Kinetics and Isotherm on the Adsorption of Zn (II) from Aqueous Solutions by Natural Bio-sorbents

Zinc is present in high concentration in wastewater of various industries like galvanizing, metallurgical, electroplating, mining, paints, and pharmaceuticals. Adsorption has been found to be one of most popular process for the removal of zinc from wastewater due to its low initial cost other than Chemical precipitation, ion exchange, reverse osmosis, electro dialysis, and electrochemical treatment. Increasing demand for eco-friendly techniques promotes the interest to natural and bio-degradable adsorbents. The characterization of both adsorbents (lemon and banana peel) was carried out using TGA. Adsorbent concentration for both biosorbents for the maximum removal of zinc at optimum pH of 4 and temperature of 300C is found to be 1g/100ml. The optimum contact time for the equilibrium condition is 260 min for the removal of zinc. In the present study, Adsorption kinetic models as well as adsorption isotherms have been developed to facilitate mathematical modeling. Pseudo second order kinetic model for adsorption of Zn (II) on both lemon peel and banana peel has been better fitted than pseudo first order kinetic model and Weber Morris plot. The Langmuir isotherm gave better prediction of specific uptakes for Zn (II) at equilibrium for both the adsorbents.