Adsorption of essential oil components of Xylopia aethiopica (Annonaceae) by kaolin from Wak, Adamawa province (Cameroon)

Essential oils of aromatic plants are nowadays cited as suitable tools for better protection of stored grains from insect pest attacks. These chemical insecticides are less attractive to producers because of their low persistence and difficulty to use as pure product. There is therefore a need to formulate them as an easy handling chemical with better persistence. The present work aimed to study the formulation through adsorption of active components of Xylopia aethiopica Dunal (Annonaceae) essential oil on kaolin. X. aethiopica essential oil was obtained by hydrodistillation in a Clevenger type apparatus unit. Essential oil obtained was analysed by a GC–FID and a GC–MS. The adsorption measurements were performed with collected two kaolin fractions (F1 < 100 µm; F2 < 50 µm) and two kaolin fractions after H2O2 treatment (F3 < 50 µm; F4 < 2 µm). The kaolin was characterized by XRD, XRF, FTIR; its specific surface area was determined by the B.E.T method. The amount of essential oil adsorbed was inversely proportional to the particles size. Treatment of kaolin with hydrogen peroxide increased the adsorption capacity of essential oil components. The components adsorbed in highest amounts were sabinene, β-pinene, α-pinene and β-phellandrene.