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.
Highlights
In recent years, material sciences have involved the studies related to the production of materials having a controlled pore structure and improvement of porous materials found in the nature
In our previous work [23], we have studied the adsorption of thymol on sodium bentonite and the maximum amount adsorbed was 177 m2∙g−1 showing a certain affinity of thymol for anionic clay sites
The aim of this work is the study of characterization, adsorption isotherm and adsorption kinetics of thymol on pillared bentonite, for multiple applications related to the technology of encapsulate volatile material in clay mineral nano-capsules
Summary
Material sciences have involved the studies related to the production of materials having a controlled pore structure and improvement of porous materials found in the nature. The production principle is to hold the inorganic layers a part from each other, introducing a bulky guest agent between them. When the used materials are clay minerals, the resulting materials after pillaring are called Pillared Layered Clays (PILCs). The host solid and the production conditions have rather important effects on the quality of the product. Due to its high cation exchange capacity, swelling properties, and large sheets, montmorillonite type clay have an important place in the production of pillared clays. Any material which could enter between the layers and has a thermal stability and suitable dimensions can be used as pillaring agent [1]-[5]
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