RO Ajemba, V I Ugonabo, PK Igbokwe and OD Onukwuli
Keywords: Adsorption, bleaching, surface area, color pigment, isotherm, equilibrium
Abstract: This study analyzed the structural transformations and adsorption properties of Ukpor clay after nitric acid activation. The clay samples were mined, sun-dried, sized, and reacted with different concentrations of nitric acid ranging from 2 to 16mol/L at various times of 0.5 to 3 hours. The untreated and treated samples were characterized using X-ray Fluorescence and Fourier Transform Infrared (FTIR) Spectroscopy. The adsorptive capacities of the treated samples were investigated by using them to adsorb color pigments from palm oil. The analyses showed that nitric acid leaching caused an exchange of the octahedral cations; Al3+, Fe3+, and Mg2+ with H+ ions and this exchange increased with increase in acid concentration and period of activation. The surface area of the activated samples was observed to increase with increase in concentration and time to about four times that of the raw sample. The adsorption results showed that the adsorptive performance of the modified samples was improved from 27.6% to 85.4%. The equilibrium results fitted Freundlich isotherm model. This study has shown that acid activation led to some structural transformations of Ukpor clay which enhanced the adsorption performance of the clay thereby making it an effective adsorbent for palm oil bleaching.
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