected by high-performance liquid chromatography/mass spectrometry (HPLC/MS). Based on this result, the possible degradation pathways of SMZ are proposed.