Green Biosynthesis of CdS NPs and CdS/Fe3O4 NCs by Hawthorn Plant Extract for Photodegradation of Methyl Orange Dye and Antibacterial Applications

Abstract

In the present study, green nanomaterials were synthesized using hawthorn plant extract as a natural stabilizer, reducing and capping agent. Biosynthesized CdS nanoparticles (NPs) and the coupled CdS/Fe3O4 nanocomposites (NCs) have been verified by various techniques such as XRD, SEM, EDS, TEM, FTIR and Uv–Vis. The average size about 24.2 nm was estimated for the composite crystals of SEM images and XRD (by the Scherrer and Williamson-Hall methods). The EDS results showed a mole ratio of 1:1 for the CdS NPs and 1:2 for CdS/Fe3O4 nanocomposite. Photocatalytic activity studies have shown that green synthesized CdS/Fe3O4 NCs (dosage: 0.1 g/L) have high photocatalytic activity toward photodegradation of methyl orange (MO) 1.2 × 10–5 M in aqueous solution under UV irradiation. Impacts of reaction conditions such as solution pH of rage (3–10) and contact time for about 105 min on the photodegradation rate of MO dye by CdS/Fe3O4 NCs photocatalysts have been investigated. Photocatalytic experimental results showed that the highest photodegradation rates occurred in a basic solutions at pH 10. Adsorption kinetics followed the pseudo-first-order kinetics model for photodegradation of MO. The adsorption kinetics results showed that degradation rate was increased toward increase of pH of 3 to 10 with apparent rate constant (0.090, 0.107, 0.187 and 0.268 min−1), respectively. In addition, the antibacterial effect of CdS/Fe3O4 NCs against pathogenic bacteria was tested, which revealed that nanocomposites had moderate antibacterial activity against both gram-positive (Enterobacter aeruginosa) and gram-negative (E. coli, Pseudomonas aeruginosa, and Klebsiella pneumonia) at different concentrations of CdS/Fe3O4 NCs (0.001 to 0.025 g/ml).