SYNTHESIS AND CHARACTERIZATION OF POLYANILINE SUPPORED CdS-ZnO-Ag3PO4NANOCOMPOSITE FOR PHOTOCATALYTIC AND ANTIMICROBIAL APPLICATIONS

Abstract

In this work, different types of photocatalysts, single systems; ZnO, Ag3PO4,and CdS binary systems; ZnO-Ag3PO4, and ZnO-CdS, and ternary systems with different molar ratio of; CdS-ZnO-Ag3PO4 (15:80:5), CdS-ZnO-Ag3PO4 (10:80:10), CdS-ZnO-Ag3PO4 (20:70:10), CdS-ZnO-Ag3PO4 (25:70:5) were prepared by precipitation method and a polyaniline supported CdS-ZnO-Ag3PO4 was prepared by impregnation method using precursor solutions of CdS, ZnO, Ag3PO4 and polyaniline powder. Analysis of metal contents, crystal structure, thermal stability, band gap energy, functional groups and optical properties of the photocatalysts were characterized by using AAS, XRD, TGA-DTA,Uv-vis, FTIR, PL instruments respectively. Photocatalytic activities and antimicrobial efficiencies of the supported and unsupported nanocomoposites were evaluated using methyl orange as a model organic pollutant and Gram negative and Gram positive bacteria as test microbes respectively. Photocatalytic and antibacterial activities of CdS-ZnO-Ag3PO4 were found to be higher than that of binary, ZnO-Ag3PO4, and ZnO-CdS, and single,ZnO, Ag3PO4, and CdSforms. The effects of pH, initial dye concentration, catalyst load as well as mechanism of scavenger reaction were investigated using photocatalytic degradation of CdS-ZnO-Ag3PO4 (15:80:5). The results obtained indicate the efficient degradation at pH= 6 which extent to 78.1%, at 12ppm extent to 78.8%, at 140 mg/L extent to 79%, mechanism of scavenger reaction also assure the most important species in the degradation process would be (_*O2) and (*OH). Stability towards photocatalytic degradation of the polyaniline supported CdS-ZnO-Ag3PO4 was evaluated using 12ppm MO, 140 mg/L of catalyst, at pH=6. The results show four degradation cycles extent to 95.6%, 92.1%, 84.2% and 70% that can confirm the desired prospect of having supported nanocomoposite. Antibacterial efficiency of the polyaniline supported CdS-ZnO-Ag3PO4 over both Gram negative and Gram positive bacteria were found to be relatively higher than its binary and ternary systems