Role of biochar in superoxide-dominated dye degradation in catalyst-activated peroxymonosulphate process.

In recent times, the application of biochar (BC) as an upcoming catalyst for the elimination of recalcitrant pollutants has been widely explored. Here, an iron loaded bamboo biochar activated peroxymonosulphate (PMS) process was tested for removing Congo red (CR) dye from water medium. The catalyst was synthesized using a green synthesis method using neem extracts and characterized using SEM, FTIR, and XRD. The effects of various operating parameters, including solution pH, catalyst dosage, and pollutant dosage, on dye degradation efficiency were examined. The results showed that at the optimized conditions of 300 mg L−1 PMS concentration, 200 mg L−1 catalyst dosage, and pH 6, about 89.7% of CR dye (initial concentration 10 ppm) was removed at 60 min of operation. Scavenging experiments revealed the significant contribution of O 2 •−, •OH, and 1O 2 for dye degradation, with a major contribution of O 2 •−. The activation of PMS was mainly done by biochar rather than iron (loaded on biochar). The catalyst was highly active even after four cycles. [Display omitted] • Application of green synthesized iron-loaded biochar as a PMS activator. • The superior performance of biochar in the activation by PMS. • O 2.•− is the primary oxidant responsible for dye degradation • •OH and 1O 2 were also produced in the catalyst-activated PMS process • SO 4.•− has less contribution to dye degradation [ABSTRACT FROM AUTHOR]