Effects of Polystyrene Microplastics on Multiple Tetracycline Removals by Ferrate

Abstract

Water treatment processes typically focus on eliminating organic pollutants in wastewater but often overlook the presence of coexisting microplastics. In this study, we examined the effects of polystyrene microplastics on removing three tetracyclines using ferrate. The presence of polystyrene microplastics influenced the efficiency of oxidation, adsorption, coagulation, and complexation, leading to varying degrees of tetracycline removal by ferrate. Our results showed that unaged polystyrene microplastics increased tetracycline removal by 29.2%, while three aged polystyrene microplastics showed an increased removal ratio, and ten soaked polystyrene microplastics inhibited tetracyclines removal by up to 41.6%. The breakdown of polystyrene microplastics also released small molecules and contributed to a 7.4% increase in total organic carbon. The carbonyl index of polystyrene microplastics also rose to 1.68, and specific functional groups, including C−O, C�O, Fe−O, and C−N−C, appeared on the surface. While polystyrene microplastics weakened the oxidation capacity of ferrate in removing tetracyclines, their increased surface area and pore volume aided in tetracyclines adsorption. Furthermore, polystyrene microplastics acted as support sites for Fe 3+ and Fe(OH) 3 , facilitating the formation of polystyrene-Fe-tetracycline complexes, which aided in tetracycline removal via complexation. Fe(OH) 3 helped with the adsorption and coagulation removal of tetracyclines. The potential adverse effects of polystyrene microplastics are widespread and require more attention in removing pollutants when microplastics coexist in aquatic environments.

Effect of Microplastics on the Flow-Through Electro-Peroxone Process: A Computational Fluid Dynamics Simulation

“…However, the diffusion pattern of HO· in these sections resembled scenarios without MPs, yet its concentration between the electrodes decreased. Previous studies have suggested that HO· can potentially degrade MPs. ,, Analysis in Table S1 highlighted slight differences in velocity, turbulent kinetic energy, dissipation rate, and pressure distribution with MPs, indicating their minor influence on hydrodynamic parameters but significant impact on HO· diffusion. Overall, the presence of MPs reduced the HO· concentration between electrodes, thereby affecting the oxidative efficiency of the flow-through EP process.…”

“…Aquatic environments are the primary repositories for a diverse array of contaminants, and the coexistence of organic pollutants and MPs is increasingly problematic, leading to the formation of composite pollutants. ,− Current research on advanced oxidation processes (AOPs) predominantly focuses on removing individual organic pollutants, − often neglecting the simultaneous presence of MPs. MPs can act as carriers and adsorbents, potentially causing secondary pollution or altering the physicochemical properties of the reaction medium, which can affect the degradation rate of pollutants and the formation of byproducts in AOPs. , This oversight prevents an accurate portrayal of organic pollutant removal under different AOPs, highlighting the need to investigate the effects and mechanisms of MPs on the removal of organic pollutants using typical AOPs.…”

“…In our previous studies, , we explored the interplay between MPs and the removal of multiple sulfonamide and tetracycline antibiotics through the Fenton process and ferrate treatment. We identified the mechanisms of free radical capture and pollutant adsorption by MPs.…”

Complementarity and action mechanisms of Fe2+‐activated persulfate and H2O2 system

“…However, when 10‐mM CO 3 2− and HCO 3 − were introduced, the SA removal ratio in the coupled system remained commendable at 57% and 53% (Figures 3d–e and S4d–e). CO 3 2− and HCO 3 − quenched SO 4 • − and •OH by Equations ()–() 64–66 . In addition, CO 3 2− and HCO 3 − changed the solution pH, reducing the valid concentration of Fe 2+ 67 .…”