Ryotaro Kiyono

Solvent transport across anion-exchange membranes under a temperature difference and an osmotic pressure difference

Abstract Solvent transport across anion-exchange membranes was measured for water and aqueous KCl, KF, KIO 3 , KClO 3 , HCOONa, CH 3 COOK, C 2 H 5 COONa, C 6 H 5 COONa, C 6 H 5 SO 3 Na solutions under a temperature difference and an osmotic pressure difference. Anion-exchange membranes Neosepta® AFN and modified porous AFN(P) were used. The porous membrane AFN(P) was prepared by treating Neosepta® AFN with NaOH solution. Plots of the volume flux against the temperature difference between the solutions on both sides give straight lines starting from zero. The direction of thermoosmosis was from the cold side to the hot side. Solvent transport across anion-exchange membranes under a temperature difference and an osmotic pressure difference is proportional to the water content of the membranes that is represented by the weight of absorbed water per one gram of dry membrane matrix without counterions, and is almost independent of the counterion species.

Thermal membrane potential across anion-exchange membranes in KCl and KIO3 solutions and the transported entropy of ions

New simple thermal membrane potential cells with a solution inlet channel were constructed from two blocks of poly(methyl methacrylate) resin. Using these cells the thermal membrane potentials across anion-exchange membranes Aciplex® A-201 and A-211, Neosepta® AM-1 were observed in KCl and KIO3 solution systems. It is easier to handle the new cells because of the simple cell construction compared with the cells with a solution inlet nozzle used up till now. The thermal potentials measured with the new cells were similar to those obtained with the old ones. The thermal membrane potential Δψ across the anion-exchange membranes was always positive at the cold solution side. The temperature coefficient of the thermal membrane potential per unit temperature difference Δψ/ΔT is proportional to the logarithm of the activities of the ions and the slope of this plot was R/F in the range of ideal permselectivity for counterions as expected from the previously presented theory. The transported entropies of the counterions in the membrane were estimated by combining data for the thermal membrane potential, thermoosmosis and electroosmosis. It is shown that the contribution of the water term to the thermal membrane potential as well as to the concentration membrane potential plays an important role.

Chiral Lewis Acid-Catalyzed Enantioselective Cycloadditions between Indoles and Cyclic Carbonyl Ylides Derived from Diazodiketone or Diazoketoester Derivatives.

Asymmetric 1,3-dipolar cycloaddition reactions between N-methylindoles and several cyclic carbonyl ylides that were derived from diazodiketone or diazoketoester precursors in the presence of both achiral Rh and chiral lanthanoid metal catalysts are described. For the six-membered cyclic carbonyl ylides derived from 1-diazo-5-aryl-2,5-pentanedione precursors, the cycloaddition reactions were carried out using Rh2(OAc)4 (2 mol %) and the chiral Pybox-Ph2-Lu(OTf)3 complex (10 mol %) as catalysts, resulting in high enantioselectivities (83% to >98% ee (exo)) along with relatively good exo-selectivities (exo:endo = 65:35 to 94:6) and yields (63-85%). For the five-membered cyclic carbonyl ylide derived from 1-diazo-2,4-pentandione precursor, the cycloaddition reaction with 5-bromo-1-methylindole was carried out in the presence of Rh2(OAc)4 (2 mol %) and the chiral Pybox-Ph2-Er(OTf)3 complex (30 mol %) as catalysts, resulting in relatively good enantioselectivity (78% ee) and endo-selectivity (endo:exo = 81:19).

Relaxation of polymer chains dissolved in the liquid phase of membranes under a pressure gradient

Abstract The dependence of streaming potential on time was measured by applying a pressure difference across collodion-poly(acrylic acid) membranes, collodion-poly(acrylic acid) membranes partially complexed with Fe(II), and poly (styrenesulfonic acid) -type cation-exchange membranes. It has become apparent that the time dependence of the streaming potential reflects the relaxation phenomena of the polymer chains dissolved in the liquid phase of the membranes. The relaxation time becomes longer, the more flexible and longer are the polymer chains dissolved in the liquid phase.

