Adsorption and photodegradation of Procion yellow H-EXL dye in textile wastewater over TiO2 suspension

Removal of a commercial dye (Procion yellow H-EXL) in both synthetic and real wastewater from textile industry over TiO2 suspension has been investigated. The study included both adsorption process (over TiO2) and photocatalytic degradation process in the presence of UV illumination (UV/TiO2). The processes were carried out in aqueous solutions containing the dye in the presence of titanium dioxide, TiO2, (Degussa P-25) upon UV irradiation of 100 W. The photocatalytic process used the photogenerated holes (at the surface of TiO2) and hydroxyl radicals (at the solution bulk) as oxidizing species for the dye. Different parameters affecting the adsorption and photocatalytic degradation processes such as solution pH, initial dye concentration, and TiO2 dosages were investigated, Results obtained revealed that various dye concentration loads were removed at optimum solution pH = 5 with TiO2 dosage of 1 g/L. The dye removal % is inversely proportional to its concentration, the lower the dyes concentration, the higher the efficiency of dye removal. The efficiency values of both adsorption and photocatalytic degradation processes reached maximum values of 46.4 and 100%, respectively, with dye concentration of 10 mg/L. The photocatalytic degradation of the investigated dye exhibited pseudo first-order kinetics according to the Langmuir–Hinshelwood's heterogeneous catalytic model