Removal of Chromium(VI) from Aqueous Solution by Clayey Diatomite: Kinetic and Equilibrium Study

Abstract

The clayey diatomite from the village of Suvodol (Bitola region) used in this research has shown to be a very effective and efficient natural material for the removal of Cr(VI) ions from aqueous solutions. The adsorption of Cr(VI) ions onto a clayey diatomite was shown to occur very efficiently with 96.7%. During the experiments the effect of operating parameters, such as amount of adsorbent (0.5–5.5 g/l), initial adsorbate concentration (0.3, 0.4, 0.5, and 0.6 mg/l), and time of adsorption (5–180 min) at pH of the solution 3, was examined. It was found that 2.5 g/l is optimal adsorbent dosage for maximal removal of Cr(VI) ions. Atomic absorption spectrophotometric (AAC) method and UV-Vis spectrophotometric analysis are used for quantitative monitoring of the dynamics of the studied system regarding the presence of Cr(VI) ions in the model solutions. The effect of the initial concentration and quantity of adsorbent is examined, in order to determine the conditions that enable maximum removal of Cr(VI) ions with clayey diatomite. For the purpose of modeling the equilibrium, the kinetics, and dynamics of the tested system of the process of elimination of Cr(VI) ions with the raw material in different operating conditions, MATLAB/Curve Fitting Toolbox was conducted. KeywordsAdsorptionEquilibriumKineticsClayey diatomiteCr(VI) ions