Equilibrium and kinetics study of uranium(VI) from aqueous solution by Citrus limetta peels

The potential of the biowaste Citrus limetta peels (CLP) was assessed for adsorption of uranium(VI) from uranyl nitrate solution. Maximum adsorption capacity of 75.33 mg g^?1 was achieved at pH 4, showing drastic falls thereafter. This was attributed to the presence of UO₂ ²⁺, UO₂OH⁺, (UO₂)₃(OH)⁵⁺ and (UO₂)₂(OH) ₂ ²⁺ ions. The peels were characterized for elucidating the role of functional groups and morphology on the sorption capacity. The isotherm studies revealed that Langmuir, Freundlich as well as Sips models give the best fit for the experimental data observing pseudo second order kinetics. The equilibrium was achieved in 90 min. The adsorption shows complex mechanism, took place by both physical and ion-exchange mechanism.