Kinetic and equilibrium studies on adsorption of cadmium from aqueous solution using Aesculus Indica seed shell

Abstract

Present study has been carried out to evaluate feasibility of <em>Aesculus indica</em> seed shell (AISS) for the removal of Cd (II) ions from water. The prepared adsorbent has been characterized by Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS) and Fourier Transform Infrared Spectroscopy (FTIR). The adsorption influencing parameters such as dose (0.06 g), <em>p</em>H (6.0) and time (40 min) are optimized. Maximum adsorption capacity (q_max) is found to be 34.36 mg/g for Cd (II) ions adsorption onto AISS using Langmuir adsorption isotherm. The experimental data followed pseudo-second order kinetics for adsorption of Cd(II) onto AISS. Negative value of <img src='http://www.niscair.res.in/jinfo/delta.gif' border=0><em>H</em>° indicates exothermic nature of reaction and adsorption decreases as temperature increases from 303 to 333 K. The negative value of <img src='http://www.niscair.res.in/jinfo/delta.gif' border=0><em>S</em>° show that there was no affinity of AISS and indicates decrease in randomness during adsorption process. The recovery and reuse processes for AISS can be continued up to 2 cycles. Thus, <em>Aesculus indica</em> seed shell can be used as an effective and low-cost adsorbent for removal of Cd (II) ions from aqueous solution.