The adsorptive potential of chicken egg shells for the removal of oxalic acid from wastewater

Abstract

Chicken egg shells were grinded and sieved to an exact particle size of 125 micron and treated with excess aqua regia and n-hexane to remove inorganic and organic impurities. Adsorption of oxalic acid from waste water was studied on treated powder egg shells by kinetics and batch adsorption techniques at different temperatures, 20ºC, 30ºC and 40ºC. The samples were characterized by BET surface area, scanning electron microscopy (SEM), and Fourier Transform Infra-red Spectroscopy (FTIR) and energy dispersive spectroscopy (EDS) techniques. The amount of acid adsorbed was determined with respect to initial acid concentration, equilibrium time and different acid concentration manually by titration method. Intra-particle diffusion, Elovich and Bhangam models were used for adsorption kinetics and thermodynamic parameters ΔH≠, ΔS≠ and ΔE≠ were calculated. The results obtained showed that adsorption process was spontaneous and entropy of adsorption had negative value. Freundlich, Langmuir, Tempkin and Harkins-Jura linear equations were used to investigate adsorption isotherms. This work will provide feasible routes for waste water treatment.