| Abstrakt: |
This study investigated the controlled-release properties of thymol, a biological insecticide, encapsulated within sodium purified (Na-Mont), pillared modified with Al13 (Mont-Pil-Al13) and organophilic (modified with cetyl pyridinium (Mont-CPC)) montmorillonites clay matrices. The clays were characterized using elemental analysis, XRD, FTIR, and TGA. Na-Mont, Mont-Pil-Al13, and Mont-CPC exhibited maximum thymol adsorption of 177 mg/g, 319 mg/g, and 183 mg/g, respectively. Thermal analysis revealed thymol release from the microcapsules followed zero-order kinetics and was dependent on temperature (20–120 °C), time (0–240 min), encapsulated concentration, and clay matrix. Mont-Pil-Al13 microcapsules showed the fastest release, with 50% thymol released after 610s and 100% after 1386s at 35 °C. Mont-CPC and Na-Mont microcapsules released 50% thymol after 1579 s and 2019s and 100% after 3597s and 3882s, respectively. Activation energies calculated using the Friedman method were 26 kJ/mol for Mont-Pil-Al13, 78 kJ/mol for Mont-CPC, and 120 kJ/mol for Na-Mont, correlated to their release rates. Kinetic models demonstrated thymol release primarily followed zero-order diffusion, with the rate modulated by interactions between thymol and the clay matrices. Thus, thymol encapsulation within modified clay microcapsules provides a means for controlled insecticide release tuned by carrier material and thermal conditions. [ABSTRACT FROM AUTHOR] |
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