TITLE:
Characterization and Adsorption Study of Thymol on Pillared Bentonite
AUTHORS:
Mohamed El Miz, Samira Salhi, Ikrame Chraibi, Ali El Bachiri, Marie-Laure Fauconnier, Abdesselam Tahani
KEYWORDS:
Clays, Bentonite, Thymol, Adsorption, Desorption, Kinetics, Pillared Clay
JOURNAL NAME:
Open Journal of Physical Chemistry,
Vol.4 No.3,
July
30,
2014
ABSTRACT:
Pillared clay (PILC) was prepared from Moroccan clay and
characterized, and its aqueous thymol adsorption capacities were studied using
a batch equilibrium technique. So, we tested the encapsulation of thymol by
aluminum pillared clay (PILC). The PILCs displayed a total surface area of 270
m2/g, a total pore volume of 0.246 cm3/g and an average
pore diameter of 8.9 A, which corresponds to the size of Al13 forming the pillars between the clay
layers. The adsorption capacity shown by the PILCs for thymol from water is
close to 319 mg?g-1 for
low solid/liquid ratio (0.2%). This result suggests that the PILCs have both
hydrophobic and hydrophilic characteristics, as a result of the presence of
silanol and siloxane groups formed during the pillaring and calcination of the
PILCs. The experimental data were analyzed by the Freundlich and the Langmuir
isotherm types for low values of equilibrium concentration. The rise of the
isotherm in this range of concentrations was related to the affinity of thymol
for clay sites, and the equilibrium data fitted well with the Freundlich model
with maximum adsorption capacity of 319.51 mg/g for a ratio RS/L = 0.2%. Pseudo-first and
pseudo-second-order kinetic models were tested with the experimental data and
pseudo-first order kinetics was the best for the adsorption of thymol with
coefficients of correlation R2 ≥0.986, and the adsorption was rapid with 90% of
the thymol adsorbed within the first 20 min.