Preparation Of Bipolar Membranes And Studies On The Enhancement Of Water Splitting

Bipolar membrane is composed of cation-exchange、anion-exchange layers and intermediate area between these two layers. Under a reverse bias condition, water split into H+、OH-and then migrate to external solutions. It’s much more economic than electrolysis of water directly. So with the development of high performance bipolar membrane, we can further expand the use of electrodialysis. It’s been used for chemical process、pollution control and other industrial scale. Thus, developing new materials and preparation methods of bipolar membranes become more and more important.The construction of spray self-assembly system was built first and then we prepare three kinds of bipolar membranes.They are PEI/PAAS、 AM-1/PAAS and PEI/CM-1bipolar membranes. Compared to each other, the PEI/CM-1bipolar membranes owns a high performance. Compared with the traditional casting method, spray self-assembly system not only can control the thickness of bipolar membrane at a micro level, but also can improve charge density and ion exchange capacity by synchronizing spraying and chemical cross-linking reaction. To further optimize the water splitting performance, we can change the forming conditions of bipolar membranes. In this paper, the optimum forming conditions: PEI=5wt%, GA=3wt%, PVA=3wt%, layers of complex=3, spraying time=3s, waiting time=20min. By this conditions, we can prepare a bipolar membrane which water splitting voltage at100mA/cm2is only1.83V. FTIR analysis showed that polyelectrolyte is successful assembled on the membrane surface; SEM results show that there is a thin polyelectrolyte layer on the surface of CM-1membrane, with the increase of spray times, the thickness of film are also increase; Besides, the swelling degree in acid and alkali are small which display a good mechanical stability.