Novel evolution of gamma irradiated PVP/Cu–Ag nanocomposite for dye polluted water treatment

Abstract

A novel polyvinylpyrrolidone/copper–silver (PVP/Cu–Ag) nanocomposite was synthesized via aqueous solution reduction and gamma radiation techniques for the treatment of methylene blue dye (MB) polluted water as a common organic dye pollutant in wastewater which is harmful to human health and aquatic life. Different analyses were used for the characterization of the synthesized Cu–Ag nanoparticles (NPs) and PVP/Cu–Ag nanocomposites such as XRD, TEM, DLS, FTIR, EDX, and TGA The XRD results indicated the typical peaks of CuNPs and AgNPs and the formation of pure crystalline nanoparticles in addition to their corresponding peaks were noticed in the PVP/Cu–Ag nanocomposite. Results of FTIR for the PVP/Cu–Ag nanocomposite confirmed the successful interaction between Cu–Ag NPs and PVP chains. The SEM of the PVP/Cu–Ag nanocomposite appeared rough and dense porous surface with white spots of Cu–Ag nanoparticles that dispersed homogeneously all over the surface of the PVP matrix. The effect of the dose of gamma radiation on the gelation and swelling of PVP hydrogel and PVP/Cu–Ag nanocomposite was studied. Using 15 kGy, the gel content of 89% and 97.1% for PVP and PVP/Cu–Ag, respectively. The swelling degree of PVP/Cu–Ag nanocomposite shows pH dependence and the maximum swelling was at pH 6. The point of zero charge (pHpzc) of PVP/Cu–Ag nanocomposite was 5.8. The factors affecting the removal of MB dye were evaluated as the effect of reaction time, dosage, temperature, pH, and dye concentration. The PVP/Cu–Ag nanocomposite shows fast adsorption of MB dye with a removal percentage of 95% after 50 min, at pH 8, 200 mg/L dye concentration, and 0.1 g nanocomposite dosage. Based on the kinetic, isotherm, and thermodynamic studies, it was found that the adsorption of MB dye onto PVP/Cu–Ag nanocomposite fitted to the Pseudo-second-order kinetic model and the Langmuir isotherm model and the reaction was an endothermic, spontaneous, and chemisorption. The fast removal of the dye using the PVP/Cu–Ag nanocomposite confirms its possible use in wastewater treatment applications as an effective adsorbent for dye treatment.