Estudo do comportamento adsorvente de argilas esmectíticas.

Abstract

The smectic clays have applications in several technological sectors, among their various applications, have been outstanding in recent years their use as adsorbent. In this sense, the aim of this work is to investigate the adsorption, equilibrium and kinetic process of the rhodamine B dye (RB) in the aqueous medium. The adsorptive processes of these clays were studied both in the natural form and after treatment with hydrochloric acid, organophilization (quaternary salt of ammonium) and purification by centrifugation. All adsorbents were characterized by X-ray diffraction (XRD), X-ray diffraction (XRD) and thermal analysis (TG, DTG and DTA). The adsorption assays of the dyes were examined by batch system, changing contact time, dye concentration and initial pH. For the adsorption behavior analysis, UV-VIS spectrophotometry was used. The kinetics and the equilibrium of the adsorption were studied. For the kinetic adsorption data, three models were used: pseudo-first order, pseudo-second order and intraparticle diffusion. For adsorption equilibrium, four isothermal models were evaluated: Langmuir, Freundlich, Temkin and Dubinin-Raduskevich. The kinetic adsorption mechanism was first identified as pseudo-second order and the Freundlich adsorption isotherm model showed the best fit to the experimental data. In general, the studied smectite clays have been found to be suitable adsorbents for the removal of the RB dye, and which can be considered as a good alternative for the removal of this dye in aqueous medium, however, specific treatments are needed to maximize or improve the adsorption of the dye.