ADSORPTIVE REMOVAL OF COLOUR PIGMENT FROM PALM OIL USING ACID ACTIVATED NTEJE CLAY. KINETICS, EQUILIBRIUM AND THERMODYNAMICS

The kinetics of colour pigment removal from palm oil using acid activated clay from Nteje has been investigated. To determine the equilibrium adsorption capacity, the effects of temperature, contact time, adsorbent dosage and particle size were studied. The experimental adsorption data were analyzed using pseudo-first order, pseudo-second order, and Elovich kinetic models. The pseudo-second order model fitted very well to the kinetic experimental data. Equilibrium isotherms were analyzed by Langmuir and Freundlich adsorption models. The data was in line with the Freundlich isotherm indicating a monolayer adsorption. The activation energy was calculated as 12 kJ/mol, and other thermodynamic parameters were determined as Delta S degrees = 0.063 J/mol, Delta H degrees = -34.994 J/mol, and Delta G degrees = -58.606 kJ/mol. These values indicate that the adsorption of colour pigment from palm oil onto acid activated clay was exothermic and can be attributed to physico-chemical adsorption process.