CoS produced in Porphyra biochar by exogenous Co and endogenous S doping to enhance peroxymonosulfate activation for carbamazepine degradation

Exploiting low-cost and high-performance biochar catalysts is vital for the detoxification of organic wastewater and the resource utilization of algal biomass. Herein, CoSx containing biochar (CoSBC) was prepared using exogenous Co salt and endogenous Porphyra rich in S elements for enhanced degradation of carbamazepine (CBZ) by peroxymonosulfate (PMS) activation. 95.73% of CBZ (20 mg/L) can be removed within 20 min in CoSBC-900/PMS system with a degradation rate of 0.1287 min−1, and maintained a higher catalytic efficiency after five cycles (> 90%). Besides, the CoSBC-900/PMS system held excellent resistance over various coexisting substances, and could efficiently degrade multiple organic contaminants. Mechanism analyses revealed that 1O2 and SO4•− collaborated for CBZ degradation, in which 1O2 played the dominant role and 1O2 mainly originated from the formation process: PMS→O2•−→1O2. The low redox potential of S species accelerated Co(II)/Co(III) circulation, while Porphyra biochar also served as the highly active centers, producing abundant active species (SO4•−). The possible intermediate products accompanying CBZ degradation were proposed based on LC-MS analysis and the corresponding toxicity assessment verified that the CoSBC-900/PMS system possesses desirable CBZ detoxification ability. This study provides novel insight into the development of transition metal-based biochar catalysts from algal biomass for the purification of organic wastewater.