Removal of acid blue 80 from aqueous solutions by adsorption on chemical modified bentonites

Abstract

Batch sorption experiments were performed to study the adsorption of Acid Blue 80 (AB80) dye from aqueous solutions using chemical modified bentonites as adsorbents. A raw-bentonite (RB) was converted to sodium bentonite (NaB). The NaB was activated by acid leaching with sulfuric acid in order to obtain a sample (ANaB) with modified adsorption properties. The NaB and ANaB samples were exchanged with two alkyltrimethylammonium bromides (alkyl = C16 and C18) to evaluate the effect of the carbon chain length on the AB80 adsorption. The obtained samples were characterized by XRD, fourier transform infrared spectroscopy, nitrogen adsorption at −196°C, and through the determination of pH_zpc. The effect of several operational parameters like pH, initial concentration of AB80, contact time, on the sorption behavior was studied. The adsorption kinetics were studied using pseudo-first-, pseudo-second-order and intraparticle diffusion models. The equilibrium adsorption data were analyzed using the Freundlich and Langmuir isotherm equation models. The Langmuir adsorption capacities (q_e) were found to be 201, 179, 170, and 126 mg/g at 30°C respectively for ANaBC18, NaBC18, ANaBC16, and NaBC16.

Keywords:

• Adsorption
• Acid blue 80
• Clay acid activation
• Clay organo modification
• Organoclay