Preparation and characterization of hybrid compounds of double lamellar hydroxide salts (SHDLs) or layered double hydroxides (LDHs) with anions derived from benzoic acid

• Grant number: 05/00320-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2005
• End date: March 31, 2006
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Physical-Chemistry
• Principal Investigator: Joao Barros Valim
• Grantee: Katia Cristina Sanchez
• Host Institution: Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

There is a considerable interest in the study of lamellar compounds that present anionic exchange capacity, like layered double hydroxides (LDHs) or layered hydroxy double salts (HDSs). Both of these classes of compound present structures similar to that of brucite. The HDLs can be represented by the general formula [MII(1-x) MIII(x)](OH)2Am-(x/m) . nH2O where MII represent a divalent cation; MIII represent a trivalent cation and Am- an intercalated anion with m- charge. The HDSs can be represented by the general formula [(Me,M)2(OH)3NO3], with Me and M representing divalent cations, which can be either of the same or of different species. These classes of compounds can be prepared and characterized with respect to their structures, compositions and others physical chemical properties. A great variety of these kind of materials can be obtained, due to the possibility of varying the cations and of exchanging the intercalated anions in their structures. Depending on their compositions, their crystallinity, their thermal stability and on others physical chemical properties, these materials can present a wide range of applications. Due to the possibility of intercalating electrochemical active species between their layers, these materials can be applied as modified electrodes, which study has scarcely been explored. The aim of this work is the preparation and characterization of bidimensional LDHs and HDSs matrices intercalated with benzoic acid derivatives anions. The obtained materials will be characterised by powder X-ray diffraction analysis, infrared spectroscopy, scanning electron microscopy coupled with energy dispersion X-ray spectroscopy, specific surface area analysis, simultaneous thermogravimetric and differential thermal analyses and cyclic voltametry analysis. (AU)