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Calcium hydroxyapatites (CaHAP) substituted with Fe3+ ions of different atomic ratios Fe/(Ca + Fe) = XFe from 0 to 0.23 were synthesized and characterized by various methods. The number of Ca2+ ions in CaHAP substituted by one Fe3+ ion was higher than one, implying that the formation of cation vacancies and the protonation of PO43− ions are caused by Fe(III)-substitution. XFe of the surface layer of the particles determined by XPS was less than the total XFe. IR spectra of Fe(III)-substituted CaHAP contain a band at 3707 cm−1 assigned to the surface Fe–OH groups in addition to the surface P–OH bands at 3688, 3677, and 3658 cm−1. With an increase in XFe, the amount of irreversible adsorption of CO2 decreased whilst those of CH3OH and H2O first decreased and then increased. IR results showed that the surface Fe–OH groups act as stronger irreversible adsorption sites for CO2 and CH3OH compared to the surface P–OH groups.

Corrosion inhibition of copper in a low-conductivity medium ( < 10 μS cm−1) containing benzotriazole (BTA) and/or 2-mercatobenzothiazole (MBT) was studied by using the AC impedance technique, Auger electron spectroscopy and corrosion tests. As the MBT concentration increased, the corrosion rate of copper abruptly rose to a peak, rapidly fell, and then finally decreased steadily. The maximum corrosion rate appeared at a MBT concentration of about 0.5 ppm. However, a concentration of more than 1.5 ppm MBT could effectively inhibit copper corrosion. The results from AC impedance measurements agreed with those from corrosion tests. The film resistance could be observed only when the MBT concentration was in excess of 1.5 ppm. A combination of BTA and MBT proved to be more effective than either compound used alone.

The change in the dielectric constant of α-FeOOH, β-FeOOH, and γ-FeOOH with the amount of adsorbed water was examined at 30.0 °C in the frequency range 200 Hz–100 kHz for the purpose of clarifying the mechanism of water adsorption. The adsorption isotherms belong to the BET II type. The sample with the adsorbed water shows a particular dispersion of the dielectric constant with frequency in the low frequency range. The dispersion was ascribed to the transition between different orientational directions of the dipole moment of the adsorbed water. The change in the dielectric constant with the amount of adsorbed water for each iron(III) oxide hydroxide was interpreted in relation to the surface structure of predominant faces of crystals, in particular the number and position of hydroxyls on crystal surfaces. The following adsorption process was suggested below the monolayer adsorption coverage for each iron(III) oxide hydroxide. For α-FeOOH, water molecules are adsorbed on the (100) planes in three successi...

The adsorption behaviors of methyl and propyl iodides, propyl chloride and chlorobenzene were examined on silica gels impregnated with 1,4-diazabicyclo[2.2.2]octane (DABCO), pyperazine (PPZ), hexamethylene tetramine (HMTA), and modified with (3-aminopropyl)triethoxysilane (ATS) and dimethoxybis[3-(rnethylamino)propyl]silane (DAS). The irreversibly adsorbed amount of these halides except chlorobenzene was proportional to the amount of impregnated amines. The molar ratios of irreversible adsorption of the halides to the impregnated amine were less than 2 and in the order of DABCO>PPZ>HMTA>ATS>DAS. The former three amine compounds are less stable than the last two materials against thermal pretreatment.

The state of Cl in β-ferric oxide hydroxide (β-FeOOH) was examined by X-ray diffraction, IR absorption, chemical analysis, DTA, and TGA. The adsorption of SO2 was determined as a measure of the surface activity. No influence of Cl contained in the crystal appeared in the X-ray diffraction patterns and surface area. The absorption bands at 640 and 840 cm−1 in IR spectra showing the deformation vibration of OH group diminished with the decrease of Cl content. It was shown that the path for β-FeOOH to transform into α-Fe2O3 by heating differentiates from the sample including more than 11.5% Cl/Fe to one including less than 11.5% Cl/Fe. This critical Cl content is equal to the amount of Cl when Cl fills up the characteristic tunnels existing in the β-FeOOH crystal. Cl in β-FeOOH interferes both its transformation into α-Fe2O3 and the recrystallization of resultant α-Fe2O3. These effects were explained by the stabilization of the β-FeOOH structure by Cl in tunnels and the bonding between Cl and Fe. The amount ...

The ultra-fine ferric oxides of 50 to 650 A in diameter were examined by X-ray diffraction, differential thermal analysis, electron microscope and H2O adsorption in order to find the cor- relation of the ultimate and agglomerated structures of the ferric oxides with the heat of im- mersion in water, ΔHI.It was shown that ΔHI is almost independent of the particle size, except B-500-1 and B500-2, samples which showed higher ΔHI values (Fig.2). These two samples were prepared by heating amorphous hydrous oxide at 500d C, and showed partial crystallization to α-Fe2O3 and considerable sintering. Higher ΔHI values of the sintered samples were interpreted by the' presence of interparticle micropores, through which H2O molecules are more easily permeable than N2 molecules. The surface activity incident to the structural change is also thought to be pertinent to the higher ΔHI.

