Harnessing bromide ions to boost peroxymonosulfate for reactive yellow 145 dye degradation

Abstract

Bromide (Br- ) was found in the fresh waters at concentrations from 0.1 to 1 mg/L and can be used to activate peroxymonosulfate (PMS) as a widely used chemical oxidation agent. In the present study, the reaction between PMS and Br- ions (PMS/Br- process) for the effective degradation of reactive yellow 145 (RY-145) dye was investigated by changing operational parameters vis solution pH, dosage of Br- ions and PMS, RY-145 concentration, and reaction time. Based on the results, the simultaneous presence of PMS and Br- ions in the solution led to efficient degradation of RY-145 with a synergistic index of 11.89. The degradation efficiency of RY-145 was decreased in severe basic pH and the presence of CO32- ions as a coexisting anion. Likewise, 4 mg/L of humic acid (HA), used as a classic scavenger, led to a 26.53 decrease in the RY-145 degradation efficiency. The free bromine (HOBr/OBr- ), superoxide radical (center dot O2- ), and singlet oxygen (1O2) was the dominant oxidation agents in RY-145 degradation, which confirmed the nonradical degradation pathway. In addition, PMS/Brprocess showed excellent ability in mineralizing RY-145 in different aqueous solutions (total organic carbon (TOC) decreased 86.39 in deionized water and 78.23 in tap water). Although pollutants such as azo dyes can be effectively removed in the PMS/Br- process, the formation of byproducts should be strategically controlled and special attention should be paid when the PMS-based advance oxidation process is applied to treat Brcontaining solutions.