Etude de l’adsorption du β-carotène contenu dans l’huile de palme brute par les argiles activées et imprégnées aux nanoparticules de fer.

Abstract

This thesis is dealing with the evaluation of two clay materials from Cameroon as potential bleaching earth for the removal of β-carotene from palm oil. The clays were collected from Mbembe in the Centre Region and from Mayo Ferngo in the Far North and respectively coated as MB and MF. Both samples were acid activated using sulfuric acid and impregnated with iron nano-particles. The iodine index of the various modified clay was evaluated to access their adsorption capability and nine modified samples (Four from MB and five from MF) were retained for testing toward β-carotene removal. Prior to their used for oil bleaching, the retained samples were characterized using X-ray fluorescence, X-ray diffraction, Scanning electron microscopy and Fourier Transform Infrared Spectroscopy. Adsorption test for β-carotene removal were done in batch mode and the kinetic of the models were examined. The raw material characterization show that kaolinite is the main clay mineral in both samples with main associated minerals being quartz and goethite. The evidence of iron coated was revealed from FTIR, XRD and XRF. The β-carotene removal is optimal at 95 °C and driven by the second order kinetic model. The Freundlich and the Temkin models are the better fitting adsorption models. This indicate that both clays have heterogeneous surface which lead to multilayer adsorption. Also, the adsorption process appear to be spontaneous and endothermic with a growth of disorder at the solid/liquid interface. The endothermic character is related to a physical adsorption driven by weak Van der Wall’s interactions between the β-carotene and the clays surface.