Photocatalytic degradation of lignin model compounds and kraft pine lignin by CdS/TiO2 under visible light irradiation

Abstract

Cadium sulfide/titanium dioxide (CdS/TiO2) catalyst was prepared by two different methods: microemulsion-mediated solvothermal hydrolyzation (CdS/TiO2 (SH)) and in-situ sulfurization under supercritical conditions (CdS/TiO2 (SS)). The photocatalysts were characterized by nitrogen adsorption-desorption, X-ray diffraction, X-ray photoelectron spectra, UV-Vis absorption spectra, and PL spectra. Photodegradation reactions of three monomeric and one dimeric lignin model compounds, and kraft pine lignin (Indulin AT) were carried out at room temperature in a weak alkaline aqueous system by visible light irradiation with air bubbling. Quantitative results showed that these lignin model compounds and kraft lignin were effectively degraded. While both phenolic and non-phenolic lignin units are reactive, the phenolic units appeared to react faster and preferentially reacted.