Application of Response Surface Methodology for Hexavalent Chromium Adsorption onto Alluvial Soil of Indian Origin

Abstract

In the present study adsorption of chromium (VI) ions from aqueous solution by alluvial soil of Bhagirathi River was investigated under batch mode. The removal of hexavalent chromium was optimized by using response surface methodology. The influence of various process parameters such as initial chromium(VI) concentration, solution pH, sorbent dose and contact time on the removal process were investigated. A total of 29 sorption experimental runs were carried out employing the detailed conditions designed by response surface methodology based on the Box-Behnken design. The analysis of variance (ANOVA) depicted that the quadratic model was suitable for all the responses. Contour and response surface plots were used to determine the interaction effects of main factors and optimum conditions of process, respectively. From the experimental result, maximum chromium(VI) removal of 93 % was obtained at the optimum condition of initial chromium (VI) concentration (10 mg/L), pH (2), adsorbent dose (1.5 g) and contact time (62.5 min). The experimental removal efficiency (93 %) agreed very well with the predicted one (91.79 %), indicating the suitability of the model employed and the success of response surface methodology in optimizing the conditions of the removal of chromium (VI) ions from aqueous solution.