Assessment of Rhodamine B Dye Removal by ZnO Nanodisks under Visible Light

Abstract

The organic dye from the textile and dye industries are highly hazardous to aquatic living and human. They cause serious damage to the surrounding environment. Zinc oxide (ZnO) photocatalyst has attracted much attention because of its high efficiency applications, especially in organic dyes removal, for instance Rhodamine B (RhB) dye. The precipitation method was used to synthesize ZnO nanodisks (NDs) by using zinc acetate dehydrate, aluminium sulphate and ammonia hydroxide as precursors. The X-ray powder diffractometry (XRD) shows that the as-synthesized particles consisted of ZnO and zinc aluminium carbonate hydroxide hydrate (ZnAlOHCO3) phases. These diffraction peaks matched with the Joint Committee on Powder Diffraction Standards (JCPDS) No. 98-002-7791 and No. 98-010-5856, respectively. The morphology of ZnO NDs was clearly observed by scanning electron microscope (SEM). An average diameter and thickness of ZnO hexagonal disk were 2.12 µm and 74.9 nm, respectively. The UV-Visible spectroscopy showed that the photodegradation efficiency of ZnO NDs in removal of RhB dye in aqueous solution was 39% under visible light illumination of 5 hours. The possible photodegradation mechanism was studied by the examination of active species e.g. •HO, •O2−, h+ through adding their respective scavengers such as methanol, benzoquinone and potassium.