Adsorption kinetics of 3-hydroxybenzaldehyde on native and activated bentonite

Abstract In this study, the adsorption kinetics of 3-hydroxybenzaldehyde dissolved in ethanol on native and activated (acid/heat activation) bentonites were examined. The specific surface areas, pore size and pore-size distributions of the samples were fully characterized. The cation exchange capacities (CEC) of the native and activated bentonites were found as 65 and 97 meq/100 g, respectively. The adsorption efficiency of 3-hydroxybenzaldehyde onto the native and activated bentonites was increased with increasing initial bentonite amount and temperature. Also, it was found that the adsorption efficiency with activated bentonite was greater than native bentonite. The kinetics of adsorption of 3-hydroxybenzaldehyde was discussed using three kinetic models, the pseudo-first-order, the pseudo-second-order and the intra-particle diffusion model. The experimental data fitted very well the pseudo-second-order kinetic model and also followed the intra-particle diffusion model up to 20 min. The rate constants of pseudo-first-order, pseudo-second-order and intra-particle diffusion kinetics and the amount of the solute sorbed at equilibrium were determined. The initial sorption rate and the activation energy were also calculated. The activation energy of the sorption was calculated using the pseudo-second-order rate constant, and it was found to be 53.36 kJ mol− 1 and 14.03 kJ mol− 1 for native and activated bentonites, respectively.