Sorption of Lead From Aqueous Solution On Raw And Modified Shea Butter (Vitelaria Paradoxa) Seed Husk

Abstract

The adsorption of Pb from aqueous solution using raw and modified shea butter seed husks was studied. Encapsulation technique was employed to modified the husks. Instrumental analysis such as FT-IR, XRD, BET and SEM were used to characterize the sorbent. The functional groups responsible for metallic biosorption were the –OH, -COOH and –NH2. Batch adsorption process was used to study the effect of various parameters ranging from the effect of initial metal ion concentration; pH; equilibrium time; and temperature. Optimum pH was 6 and equilibrium time was 30mins. Adsorption isotherm was applied to experimental data by Langmuir, Freundlich, Temkin, and Dubunin-Radushkevich (D-R) isotherms. The Langmuir best fits the data with the highest correlation coefficient 0.99 for RSBH. The maximum sorption capacity was 22.222 mg/g for RSBH and 2222.22 mg/g for MSBH. The mean free energy Ein the range of 0.45 to 4.5KJ/mol obtained by D-R isotherm indicated that the process of adsorption is physiosorption. The calculated amount adsorbed of the Pb(II) was approximately equal to the experimental amount adsorbed by the Kinetic model of Pseudo-second-order. The thermodynamic properties indicated that the Gibbs free energy is spontaneous and feasible for both sorbents. The results obtained showed that the shea butter seed husks and the modified one can serve as potential adsorbent for the removal of Pb(II) ions.