ADSORPTION OF CRYSTAL VIOLET DYE FROM AQUEOUS SOLUTION USING ACTIVATEDKAOLIN CLAY

Abstract

In this research, modification of raw Kaolin was carried out by three ways: thermal activation (TA); acid treatment (AA) and combined acid and thermal activation (ATA). The characterization of the modified kaolin clays was carried out using scanning electron microscopy (SEM) and Fourier transformation infrared (FTIR) spectroscopy. The microscopic images obtained through SEM showed that the modified clay has become more porous, offering additional adsorption sites enhancing the surface properties of kaolin. The modified Kaolin samples were examined for their performance as adsorbent for crystal Violet dye removal. The effect of key operational parameters, such as contact time, dye concentration, adsorbent dosage, pH and temperature were experimentally studied. The pH changes have significant impact on the crystal violet dye adsorption with increase in pH, leads to increase in adsorption. The percentage bound decreased with increase in temperature and concentration suggesting favorable adsorption at low temperatures for all modified Kaolin samples. The evaluation of thermodynamic parameters revealed that adsorption process is non-spontaneous. The equilibrium data were analyzed using Langmuir, Freundlich and Temkin adsorption isotherms. The isotherms provided fit to the experimental data Langmuir isotherm more fitted. Results from kinetic study revealed that the crystal violet adsorption on all modified Kaolin samples occurred in monolayer. The adsorption data were analyzed using pseudo first-order and pseudo second-order kinetics, Intra-particle diffusion and Elovich models. The results revealed that adsorption followed pseudo second-order kinetics. The results from this study suggest that a combination of thermal and acid treatment of kaolin is an effective method to improve adsorption capacity of Kaolin. The Kaolin modified by acid and thermal activation can be successfully employed for the removal of dyes from wastewater.