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The temperature dependence of the magnetic susceptibility (χ) of O2 molecules adsorbed in slit-shaped carbon micropores of 1 nm in width was measured as a function of the coverage r at 1.7-100 K. The adsorbed O2 molecules below ρ = 0.2 showed the paramagnetism without any obvious magnetic transition, which was quite close to the magnetism of bulk gaseous oxygen. An antiferromagnetic behavior appeared with an increase in ρ. This behavior was not caused by the formation of 2D lattices or bulk solid structures, but by the random magnetism. These results indicated that O2 molecules adsorbed in the micropore do not form any 2D magnetic lattice, but clusters before the formation of the bulk solid structure. © 1995 American Chemical Society.

異なる径の粒状マンガン酸化物のリチウム吸着速度をバッチ法で測定した. フロインドリッヒ型吸着等温線に基づく吸着速度の数値解析結果を用いてリチウムの粒内拡散係数を求めた, 拡散係数は, 粒径に依存せずほぼ2×10<SUP>-6</SUP>cm<SUP>2</SUP>・s<SUP>-1</SUP>となった.<BR>カラム吸着実験結果について,無限槽内での吸着モデルを用いて解析し粒内拡散係数を求め, バッチ法とほぼ同じ拡散係数値を得た. カラム法では空間速度200h<SUP>-1</SUP>以上で, 粒内拡散律速であることが予測された.<BR>リチウム採取コストは, リチウムの吸着速度に大きく影響される. 今回求めた粒内拡散係数は溶液内でのリチウムの自己拡散係数と同じオーダーである. このことは, 液中硬化被覆法で造粒した今回の吸着剤は良好な吸着速度性能を保持していることを示している. 今後の課題としては, 吸着終期付近で見られる吸着速度の低下を防ぐこと, さらに多孔化して吸着速度性能を上げることが挙げられる.

脱着液から炭酸リチウムを製造する全工程のフローシートをFig.-8に示した.<BR>炭酸リチウムの純度および収率を高めるために, 1) アルカリ処理, 2) 濃縮処理, 3) 晶析処理, 4) 洗浄処理を行い, それらの処理条件を明らかにした.<BR>アルカリ処理においてpH12以上で不純物の二価金属元素を沈でんさせた. マンガン, マグネシウムはほぼ定量的にろ別除去することができた. カルシウムの除去率は92%程度であった.<BR>次いで, 濃縮処理において, 濃縮率80%程度までに加熱濃縮してリチウム濃度8,500mg・dm<SUP>-3</SUP>以上の濃厚溶液を調製した. このとき, 残存カルシウムは再び析出し定量的にろ別除去することができた.<BR>濃厚リチウム溶液に炭酸ナトリウムを1.2モル加えて, 炭酸リチウムを晶析させた. これをろ別し, ただちに少量の熱水 (20cm<SUP>3</SUP>・g<SUP>-1</SUP>)を用いて洗浄処理を行った.<BR>これらの処理条件により, 脱着液から市販一級品と同等の炭酸リチウムを収率75%程度で製造することができた.<BR>実用的には, このプロセスで使用する酸, アルカリ, 炭酸塩については廃工業薬品の使用が経済的であり, その場合, 生成炭酸リチウムの品位への影響について別途検討する必要があると考えている. また, 炭酸リチウム晶析残液からのリチウムの回収については, 溶媒抽出による分離・回収法の検討を進めている.

海水からのリチウムの大量採取を目的としてベンチ吸着試験装置を設計・試作した. 約7ヵ月間での吸着-脱着試験を行った結果をTable-2に示した. 吸着剤2.5kg (乾燥重量), 海水量4,200m<SUP>3</SUP>を使用した.<BR>脱着液から炭酸リチウムを製造した結果, 純度99.1%のものを約750g製造することができた. この実験での海水からのリチウム吸着率は約27%, 炭酸リチウムとしての採取率は20%程度であった.<BR>この採取ベンチ試験の結果, 海水からのリチウム採取が技術的に十分可能であることを実証できた.

Todorokite-type magnesium manganese oxide (ToMO(Mg)) was prepared by hydrothermal treatment of Mg2+-exchanged buserite-type manganese oxide. The extraction/insertion reactions of the metal ions with the manganese oxide were investigated by chemical and X-ray analyses, FT-IR spectroscopy, pH titration, and Kd measurements. Mg2+ and Mn2+ ions in the (3 x 3) tunnel sites of the manganese oxide were topotactically extracted by acid treatment. Alkali metal ions could be inserted into the (3 x 3) tunnel sites of the acidtreated sample (ToMO(H)). The extraction reaction proceeded by redox-type and ionexchange- type mechanism, and most of the insertion reaction by ion-exchange-type mechanism. In the pH titration studies, the acid-treated sample showed dibasic acid behavior toward Li+, Na+, and K+ but monobasic acid behavior toward Cs+ and (CH3)4N+. The affinity order was (CH3)4N+ &lt Cs+ - Li+ &lt Na+ &lt K+ at pH 5 and (CH3)4N+ &lt Cs+ &lt K+ &lt Na+ &lt Li+ at pH 10. The distribution coefficient (Kd) of the metal ions increased with an increase in the effective ionic radius. The effective pore radius of ToMO(H) was evaluated as about 2.7 Å from the structural parameters of the (3x3) tunnel. © 1995, American Chemical Society. All rights reserved.

