Valorization of hazardous chrome tanned leather buffing waste for the production of Cr2O3/carbon/TiO2 composite semiconductors with the removal of chlorophenol from its wastewater

Highly stable semiconducting, photocatalytic Cr2O3/carbon/TiO2 composites have been successfully synthesized from toxic chrome-tanned buffing dust. The presence of Cr2O3 (eskolaite) and impregnation of TiO2 (anatase) were confirmed through XRD and XPS analysis. Moreover, it was observed that Cr2O3/carbon/TiO2 composite bandgap decreased compared to TiO2. The synergetic effect of Cr2O3/carbon/TiO2 composite was evaluated by degradation of 2-chlorophenol (2-CP) and 4-chlorophenol (4-CP) using light energy sources of 254 nm and 365 nm. Nearly 100% of 2-CP and 4-CP was degraded within 30 min following first-order kinetics, and the nanocomposite (10% ACTi) showed seven and two times higher activity than TiO2 and Cr2O3/carbon materials. Degradation efficiency was further confirmed by HPLC and CV analysis. The higher degradation activity noted was attributed to the generation of hydroxyl radicals, which was confirmed by fluorescence spectroscopy analysis. Furthermore, the nanocomposite is highly stable even after 96 h of reaction, which was confirmed by XRD analysis. The results conclude that waste materials can be utilized for synthesizing semiconducting photocatalytic materials.

Automated summary

Highly stable semiconducting, photocatalytic Cr2O3/carbon/TiO2 composites were successfully synthesized from toxic chrome-tanned buffing dust. The presence of Cr2O3 and TiO2 were confirmed through XRD and XPS analysis. The Cr2O3/carbon/TiO2 composite showed higher degradation activity compared to TiO2 and Cr2O3/carbon materials, attributed to the generation of hydroxyl radicals.