Intercalação e caracterização do interestratificado caulinita-ilita com DMSO e aplicação em remoção de azul de metileno em meio aquoso : cinética e termodinâmica de adsorção

Abstract

The interstratified clay mineral kaulinite-ilite natural (KA-IL), was found in the area of the city of Capinópolis – MG, with a brawn color and material of low particle size. This research aims to characterize the chemical modification and apply the material in the adsorption process. The material was subjected to chemical modification has been carried out with the compound dimethylsulfoxide (DMSO), which has high binding to the structure of interstratified and non toxic. The natural material (KA-IL) and chemically modified (KA-IL/DMSO) were characterized by elemental analysis (X-ray fluorescence), scanning electron microscopy (SEM), infrared (FTIR) and X-ray difraction (XRD). The peaks obtained in well-defined X-ray diffraction, shows that there fixing the organic compound that increased the basal spacing d001 of kaolin is naturally 7.0 Å to 11.50 Å, with the spacing of the clay mineral ilite, not changed, and confirms the existence of these minerals in the sample. The ability of these materials to remove methylene blue aqueous solution was verified by a series of isotherms in environmental temperature and pH 6.0. The maximum number of g.g-1 (weight of dye adsorbent on clay weight) was determined by 0.0625 and 0.0590 for KA-IL and KA-IL/DMSO respectively. The kinetic data were best modeled by isothermal pseudo-second order Lagergren, with a correlation coefficient (r2 ) of 0.94305. To evaluate the effect caused by variation of the concentration of methylene blue dye in the reaction of adsorption isotherm the theoretical closest to the experimental data was the Langmuir model with r2 0.950. The energetic effect caused by the adsorption of methylene blue was determined using the Langmuir parameters, thermodynamic data indicate the existence of favorable conditions for the interaction of methylene blue-clay mineral surface, with values of Gibbs free energy (∆G0) in -18.83 KJ.mol-1 to form natural material, -27.16 KJ.mol-1 for the chemically modified.