The activity and mechanism differences of typical tourmalines in the activation of persulfate for tetracycline degradation

Abstract

As a kind of natural and non-toxic mineral, tourmaline has different compositions and types, and some of them show the activity of persulfate activation for the degradation of organic pollutants in aqueous solution. However, the relativity between the types of tourmalines with their persulfate activation mechanism is poorly understood. Herein, the tetracycline degradation through three kinds of typical tourmalines activating persulfate were investigated. Compared with Mg-based and Li-based tourmalines, higher activity of tetracycline degradation was observed for two types of Fe-based tourmalines. For the tourmalines with high-Fe content, the activation of persulfate was found to be originated from the dissolution of Fe ions from tourmaline powders, and SO4•– and •OH are the active species for tetracycline degradation. In the low-Fe content tourmalines reaction system, the direct reaction of persulfate and tourmalines resulted in the activation of persulfate and the formation of 1O2 active specie, which initiate the degradation of tetracycline.