Supplementary material from "Synthesis and assessment of schwertmannite/few-layer graphene composite for the degradation of sulfamethazine in heterogeneous Fenton-like reaction"

Schwertmannite, an iron oxyhydrosulfate mineral, can catalyze Fenton-like reaction to degrade organic contaminants, but the reduction of Fe(III) to Fe(II) on the surface of schwertmannite is a limiting step for the Fenton-like process. In the present study, the schwertmannite/few-layer graphene composite (sch–FLG) was synthesized to promote the catalytic activity of schwertmannite in Fenton-like reaction. It was found that schwertmannite can be successfully carried by FLG in sch–FLG composite, mainly via the chemical bond of Fe–O–C on the surface of sch–FLG. The sch–FLG exhibited a much higher catalytic activity than schwertmannite or FLG for the degradation of sulfamethazine (SMT) in the heterogeneous Fenton-like reaction, which resulted from that the few-layer graphene can pass electrons efficiently. The degradation efficiency of SMT was around 100% under the reaction conditions of H₂O₂ 200–500 mg l⁻¹, sch–FLG dosage 1–2 g l⁻¹, temperature 28–38°C, and initial solution pH 1–9. During the repeated uses of sch–FLG in Fenton-like reaction, it maintained a certain catalytic activity for the degradation of SMT and the mineral structure was not changed. In addition, SMT may be finally mineralized in Fenton-like reaction catalyzed by sch–FLG, and the possible degradation pathways were proposed. Therefore, the sch–FLG is an excellent catalyst for SMT degradation in heterogeneous Fenton-like reaction.