A kinetic study to test silver nanoparticle/chitosan architecture on heterogeneous catalyst surface

Abstract

The catalyst building-up is studied with the goal of assessing effective procedures which lead to optimal performance devices. Tailor-made copolymeric networks of ethylene glycol di-methacrylate and 2-hydroxyethyl methacrylate (EGDMA-HEMA) and the composite of silver nanoparticle / chitosan (AgNP/CS) were separately synthesized and used to build-up heterogeneous catalysts. The AgNP/CS composite adsorption is controlled by the hydroxyl-group content within the platform surface, since changing this factor leads to monolayer or multilayer architectures to be obtained. Complementary to characterization techniques (immobilization degree, contact angle and SEM), a kinetic study of catalyst behavior is used as at testing surface architectures. The overall kinetics of 4-nitrophenol reduction with sodium borohydride is governed by the conversion process on AgNP and the matter transport through surface chitosan architecture. Consistently, multilayer architectures behave as a flux-resistant structure and their kinetics obey this general description, raising the activation energy up to ∼61 KJ.mol−1. For temperatures over 35 °C, monolayer architectures kinetically behave as solely governed by the conversion process on AgNP and its intrinsic activation energy is estimated in 14 KJ.mol−1.