Tratamento da vermiculita por ionização escalonada para remoção de íons cálcio associados à dureza da água

Abstract

Vermiculite has cationic exchange properties, allowing its use as an adsorbent for the removal of metal ions in purification and water treatment processes. In recent years, research on the use of vermiculite clay as adsorbents is being developed aimed at more sustainable solutions. This study investigated the potential of ionized modified vermiculite as calcium ion adsorbent material in aqueous medium. The first step consisted of separating the samples of vermiculite, which were classified granulometrically and washed with bidestilled water. The activation of clay was performed with solutions of graduated concentrations of sodium chloride and potassium cloride salts. Subsequently, a study was conducted to determine the zero load point of vermiculite in nature, establishing the best pH parameter in the process of cation adsorption. Trials at different time intervals were conducted to determine the balance time. Kinetic analyses, adsorption isotherms and thermodynamic adsorption trials were carried out to understand the mechanism of calcium ion adsorbtion in ionized vermiculite. The clay was characterized by means of analytical techniques MEV, EDS, DRX and FRX. The ionization process achieved the proposed targets in relation to the graduation. Vermiculite treated with 100% NaCl showed significantly higher calcium ion removal in aqueous solution. Through analysis with MEV-FEG, no significant differences were found in the structure of vermiculite compared to vermiculite in nature, indicating that the ionization process did not substantially affect its morphology. After regeneration, the adsorbents showed increased adsorption capacity. Adsorption was observed as an endothermic process.