G.B. Adebayo, F.A. Adekola, A.A. Jimoh, F.O. Alao, H.I. Adegoke
University of Ilorin, Nigeria
pp. 249 - 250
Keywords: vitellaria paradoxa, adsorbent, adsorption, SEM and TEM, heavy metals, kinetics, thermodynamics
Activated carbon prepared from vitellaria paradoxa shell using ortho-phosphoric acid as activating agent was used for the removal of Cd (II) ions from aqueous solution. The adsorbent sample was characterized by some physicochemical and spectroscopic methods such as pH, point of zero charge, moisture content, iodine number, loss on ignition, bulk density, XRF, SEM and TEM. The pH and PZC of the sample were found to be 4.0 and 5.8 respectively. The adsorbent has moisture content of 5.22 ± 0.1%, iodine number of 256.50 ± 59%, loss on ignition of 10.71 ± 0.18% and bulk density of 0.84 ± 0.09%. The XRF analysis indicated that Ca, Si and Fe were major constituents in the adsorbent sample. The equilibrium adsorption of Cd (II) ions data were well fitted with Langmuir and Freundlich isotherms with correlation coefficient of 0.996 and 0.998 respectively. The kinetics study revealed that the experimental data fitted pseudo-second order kinetic better when compared to zero-order kinetics. Thermodynamics experiment indicated that the adsorption process was endothermic with ∆H value of +27.84 kJ/mol and ∆S of +0.993 kJ/molK and ∆G is negative at all temperature indicating the feasibility of the adsorption process.