Nitrogen and sulfur co-doped watermelon rind as an ordered mesoporous biochar activated peroxymonosulfate (PMS) for efficient tetracycline degradation

Abstract

The ever-increasing tetracycline pollution and a large amount of watermelon rind waste have caused a double burden on the environment. How to realize the circular economy of treating waste with waste is of great practical significance, but still challenging. In this work, N, S co-doped/biochar (NSBC) with high adsorption and catalytic properties was successfully prepared from watermelon rind waste for the first time, and showed excellent performance in the degradation of tetracycline by activated peroxymonosulfate, with the degradation rate of TC reaching 90.02% in 40 min. The optimal preparation conditions of NSBC were determined by exploring the doping amount of thiourea and the carbonation temperature. On this basis, a series of characterization and experimental analyses demonstrated that suitable thiourea doping not only increased the active sites, defect edges, SSA and electron transfer of NSBC, but also possessed good stability properties. Free radical pathway (•OH, SO4•−, O2•−) combined with non-radical pathway (1O2 and charge transfer) resulted in the TC degradation, in which the non-radical pathway mainly contributed to the degradation process, and the intermediates of the degradation pathway were analyzed. This work provides a great prospect for resource utilization and environmental remediation of watermelon rind waste.