AS-101

Polystyrene (PS) and polyethylene terephthalate (PET) are commonly used materials that degrade into microplastics in the environment. These microplastics, possessing unique physical properties, can adsorb pollutants and contribute to composite pollution effects. This study examined the loading characteristics and toxic effects of PS and PET on six arsenic compounds, revealing that PS and PET displayed different adsorption capacities for these compounds, with PS demonstrating high adsorption for monomethylarsonic acid (MMA). The adsorption kinetics and isotherm analyses indicated that arsenic compounds quickly reached equilibrium on PS and PET. The kinetics were effectively described by pseudo-first-order models, and the isotherms aligned with the Langmuir and Freundlich models. Furthermore, simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) were used to desorb arsenic compounds bound to PS and PET. The effects of aging, pH, salinity, anions, and humic acid (HA) on the ability of inorganic arsenic (iAs) to bind to PS and PET were analyzed. The results indicated that aging and HA increased the adsorption capacity of the microplastics, while salinity, anions, and elevated pH negatively affected this capacity. Additionally, the influence of microplastics and iAs on the clearance of free radicals by reduced glutathione (GSH) was explored. Microplastics inhibited the clearance of 1,1-diphenyl-2-picryl-hydrazyl (DPPH) by GSH, whereas iAs, especially arsenate, facilitated this process, likely due to synergistic effects with the oxidized form of GSH generated through GSH reactions. This study offers a theoretical foundation for understanding how microplastics transport various forms of arsenic compounds and their potential environmental risks.

P-arsanilic acid (AA) has received widespread attention because of its conversion to more toxic inorganic arsenic compounds (arsenate and arsenite) in the natural ecosystems. Its removal process and mechanisms with co-existence of microplastics remain unkown. In this study, biochar loaded with nano zero-valent iron (nZVI) particles (ISBC) was prepared by using iron scrap obtained from a steel works and wood chips collected from a wood processing plant. The advanced oxidation system of sodium persulfate (PDS) activated by ISBC was applied for AA degradation and inorganic arsenic control in aqueous media. More than 99% of the AA was completely degraded by the ISBC/PDS system, and the As(III) on AA was almost completely oxidized to As(V) and finally removed by ISBC. HCO₃^- inhibited the removal of AA by the ISBC/PDS system, while Cl^- had a dual effect that showing inhibition at low concentrations yet promotion at high concentrations. The effect of microplastics on the degradation of AA by the ISBC/PDS system was further investigated due to the potential for combined microplastic and organic arsenic contamination in rural/remote areas. Microplastics were found to have little effect on AA degradation in the ISBC/PDS system, while affect the transport of inorganic arsenic generated from AA degradation. Overall, this study provides new insights and methods for efficient removal of p-arsanilic acid from water with coexisting microplastics.