Boric acid modified zero-valent iron enhanced activation of periodate for sulfamethazine removal: Performance and mechanism

This study investigated the enhancement of periodate (PI) activation using boric acid-modified zero-valent iron (BA-ZVI) for the degradation of sulfamethazine (SMT). Only 5.4% of SMT was removed in 15 minutes in the ZVI/PI system, while 98.5% of SMT was removed in 15 minutes in the BA-ZVI/PI system. A more than 100-fold increase in the pseudo-first-order rate constant for SMT removal was observed in the BA-ZVI/PI system compared to the ZVI/PI system. Characterization of BA-ZVI revealed that BA-ZVI contained lower corrosion potential, higher proportion of Fe 2+ , lower contact angle suggesting the better activity and the presence of B on the BA-ZVI surface could accelerate the recycle of Fe 2+ . Density functional theory (DFT) calculations further revealed that the adsorption energy of PI on the BA-ZVI surface was lower than that on the ZVI surface. • OH, O 2 •- , 1 O 2 , IO 3 • and Fe IV were all involved in the removal of SMT, and • OH played most important role in BA-ZVI/PI system. The generation of intermediates during SMT degradation effectively mitigated overall toxicity, while PI remained stable and did not convert into hazardous iodine compounds. Various affecting factors affecting the SMT removal in BA-ZVI/PI system were also conducted. BA-ZVI/PI system had good recycle ability, better performance for treating various antibiotics and kept good performance for antibiotic in natural freshwater. To summarize, the present study (BA-ZVI/PI system) provides environmentally friendly methods for removing antibiotics. • BA-ZVI/PI system remove SMT could enhance 100 folds compared with ZVI/PI system. • Boric acid modification could enhance the reactivity of BA-ZVI. • • OH, O 2 •- , 1 O 2 , IO 3 • and Fe IV all participated in SMT removal. • BA-ZVI/PI process was an efficient approach for removing antibiotic.