Adsorption Kinetics for the Removal of Hexavalent Chromium from Aqueous Solution by Acid Activated Coal Fly Ash (CFA)

The adsorption of hexavalent chromium, present in effluents of various industries such as electroplating, tannery, etc., on Coal Fly Ash (CFA) has been investigated in the present study. Parameters like contact time, adsorbent dose, pH and initial chromium ion concentration were studied in kinetic batch experiments at 25°C. Among all the parameters, pH of the solution was most effective for chromium removal. The adsorption of hexavalent chromium on CFA was found to be maximum at low pH. The adsorption data fit well with Langmuir and Freundlich isotherm models. The Langmuir adsorption isotherm to the systems yielded maximum adsorption capacity of 19.77 mg/g at the solution pH of 2. Results showed that the pseudo second order kinetic model best correlate with the experimental data.