ADSORPTION OF BETA-CAROTENE FROM ACETONE SOLUTION ON NATURAL AND CHEMICALLY MODIFIED BENTONITE

The adsorption of beta-carotene on bentonite desiccated at 110-degrees-C, untreated, and acid-treated with dilute H2SO4 solutions over a concentration range between 0.25 N and 2.00 N, from acetone solution at 20-degrees-C has been studied. The samples were characterized by mercury porosimetry, IR spectroscopy and X-ray diffraction. Surface area and porosity of the samples have also been determined. The adsorption isotherms may be classified as Langmuir type of the Giles classification which suggests a moderate affinity of the beta-carotene molecules for the bentonite surface and that there is no strong competition from the solvent for adsorption sites. The experimental data points have been fitted to the Langmuir equation in order to calculate the adsorption capacities (Xm) of the samples; Xm values range from 2.14x10(-8) mol.g-1 for the untreated bentonite up to 10.80x10(-8) mol.g-1 for the sample acid treated with 2.00 N H2SO4. The removal efficiency (R) has also been calculated for all the samples; R values range from 12.4 % for the untreated bentonite up to 92.5 % for the sample acid treated with 2.00 N H2SO4.