Inorganic anion exchange membranes were prepared from the powdered hydrotalcite like materials as anion exchangers and polyvinylidene fluoride as a binder for the membrane fablication. Following hydrotalcite like materials (combination of di- and tri-valent metal ions) were prepared, Mg (II) -Al (III), Ni (II) -Al (III), and Co (II) -Al (III) systems. Each powdered material was dispersed in dimethylkformamide solution of polyvinylidene fluoride and spreaded on a glass dish to form a membrane. The electric resistance measured was ranging 200-700 Ω⋅cm^-2 and 80-150 Ω⋅cm^-2 at 25°C and 80°C, respectively. The plots of membrane potential vs. log of NaCl activity were linear between 10^-3 -1 mol⋅dm^-3. The transport numbers for Cl^- ions were around 0.94 at 80°C which approached 0.99 for the comercially available organic anion exchange membrane. The thermal stability was superior to that of organic anion exchage membrane.

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Poly (N- benzy1-4-vinyl pyridinium) resin (BVP resin) has been developted for the separation and recovery of alkylbenzensulfonate (ABS) in a dilute aqueous waste solution. Two kinds of ABS, ethylbenzensulfonate (C₂) and dodecylbenzensulfonate (C₁₂), were used in this study. Adsorption equilibria of dilute ABSs into BVP resin were measured by an usual batch method. Effects of 1) the resin type, 2) the ABS concentration and 3) the coexisting salt (NaCl) concentration on the equilibria were studied. The adsorption equilibria of both ABSs were expressed by the monovalent ion exchange equation. The Cl^- type resin showed higher selectivity to the two ABSs than the Br^- one. In particular, the exchange equilibria between C₁₂ and the Cl^- type resin kept rectangular isotherm even though the concentration of NaCl was high in the solution.
Elution equilibrium of C₁₂ adsorbed into the resin was measured by a mixed solution of hydrochloric acid and methanol. The elution equilibrium constant was affected by both HCl and methanol concentration of the mixed solution. The largest equilibrium constant was obtained for the elution when the HCl concentration of the mixed solution was 100 mol⋅-m^-3.

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The chelate resin functionalized resin with dithiol group (RES resin) has been developed for the removal of dilute As (III) from the waste geothermal water. The present investigation aims to clarify the adsorption equilibrium of As (III) onto the RES rein to discuss the feasibility of this resin to apply to the geothermal water.
The adsorption equilibrium was determined by an usual batchwise method. Effects of temperature, initial concentration of As (III), pH of the solution and coexisting solutes on the equilibrium were examined. The Langmuir equation could reasonably express the adsorption data. The adsorption capacity and the equilibrium constant suggested that the RES resin was suitable for the separation of As (III) from the hot water (368K) . The effect of As (III) concentration on the isotherm was not observed. The adsorption capacity of the RES resin approximately gave a constant value at pH lower than 10, while it decreased remarkably at pH higher than 10. This result suggests that the alkaline solution (pH>10) is effectively employed as an eluent. Neither NaCl nor silica which are most commonly found as a coexisting solute in the geothermal waste water did not interfere seriously with the adsorption of As (III) . Therefore, the RES resin is promise for the selective adsorption of As (III) from the hot waste water.

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