Copper-doped orange peel biochar activated peroxydisulfate for efficient degrading tetracycline: The critical role of C-OH and Cu.

Abstract

The usage of biomass waste has aroused great concern in water purification. In this study, copper-doped orange peel biochar (Cu-OPB) prepared by one-step carbonization was firstly used to activate peroxydisulfate (PDS) to eliminate tetracycline (TC). The optimized Cu-OPB showed great activation ability for PDS and could degrade 93.7% of TC at pH 9.07. The presence of H2PO4-, Cl-, and HCO3- did not affect the degradation, while HA and SO42- inhibited TC degradation. SO4•-, •OH and 1O2 were confirmed as the primary active oxygen species in the Cu-OPB/PDS system. Moreover, Cu and the C-OH functional groups on the surface of Cu-OPB played a critical role in the activation by accelerating the electronic migration between Cu-OPB and PDS in the catalytic system. 15 possible intermediate products were found and three feasible degradation pathways were proposed. The toxicity of aquatic organisms of TC was reduced. Furthermore, Cu-OPB could be used as an economically efficient and environmentally friendly catalyst for PDS activation to degrade organic pollutants.