Adsorption of Triterpene Extracts of Momordica charantia (Cucurbitaceae) Leaves by Local Kaolin from Boboyo, Far North Region (Cameroon)

Abstract

Plant extracts are nowadays cited as suitable tools for better protection of stored grains insect pest attacks. These chemical insecticides are less attractive to producers because of their low persistence and difficulty to use as pure product. The present work aimed to study the formulation through adsorption of tetracyclic triterpene of the leaves of Momordica charantia (Cucurbitaceae) on kaolin. tetracyclic triterpene was obtained by macerated in methanol solvent. In this study, we tested the technical properties of kaolin physically and chemically, which include XRF, XRD, and FTIR. Based on the XRF test, the main composition of kaolin, SiO2, Al2O3, and Fe2O3, CaO, MgO, K2O, Na2O, SO3, P2O5 were 45.41, 20.54, 8.10, 0.13, 0.79, 01.10, 01.09, 0.04, and 0.03% respectively, while the rest were impurities. The FTIR spectra showed the functional groups of Al-OH, Al-O and Si-O. While the XRD diffractogram identified kaolinite as the main mineral phase in the presence of quartz, muscovite, and grossite tested in small quantities in the sample. The experimental parameters such as contact time, adsorbent dose, initial concentration of extract of triterpene and temperature were studied. The study revealed that the maximum quantity of adsorption is reached after 10 minutes, it is believed that the quantities adsorbed with the increase in the concentration of the adsorbate and quantities adsorbed decreases with the increase of the mass of the clay and temperature. The adsorbent showed good potential for adsorption with a maximum take up of 0.34 mg/g. The equilibrium data were well fitted by the Langmuir isotherm. Thermodynamic parameters suggested that the adsorption involved a chemical process, spontaneous, and endothermic in nature. The kinetic study showed that the second-order model gives a better description of the kinetics of the adsorption reaction. The study of the adsorption of triterpene extract by kaolinite can be used for a powdery formulation of insecticide.