Adsorption Studies of Pb2+ From Aqueous Solutions Using Unmodified and Citric Acid – Modified Plantain (Musa paradisiaca) Peels

Natural plantain peel biomass and the citric-acid-modified form were used to study the adsorption of Cu 2+ from a simulated aqueous solution in a batch adsorption system. The adsorption was strongly pH-dependent as maximum adsorption was recorded at a pH of 5 for the modified biomass and pH of 4 for the unmodified. The kinetics of the adsorption processes was studied with Pseudo-first-order, Pseudo-second-order, Intra-particle diffusion, Elovich and Fractional power kinetic models and the results were best fitted by the pseudo-second-order model. The experimental data were also subjected to Langmuir, Freundlich and Temkin isotherms for adsorption studies and the unmodified biomass was best fitted by the Temkin adsorption isotherm while the modified biomass, on the other hand was best fitted by the Freundlich isotherm. Thermodynamic studies revealed that the heat of adsorption of the unmodified biomass was higher than the modified.  The maximum adsorption capacity obtained was 48.31 mg/g.