Spinel-type lithium manganese oxide (LMO) and birnessite-type sodium manganese oxide (NMO) were prepared by hydrothermal treatment of γ-MnO2 with LiOH and NaOH solutions, respectively. The extraction/insertion reactions of the alkali-metal ions with the manganese oxides were investigated by chemical, X-ray, DTA-TG analyses, FT-IR spectroscopy, pH titration, and Kd measurements. Li+ and Na+ were topotactically extracted from LMO and NMO, respectively, by two different mechanisms: redox-type and ion-exchange-type reactions. The pH titration studies indicated that the acid-treated LMO (LMO(H)) has a remarkably larger adsorptive capacity for Li+ than those for the other alkali-metal ions. The acid-treated NMO (NMO(H)) showed tetrabasic acid behavior toward Li+, but monobasic acid behavior toward the other alkali-metal ions. A new model was proposed for the insertion reaction of alkali-metal ions with NMO(H). LMO(H) and NMO(H) showed ion-sieve properties for the adsorption of alkali-metal ions. The Kd measurements suggested that the effective pore radii of the ion sieves are about 0.7 Å for LMO(H) and 1.5 Å for NMO(H). © 1995, American Chemical Society. All rights reserved.

H+-form hollandite-type manganese oxide (HolMO) was prepared directly by reacting LiMnO4 with Mn2+ in H2SO4 solution. The insertion/extraction reactions of alkali metal ions with HolMO were investigated by chemical, X-ray, DTA-TG analyses, FT-IR spectroscopy, pH titration, and K-d measurements. The alkali metal ions were inserted/extracted by two different mechanisms: redox-type and ion-exchange-type reactions. A model for the insertion/extraction reactions was proposed. The hollandite-type manganese oxide showed an ion-sieve property (the effective pore radius of the ion sieve is 1.41 Angstrom) for the adsorption of alkali and alkaline earth metal ions.

Kinetic properties of a Pt/λ-Mn02 electrode for the electrochemical insertion of lithium ions were studied in the aqueous phase by cyclic voltammetry (CV) and potential step chronoamperometry (PSCA). The cyclic voltammogram showed that the electrochemical insertion reaction of lithium ions proceeds in two steps in the potential range between 0.60 and 0.98 V (vs. saturated calomel electrode). The chemical diffusion coefficients of lithium ions in the manganese oxide were evaluated from the PSCA data using a finite diffusion model. They were in the range of 6.6 x 10 -11 to 1.4 × 10-10 cm2 s-1, depending slightly on the applied potential. The activation energy of the diffusion was evaluated as about 44 kJ mol”1 from the temperature dependence of the PSCA. These results suggested that lithium ions diffuse by a hopping mechanism in the spinel phase. The diffusion coefficients, transfer coefficients, and standard rate constants also were estimated from the CV data. The diffusion coefficients agreed reasonably well with those obtained by PSCA. © 1995, The Electrochemical Society, Inc. All rights reserved.

Spinel-type lithium-zinc-manganese oxide (Li0.5Zn0.5)[Li0.5Mn1.5]O4 was prepared by a coprecipitation/thermal crystallization method. The Li+ extraction/insertion reactions with the spinel in the aqueous phase were investigated by X-ray diffraction, DTA-TG analyses, FT-IR spectroscopy, pH titration, and distribution coefficient (Kd) measurement. The Li+ extraction and insertion proceed by topotactic ion-exchange-type mechanisms. The Zn2+ at the tetrahedral sites caused a decrease in the extractabilities of Li+ during acid treatment. The spinel with ordered arrangement of Li+ and Zn2+ at 8a tetrahedral sites showed a markedly lower Li+ extractability than the spinel with random arrangement of Li+ and Zn2+ at the same sites. The inhibiting effect of Zn2+ on Li+ extractability was discussed in terms of the Li+ migration pathway in the spinel structure. The Li+-extracted sample showed a lithium ion-sieve property from microamount to macroamount of metal ion loading. © 1995, American Chemical Society. All rights reserved.

