Activation of peroxymonosulfate by natural molybdenite for dye degradation: Identification of reactive species and catalytic mechanism

Abstract

In this study, natural molybdenite (MDN) was employed to activate peroxymonosulfate (PMS) to remove organic contaminant orange G (OG). Degradation rate reached up to 100% and 44.4% TOC decayed in the MDN/PMS system within 60 min. The degradation rate increased with the increase of temperature, catalyst and PMS dosages, but initial pH affected little to the system. Moreover, the sensitivity test of coexisting anion and other organic contaminants to the MDN/PMS system was studied to investigated its application in natural water matrix. Through the analysis of electron paramagnetic resonance and quenching experiments, reactive oxygen species including sulfate radicals ( SO 4 ⋅ − ), hydroxyl radical ( ⋅ OH), superoxide radical (O 2 ⋅ − ) and singlet oxygen ( 1 O 2 ) had been proven to account for OG degradation in the MDN/PMS process. Surface-bonded Mo(IV) activated PMS producing radicals and it could be regenerated by the reaction with vicinity sulfur element in MDN. This work not only provided a reference for PMS activation by natural sulfide mineral but also elucidated the activation mechanism. • MDN could active PMS for organic pollutants degradation. • The roles of molybdenum and sulfur species of MDN were investigated. • SO 4 ⋅ − , ⋅ OH, O 2 ⋅ − and 1 O 2 were responsible for the removal of OG in MDN/PMS system. • The activation mechanism of PMS by MDN was proposed.