Photocatalytic removal of cadmium (II) and lead (II) from simulated wastewater at continuous and batch system

 The aim of this study was to evaluate the photocatalytic processes for cadmium (Cd 2+ ) and lead (Pb 2+ ) removal at continuous and batch system. 

 This study was performed at laboratory scale. The reactors used in this study consisted of three parts: Ultraviolet (UV) source, reaction cell, and mixing chamber. The experiments were carried out in a batch and continuous reactor for synthetic wastewater. The concentration of Cd 2+ and Pb 2+ was constant (25 mg/L) in all experiments and effect of titanium dioxide (TiO 2 ) dose, pH, and air dispersion was investigated on the removal efficiency. 

 The results showed that with increasing TiO 2 dose and pH, the cadmium and lead removal increase. The maximum removal of cadmium and lead was obtained in TiO 2 dose 0.9 g/L and pH: 11 that were equal to 99.8 and 99.2% respectively. Furthermore, when air dispersion increased, the removal efficiency increased; while in the air dispersion 2 cm 3 /L the removal efficiency was maximum (88 and 93.2% at the contact time 56 min for Cd 2+ and Pb 2+ , respectively). 

 According to these results the TiO 2 has been considered as photocatalyst is the separable and recyclable, so UV/TiO 2 process is an environment friendly process for toxic metal removal.