Characterization of inorganic and organic clay modified materials: An approach for adsorption of an insecticidal terpenic compound

• Modifications of bentonite improve the adsorption capacity of the raw material.
• Treatment of bentonite with metallic polymers induces exfoliation.
• Alkylammonium modification induces a pillaring in the bentonite interlayer space.
• Interlayer space increase from 10 Å to 14 Å and 20 Å for Bent-PTMA and Bent-CTMA.
• Organic and inorganic bentonites can be an adsorbent for terpenic components.

Two organic molecules and two inorganic polymers have been used to modify the structure of bentonites as to obtain a high adsorption capacity of thymol, an insecticidal terpenic compound. The selected organic molecules were cetyl and phenyl trimethyl ammonium chlorides (CTMA and PTMA); the inorganic compounds were aluminium hydroxyl and iron hydroxyl polymers. Organic bentonites were obtained after treatment with CTMA and PTMA solutions. Inorganic bentonites were obtained after treatment with polymeric solutions of Alx(OH)y and Fex(OH)y. Materials were characterized by several physicochemical techniques including X-ray diffraction (XRD), thermal gravimetric and differential analysis (TGA, TDA), infrared spectroscopy (FTIR) and nitrogen adsorption–desorption. Adsorption capacities of modified and unmodified bentonites for terpenic compounds were also carried out. Results show that the organic cations have been intercalated successfully into the bentonite interlayer space. XRD measurements show that PTMA and CTMA induce an interlayer space expansion of 4.1 Å and 10.5 Å, respectively. The increase of specific surface areas (SSA) of materials treated with metallic polycations attests the occurrence of exfoliation. The highest adsorption capacity of thymol is obtained with bentonites modified by alkylammonium, which proves that the modification of the interlayer space is an interesting way to improve adsorption properties of clays usable as support for natural insecticides.