Research Article
Jimoh AA, Adebayo GB, Otun KO,
Abstract
Activated carbon prepared from vitellaria paradoxa (shea nut) shell using otho-phosphoric acid has been used for the removal of Cd(II) ion from aqueous solution. The adsorbent sample was characterized by some physicochemical and spectroscopic parameters such as pH, point of zero charge (PZC), moisture content, iodine number, loss on ignition, bulk density, XRF, SEM and TEM. The pH and the PZC of the sample were found to be 4.0 and 5.8 respectively. The adsorbent sample has moisture content of 5.22 ± 0.1%, iodine number of 456.50 ± 59%, loss on ignition 10.71 ± 0.18% bulk density of 0.84 ± 0.09%. The XRF analysis indicated that Ca, Si and Fe were major constituents in the adsorbent sample. The SEM and TEM analysis results indicated good adsorptive characteristics of the adsorbent. Result from the FTIR analysis indicate presence of some important components such as C=O, O-H, C-O N-H, and P-H which responsible for high adsorptive capacity of the adsorbent. The equilibrium adsorption of Cd(II) ion data was well fitted with Langmuir and Freundlich isotherms with correlation coefficient of 0.996 and 0.998 respectively. The kinetic study revealed that pseudo-second order kinetic was better fitted compared to pseudofirst- order kinetic. Thermodynamic experiment indicated that the adsorption process was exothermic with ΔH equals +27.84 KJ/mol and ΔS equals -0.993 KJ/molK.