In this work, adsorption and thermodynamics study of the inhibition of corrosion of mild steel in H 2 SO 4 medium using Vernonia amygdalina was carried out. The inhibitive and adsorptive properties of ethanol extract of Vernonia amygdalina for the corrosion of mild steel in 0.2 M H 2 SO 4 solutions was investigated using weight loss technique. The result has proved that that the extract is a good inhibitor of corrosion of mild steel in H 2 SO 4 . The inhibition efficiencies ranged from 23.37% to 38.59% and from 22.45% to 35.78% at 303 and 323 K respectively. The inhibition efficiency of the extract decreased as temperature and time of immersion increased but increased with increase in concentration of extract. The adsorption of the inhibitor on surface of mild steel was found to be exothermic, spontaneous and consistent with the mechanism of physical adsorption as the value for heat of adsorption ranged from -2.12 to -4.87 KJ·mol -1 . The adsorption data fitted well to Langmuir, Temkin, Frumkin and Flory-Huggins adsorption isotherms.

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.

The kinetics study of alumina leaching from ogbunike clay was carried out using a solution of hydrochloric acid (HCl) for alumina dissolution. Variations in process parameters such as calcination temperature, leaching temperature, acid concentration, particle size, and solid-to-liquid ratio were considered for the leaching of alumina. The shrinking core model was used to analyze the experimental data. Alumina removal is feasible with 24.035% extractable alumina, and this can improve the economic value of ogbunike clay, which can be an alternative raw material in Nigeria’s aluminum industries. According to the data the dissolution rate increases with increasing calcination temperature, leaching temperature and acid concentration and decreasing particle size and solid-to-liquid ratio. The statistical and graphical analysis revealed that the dissolution followed the product layer diffusion-controlled semi-empirical kinetic model. The activation energy was calculated to be 18.36 kJ/mol for HCl. The optimum conditions for the dissolution of the alumina in HCI include activation temperature of 700 ⁰C for 60 minutes, leaching temperature of 90 ⁰C, HCl concentration of 3 M, particle size of 75 µm, and the solid-liquid ratio of 0.2 g/ml yielding the alumina dissolution rate of 84.72%. The kinetic data can be used to construct large-scale manufacturing equipment.