Resource utilization of tannery sludge to prepare biochar as persulfate activators for highly efficient degradation of tetracycline

[Display omitted] •A low-cost carbon-based catalyst (TSBC) was prepared by utilizing tannery sludge.•TSBC showed an excellent performance on persulfate activation to remove tetracycline.•SO4•- and •OH were the main reactive species for TC degradation in TSBC/PS system.•TSBC with transition metals, functional groups and defective edges is beneficial.•The used TSBC could be restored as the new after heat treatment. In this work, a low-cost carbon-based catalyst (TSBC) was prepared by the facile one-pot pyrolysis of tannery sludge (TS) and used to activate persulfate (PS) for tetracycline (TC) removal. The results showed that TSBC-500 exhibited optimal physicochemical properties and the best performance for PS activation to remove TC from drinking water. Approximately 99.1% of TC was removed in the TSBC-500/PS system, which was considerably higher than those in the TSBC-500 adsorption and pure PS systems. Radical quenching experiments indicated that •OH and SO4•- played major roles in the TC removal in the TSBC-500/PS system. In addition, transition metals, functional groups, and the high degree of carbon structural defects were beneficial for PS activation to degrade TC. This study not only newly contributes to high-value utilization of TS as a PS activator but also offers an efficient method for the removal of organic pollutants.