Green synthesis of Ag-Au bimetallic nanocomposites using a biodegradable synthetic graft copolymer; hydroxyethyl starch-g-poly (acrylamide-co-acrylic acid) and evaluation of their catalytic activities

An eco-friendly method for the synthesis of Ag-Au bimetallic nanocomposites from aqueous solution using a novel biodegradable graft copolymer hydroxyethyl starch-g-poly (acrylamide-co-acrylic acid) acting as a reducing and stabilising agent was reported. The graft copolymer was prepared using a solution polymerization technique using potassium perdisulfate as the initiator at 70 degrees C and was characterized by measuring its molecular weight and molecular weight distribution using size exclusion chromatography, FTIR spectroscopy, XRD and SEM studies. Biodegradation study was carried out by enzyme hydrolysis. Ag-Au nanocomposites prepared by using the synthesised graft copolymer was characterized by using UV-VIS and FTIR spectroscopy, HR-TEM with SAED analysis, FESEM and EDAX analysis. Catalytic activities of the bimetallic nanocomposites were evaluated for the reduction of 4-nitrophenol to 4-aminophenol, degradation of 'N = N' (azo bond) bond in some azo dyes in presence of sodium borohydride. Three commercial azo dyes namely congo red, sudan-1 and methyl orange were used for azo bond degradation. The kinetics of catalytic activities were studied using UV-VIS spectroscopy. (C) 2016 Elsevier Ltd. All rights reserved.