Flexible CuS/TiO2 based composites made with recycled bags and polystyrene for the efficient removal of the 4-CP pesticide from drinking water

Abstract We report the use of flexible photocatalytic composites for the degradation of the 4-chlorophenol (4-CP) contaminant from the drinking water. These composites were made of recycled bags (RBag) or recycled polystyrene (RPS) from food packaging and CuS/TiO2 (CuST) nanoparticles. The structural and morphological characterization indicate that the CuST nanoparticles have an average size of size of 41 ± 2 nm and present a mixture of anatase/brookite phases. The CuS/TiO2 powders were dispersed in water contaminated with 4-CP and produced a maximum degradation percentage of 92% after 4 h under UV-VIS irradiation. In the case of the RBag-CuST and RPS-CuST composites, they floated on the contaminated water and produced maximum degradation percentages of 89 and 100%, respectively. After 3 cycles of continuous use, the degradation percentages decreased from 92 to 84%, from 89 to 81% and from 100 to 95% for the CuS/TiO2 powders, RPS-CuST and RBag-CuST composites, respectively. Scavenger experiments were carried out and found that the main oxidizing agent for the degradation of 4-CP was the ∙OH radical. The production of such radical decreased in the order RBag-CuST>CuS/TiO2-powders>RPS-CuST. The RBag-CuST was more efficient for the degradation of 4-CP because its production of oxidizing agents was the highest and it contained more oxygen vacancies defects (electron trapping centers) than the other photocatalysts, which was confirmed by the absorbance measurements. In general, we demonstrated that making flexible photocatalytic materials from recycled bags/polystyrene is a feasible and low cost option to remove pesticide contaminants from the drinking water. Those composites can be removed manually from the cleaned water, which is not possible with the conventional photocatalytic powders.