Sustainable synthesis of silver nanoparticles using exposed X-ray sheets and forest-industrial waste biomass: Assessment of kinetic and catalytic properties for degradation of toxic dyes mixture.

Silver being the precious metal, its recovery from the waste and utilization is a worthy attempt. The present study represents a very promising sustainable approach for the synthesis of silver nanoparticles (AgNPs), where prime raw materials are waste products (silver metal extracted from waste X-ray sheets and Sal deoiled seed cake (DOC), a plant-based waste as reducing-capping agent). Upon reaction of silver nitrate extracted from waste X-ray sheets and Sal DOC extract at room temperature, the characteristic yellowish-brown color appeared within 30 min. Peak at 485-495 in UV-visible spectrophotometer confirmed the synthesis of AgNPs. X-ray waste synthesized (XRWS) AgNPs were polycrystalline in nature and have face centered cubic (fcc) lattice. Majority of them were polygonal in shape (size range 30-150 nm) with some flower like aggregates as revealed by Transmission Electron Microscope. The XRWS-AgNPs were stabilized by organic groups adhered to their surface and had good stability with a zeta potential of -27.60 mV. These XRWS-AgNPs could work as an efficient catalyst for the reduction of five selected azo dyes individually as well as mixture of these dyes. The degraded products of the individual dyes were identified using Gas Chromatography Mass Spectroscopy. Experimental values obtained for dye degradation study were fitted with first and second order linear kinetic model to know about rate of the reaction.