Removal of Evans Blue and Yellow thiazole dyes from aqueous solution by Mg-Al-CO3 Layered Double Hydroxides as anion-exchanger

Abstract

Mg-Al-CO3 Layered double hydroxide (LDH) was prepared by co-precipitation method at constant pH, and subsequently used to remove Evans Blue (EB) and Yellow thiazole (YT) dyes from aqueous solutions.The obtained material was characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), thermal analysis and BET. The kinetic and equilibrium aspects of sorption of the anionic dyes from aqueous solution by Mg-Al-CO3 were investigated in batch mode. The sorption kinetic data were found to be consistent with the pseudo-second-order model. Data for YT and EB sorption by Mg-Al-CO3 were fitted better by the Langmuir equation than by the Freundlich equation based on the determination coefficient values R2. The maximum adsorption capacities of 222.2 mgg-1 for Yellow thiazole and 107.5 mgg-1 for Evans blue. The thermodynamic parameters including Gibbs free energy ( G°), standard enthalpy change ( H°), and standard entropy change ( S°) for the process were calculated. The negative  G° value indicates the spontaneity of the removal process.