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.
