Engineered hydrochar from waste reed straw for peroxymonosulfate activation to degrade quinclorac and improve solanaceae plants growth

Hydrochar from agricultural wastes is regarded as a prospective and low-cost material to activate peroxymonosulfate (PMS) for degrading pollutants. Herein, a novel in-situ N-doped hydrochar composite (RHCM4) was synthesized using montmorillonite and waste reed straw rich in nitrogen as pyrolysis catalyst and carbon source, respectively. The fabricated RHCM4 possessed excellent PMS activation performance for decomposing quinclorac (QC), a refractory herbicide, with a high removal efficiency of 100.0% and mineralization efficiency of 75.1%. The quenching experiments and electron spin resonance (ESR) detection disclosed free radicals (•OH, •SO4−, and •O2−) and non-radicals (1O2) took part in the QC degradation process. Additionally, the catalytic mechanisms were analyzed in depth with the aid of various characterizations. Moreover, the QC degradation intermediates and pathways were clarified by density functional theory calculations and HPLC-MS. Importantly, phytotoxicity experiments showed that RHCM4/PMS could efficaciously mitigate the injury of QC to Solanaceae crops (pepper, tomato, and tobacco). These findings give a new idea for enhancing the catalytic activity of hydrochar from agricultural wastes and broaden its application in the field of agricultural environment. •RHCM4 was firstly synthesized from waste reed straw and Mt via hydrothermal method.•Graphitic/pyridinic N and OFGs played important roles in activating PMS.•RHCM4 has remarkably excellent activating performance for PMS to degrade QC.•DFT was applied to analyze the degradation ways of QC.•RHCM4/PMS effectively reduced the phytotoxicity of QC to solanaceae crops.