After completing the adsorption experiment alongside four h, the residue was transferred into a quartz tube, where the UV photodegradation was performed under stirring. The exposure of UV light was performed using a 450 W medium pressure mercury vapor lamp. 5 mL of the reaction mixture were withdrawn and filtered at a particular exposure time. The degradation process was monitored using a UV-Vis spectrophotometer. The degradation efficiency was calculated using Eq. ( ), where the A(UV,0 ) and A(UV, t) are the UV-Vis absorbance before UV exposure and after UV exposure at a particular reaction time (t, min), respectively.