Adsorption of Pb (II) Using Sheep Fur: Isotherm, Kinetics and Thermodynamic Studies

Abstract

Sheep fur (SF), a keratinous biomaterial, was used as a low cost adsorbent for removal of Pb (II) from aqueous solution. The sorbent was characterized, where moisture content, pH, bulk density and loss on ignition were determined. The experimental data were analyzed by Langmuir, Freundlich, Temkin and Dubinin Radushkevich model with the Langmuir model showing the best fit. Maximum adsorption capacity of Pb (II) by the SF was 45.46 mg/g. Separation factor RL was 0.037 indicating a favourable adsorption process. The results also indicated that kinetic data were best described by the pseudo second-order model with a correlation coefficient (R2) of 0.997.  Negative standard Gibb’s free energy (ΔG) obtained indicated that the Pb (II) adsorption process was spontaneous and thermodynamically feasible. Fourier Transform Infra-red Spectroscopy (FTIR) analysis confirmed the presence of carboxyl, hydroxyl, amino and sulphur-containing functional groups on the SF.