We have been tackling research and development of next generation ion-exchange membranes for salt manufacturing process by electron–beam–induced graft polymerization from 2006 to 2010 on the research and development project of high–degree seawater concentration process for salt–manufacturing technology. First, an ultra high molecular weight polyethylene film was selected for a synthetic base film, and optimization of a synthetic method of ionexchange membranes was studied. Next, scale-up of the synthesis method of the ion–exchange membranes was studied, and pilot–scale synthetic equipments were constructed. Furthermore, the next generation ion–exchange membranes were produced by using the pilot–scale synthetic equipments. The produced ion–exchange membranes had high concentration performance, practical use and long-term stability.

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This article presents an overview of recent research about pore filling membranes applied to fuel cells. Polymer electrolyte fuel cell is a promising energy conversion devise with high efficiency although a high performance electrolyte membrane is still necessary to make this device prevailing technology. Pore filling membrane is a concept to compensate mechanical strength and to control the state of water or nanostructure of the filling material. The technology leads to develop next generation fuel cells operate at low temperature.

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An amphoteric charged membrane (mosaic charged membrane) consists of negatively and positively charged fixed ions distributed in a neutral polymer matrix. When a gradient of electrolyte concentration is established across the membrane, anions and cations can flow through their respective pathways keeping macroscopic electroneutrality. As a result, the amphoteric charged membrane shows salt permeability much greater than its permeability to nonelectrolytes. The amphoteric charged membranes can be applied for the separation of salts from sea water, waste streams and food; however, commercial amphoteric charged membrane is still not available. The aim of this report is to give a brief summary of the preparation and characteristics of the amphoteric charged membranes. Several novel methods to prepare the amphoteric charged membranes are introduced such as radiation grafting technology, microsphere gel formation, an inorganic–organic hybrid technique. The results of a project about hollow fiber amphoteric charged membranes carried out in the author’s laboratory are also mentioned.

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A bipolar membrane composed of a cation and an anion exchange layer has unique electrochemical properties which results in the accelerated dissociation of water, i.e. generation of protons and hydroxyl ions, when a high electric field is established across the membranes. This water splitting function of bipolar membranes can be utilized for the production of an acid and a base from corresponding salt in combination with conventional monopolar ion exchange membranes. Over last 20 years, there was a remarkable progress for bipolar membrane technology basically and commercially. Besides still now the bipolar membrane technology is on the way to open up the further possibilities for their possessing the technical potential. In this paper, the basic of the bipolar membrane technology and its application were reported.

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Salinity gradient power (SGP) is one of a renewable energy that is available when two solutions of different salinity mix. The global potential for SGP is calculated to be 2.6 TW when the flow of all rivers is taken into account. There are two membrane–based technologies that can change SGP into useful electricity; reverse electrodialysis (RED) and pressure retarded osmosis (PRO). In the case of river water with seawater, RED is a promising technology. The key components in a RED system are ion–exchange membranes (IEMs). Membrane requirements for RED are high perm-selectivity, low electrical resistance, sufficient mechanical stability, high chemical stability, high anti–fouling properties and low cost. Here, the principle and technological trend of the system and IEMs for RED are presented.

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Membrane fouling phenomena, which can be promoted by the adsorption of various foulants such as proteins, have been one of the significant challenges in membrane separation. In this study, to conduct a theoretical design of an antifouling membrane material, free energy calculations are performed from molecular dynamics simulations. Particularly, the intermolecular affinities between an amino acid residue and a repeating unit of a candidate material are assessed, by calculating free energy profiles for a residue approaching a repeating unit in explicit water molecules. The predicted profiles for highly biocompatible materials have almost no energetically stable points, regardless of the type of residue. In contrast, the profiles for conventional materials show some energetically remarkable minima. These results agree with previous experimental reports of differences in the amount of protein adsorbed on these materials. Further applications of free energy calculations certainly lead to the development of drastically simplified screening approaches of an optimal antifouling material.

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The water softening performance of the modified reverse osmosis (RO) membranes were investigated. The commercial RO membranes of polyamide type (ES15) were modified by chlorine treatment and sulfonic acid polymer coating. The values of flux and total hardness rejection of the modified membranes were 32.2 L m–2 hr–1, over 90%, respectively, when tested at 0.35 MPa of feed pressure, 66% of recovery ratio and 25 ℃ on 250 mg as CaCO3 L–1 hard water. The degree of flux down for the modified RO membranes was negligible in this study comparing with that for the unmodified RO membranes.

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In the membrane industrial field, from improving the quality of filtration for water treatment, separation technology of medical field, performance improvement of the electrode and separator of the battery, and up to the dust filter, the pore size distribution is very important to maintain its quality. Not only contribute directly to provide the analyzer in research and development, but also we have been supported by ideas and a wealth of experience to the quality control and commercialization of our customers. The trend in recent years, research and development of gas separation membrane has become popular for the analysis of ultra- micro pores of Angstrom order. Quantachrome can offer a more accurate pore size distribution by new analysis technology NLDFT (Non–Local Density Functional Theory) that simulates the behavior of gas molecules in the pores. The pore size analysis technology and our product line-up that are related to the membrane are introduced in this journal.

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