Lithium isotope fractionation properties were studied on five kinds of inorganic ion exchangers with different ion-sieve properties. The lithium isotope separation factors were determined batchwise in a LIOH or (LiCl + LiOH) solution at 25 or 20 degrees C, respectively. The separation factor increased in the order birnessite-type manganese oxide < hollandite-type manganese oxide < spinel-type manganese oxides < cubic antimonic acid in the LIOH solution. It was dependent on the pore radius (r(is)) of the ion-sieve and was a maximum at r(is) = 0.10 nm. The difference in the separation factor with r(is) could be well explained by considering two factors; the difference in hydration circumstances of Li+ between the ion-exchanger and the solution phase, and the influence of Li+ stabilization in the solid phase.

塩酸を脱着液として用い, 回分式およびカラム式脱着条件について検討した結果を次のように要約する.<BR>塩酸濃度は両方式とも0.5Nが適切であった. その場合, 回分式では脱着時間1時間で脱着率83%が得られた. カラム式では吸着剤量の1.5倍の脱着液量の使用により, 脱着率92%が得られた. また, 吸着剤からのマンガンの溶出率は1～1.5%であった.<BR>溶離リチウム濃度は, カラム式の場合1,400mg・dm^-3となり, 回分式多段脱着処理を5回行った場合は2,100mg・dm^-3に達した.<BR>リチウムと他の吸着元素との分離は, カラム式においても困難であることがわかった.<BR>回分式多段脱着法およびカラム脱着法には, それぞれ特徴があり, 実用的な脱着法としてどちらを選定するかは今後の課題の一つと考えている.<BR>脱着処理における吸着剤の溶解性を抑えるために, 化学的により安定な吸着剤の開発と脱着法の改善の検討が必要である.

A hollandite-type manganese dioxide (HolMO), without foreign metal cations (K+, NH4+, Na+) in the (2 x 2) tunnel, was prepared directly by reacting LiMnO4 with Mn(NO3)2 in an H2SO4 acidic solution. The HolMO belonged to a body-centered tetragonal system (space group 14/m) and could be expressed by the formula H4xMn8-x. O16• yH2O. A preliminary electrochemical study suggested that the HolMO is promising as the cathode for a lithium rechargeable battery. © 1994, The Electrochemical Society, Inc. All rights reserved.

Equilibrium potentials of spinel-type manganese oxide, λ-MnO2, were measured in various aqueous solutions. The Pt/λ-MnO2 electrode showed a nearNemstian response to lithium ions and not to other alkali metal and alkaline earth metal ions in the concentration range between 3 X 10-6 and 0.5 mol/dm3. The selectivity coefficents for lithium ions against sodium, and potassium ions and protons were found to be: log /cfSa = -4.8, log kg&amp = -4.6, and log /c£°A = +1.9. The equilibrium potential was stable and pH-independent over a wide pH range (pH 4 to 9.5) in a solution with a lithium ion concentration above 5 mmol/dm3. The thermodynamic parameters for Li+ insertion/extraction with -MnO2 were evaluated from the temperature dependence of the equilibrium potentials in the temperature range between 298.15 and 318.15 K. © 1993, The Electrochemical Society, Inc. All rights reserved.

The electrochemical insertion of lithium ions into a Pt/lambda-MnO2 electrode was investigated in various metal chloride solutions. The Li+ insertion occurred effectively in LiCl solutions with higher concentration than 10 mmol/dm3, but it could hardly occur in a 0.1 mmol/dm3 LiCl solution. Alkaline earth metal ions showed a stronger inhibition effect against the Li+ insertion into the Pt/lambda-MnO2 electrode than alkali metal ions. However, since only Li+ ions were taken up from a mixed solution of lithium and alkaline earth metal chlorides, a high selectivity of the electrode for lithium ions was shown. It was possible to recover lithium ions from geothermal water by this electrochemical method using the Pt/lambda-MnO2 electrode; the lithium uptake was 11 mg/g-MnO2.

Spinel-type lithium magnesium manganese oxide LiMg0.5Mn1.5O4 was prepared by a coprecipitation/thermal crystallization method. Li+ and Mg2+ in the spinel-type lithium magnesium manganese oxide could be extracted by an acid treatment. The Li+ and Mg2+ extraction reaction with LiMg0.5Mn1.5O4 and the Li+ insertion reaction with the acid-treated oxide were investigated by chemical, X-ray, DTA-TG analyses, FT-IR spectroscopy, pH titration, and Kd measurement. The extraction and the insertion proceed topotactically by ion-exchange-type mechanisms. The acid-treated oxide showed a lithium ion sieve property from microamount to macroamount of metal ion loading. The selectivity sequence for alkali metal ions was Na &lt K &lt Rb, Cs ≪ Li over the pH range studied. © 1993, American Chemical Society. All rights reserved.

