Activation of Peroxymonosulfate by Chrysotile to Degrade Dyes in Water: Performance Enhancement and Activation Mechanism

Abstract

An environmentally friendly activation method of peroxymonosulfate (PMS) provides a promising advanced oxidation processes for the degradation of organic wastewater. In this article, chrysotile, extracted from asbestos tailings, was found to be a kind of one-off catalyst relying on hydroxyl groups to activate PMS. Furthermore, the activation performance of the chrysotile had been greatly improved by the mean of calcining at 850 °C (850CC). It is worth mentioning that 850CC could not only realize three effective cycles, but also the mineralization ratio of Rhodamine B (RhB) could be impressively higher than 60%. According to characterization results, it was discovered that the chrysotile had transformed into forsterite with a fibrous morphology after calcination at 850 °C due to the loss of hydroxyl groups and the recombination of silicon, oxygen and magnesium atoms. Besides, the main active species produced by 850CC activating PMS were singlet oxygen and sulfate radicals. Further studies uncovered that PMS was successfully activated by a large number of unsaturated coordination oxygen on 850CC surface, and the activation mechanism was further elucidated. This study provides a new route for the comprehensive utilization of chrysotile and a valuable strategy for the degradation of hazardous organic pollutants in wastewater by PMS activation.