Enhanced activation of peroxymonosulfate by nickel sulfide with sulfur vacancies for ultrafast organic pollutants degradation: Roles of active sites and mechanism

The transition metal sulfide-activated peroxymonosulfate (PMS) has been proven to be a promising alternative for removing organic pollutants in wastewater. However, the interaction among active sites was not fully elucidated. To clarify this issue, a simple nickel sulfide with sulfur vacancies (NSHC10-400) via the hydrothermal-calcination successive treatments was successfully fabricated and employed for activating PMS for Acid Orange II (AOII) removal. The results showed that the Ni2+, reductive sulfur species and sulfur vacancies acted as main active sites on the activation of PMS. Due to their synergistic effect, the NSHC10-400 exhibited extraordinary catalytic activity, degrading nearly complete AOII only for 1.0 min with small PMS concentration. Besides, it still kept high degradation in the existence of foreign interference. The electron spin resonance and quenching experiments indicated that both radical and non-radical species jointly contributed to the degradation of AOII. Finally, the bio-toxicity of solution was reduced after the reaction. Overall, this work provided an effective process for removing organic pollutants from the wastewater.