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

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 con-structed 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 photo -generated 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 appli-cability in real wastewater samples. Finally, a mechanism was proposed to explain the photocatalytic degra-dation of MO. Overall, this work provides important insights into the role of biochar in improving the photocatalytic degradation of organic contaminants.

Automated summary

In this study, a novel ternary CdS-WPB-CN heterojunction was constructed for the efficient degradation of methyl orange in wastewater. Wood powder biochar was used as an electron transfer medium, significantly improving the separation efficiency of photogenerated carriers. The composite showed high degradation efficiency for methyl orange under both UV and visible light, and demonstrated excellent reusability and stability.