Solvent transport across anion-exchange membranes under a temperature difference and transported entropy of water

Abstract Solvent transport across anion-exchange membranes was measured for aqueous KF, KCl, KNO 3 (or NaNO 3 ), KIO 3 , HCOONa, CH 3 COONa (or K), C 6 H 5 COONa, C 6 H 5 SO 3 Na and p -CH 3 C 6 H 4 SO 3 Na solutions under a temperature difference and an osmotic pressure difference. Hydrocarbon-type anion-exchange membranes Neosepta® AM-1, Aciplex® A-201 and A-221, test membranes STA-1 to STA-5, and fluorocarbon-type anion-exchange membrane Tosflex® IE-DF 17 were used. The water content is represented by the unit: g H 2 O per g dry membrane without the weight of anhydrous counterions. Plots of the volume flux against the temperature difference of both side solutions gave straight lines starting from zero. The direction of thermoosmosis was from the cold to the hot side. The order of water content of membranes is F − >IO − 3 >Cl − >NO − 3 for inorganic ions and CH 3 COO − >HCOO − >C 6 H 5 COO − > p -CH 3 C 6 H 4 SO − 3 (or C 6 H 5 SO − 3 ) for organic ions regardless of the type of membrane. The order of the absolute value of the entropy difference between transported entropy in membranes and partial molar entropy of water in the external solutions is IO − 3 >F − >Cl − >NO − 3 for inorganic ions and C 6 H 5 COO − >CH 3 COO − >HCOO − for organic ions for all membranes.

Thermal membrane potential across cation-exchange membranes for various halide solutions

Thermal membrane potential across cation-exchange membranes was measured for various halide solutions. Linear relationships between thermal membrane potential (ΔΨ) and temperature difference (ΔT) were observed, and the temperature coefficient of thermal membrane potential (ΔΨ/ΔT) decreases with increase in the molality of the external solution as predicted by a theory reported. When counterions of membranes are hydrogen ions, the sign of the coefficients turns into minus near 0.01 mol/kg of the external solution for all membranes, although the coefficients are always positive for all the other forms. The dependence of the coefficients on the molality of the external solutions sometimes deviated slightly from the theory. This deviation is attributed to some change in water content of the membranes. A reproducible method of measuring water content of membranes was applied to discuss the change in the state of the membranes.

Relaxation of polymer chains dissolved in the liquid phase of membranes under a pressure gradient. II: Correlation with membrane composition

Abstract The time dependence of the streaming potential across collodion membranes, oxidized collodion membranes and interpolymer membranes of collodion and poly (acrylic acid) was measured and analyzed in detail as relaxation phenomena with plural components. The number of components of the relaxation varies with the membrane: one for collodion membranes, two for oxidized collodion membranes, and three components for collodion-poly(acrylic acid) membranes, respectively. Each relaxation component was assigned to the chemical component of the membrane: relaxation times are approximately 200, 50 and 10 sec for poly(acrylic acid), collodion and oxidized collodion, respectively. The effects of cross-linking, concentration of the external solution and temperature on each relaxation component were also explored.

Nonisothermal membrane phenomena across perfluorosulfonic acid-type membranes, Flemion S: part I. Thermoosmosis and transported entropy of water

Solvent transports across the perfluorosulfonic acid-type membrane Flemion S were measured for aqueous electrolyte solutions under a temperature difference and under an osmotic pressure difference. H+, Li+, Na+, K+, NH4+, CH3NH3+, (CH3)2NH2+, (CH3)3NH+, (CH3)4N+, (C2H5)4N+, (n-C3H7)4N+ and (n-C4H9)4N+ were used as counterions. Water flux across the membrane in HCl solution is higher than that in the other electrolyte solutions because hydrogen ions can exchange with the hydrogen of the neighbor water molecules and contribute to the water transport across the membrane as a proton jump in conductivity. The direction of thermoosmosis across the membrane in HCl, NaCl, (CH3)4NCl and (C2H5)4NCl solutions was from the cold side to the hot side and that in LiCl, KCl, NH4Cl, CH3NH3Cl, (CH3)2NH2Cl and (n-C4H9)4NBr solutions was from the hot side to the cold side, although thermoosmosis across anion-exchange membranes always occurs toward the hot side.

Nonisothermal membrane phenomena across perfluorosulfonic acid-type membranes, Flemion S: Part II. Thermal membrane potential and transported entropy of ions

AbstractThermal membrane potentials across the perfluorosulfonic acid-type membrane, Flemion S, were measured for HCl, alkali metal chlorides, and ammonium and methyl ammonium chlorides. The difference between the mean molar transported entropy of the counterions in the membrane and the partial molar entropy of the counterions in the external solution