Intracrystalline structure and release pattern of ferulic acid intercalated into layered double hydroxide through various synthesis routes

Abstract

We intercalated ferulic acid (FA) molecules into a layered double hydroxides (LDHs) via three different synthesis routes ion-exchange, exfoliation-reassembly, and reconstruction to obtain FA-LDH nanohybrids. All the nanohybrids started from same MgAl-CO3-LDH pristine, with a homogeneous particle size of 80 nm, in order to control particle size of final products. According to infrared spectroscopy, all the synthesis routes resulted in successful hybridization between anionic ferulate and positive LDH layers. X-ray diffraction, UV Vis spectroscopy and thermal analyses showed that the FA molecules were arranged in a zig-zag manner to maximize n-n interactions among them. From scanning electron microscopy, it was revealed that reconstruction gave rise to structural re-organization of LDH layers resulting in a house-of-cards morphology in the nanohybrid, while other methods produced a hexagonal plate-like shape. It seems that FA moieties intercalated by a reconstruction method could be accommodated in the inter-particle cavity as well as the interlayer space in FA-LDH nanohybrids. We investigated time-dependent FA release profiles from each nanohybrid in deionized water and saline. The release patterns and kinetic model fitting results revealed that the release behavior was different each nanohybrid according to the synthesis method and followed Elovich and power function models. (C) 2015 Elsevier B.V. All rights reserved.