Masahiro Henmi

Self‐Organized Liquid‐Crystalline Nanostructured Membranes for Water Treatment: Selective Permeation of Ions

A membrane with ordered 3D ionic nanochannels constructed by in situ photopolymerization of a thermotropic liquid-crystalline monomer shows high filtration performance and ion selectivity. The nanostructured membrane exhibits water-treatment performance superior to that of an amorphous membrane prepared from the isotropic melt of the monomer. Self-organized nanostructured membranes have great potential for supplying high-quality water.

High performance RO membranes for desalination and wastewater reclamation and their operation results

Reverse osmosis (RO) membrane is one of the most powerful tools for solving the global water crisis, and is used in a variety of water treatment scenes such as drinking water purification, waste-water treatment, boiler feed water production, ultra pure water production for semiconductor industry, etc. The desired performance of RO membrane varies according to quality of feed water being treated, and Toray has been developing RO membranes with suitable characteristic for each operating condition. RO membranes for seawater desalination and wastewater reclamation are especially regarded as most promising targets. Recently, high boron removal and energy saving RO membrane for seawater desalination and low fouling RO membrane for wastewater reclamation have been developed. In this paper, the prospect of attaining these renovative RO membrane, and furthermore, job references will be discussed.

Cesium (Cs) and strontium (Sr) removal as model materials in radioactive water by advanced reverse osmosis membrane

Abstract Reverse osmosis (RO) membrane is among the most powerful tools for solving the global water crisis, and Toray has developed high-performance RO membranes for seawater desalination, brackish water desalination, and wastewater reclamation by molecular design in the preparation of cross-linked aromatic polyamide membrane, which produces more appropriate water quality and quantity as compared with conventional ones. Several previous papers provided the removal performances of radioactive substances by RO membranes, but accurate data have not been reported about the advanced RO membranes. It is more recently desired to demonstrate Cesium (Cs) and Strontium (Sr) removal performance in radioactive water by RO membrane because of the considerable concern of the water quality control for nuclear power stations. In this study, removal performance of Cs, Sr, and Iodine was examined to use model compounds adding nonradioactive chemicals to seawater and analyzed by inductively coupled plasma mass spectrometry...

Hollow fiber membrane based on polyacrylonitrile with a high degree of polymerization and its properties

Abstract For the first time a hollow fiber membrane has been prepared based on polyacrylonitrile with a high degree of polymerization. From the examination of its microstructure using FE-SEM and UHR-FE-SEM microphotographs it was shown that the outer surface consists of a skin layer with a pore size of 10 to 30 nm and that the interior consists of a sponge-like layer without large voids. The pure water flux was 500 ml/hr-mmHg-m2 at 25°C. The rejection of polystyrene latex beads of uniform size with an average diameter of 38 nm was > 99% and that of dextran with an average molecular weight of 2 × 106 was approximately 70%. Although the differential pressure of the membrane gradually rose caused by the capture of particles on the membrane surface when water containing suspended iron compounds was fed to the hollow fiber, the pressure could be easily returned to its initial value using the backwash method.

Highly Efficient Virus Rejection with Self‐Organized Membranes Based on a Crosslinked Bicontinuous Cubic Liquid Crystal

To remove viruses from water, the use of self-assembling liquid crystals is presented as a novel method for the synthesis of membranes with a regular pore size (below 1 nm) and controlled pore structures. Nanostructured bicontinuous cubic liquid-crystalline (LC) thin films are photopolymerized onto a polysulfone support layer. It is found that these membranes reject the virus, Qβ bacteriophage (≈20 nm diameter) by >99.9999%. Prepressurization of the membrane appears to enhance their virus rejection properties. This is the first example of nanostructured LC membranes that are used for virus rejection, for which they show great potential.

