Nearly 70% of agricultural lands in Tehran are irrigated with wastewater. Industrial wastewater contains a variety of inorganic pollutants such as heavy metals that make pollution to soil, water, and plant. Methods to remove heavy metals from industrial wastewater are not so effective or they are costly. In this study, three kind of natural Zeolites with four different sizes have been used to investigate their adsorption characteristics on five types of important heavy metals. The result shows that the Firouzkoh Zeolite adsorbs heavy metals more than the others. The adsorption efficiency increases with decreasing size. The effect of retention time on adsorption ratio shows that 80% of the Pb is adsorbed by Zeolite during early 70 minutes.

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Ion exchange is well known as an excellent technique for chemical separation and applicable even for separation of isotopes. The present paper describes the principle of isotope effects in chemical exchange equilibrium, and the application to the separation of isotopes by using ion exchange resins. Separation coefficients and height equivalent to a theoretical plate have been determined for the experimental systems at different conditions. In particular, flow rate dependence of HETP has been studied on ¹⁵N enrichment processes. The study has been extended to the isotope effects of more heavier elements, such as transition elements, lanthanoid and uranium. The isotope effects in complex formation of transition elements have shown to be relatively smaller than those of electron exchange reactions observed by redox chromatography using anion exchange resin. The strange isotope effects observed for U (IV) -U (VI) electron exchange reaction has been elucidated as the isotope effects due to the electron-nuclear interactions.

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Development of ion exchangers that show large lithium isotope effects is hoped for to establish highly efficient chromatographic processes of lithium isotope separation. In this paper, preparation, characterization, ion exchange properties, and lithium isotope selectivity of inorganic materials that have been and still are being studied by my research group at Sophia University are reviewed. They include manganese oxides-based ion exchangers, antimonic acids and titanium/zirconium phosphates-based ion exchangers. As a result, the lithium isotope separation effects that were one order of magnitude larger than those of organic ion exchangers were obtained. Some inorganic ion exchangers were found to show ion exchange rates more than comparable to those of organic ones.

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This article reviewed author's studies on the selective adsorption and separation of ionic species based on ion exchange or chelate formation. In order to develop the new adsorbents and processes for recovery and separation of precious metals, heavy metals and harmful ions, the authors have synthesized new ion exchangers and chelating resins using various materials such as inorganic materials, organic materials and natural polysaccharides (cellulose, alginic acid, pectinic acid and chitosan) to apply to the industrial separation and purification processes. In this paper, the author's studies on the development of the chelating resins using chitosan were mainly reviewed. The six kinds of chitosan derivatives were synthesized by chemically modifying chitosan. In order to protect the amino groups of chitsoan from the attack of cross-linking reagents, we have developed a new synthesis process using Schiff's base as an intermediate. These chitosan derivatives exhibited high selectivity for gold (III), palladium (II), and platinum (IV) over base metals in hydrochloric acid. In addition, the chitosan derivative containing a pyridyl group exhibited high selectivity for copper (II) over iron (III) in the aqueous ammonium nitrate solution. The adsorption capacities of these chitosan derivatives for palladium (II) were found to be about 2-4 times greater than those of the cross-linked original chitosan and commercial chelating resins.

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Small size fuel cell units for driving portable electrical devices were rapidly developed recently. This report is dealing with recent trend of small size fuel cell.

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Developments of perfluorinated ion exchange membrane for polymer electrolyte fuel cell in Asahi Kasei Corporation were introduced. The main topic was new membrane based on newly designed perfluorinated polymer. Its polymer had high Tg of around 150°C and high ion exchange capacity of 1.4 meq g^-1. The membrane based on the polymer therefore had good thermo-stability and excellent proton conductivity. The membrane was expected to suit the high temperature cell operation with low humidification. This paper included the results of the work carried out under con-tract with New Energy and Industrial Technology Development Organization (NEDO) .

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The recent advances in inorganic ion-exchangers in Chinese universities are briefly reviewed in the following groups: (1) clay minerals, (2) zeolites, (3) hexacyanoferrates, (4) salts of heterpoly acids, (5) oxides and hydrous oxides. The preparations, the ion exchange properties and the applications of these inorganic ion exchangers are presented and discussed. Some representative research articles in this field are introduced in detail.

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