The effectiveness of Ibusa kaolinite as an adsorbent in removing pigments from palm oil has been investigated in this study. Ibusa kaolinite was prepared as an adsorbent by treating it with hydrochloric acid. The surface area of the clay was found to increase with increase in acid dosage up to a maximum and then decreased while its cation exchange capacity decreased with increase in acid dosage. The activated clay was used as an adsorbent for the removal of pigments from palm oil. The bleaching process was investigated by varying the clay dosage, acid concentration and temperature. The highest removal of pigments was recorded at 7 M HCl concentration, 4 g clay dosage and 100˚C temperature, and about 97.4% pigments were removed in 80 minutes. Four isotherm models, three kinetic models, and the intra-particle diffusion model were applied to fit the experimental data. It was found that the equilibrium data were best represented by the Temkin isotherm model. The experimental data fitted well the pseudo-second-order kinetic model. Diffusion studies indicated that intra-particle diffusion is not the sole rate-controlling factor. The bleaching process was found to be spontaneous and endothermic, with increasing randomness of adsorbed species.

Abstract:Clay from Kono-bowe, Nigeria, was activated thermally and chemically and used to remove lead(II) and chromium(III) ions from aqueous solution. The effects of adsorption process variables were studied as well as the kinetics and equilibrium of the process. Analysis of the activated samples showed that the surface area, cation exchange capacity, and adsorption performance were positively favored by both activation processes. It was observed that the adsorption rate increased with an increase in temperature, contact time, adsorbent dosage, initial ion concentration, and solution pH values. The pH P ZC of the adsorbents was determined to be 6.5, 7.4, and 7.2, for KBR, KBTA, and KBAA, respectively.It was observed that sample KBAA yielded maximum adsorption efficiency of 99.9% for the removal of chromium(III), and gave maximum adsorption efficiency of 98.7% for lead(II) removal. The results of the kinetics analysis of the adsorption data revealed that adsorption follows pseudo-second-order kinetics. Analysis of the equilibrium data showed that the Langmuir isotherm provided a better fit to the experimental data for KBR, while the Freundlich isotherm fitted the experimental data of KBTA and KBAA. Evaluation of the thermodynamic parameters revealed that the adsorption process is spontaneous and endothermic.

The dissolution kinetics and mechanisms of reaction of Udi clay in nitric acid have been studied. Leaching temperature, acid concentration, particle size, solid-to-liquid ratio, and stirring speed were selected as process parameters. It was observed that the dissolution rate increased with decreasing particle size and solid-to-liquid ratio and increased with stirring speed, acid concentration, and leaching temperature. (S/L) -0.3104 (w) 0.2709 exp (-2621/T) t. The activation energy of the process was determined to be 21.791kJ/mol. The experimental data were tested by graphical and statistical methods and it was found out that the above model best fitted the data.

The aim of this study was to investigate the optimum operating process parameters during the adsorption of color pigments from palm oil onto activated Ukpor clay using Response Surface Methodology (RSM). The clay was activated using sulphuric acid solution. The process parameters investigated include; temperature, time, adsorbent dosage, adsorbent/oil ratio and stirring speed. The results showed that the bleaching efficiency was significantly affected by the linear, quadratic and some of the interaction terms. The optimum conditions derived via RSM were: temperature-152.73 °C; time-2.60 h; adsorbent dosage-6.09 g; adsorbent/oil ratio-0.05g/mL; stirring speed-39.34rpm; and under these conditions the predicted bleaching efficiency was 82.67% which has good correlation with the experimental value of 82.25%. The high prognosis obtained in this study has shown that 5-level 5 factor fractional central composite design of the RSM is suitable for predicting the optimum adsorption conditions of color pigments from palm oil using activated Ukpor clay.

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