Spinel-type lithium manganese oxides which can be expressed by a general formula LinMn2-xO4 (1 less-than-or-equal-to n less-than-or-equal-to 1.33, 0 less-than-or-equal-to x less-than-or-equal-to 0.33, n less-than-or-equal-to 1 + x) were prepared by reacting MnCO3 with Li2CO3 at 400-degrees-C and 800-degrees-C. The extraction/insertion reactions of lithium ions with the spinel samples were investigated by chemical, X-ray, and thermal analyses, FT-IR spectroscopy, and pH titration. Lithium ions were extracted/inserted by two different mechanisms: redox type and ion exchange type. Therefore, the Li+ extraction/insertion sites could be classified into redox type and ion exchange type. Li+ ions were preferentially extracted/ inserted from/into the ion-exchange sites. The spinel-type lithium manganese oxides could be divided into two parts: those with trivalent Mn ions and those with only tetravalent Mn ions (with Mn defects in 16d octahedral sites). The numbers of redox-type and ion-exchange-type sites correlated well with the amounts of trivalent Mn ions and the Mn defects, respectively. The proportions of the two types of sites varied depending on preparation conditions (heat treatment temperature and Li/Mn mole ratio of starting material) of the lithium manganese oxide spinels.

1. 1. A novel hemagglutinin was isolated from the red alga Gracilaria verrucosa and characterized as a sulfated proteoglycan with 92% carbohydrate content. 2. 2. It is a dimer (MW 27,000 and MW 23,000) its molecular weight (MW) and isoelectric point are 49,000 and 3.8, respectively. 3. 3. It agglutinates rabbit &gt horse &gt guinea pig &gt goose erythrocytes. 4. 4. This activity is sensitive to heat, but insensitive to protease or periodate. It is not inhibited by simple sugars but by fetuin. 5. 5. Since the periodate treatment of the rabbit erythrocyte lowers agglutination, this hemagglutunin is probably a lectin or a lectin-like molecule with complex saccharide specificity. © 1992.

The electrochemical insertion of alkali-metal ions in the aqueous phase was investigated by using a Pt/lambda-MnO2 electrode which was obtained by the electrochemical extraction of Li+ from a Pt/LiMn2O4 electrode. The cyclic voltammogram of a 0.01 mol/dm3 LiCl solution showed a definite electric current, corresponding to the Li+ insertion/extraction reaction with a lambda-MnO2 electrode involving the redox of manganese. The same electrodes in a 0.01 mol/dm3 NaCl or KCl solution showed little electric current in the region between 0.2 and 1.0 V vs calomel electrode. Only Li+ ions were taken up by the Pt/lambda-MnO2 electrode from a mixed solution of alkali-metal chlorides.

Increase of the β sheet content and aggregation of concanavalin A (con A) induced at about 60°C were followed with circular dichroism (c.d.) and scattered light intensity (T90) on both metal-complexed and demetallized species. The conversion occurred at a higher temperature for metal-complexed species than for demetallized one. A concentration-independent conversion curve of metal-complexed species, obtained for a concentration range below around 6 μg/ml (6 × 10-3 kg m -3) with a midpoint at 57°C, was well described in terms of a conformational equilibrium between two conformers. However, aggregation did exist even at a low concentration of 1 μg/ml. Aggregation also occurred without the conformational change as found at the initial stage or in Tris buffer, which suggested the absence of direct coupling between the conformational change and the aggregation. Changes of c.d. at 222 nm, expected to represent the main chain conformation, differed from those at 290 nm reflecting the environment of side chain chromophores. Time courses of three properties examined, c.d. at 222 nm, at 290 nm, and I90, always exhibited a lag in the case of metal-complexed species while the lag was not observed in the case of demetallized species, however. Lag became longer in c.d. but it became shorter in I90 as the protein concentration increased. © 1989.

Three properties, the binding activity to Sephadex G-75, conformation, and the extent of aggregation, of concanvalin A. (con A) in alkaline pH solutions were examined with special attention to the time course and their time-independent final values. Highly cooperative conformational changes among four subunits were suggested which were coupled either with protonation in the case of demetallized con A or with metal binding in the case of metal-liganded con A. Midpoints of the conversions of the metal-liganded con A were about pH 8.8, 9.1 and 9.1 with respect to the activity, the conformational change and the aggregation, respectively. These values were about 1 pH higher than the corresponding values of demetallized con A: 7.9, 8.05 and 8.2. Each conversion took place in narrow pH ranges. The pH range for the loss of activity was found to be significantly lower than those of the other two. The aggregation was suggested not to be coupled with the conformational change. Dissociation into subunits did not take place indicating strong interactions among four subunits in the tetramer. © 1988.

Tetrameric concanavalin A at neutral pH dissociated into the dimer when CuCl2 was added in a concentration range comparable to protomer concentration. This effect of CuCl2 was largely suppressed when NaCl concentration was increased. Neither the conformation of the protein nor its binding activity to 4‐methylumbelliferyl α‐D‐man‐nopyranoside was affected on addition of CuCl2. © 1987 Munksgaard International Publishers Ltd.