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With the aid of atomic absorption, a systematical and analytical evaluation method called Taguchi’s quality engineering has been applied for the separation of copper ions from a solution using a laboratory electrodialysis set-up to evaluate the optimal experimental conditions and hence to achieve the highest removal percentage and the best robustness of the quantitation from the least number of experimental runs. Four parameters at three levels were studied: concentration (100, 500, 1000 ppm), temperature (25, 40, 60°C), flow rate (0.07, 0.7, 1.2 mL/s) and voltage (10, 20, 30 V). Two types of different membranes with different ion-exchange capacities were used. The optimal levels thus determined for the four influential factors were: concentration 1000 ppm, temperature 60°C, flow rate 0.07 mL/s and voltage 30 V. It has also been found that using a membrane pair with higher ion-exchange capacity improves performance. The highest removal percentage was found to be 94.94% and 97.33% for the two types of membranes.

The effect of membrane type and operating conditions (temperature, concentration, flow rate and voltage) on performance of electrodialysis was studied with the Taguchi method. As a result, higher temperature, higher concentration (concentrations greater than 500 ppm have almost no effect on the performance), higher voltage and a lower flow rate are recommended as optimal operating conditions for the electrodialysis cell using platinum electrodes (CR67,MK111)(AR204SXR412) and CMV–AMV as ion-exchange membranes. Optimum operating conditions for maximizing SNL are: concentration, 1000 ppm; temperature, 60°C; flow rate, 0.07 mL/s and voltage, 30 V. The same results were obtained for maximizing mean response with the exception of a concentration of 500 ppm having a greater mean response than a concentration of 1000 ppm. All factors had a significant effect on the response, but the effect of flow rate on the mean response was more significant than the other factors. The results confirm that membranes with higher ion-exchange capacity produced better results. Electrodialysis was found to be very effective for copper removal from wastewater.