Bromide-activated peroxymonosulfate for efficient ammonium removal: Performance, mechanism and applicability

Ammonium nitrogen (NH 4 + −N) pollution represents a considerable risk to both aquatic ecosystems and public health, necessitating efficient and sustainable treatment methods. In this study, bromide ion (Br − ) commonly present in wastewater was employed as an activator for peroxymonosulfate (PMS) to markedly enhance NH 4 + –N removal. NH 4 + –N elimination by Br − /PMS system followed the pseudo -zero-order kinetics, and the observed rate constant reached 0.52 mg L −1 min −1 in the presence of 825 μM Br − at pH 8.0. Quenching experiments demonstrated that primary reactive species for NH 4 + −N removal in Br − /PMS system was hypobromous acid (HBrO), rather than Br • , Br 2 •− , 1 O 2 , • OH and SO 4 •− . HBrO was primarily generated through the direct reaction of PMS and Br − . Notably, the primary product of NH 4 + –N elimination was the environmentally friendly gas N 2 (about 86%) in Br − /PMS system. Increasing Br − and PMS concentrations was advantageous for increasing NH 4 + –N elimination rate. Common anions in water (e.g., SO 4 2− , NO 3 − , and PO 4 3− ) and natural organic matter (e.g., humic acid) exhibited negligible effects on removing NH 4 + –N in Br − /PMS system, while Cl − promoted NH 4 + –N elimination. Furthermore, Br − /PMS system demonstrated exceptional performance in removing NH 4 + –N from actual aquaculture wastewater samples. To conclude, this study presented an efficient strategy to enhance the oxidative ability of PMS for NH 4 + –N elimination and highlighted its potential application in treating bromine-containing wastewater.