Thermal Activation of Brazilian Smectite Clay (Primavera) and its Application for the Removal of Cadmium from Aqueous Solution
Background: Region-based solutions for water cleaning could be critical to tackle the water challenges faced in enhancing the in the future. Brazilian Primavera clay is cheap, abundant, and an untested material that has the potential to be used for water cleaning. Objective: the objective of the present work was to thermally activate and characterize the Brazilian clay and then determine the potential to remove Cd2+ from an aqueous solution. Methods: Primavera clay was thermally activated at 300 oC and characterized using X ray diffraction, X-ray Spectroscopy Energy Dispersive, and N2 adsorption. Sorption equilibrium was determined using the following experimental conditions: constant pH 4.5, 5 h, and 27 oC. Langmuir, Freundlich, Dubinin-Radushkevich and Temkin isotherms models were applied in order to determine the efficiency of clay used as an adsorbent. Adsorption kinetics was analyzed using the pseudo-second-order kinetic model. Results: In this study, results revealed that even though the heat treatment did not cause profound alterations on the clay structure(smectite) and surface area (78 m2 /g), a pseudo-second-order kinetic constant of 0.5563 mg/g/min was found for the cadmium removal. Conclusion: The mathematical models of the Langmuir and Temkin showed a better fit to the experimental data. A high affinity between the cadmium and the thermally activated Primavera clay was found up to 88 % with removal efficiencies.