I acknowledge for Achievement Award 2016 from Japan Society of Ion Exchange. I have been a society member since the foundation of the society, and congratulate the success of this society so far. This society is characterized by the high level of the science and the engineering of ion exchange and the cooperation of the industry-government-academia research groups. I expect the further development of this society.

Ion-exchange membranes are useful materials for many separation processes. Amino acids have been one of the targets of separation with the membranes because amino acids are amphoteric electrolytes and can permeate across both cation-exchange membranes and anion exchange membranes. We have used double ion-exchange membrane system composed of a cation-exchange membrane and an anion-exchange membrane. In this system, neutral amino acids are separated efficiently with acidic or basic amino acids. For the mutual separation of neutral amino acids, molecular weight and hydrophobic-hydrophilic properties are important and they are separated to each other in some conditions.

In separation chemistry, the treatment of radioactive cesium in Fukushima is very important and electrokinetic remediation is a possible method for the on-site treatment. In the method, ion-exchange membranes are used to separate suspended soil solution from electrode compartment solution. The electrokinetic remediation resembles to elctrodialysis, although salt solution in ED is replaced to suspended soil solution. ED has been investigated eagerly in Japan, and the development of electrokinetic remediation can be expected in future.

Membrane separation is a sustainable technology and the breakthrough of this technique should appear in the further development.

The Great East Japan Earthquake and Tsunami struck the Fukushima Daiichi Nuclear Plant in March 2011, which caused significant volume of high-level radiation contaminated water on the premises. Impurities such as magnesium and calcium in the contaminated brine water made conventional type of adsorbents difficult to thoroughly remove nuclides from the water. With the support of research institutions and customers, Union Showa K.K. successfully co-developed a series of high performance adsorbents with enhanced selectivity in the brine water such as adsorbent for cesium, simultaneously removing cesium and strontium, silver mounted zeolite for iodine removal and so on. These new adsorbents have contributed to the purification of contaminated water on the site. The company has also developed the method of stable solidification of cesium captured in ferrocynide compound and the regenerative adsorbent for the Harbor Cleanup Project. The company now focuses on the development of adsorbent for removing actinide elements for fuel debris retrieval.

In the production of semiconductors, ultrapure water is used for cleaning in each process. In recent years, the adverse effects of impurities in ultrapure water for cleaning have increased with the miniaturization and high integration of the circuit-line width of semiconductors. Therefore the demand for high-quality ultrapure water has increased. We examined the metal adhesion restraint on silicon wafers based on the adsorption of polystyrene sulfonate (PSA) and metal ions. PSA was microinjected into a sample of ultrapure water containing the metal, and a cleaning vessel was allowed to overflow with the sample. Subsequently, the wafers in the sample were immersed and the amount of the metal deposited on them was measured. In addition sulfur concentration was calculated. It was found that the adhesion of the metal ions adsorbed with PSA in ultrapure water on the wafers is suppressed. A metal adhesion restraint rate greater than 95% was obtained with the polyvalent metal ions. Furthermore, it was revealed that the adhesion of PSA to the wafer was negligible. We may apply this technique as a metal contamination restraint method for each cleaning process in the production of semiconductors.

A new electrodialysis technique with a bipolar and ion-exchange membranes was developed. The electrodialyzer has a separating zone with alkaline pH steps between compartments, which were divided by a cation-exchange membrane, a bipolar membrane, and three anion-exchange membranes, respectively. When a voltage was applied to the electrodialyzer, hydroxide ions were electrically generated by the anion-exchange layer in the bipolar membrane, and moved to anode side compartments through anion-exchange membranes. In steady state, the hydroxide ion concentration in each compartment was almost equal to the concentration of coexisting cations, and formed alkaline-pH steps in the electrodialyzer. Moreover, we attempted to apply the technique to separation of L-glutamic acid and L-methionine. In the range of pH steps 8 to 13, L-glutamic acid permeated through the anion-exchange membranes, and accumulated in the anode compartment, though L-methionine remained in feed compartment. The separation of L-glutamic acid and L-methionine using alkaline pH steps successfully achieved.