Gamma irradiated green synthesized zero valent iron nanoparticles as promising antibacterial agents and heavy metal nano-adsorbents

Abstract

There is an urgent need to synthesize multifunctional high performance nanomaterials using green methods especially for wastewater treatment applications. Zero valent iron nanoparticles (ZVI NPs) were synthesized using a rapid, single step, and completely green method employing aqueous tea extract as both the reducing and capping agent. The synthesized ZVI NPs was further irradiated by 60Co gamma radiation source with a dose of 100 kGy. Both samples before and after irradiation were characterized using XRD, FT-IR, particles size, BET surface area, FESEM and HRTEM techniques. Gamma irradiation caused structural and morphological changes in the ZVI NPs sample. The crystallinity was improved significantly and the spherical particles fused together after radiation forming sheet like morphology. ZVI NPs were tested as nano-adsorbents for the removal of Cu2+ ions from aqueous solutions and as antibacterial agents. Various physicochemical parameters such as pH, dose and initial metal ion concentration were studied. ZVI NPs demonstrated 81.67 % and 97 % removal effeciencies before and after irradiation respectively. Recyclability of the adsorbent shows stable utilization through seven adsorption/desorption cycles. The effect of temperature was investigated on the adsorption process and the thermodynamic parameters were calculated and discussed. The antibacterial activity had been evaluated through MIC (minimum inhibitory concentration), MBC (minimum bactericidal concentration) and Agar disc diffusion method, before and after irradiation. Also for safety evaluation of the ZVI NPs; LD50 was estimated and showed safe use of the ZVI NPs therapy in-vivo. The reported results have significant implications in the area of remediation of water from bacteria with little cost, simple operation, high productivity and easiness of the equipment.