Modification of a Heterogeneous Anion Exchange Membrane via Amination process using Response Surface Methodology
Paper ID : 1343-MST2015-FULL
Authors:
Tavan Kikhavani *1, Seyed Nezameddin Ashrafizadeh2, Morteza Ghavami3
1Ilam University
2Research Lab for Advanced Separation Processes, Department of Chemical Engineering, Iran University of Science and Technology (IUST)
3Research Lab for Advanced Separation Processes, Department of Chemical Engineering, Iran University of Science and Technology, Narmak, Tehran 16846-13114, Iran
Abstract:
Modification of a heterogeneous anion exchange membrane with the aim of increasing its nitrate selectivity was investigated. The modification was carried out using a solution of dipropylamine (amination process). The effects of different parameters, i.e., concentration of amine solution, temperature and reaction time, were studied on the selectivity of the membrane between counter ions (nitrate and chloride). The optimum conditions for membrane modification were determined by response surface methodology (RSM). The central composite experimental design with quadratic model was employed to investigate the effects of variable factors on the membrane selectivity. The nitrate/ chloride selectivity of the membrane was enhanced because of hydrophobic nature of dipropylamine. The modification of membranes was verified using FTIR, SEM and elemental analyses techniques. The results show that all linear variables have significant effects on the membrane selectivity toward nitrate ion (have P values below 0.05). Also it appeared that among the quadratic variables, amination temperature is more significant. Meanwhile, among the interactive terms, the interaction of amination temperature and concentration is the most significant term. The optimum conditions for membrane modification were obtained at temperature of 65 °C, solution concentration of 35 wt%, and reaction time of 36 hrs. The electrochemical properties of an anion exchange membrane, i.e., transport number, ion exchange capacity, water content, fixed ion concentration and resistance, were enhanced through modification with amine.
Keywords:
Heterogeneous anion exchange membrane; Nitrate selectivity; Dipropylamine; Surface modification; Response surface methodology
Status : Paper Accepted (Oral Presentation)