Comparative study on adsorption of basic and acid dyes by hydroxy-aluminum pillared bentonite

Hydroxy-aluminum pillared bentonite (Al-Bent) was prepared and characterized in this work, and its dye adsorption capacity was comparatively studied in batch experiments. Results of characterization revealed that because of the intercalation of hydroxy-aluminum polyoxycations, a significant increase of interlayer basal spacing, BET surface area and total pore volume was beneficial to dyes' adsorption. The sodium bentonite had a higher adsorption affinity for Basic Fuchsin (BF) and Basic Green (BG) than Acid Turquoise Blue A (ATBA). After pillaring, the adsorption capacity of the three dyes increased and the rise of pH changed insignificantly with solution from 2 to 8. The pseudo-second-order kinetic model provided the best correlation of the experimental data (R-2 > 0.99). Henry and Freundlich models both described the adsorption isotherm data well. The adsorption capacity of Al-Bent for the three dyes, especially the basic dyes BF and BG, was high over a wide range of aqueous concentrations and followed the order of BG > BF > ATBA. (C) 2014 Elsevier B.V. All rights reserved.