Hybrid hydrogels containing one-step biosynthesized silver nanoparticles: Preparation, characterization and catalytic application

摘要

Silver nanoparticles (AgNPs) were synthesized using an innovative strategy that makes use of tangerine peels extract, which acts as a reducing and stabilizing agent. This eco-friendly synthetic route allowed obtaining spherical nanoparticles with narrow size distribution (19.2 +/- 6.7 nm) within a short reaction time (40 min). Later, the AgNPs suspension was entrapped in a poly(vinyl alcohol) (PVA) matrix forming a hybrid hydrogel (PVA-gel/AgNPs), which was characterized by different techniques. Its catalytic activity was explored in the reduction of nitrobenzene to aniline in aqueous media. The reaction catalyzed by PVA-gel/AgNPs exhibited kinetics (k(app) approximate to 2.07 x 10(-3) min(-1)) and energy of activation (E-a approximate to 50.36 kJ mol(-1)) comparable to or lower than similar reactions catalyzed by other metals. Moreover, a better catalytic performance was noticed to the hybrid hydrogel as compared to "free" AgNPs, highlighting their entrapment within the hydrogel. The anchoring of the AgNPs in the hydrogel network, prevents their aggregation and leaching. The hybrid hydrogel is recovered quickly from the reaction medium, and it can be successfully reused for six consecutive runs without significant loss of its activity. Overall, it is presented here a cheap, efficient, and eco-friendly methodology to synthesize AgNPs and newly hybrid hydrogels, which have the potential to catalyze the reduction of nitroaromatic compounds. (C) 2019 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.