Enhanced degradation of decabromodiphenyl ether (BDE-209) using ferrate(VI)-peroxymonosulfate combined process: Influencing factors, reaction kinetics, pathways, and toxicity control

Abstract

In this study, enhanced degradation of decabromodiphenyl ether (BDE-209) was systematically investigated using ferrate(VI)-peroxymonosulfate (Fe(VI)-PMS) combined process, including influencing factors (oxidant dosages (0.01–0.5 mmol/L), initial pH (3.0–11.0), temperatures (10–30 ℃) and BDE-209 concentrations (0.5–5.0 μmol/L)), reaction kinetics, products (inorganic and organic ones), pathways and toxicity control. Compared to the sole Fe(VI) and PMS oxidation process, the Fe(VI)-PMS combined process exhibited a synergistic effect on BDE-209 degradation. Under pH 7.0 and 30 ℃, complete degradation of BDE-209 (0.5 μmol/L) was achieved within 60 min by low dosages of Fe(VI) and PMS (0.1 mmol/L). Additionally, Fe(VI)-PMS combined process demonstrated strong adaptability to a wide pH range (5.0–9.0), maintaining over 85 % removal of BDE-209. Active species, including •OH and SO4•-, contributed to the oxidative removal of BDE-209. The detection of inorganic products indicated a 66.87 % debromination rate in Fe(VI)-PMS combined process, with no bromate by-products formed. Lower brominated intermediates were identified as the primary organic products, undergoing various reaction pathways such as debromination, radical addition, substitution, beta scission and oxidation. Moreover, toxicity assessment revealed effective control of the relative inhibitory rate of water samples (reduced to 3.56 %), significantly lower than that of BDE-209 itself (15.0 %). In practical water treatment applications, over 95 % removal of BDE-209 was achieved, highlighting the prospective potential of Fe(VI)-PMS combined process in organic pollutant degradation.

Keywords

• Ferrate(VI)
• Peroxymonosulfate
• Decabromodiphenyl ether
• Degradation
• Toxicity
• Pathway