Efficient activation of persulfate by a magnetic recyclable rape straw biochar catalyst for the degradation of tetracycline hydrochloride in water

A recyclable magnetic rape straw biochar (MRSB) catalyst was synthesized by a high value-added and energysaving method using abandoned rape strawas the rawmaterial. TheMRSB catalyst showed high catalytic activity and recyclability for activating persulfate (PS) to degrade tetracycline hydrochloride (TC) in water. The Fe3O4 in the MRSB greatly promoted the activation of PS. More importantly, the MRSB catalyst exhibited high catalytic performance over a wide pH range (2.99-11.01) for activating PS to degrade TC in water. Moreover, MRSB still had good catalytic activity for TC degradation after 8 recycling cycles and was easily separated by an external magnetic field for reuse. The electron spin resonance (ESR) analysis indicated that the generation of the sulfate radicals (SO4 center dot), hydroxyl radicals (center dot OH) and superoxide radicals (O-2(center dot)) was greatly promoted in the MRSB/PS system. As a result, MRSB exhibited 13.24-fold higher reaction rate for activating PS than those of rape straw biochar (RSB). Both radical mechanism and non-radical mechanism existed in the MRSB/PS system, and SO4 center dot- and singlet oxygen (O-1(2)) played a determinative role. This studymight give a newway to reuse abandoned rape straw and synthesize new recyclable catalysts for activating PS to degrade organic pollutants in water. (C) 2020 Elsevier B.V. All rights reserved.