SYNTHESIS AND CHARACTERIZATION OF rGO/UiO-66/Ag3PO4 NANOCOMPOSITES FOR PHOTOCATALYTIC DEGRADATION OF METHYL ORANGE (MO) UNDER VISIBLE LIGHT IRRADIATION

Abstract

Various industries like textile, plastic, pulp, and paper produce dye-containing waste waters that have harmful effect on the environment as well as human health. Developing a method to abate the pollution problem by dyes is therefore crucial. To this effect, single, binary and ternary nanocomposites were synthesized by different methods such as precipitation, solvothe rmal and simple solution methods. The as-synthesized nanocomposites were characterized by various techniques, including powder X-ray diffraction (XRD), Fourier Transforms Infrared Spectroscopy (FTIR), Photoluminescence (PL),Scanning electron microscopy (SEM) and UV–Vis diffuse reflectance to determine the structures, surface functional groups, recombination rate, morphology and band gap energies respectively. Photocatalytic degradation activities of the as synthesized nanocomposites under visible light irradiation were evaluated in aqueous solution comprising model pollutant (Methyl orange dye) as well as a real sewage sample solution collected from Bahirdar Textile Share Company. The results showed that the degradation efficiency of ternary nanocomposite rGO/UiO66/Ag3PO4 (RUA3) exhibited a relatively higher efficiency on the photodegradation of Methyl Orange (MO) compared to the binary and single counterparts. The percent degradation of MO and real sample solution under visible light irradiation are found to be 88.09 and 63.64 respectively. The enhanced photocatalytic property of the ternary composite could be attributed to high surface area, enhanced visible light absorption, efficient charge transfer process, as well as the synergetic effect among rGO, UiO-66 and Ag3PO4. The effect of key parameters such as solution pH, initial dye concentration and photocatalyst load were also examined. The result showed that at optimum pH (4), catalyst load (0.2 g L -1 ) and initial dye concentration 10 ppm, the nanocomposite possessed very good MO degradation and ads orption effecincy. Mechanism of photocatalytic degradation of methyl orange (MO) was investigated by using different scavengers. The addition of AgNO3 to the photocatalyst system is much suppressed. Generally MOF-based ternary composites have great potentiality in environmental remediation fields.