The relationship between the activity of ferric oxyhydroxides (α-, β-, and γ-FeOOH) and structural changes has been investigated by determining the heat of immersion in H2O and H2O vapor adsorption. For each ferric oxyhydroxide, the monolayer capacity of H2O adsorption and the heat of immersion decreased with the progress of transformation into α-Fe2O3. Above the transformation temperature the heat of immersion increased with the outgassing temperature. The heat of immersion of α-Fe2O3 obtained by outgassing each ferric oxyhydroxide at 400 and 500 °C increased with the accompanying increase in crystallite size. β-FeOOH showed higher heat of immersion and larger monolayer capacity per unit surface area than other ferric oxyhydroxides. It is presumed that the higher heat of immersion and larger monolayer capacity observed for β-FeOOH are ascribed to micropores in β-FeOOH crystals produced by the removal of molecular water originally contained.

界面活性剤非水溶液中への水の可溶化状態や機構を知り, また可溶化の溶媒依存性, 活性剤依存性について一般的関係を得る目 ,活性剤依存性について一般的関係を得る目的で, 種々の無極性溶媒, 油溶性界面活性剤を用い, 可溶化した水の蒸気圧の温度変化を測定した。水の蒸気圧の添加水量による 変化から可溶化限界量を, 蒸気圧の温度変化から可溶化熱を求めた。可溶化限界量の大きさは, 同じ溶媒ではAerosol OT>ドデシルアンモニウム塩> ポリオキシエチレンノニルフェノールエーテルの順であり, 非イオン性活性剤では酸化エチレン基数の順であった。Aerosol OTについては, 可溶化限界量と溶媒の溶解パラメー ターとの間の関係に極小が見出され, この関係はミセルの会合数と溶解パラメーターとの関係に対応した。非イオン活性剤についてはこうした関係は認められなかった。これは, 会合数が水の可溶化によって変化するためであろう。可溶化熱はどの場合も, 可溶化水量量により変化し, いずれも可溶化限界量で水の蒸発熱に近づく。可溶化熱の大きさの順はテトラクロルエチレン溶液ではAerosol OT>ドデシルアンモニウム塩≈非イオン活性剤の順になった。可溶化熱の可溶化水量による変化から水の可溶化機構を推論した。

プロピルからオクチルまでの直鎖1価アルコールと水とにより,活性化の各段階における一連の砂糖炭に対する湿潤熱を双子型伝導熱量計を用いて測定した。比較的活性化の進んだ炭では湿潤熱は活性化による表面積の増加とともに増加し,単位表面積あたりの湿潤熱はGraphon簸に対する交献値とほぼ同程度である。このことから,これらの活性炭の表面の化学的状態は全体としては極性でないと思われる。活性化度の低い炭では,アルコールの単位表面積あたりの湿潤熱は活性化の進んだ炭にくらべてかなり小さく,しかも高級なアルコールほど小さい。このことはすでに活性炭の孔径分布から推定されている細孔組織を考えることによって説明され,活性炭の湿潤熱が試料の細孔組織によって影響されることが示された。

α-, β-, and γ-FeOOH calcined at various temperatures up to 500°C have been examined by determining adsorption isotherms in order to relate the reactivity to SO2 with the structural transformation. For each ferric oxyhydroxide, the amount of chemisorbed SO2 per unit surface area (Ac), a measure of reactivity to SO2, decreases with the progress of transformation into α-Fe2O3. At temperatures of calcination below 200°C the Ac value of β-FeOOH is larger than that of α-FeOOH or γ-FeOOH. It is shown by thermogravimetric analysis that the weight loss of β-FeOOH caused by heating is larger than the theoretical value corresponding to the dehydration of hydroxyl groups; 2FeOOH→Fe2O3+H2O. Changes in the X-ray diffraction patterns and Cl content of β-FeOOH with calcination indicate that β-FeOOH is transformed into α-Fe2O3 with elimination of inherently contained Cl at a higher temperature than other oxyhydroxides. The high reactivity to SO2 and large weight loss of β-FeOOH caused by heating have been discussed with r...

Adsorption behaviors, IR spectroscopy and surface electric properties were studied on the surfaces of well-defined mesoporous silica gels modified with triethoxy(3-aminopropyl)silane (TAS) and [3-(dimethylamino)propyl]diethoxymethylsilane (DDS). Surface free silanol groups react with ethoxyl groups of these compounds rigidly. Isoelectric points and points of zero charge of modified silicas shift from pH 3 of pure material to alkali, but DDS-modified silica gels dissolve themselves in aqueous phase because of their strong alkali environment.

The effect of Cu(II) added to β-FeOOH in various ratios up to 6% Cu/Fe was examined by X-ray diffraction, electron microscope, BET surface area, DTA, TGA and chemical analyses. Differing from other cases reported previously, Cu(II) showed no effect, but thermal changes of the Cu-doped samples indicated a reinforcement of bonding by Cu.