Estudo cinético e termodinâmico da adsorção dos iões hidrogénio e zinco em argila

Abstract

Clays are rocks made up of a number of different minerals, which belong to the group of phyllosilicates which have a relatively low specific weight as a characteristic, which is due to the predominance of the silicon-oxygen group of indefinite extension, with chemical properties derived from its structure and particle size, having different mineralogical and genetic characteristics, and having different technological properties and applications. In this work the determination of the kinetic and thermodynamic study of the adsorption of hydrogen and zinc ions in natural clay and activated with inorganic acids was carried out, with the purpose of evaluating the efficiency of the activation of the clays. The sample under study is a clayey rock from the Maputo region harvested at depths of 13-25 meters, at coordinates 25º 58´ 16.43 ̋ longitude and 32º 35´ 11.59 ̋ latitude. Physical and chemical parameters were determined for the study. The physical characterization of the sample was made from the determination of the apparent density, pycnometric density, apparent density by trapping, compressibility, porosity, zero load point and tortuosity; chemical characterization was made from chemical analysis, X-ray diffraction analysis, thermal and infrared analysis. From the kinetic experiments, it was observed that the minimum time for the system to be in equilibrium is 60 and 70 minutes for the natural clay in exchange with the H + and Zn2 + ions, and 50 minutes for the clay activated with inorganic acids, being the pseudo-second order model is the most efficient, compared to the other adsorption models proposed in the work. In the thermodynamic study, the Tempkin and Langmuir models proved to be suitable for the adsorption of the ions under study in comparison to the BET and Freundlich models.