Photodegradation and antibacterial studies of ZnS enwrapped fly ash nanocomposite for multipurpose industrial applications

Abstract

A ZnS-enwrapped amine-functionalized fly ash nanocomposite (ZnS/A-FA) has been prepared by using various weight percentages of amine functionalized fly ash, zinc nitrate hexahydrate and sodium sulphide through wet chemical synthesis method. The synthesized ZnS/A-FA photocatalyst is characterized using XRD, UV-visible DRS, PL, FT-IR, FE-SEM, EDX, elemental mapping, HR-TEM, TGA and BET techniques. The BET surface area results conclude that the fly ash-supported ZnS has a higher surface area of 153.5 m² g⁻¹ than that of bare ZnS (68.5 m² g⁻¹). The photocatalytic activity of the ZnS/A-FA nanocomposite has been investigated for the degradation of methylene blue (MB) dye under UV irradiation. The percentage dye degradation experiments are conducted by varying the weight percentage of A-FA supported ZnS to 0.25%, 0.5%, 1%, 2% and 3%. In addition, kinetic studies are carried out by varying the pH, catalyst dosage of ZnS-enwrapped A-FA nanocomposite and dye concentration. From the results, it has been concluded that the fly ash-supported ZnS shows higher catalytic activity compared to that of bare ZnS nanoparticles. Further, one weight percent A-FA-supported ZnS nanocomposite exhibits higher photocatalytic performance when compared to other ratios. The antibacterial properties of A-FA, bare ZnS and the ZnS/A-FA nanocomposite are studied against Gram-positive and Gram-negative bacteria. From the antibacterial studies, it has been found that the ZnS-enwrapped A-FA material exhibits good antibacterial activity compared to that of A-FA and bare ZnS nanoparticles. Hence, ZnS-enwrapped fly ash is a promising photocatalyst for waste water treatment, dye degradation and antibacterial applications.