Abstract The adsorption, kinetics, and thermodynamics of some metal ions (Cr+6, Pb+2, and Co+2) on to activated carbon derived from lemon peel (Citrus limonum) was studied. Energy dispersive X-ray spectroscopy (EDS) was used to determine the elemental composition of the adsorbents while Scanning Electron Microscope (SEM) was used for surface texture and morphological characteristics of the lemon peel. The optimal parameters such as initial concentration, agitation time and adsorbent particle size was studied by using Atomic Absorption Spectroscopy (ASS). And removal efficiencies were calculated. Freundlinch and Langmuir adsorption models were employed to study adsorption pattern. The equilibrium data results of metal ions were fitted well to Freundlinch and Langmuir adsorption models. Coefficient of correlation (R2) for Freundlinch and Langmuir adsorption models was fallen within 0<R2<1. The values of Gibbs were found to decreases as the temperature increases, indicating more driving force and hence resulting in higher biosorption capacity. The positive values of Enthalpy, indicating the endothermic nature of the biosorption Cr+6, Pb+2, and Co+2 onto Lemon peel. The positive values of entropy, shows an affinity of biosorbent and the increasing randomness at the solid solution interface during the biosorption process. The study was concluded that activated carbon derived from lemon peel, have potential as an adsorbent to remove toxic heavy metals like, (Cr+6, Pb+2, and Co+2) from waste water.
Keywords Citrus limonum, Cromium, Lead, Cobalt, Adsorption Kinetics, Thermodynamics.