Synthesis of g-C3N4, Zn3(PO4)2 and g-C3N4/Zn3(PO4)2 Composites for Application in Photodegradation of Crystal Violet Dye under Solar Light

The g-C3N4/Zn-3(PO4)(2) composites were synthesized in the aqueous medium via chemical precipitation route. The photocatalytic activity of these photocatalysts was evaluated for the degradation of aqueous crystal violet (CV) dye under solar light. The optimum photocatalytic activity of g-C3N4/Zn-3(PO4)(2) composite was found for 30 % weight of g-C3N4. The comparison experiments showed the photocatalytic activity of the g-C3N4/Zn-3(PO4)(2) composite increased 2 times compare to bare Zn-3(PO4)(2) and 1.5 times of g-C3N4. The enhanced photocatalytic activity originates due to the transfer of photogenerated electrons from the conduction band of g-C3N4 to the Zn-3(PO4)(2) which makes well-separated electron-hole pairs. The degradation capacity increases with an increase in the pH of the solution up to 8 and then decreases up to 10 and then again starts increasing. The addition of scavengers decreases degradation capacity of g-C3N4/Zn-3(PO4)(2) composite in the order of Ethylene diamine tetra-acetic acid-Na-2 (EDTA)>tert-butyl alcohol (TBA)>L-ascorbic acid (AA). The degradation of CV over g-C3N4/Zn-3(PO4)(2) composite mainly attributed by the holes. The interfering anions (except Br-) decrease the degradation capacity of Zn-3(PO4)(2) whereas in the case of composite no change in the degradation capacity was observed. The recycling experiment for the degradation of CV dye was performed on bare Zn-3(PO4)(2) and g-C3N4/Zn-3(PO4)(2) composite and found better stability and recyclability of the composite material.