الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
In this study silver phosphate photocatalyst (Ag3PO4) has been prepared using simple precipitation method and then modified with pre-synthetized green graphene/SiO2 nanocomposite to develop Ag3PO4/graphene/SiO2 nanocomposite photocatalyst which revealed better photocatalytic activity and degradation efficiency for dye removal. Afterwards, the effect of merging the photocatalytic technology with membrane separation technology has been studied. The prepared photocatalysts have been embedded in a polymeric solution of cellulose acetate (CA) membrane. For the prepared photocatalysts, the photocatalytic activity, physical properties, chemical composition, and morphology have been characterized using FTIR, XRD, SEM, TEM, BET, BJH, UV-Vis spectroscopy. The specific surface area of Ag3PO4 and Ag3PO4/graphene/SiO2 nanocomposite was reported to be 1.53 m2/g and 84.97 m2/g, respectively. The band gap energy of Ag3PO4 and Ag3PO4/graphene/SiO2 nanocomposite was measured to be 2.4 eV and 2.307 eV, respectively. In order to evaluate the photocatalytic degradation performance of both photocatalysts; Trypan blue (TB) dye solution was used as a pollution source. Different parameters were studied through experiments such as pH, catalyst dosage, initial concentration, and contact time. It was found that for initial dye concentration of 20 ppm, pH= 2, and catalyst dose of 0.03 g, the degradation efficiency using Ag3PO4/graphene/SiO2 was 98.7 % within 10 minutes. Several adsorption isotherms such as Langmuir, Freundlich, and Temkin adsorption isotherms have been tested in addition to the adsorption kinetics. Both catalysts were found to follow the Langmuir isotherm model and pseudo-second-order. The rate constant (K2) of Ag3PO4/graphene/SiO2 nanocomposite was 0.00891 g/mg.min compared to 0.00281 g/mg.min for Ag3PO4. Different cellulose acetate (CA) membranes have been made with various photocatalysts dosages. The prepared ones have been characterized using EDX, contact angle test, FTIR, and SEM. The developed photocatalytic cellulose acetate membranes loaded with 0.1 g of Ag3PO4 (M3), and the other with 0.1 g of Ag3PO4 /graphene/SiO2 (Mc3) performed better than the original cellulose acetate membrane (M0) for dye removal under different operating parameters such as initial dye concentration, pH, and visible irradiation time. 99 % of TB dye removal within 100 minutes was achieved using a photocatalytic membrane reactor (PMR) at pH 4 and under a 100-watt visible light lamp. The study revealed that, Mc3 outperformed all other manufactured composite membranes and the pristine CA membrane in terms of mechanical properties and hydrophilicity.