Study of Cr (VI) removal from Aqueous solutions by Mineral absorbents by use of Taguchi method

Cr (VI) is one of heavy metal that its presence in water and waste water, results in many problems for environment and organisms especially human health. Recently, because of its low cost, availability and abundant, use of mineral adsorbent were considered. The aim of present study was to evaluate Cr (VI) removal from aqueous solutions and investigation of influence of main parameters on removal using of some mineral adsorbent by using of Taguchi experimental design method. Taguchi experimental design method save time and cost of experiments. In this experimental study, Cr (VI) removal from aqueous solutions by 4 mineral absorbent i.e., perlite, expanded perlite, zeolite and acid modified zeolite were investigated. The effect of adsorbent dose, the concentration of Cr (VI), stirring time, pH and type of adsorbent on the adsorption process were examined using Taguchi experimental design in batch extraction mode. Design Expert (v.8) and Microsoft Excel were used for experimental design and statistical analysis, respectively. Isotherm and kinetic analysis were performed. The results showed that the best adsorbent for Cr (VI) removal was expanded perlite. Optimal conditions for adsorption were Cr (VI) concentration 1ppm, expanded perlite dose 25g L-1,1h shaking time and pH 2 with 100% extraction efficiency. Percent Parameters contribution most to least is as follows: pH, Cr (VI) concentration, adsorbent dose, shaking time and type of adsorbent. Expanded perlite, has the ability of Removal of Cr (VI) under the obtained conditions experimentally designed by Taguchi method.