Influence of Seawater Characteristics on Antibiotic Pollutant Removal via Fe(II)-Peroxymonosulfate-Modified Clay

Abstract

Antibiotics have been identified as emerging pollutants, and they increasingly threaten the safety of mariculture; thus, effective treatment methods are urgently needed. In this study, Fe(II)-peroxymonosulfate-modified clay (Fe-PMS-MC), an effective mineral complex for harmful algal bloom control, was tested for sulfamethoxazole (SMX) removal from seawater. The results showed that SMX removal efficiency increased gradually from 42.3% to 100% in seawater in 6 h as the Fe-PMS-MC dose increased from 0.1 g/L to 1.0 g/L; this removal was more efficient than that in freshwater. Both an increase in temperature and the addition of inorganic anions such as Cl−, HCO3−, and SO42− improved the SMX removal efficiency; in contrast, there was no noticeable influence of a pH change from 3.0 to 9.0 or of Heterosigma akashiwo biomass addition from 103 cells/mL to 105 cells/mL. Oxidation was the main mechanism for the removal of SMX by Fe-PMS-MC treatment, and the mechanisms included radical oxidation and non-radical oxidation. PMS was the key component in Fe-PMS-MC for the production of radicals, which increased with temperature. Similarly, both radical oxidation and non-radical oxidation increased when PMS was attacked by Cl−, HCO3−, and SO42− in seawater.