Resource utilization of luffa sponge to produce biochar for effective degradation of organic contaminants through persulfate activation

Abstract

To transform low-value biowaste into valuable materials, this study provides a resource utilization strategy for loofah sponge, which can be converted into an efficient and economical persulfate activator for organic contaminants removal. Accordingly, the loofah sponge-based biochar (LSB) was prepared through one-step pyrolysis at different pyrolytic temperatures. The well-prepared LSB was then utilized to activate persulfate (PS) for the removal of Acid Orange 7 (AO7). The biochar produced at 800 °C (LSB-800) possessed the optimal catalytic capability for AO7 degradation (96% within 30 min). The high surface area (304.49 m2·g−1), abundant carbonyl groups and the graphitized structure of LSB-800 were largely responsible for its high potency. Some key reaction impact factors including the catalyst and PS dosage, original pH, co-existing substances and different water matrices were investigated. The degradation mechanism of AO7 in the LSB-800/PS process involved both free radical and non-radical channels, where sulfate radical (SO4−) was pretty vital in radical channel and electron transfer dominated in non-radical channel. LC-MS/MS analysis was applied to identify degradation intermediates. This research innovatively introduces a novel strategy for the resource utilization of loofah sponge with new insights into the mechanism of persulfate activation by the loofah sponge-derived biochar.