Treatment of dyeing and finishing waters using innovative photocatalysts

Waters coming from dyeing and finishing processes by leather industries produce serious problems because they contain dyes and other pollutants. Toxic and recalcitrant for the environmental, these pollutants are difficult to remove by conventional treatments. For this reason, the heterogeneous photocatalysis is a promising and efficient method to remove them. ZnO is an excellent and promising photocatalytic material to oxidize organic pollutants into CO2and H2O. In order to enhance the photocatalytic activity of ZnO, in this work, the doping of ZnO with praseodymium (Pr) has been realized and studied in the photocatalytic treatment of dyeing and finishing waters with a total organic carbon (TOC) values in the range 540-1200 mg·L-1. ZnO particles doped with Pr were prepared by a modified precipitation method and characterized by different techniques (XRD, Raman, UV-Vis DRS). The photocatalytic activities of the synthesized samples were investigated under UV light with a specifically photocatalytic apparatus designed for the experimental tests. Photocatalytic results showed a discoloration in the range 56-98% after 4 h of irradiation while TOC removal was about 40% after 3 h of UV irradiation for all the investigated dyeing and finishing waters. The obtained results evidenced the efficiency of the synthetized photocatalyst in the treatment of real dyeing and finishing water coming from leather industries.