Effect of operating parameters on concentration of citric acid using electrodialysis

This paper describes a robust design method for concentration of citric acid, using a laboratory electrodialysis (ED) setup. An experimental investigation was presented to determine the optimum configuration of influential factors (pH, voltage, flow rate, temperature and feed concentration) for the best performance. In order to optimize the performance, the factors which had the greatest influence were identified and their optimum values chosen. In this research, Taguchi method was used initially to plan a minimum number of experiments. AMV–CMV ion exchange membranes were utilized in all experiments. Results show that pH and temperature are the most and the less effective factors on response, respectively. Temperature was found out to possess a key role in reduction of energy consumption and it was not increased to high values due to polymer matrix destruction. Increasing voltage and decreasing flow rate caused the better performance of ED cell due to enhancement of driving force and residence time, respectively. Increasing pH decreases electrical resistance of citric acid solution and consequently better performance is acquired. Finally, it was found that to achieve an optimum operating condition pH, voltage, temperature and flow rate should be set at 7.5, 20 V, 55 °C and 4 mL/min, respectively.