Effect of pH on adsorption - photocatalysis of tungsten disulfide
Abstract
In this work, the tungsten disulfide material was prepared by calcining mixture of H 2 WO 4 and thiourea with weigh ratio of 1:5 in Ar gas at 650 o C for 1h , and denoted as WS 2 . The obtained product was characterized by X-ray diffraction (XRD), infrared spectra (IR), energy-dispersive X-ray spectroscopy (EDS), scan electron microscopy (SEM) and UV-Vis diffuse reflectance spectroscopy (UV-Vis). The relevant characterizations indicated that the main composition of sample is tungsten disulfide. The integrated adsorption and photodegradation of the cationic dye (rhodamine B) on WS 2 was evaluated in a pH range of 1.5-8.0, which showed that the decline of RhB degradation rate on WS 2 when increasing solution pH from 1.5 to 8 due to adsorption rather than the photodegradation process. Specifically at pH of 4, the strongest electrostatic interaction between the negatively charged surface of the material and cationic dye resulted in a highest adsorption and photocatalytic efficiency up to 66.98% and 20.88%, respectively, after investigating time of 8 hours .