Conversion of agricultural waste to porous hydrochar for non-metallic activation of persulfate to phenol degradation via non-radical-dominated processes: Singlet oxygen and electron transfer

Abstract

Recently, non-radical oxidation was served as an efficient approach during pollutant degradation due to its excellent environmental applicability. However, designing a green and low-cost non-metallic catalyst to activate persulfate (PS) for removal of hazardous organic contaminants via non-radical-dominated processes is still challenging. Herein, porous hydrochar (PHC) was synthesized with agricultural waste of corn straw (CS) as precursor and KHCO3 as pore-forming agent, which contained mesoporous structures with defects, thus facilitating phenol adsorption (117.14 mg/g). Moreover, 20 mg/L of phenol could achieve 100% removal at a wide pH range (7.0–11.0) within 10 min by PHC/PS system. The radical pathways induced by O·H and O2·− had certain effect on phenol removal, while non-radical pathways (1O2 and electron transfer process) played dominant contributions. Among them, 1O2 was produced from the reaction between surface functional groups on PHC and PS, and electron transfer process occurred from phenol to PS via PHC as the conductor. Whether under the interference of co-existing substances or in different water matrixes, the degradation efficiency of phenol could reach above 80%, exhibiting the excellent adaptability of PHC/PS system. This study proposed a potential resource utilization method of agricultural waste to prepare non-metallic catalyst for effective water remediation.