Chrome shaving-derived biochar as efficient persulfate activator: Ti-induced charge distribution modulation for 1O2 dominated nonradical process

Efficient degradation of organic contaminants by oxidative radicals remains a challenge due to invalid consumption of radicals and easy generation of secondary halogenated pollutants. In this work, an efficient and recyclable bimetallic biochar (Cr-Ti/BC) was developed through peroxydisulfate (PDS) activation via nonradical pathway for sulfamethox-azole (SMX) degradation. The Cr-Ti/BC exhibited excellent catalytic activity for 99.9 % of SMX removal with a high kobs of 0.13 min-1, and negligible inhibitory effects were observed under various pH condition. The activation mech-anisms were (i) metastable reactive intermediates (Cr-Ti/BC-PDS) formation via an interaction between Cr-Ti/BC and PDS on the active defective sites (e.g.,\\OH/C\\O\\C, COOH, C_O, nitric oxides, graphitic N, and pyridinic N), and (ii)1O2 generation through electron transfer between Cr-Ti/BC-PDS intermediates and dissolved oxygen. The high re-usability and strong stability of Cr-Ti/BC also verified the outstanding advantage of the Cr-Ti/BC during practical ap-plication. This study not only is the first study the catalytic performance of Cr and Ti co-doped biochar for PDS activation, but also successfully provides a promising strategy to induce a nonradical pathway for PDS activation, which is of great significance for the subsequent method design, and thus paving the path for exploiting advanced ox-idation systems in practical application for organic contaminant removal toward polluted site remediation.