Fabrication of shaddock peel biochar mediated Cd0.8Zn0.2S nanocomposite and synergistic adsorptive-photocatalytic performance for pollutant removal

Abstract

Developing inexpensive, eco-friendly and efficient catalysts is the key to photocatalytic removal of organic pollutants from wastewater. In this paper, a novel pre-treatment activated shaddock peel biochar mediated hexagonal Cd_0.8Zn_0.2S composite photocatalyst (CZS/BC) was fabricated by hydrothermal method and comprehensively characterized. The photocatalytic performance was assessed by degradation of Rhodamine B (RhB) in aqueous solution under visible light irradiation. Compared with the pristine Cd_0.8Zn_0.2S (CZS), the doping of shaddock peel biochar (BC) not only significantly reduces the band gap energy (E_g) of the CZS, but also significantly improves the adsorption and photocatalytic performance. Under the synergistic action of adsorption and photocatalysis, the optimal CZS/BC-0.3 sample exhibited the best removal performance, and could almost completely eliminate RhB pollutant within 50 min with good stability, possessing great application potential in practical environmental remediation. The removal efficiency was 6.4 folds higher than pristine CZS. Studies on photocatalytic mechanism showed that photocatalysis was mainly predominated by •O₂^- and h⁺ induced pathways, and the enhancement of photocatalytic performance can be attributed to the formation of hexagonal CZS, with biochar as an electron bridge and trap, the photogenerated carrier can be separated more effectively, thus enhancing the photocatalytic performance. This work provides a new idea for constructing new composite photocatalysts using BC as electron transport bridge.