Wood powder biochar in CdS-WPB-g-C3N4 heterojunction as an electron transfer medium for enhancing photocatalytic performance toward degradation methyl orange

Abstract

Biochar-based photocatalysts were rarely used in wastewater treatment, as the low efficiency of the electron transfer often limited their applicability. In this work, a novel ternary CdS-WPB-CN heterojunction was constructed for the efficient degradation of methyl orange (MO) under UV and visible light. As a green and low-cost electron transfer medium, wood powder biochar (WPB) plays an important role in rapidly transporting photogenerated electrons from g-C3N4 to CdS, significantly improving photogenerated carriers' separation efficiency. Under the optimal degradation condition (1 g/L photocatalyst dosage and 10 mg/L of initial MO concentration), the degradation efficiency for MO of the ternary CdS-WPB(5%)-CN composite reached 99% within 80 min under visible light irradiation. Moreover, it could completely degrade MO within 60 min under UV irradiation. Besides, the outstanding reusability and stability of the CdS-WPB-CN composite were further verified by five consecutive cycle experiments. The degradation experiment in the actual river water body confirmed the excellent applicability in real wastewater samples. Finally, a mechanism was proposed to explain the photocatalytic degradation of MO. Overall, this work provides important insights into the role of biochar in improving the photocatalytic degradation of organic contaminants.