An innovative membrane method for the separation of chromium ions from solutions containing obstructive copper ions

Chromium is one of the major pollutants of water and wastewater; this ion can be seen in different industrial effluents along with other metal ions such as Cu, As [E. Velizarova, A.B. Ribeiro, and L.M. Ottosen, A comparative study on Cu, Cr and As removal from CCA-treated wood waste by dialytic, Journal of Hazardous Material 94 (2) (2002)147–160]. In the current paper, experimental investigations have been done on the removal of the chromium ions from aqueous solutions which contain Cu2+ as obstructive ion. Electrodialysis is coupled with complexing to recommend a new technique for the elimination of chromium (III) ions. Ethylendiaminetetraacetate acid (EDTA) was used as the complexing agent. The effect of different operating conditions (feed flow rate, voltage or current density, the ratio of the chromium (III) concentration to the copper concentration, EDTA molar ratio to Cr (III) and pH of the feed) on the removal of chromium ions was investigated. The Taguchi method was implied to design the experiments. The optimum operating conditions were determined using the analysis of variance (ANOVA) method. The proposed method resulted in relatively high chromium removal (95% Cr (VI) and 87% Cr (III)) at the optimum operating conditions.

Research Highlights
► Electrodialysis- complexing method dramatically increases the chromium ions removal.
► Effect of flow rate in the removal of total chromium from the solution is ignorable.
► Voltage is a neutral parameter in the separation of chromium (III) ions.
► Change of the pH (2.5–4) does not affect the removal of chromium ions very much.