Heterogeneous anion exchange membranes were modified via amination process using dipropylamine solution as a new method. The response surface methodology (RSM) was used for the optimization of amination process to correlate the relationship among variables, i.e., amination time, amination temperature, concentration of the amine solution, and responses, i.e., the selectivity between co-ions/ counter-ions (permselectivity) and the selectivity between two counter ions. The selectivities were enhanced by increasing the concentration and amination time, as well as decreasing the temperature. The highest selectivities were obtained at amination duration of 36 h, temperature of 25 °C and concentration of amination solution of 35 w%. After modification, the permselectivity and selectivity increased by 16.7% and 34.4%, respectively. Furthermore, the effect of solvent type on the amination process was investigated and methyl acetate was chosen as the most appropriate solvent for amination process versus ethanol.