Membrane-Integrated Fermentation System for Improving the Optical Purity of D-Lactic Acid Produced during Continuous Fermentation

This report describes the production of highly optically pure D-lactic acid by the continuous fermentation of Sporolactobacillus laevolacticus and S. inulinus, using a membrane-integrated fermentation (MFR) system. The optical purity of D-lactic acid produced by the continuous fermentation system was greater than that produced by batch fermentation; the maximum value for the optical purity of D-lactic acid reached 99.8% enantiomeric excess by continuous fermentation when S. leavolacticus was used. The volumetric productivity of the optically pure D-lactic acid was about 12 g/L/h, this being approximately 11-fold higher than that obtained by batch fermentation. An enzymatic analysis indicated that both S. laevolacticus and S. inulinus could convert L-lactic acid to D-lactic acid by isomerization after the late-log phase. These results provide evidence for an effective bio-process to produce D-lactic acid of greater optical purity than has conventionally been achieved to date.

A membrane-integrated fermentation reactor system: its effects in reducing the amount of sub-raw materials for D-lactic acid continuous fermentation by Sporolactobacillus laevolacticus.

Continuous fermentation by retaining cells with a membrane-integrated fermentation reactor (MFR) system was found to reduce the amount of supplied sub-raw material. If the amount of sub-raw material can be reduced, continuous fermentation with the MFR system should become a more attractive process for industrialization, due to decreased material costs and loads during the refinement process. Our findings indicate that the production rate decreased when the amount of the sub-raw material was reduced in batch fermentation, but did not decrease during continuous fermentation with Sporolactobacillus laevolacticus. Moreover, continuous fermentation with a reduced amount of sub-raw material resulted in a productivity of 11.2 g/L/h over 800 h. In addition, the index of industrial process applicability used in the MFR system increased by 6.3-fold as compared with the conventional membrane-based fermentation reactor previously reported, suggesting a potential for the industrialization of this D-lactic acid continuous fermentation process.

Development of Nanostructured Water Treatment Membranes Based on Thermotropic Liquid Crystals: Molecular Design of Sub‐Nanoporous Materials

Abstract Supply of safe fresh water is currently one of the most important global issues. Membranes technologies are essential to treat water efficiently with low costs and energy consumption. Here, the development of self‐organized nanostructured water treatment membranes based on ionic liquid crystals composed of ammonium, imidazolium, and pyridinium moieties is reported. Membranes with preserved 1D or 3D self‐organized sub‐nanopores are obtained by photopolymerization of ionic columnar or bicontinuous cubic liquid crystals. These membranes show salt rejection ability, ion selectivity, and excellent water permeability. The relationships between the structures and the transport properties of water molecules and ionic solutes in the sub‐nanopores in the membranes are examined by molecular dynamics simulations. The results suggest that the volume of vacant space in the nanochannel greatly affects the water and ion permeability.

Studies of ion-exchange fiber IONEX' for precoating material

Abstract This paper represents studies of ion-exchange fiber “IONEX” for precoating materials at nuclear power plants. Cation-exchange fiber “IONEX” (ca. 40 μm diameter and ca. 0.3 mm length) with sulfonic acid group for cation exchange, which is suitable for precoating materials, has been prepared. The microcolumn tests, carried out by forming precoat layers using mixtures of powdered resins and “IONEX”, indicate that filter performance can be improved considerably. These results are attributed to bridge effects and large specific surface areas of “IONEX”. Based on the results of these laboratory tests, “IONEX” has already been used at several power plants.

Polystyrene-based Ion-exchange Fiber and Its Application at Nuclear Power Plant

This paper represents studies of ion-exchange fiber “IONEX” for precoating materials at nuclear power plants. Cation-exchange fiber “IONEX” (ca. 40 μm diameter and ca. 0.3 mm length) with sulfonic acid group for cation exchange, which is suitable for precoating materials, has been prepared. The microcolumn tests, carried out by forming precoat layers using mixtures of powdered resins and “IONEX”, indicate that filter performance can be improved considerably. These results are attributed to bridge effects and large specific surface areas of “IONEX”. Based on the results of these laboratory tests, “IONEX” has already been used at several power plants.