Thermal and Acid Activation (TAA) of Bentonite as Adsorbent for Removal of Methylene Blue: A Kinetics and Thermodynamic Study

Abstract

Natural bentonite grounded from Sarolangun District of Jambi Province has been modified based on Thermal and Acid Activation (TAA). The thermal activation was conducted by calcination at temperature 400 oC and followed by chemical activation using H2SO4. In order to investigate the change of the bentonite structure before and after activation process, the chemical analysis by XRF, XRD powder, BET, and FTIR was conducted. The TAA bentonite then used as an adsorbent to remove the methylene blue dye from aqueous solution by studying the kinetics and thermodynamic of the adsorption process. The result of the structural analysis showed that during the activation process, the structure of bentonite was not changed significantly and the surface area of the activated bentonite has increased from 55.6 to 75.6 m2/g. The kinetics studies of adsorption methylene blue onto TAA bentonite revealed that the adsorption process followed the pseudo-second-order kinetic equation rather than the pseudo-first order kinetics. The kinetic data obtained presented that by increasing the initial dye concentration, the adsorption speed was reduced. The thermodynamic adsorption study revealed that the adsorption process was spontaneous showed with the negative value of free Gibbs energy.