Preparation of tungsten trioxide/graphene oxide/ hydroxyapatite (WO3/GO/HAp) for photocatalytic removal of methylene blue under visible light

Abstract

The textile industry is one of the leading contributors of liquid waste in the form of synthetic dyes, which significantly contaminate water sources. Heterogeneous photocatalysts employ semiconductors that trigger photocatalytic processes with the assistance of UV or visible light to degrade waste. Tungsten trioxide (WO3) is a potential semiconductor with a small band gap (2.8 eV) that absorbs visible light. WO3 was combined with graphene oxide (GO) and hydroxyapatite (HAp) to exploit the ultrasonication method to degrade methylene blue (MB) dye. The results of the SEM-EDX characterization confirm the constituent elements of the WO3/GO/HAp material. The chemical elements were confirmed by energy-dispersive X-ray spectroscopy. The ability of the original and modified WO3 photocatalysts (WO3/HAp, WO3/GO and WO3/GO/HAp) to degrade 15 ppm of 50 ml of MB solution at concentrations of 10, 15, and 20 mg for 4 h under visible light was investigated. The breakdown of the methylene blue dye demonstrated that the reaction speed followed a first-order pattern. Meanwhile the adsorption isotherm better fit Langmuir for WO3/GO and WO3/GO/HAp. The highest pollutant degradation was achieved using 20 mg WO3/GO and WO3/GO/HAp photocatalysts, which achieved efficiencies of 99.1 % and 98.3 %. These results confirm that the WO3/HAp; WO3/GO, and WO3/GO/HAp hybrid photocatalysts exhibit better degradation performance than unmodified WO3 photocatalysts. Additionally, these photocatalysts can be reused up to three times without experiencing substantial loss in effectiveness.

Keywords

• Antifouling
• Photocatalytic degradation
• Wastewater treatment