Hydrothermal Alteration of Andesite in Acid Solutions: Experimental Study in 0.05 M H2SO4 Solution at 110 °C

Hydrothermal experiments on an andesite have been carried out under the condition of 110 °C, autogeneous pressure, 0.05 M H₂SO₄ solution and renewal of acid solution every 6 hours. The experimental results indicate that the plagioclase and pyroxenes in the treated samples show micropits and microfractures. Small crystals readily suffered from alteration, as compared with large ones, and the susceptibility of the minerals to the acid solution is decreased in the order of plagioclase, augite, hypersthene and opaque minerals. Plagioclase, which is the most reactive mineral in the experiments, shows an increase of SiO₂, but a decrease of Al₂O₃, CaO and Na₂O as the experiments proceeded. The chemical change of the treated andesite, it indicates that the relative amounts of SiO₂, TiO₂, MgO, ΣFeO, MnO and K₂O increase, while those of Al₂O₃, CaO, Na₂O and P₂O₅ decrease with an increase of the experimental duration. The relative mobility of chemical elements listed in decreasing order is P, Ca, Al, Na, Si, K, Mg, Fe, Mn and Ti in terms of the K value. It is no wonder that Ca, Al and Na are more mobile than others because these elements are readily released into solution from the more reactive plagioclase, while Mg, Fe etc. still stay in the less reactive pyroxenes and opaque minerals.     

Zum Aufbau schlecht geordneter Calciumhydrogensilicate. V 27AI-NMR-spektroskopische Untersuchungen zur Koordination des Al in C–S–H (Di,Poly)

On the Structure of Ill-crystallized Calcium Hydrogen Silicates. V. Studies on the Coordination of Al in C—S—H(Di, Poly) by ²⁷ Al-NMR Spectroscopy The coordination of aluminium incorporated into C—S—H(Di, Poly) (～0.07 Al₂O₃/SiO₂) [1] has been studied by high-resolution solid-state ²⁷ Al-NMR with magic angle spinning (MAS). It is shown that tetrahedrally as well as octahedrally coordinated Al occurs. With increasing CaO/SiO₂ ratio the amount of Al^[4] decreases, while that of Al^[6] increases. Specimens with 1 CaO/SiO₂ contain almost entirely Al—O tetrahedra and those with 1.5 CaO/SiO₂ only Al—O octahedra. Questions concerning the arrangement of Al in the lattice of C—S—H(Di, Poly) are discussed.     

Neue Verbindungen im System CaO/SiO2/CaCl2/H2O

New Compounds in the System CaO/SiO₂/CaCl₂/H₂O The hydrothermal formation of novel calcium silicate hydrates of compositions 5 CaO · 2 SiO₂ · CaCl₂ · 4 H₂O, 5 CaO · 2 SiO₂ · CaCl₂ · 2 H₂O and 4 CaO · 2 SiO₂ · CaCl₂ · H₂O from Ca₃SiO₅ and mixtures of CaO and SiO₂, respectively, in presence of calciumchloride at 200°–350 °C is described. From molybdate-reaction, ²⁹Si MAS NMR, DTA and TG measurements it is concluded that these compounds are based on disilicate anions and are to be interpreted as calcium hydroxide disilicate chlorides.     

Zur Koordination des Aluminiums in den Calciumaluminathydraten 2 CaO · Al2O3 · 8 H2O und CaO · Al2O3 · 10 H2O

On the Coordination of Al in the Calcium Aluminate Hydrates 2 CaO · Al₂O₃ · 8 H₂O and CaO · Al₂O₃ · 10 H₂O By investigations with high-resolution ²⁷Al-NMR in solids it is shown that in the compound 2 CaO · Al₂O₃ · 8 H₂O the Al merely exist in octahedral coordination. According to this and considering its structural relationship with 4 CaO · Al₂O₃ · 19 H₂O the dicalcium aluminate hydrate is proposed to be formulated as [Ca₂Al(OH)₆][Al(OH)₃ (H₂O)₃]OH. Likewise for the compound CaO · Al₂O₃ · 10 H₂O the octahedral coordination of the Al is proved by ²⁷Al-NMR. This result corresponds with literature according to which a constitution as cyclohexaaluminate Ca₃[Al₆(OH)₂₄] · 18 H₂O is proposed.     

Interaction Between Two Similar Plane Parallel Double Layers for (NH4)2Fe(SO4)2 or (NH4)2Cu(SO4)2 Type Complex Salt Electrolytes at Positive Surface Potential

Interaction energies between two similar plane parallel double layers for (NH₄)₂Fe(SO₄)₂ or (NH₄)₂Cu(SO₄)₂ type complex salt electrolytes at positive surface potential were expanded in a power series and accurate numeral results were given for 0.1 ≤ y _e  < y ₀ ≤ 20. The general expressions were given for the interaction energies of A _ν +B _ν′ +C_ν? type complex salt electrolytes at y > 0. The interaction energies for simple salts NaCl, CaCl₂, Na₂SO₄, FeCl₃, Na₃PO₄, Mg₃(PO₄)₂, Al₂(SO₄)₃, and complex salts (NH₄)₂Fe(SO₄)₂ or (NH₄)₂Cu(SO₄)₂ at y ₀ = 1 were compared. There was hardly difference between these simple salts and this complex salt for the interaction energies. The interaction energy for complex salt (NH₄)₂Fe(SO₄)₂ was close to that for simple salt Na₃PO₄.

Supplemental files are available for this article. Go to the publisher's online edition of the Journal of Dispersion Science and Technology to view the free supplemental file.     

Die Kristallstruktur des Natriumoxohydroxoaluminathydrates Na2[Al2O3(OH)2] · 1,5 H2O

The Crystal Structure of the Sodium Oxohydroxoaluminate Hydrate Na₂[Al₂O₃(OH)₂] · 1.5 H₂O The crystal structure of the sodium oxohydroxoaluminate hydrate Na₂[Al₂O₃(OH)₂] ·s 1.5 H₂O (up to now described as Na₂O · Al₂O₃ · 2.5 H₂O and Na₂O · Al₂O₃ · 3 H₂O, respectively) was solved. The X-ray single crystal diffraction analysis (tetragonal, space group P-42₁m, a = 10.522(1) Å, c = 5.330(1) Å, Z = 4) results in a polymeric layered structure, consisting of AlO_3/2(OH) tetrahedral groups. Between these layers the Na⁺ ions are situated, which form tetrameric groups of face-linked NaO₆ octahedra. The involved O^2? ions are due to Al? O? Al bridges, Al? OH groups and water of crystallization. ²⁷Al and ²³Na MAS NMR investigations confirm the crystal structure analysis. The relations between the crystallization behaviour of the compound and the constitution of the aluminate anions in the corresponding sodium aluminate solution and in the solid, respectively, are discussed.     

Nonanatrium-bis(hexahydroxoaluminat)-trihydroxid-hexahydrat (Na9[Al(OH)6]2(OH)3 · 6H2O) – Kristallstruktur,NMR-Spektroskopie und thermisches Verhalten

Nonasodium Bis(hexahydroxoaluminate) Trihydroxide Hexahydrate (Na₉[Al(OH)₆]₂(OH)₃ · 6H₂O) – Crystal Structure, NMR Spectroscopy and Thermal Behaviour The crystal structure of the nonasodium bis(hexahydroxoaluminate) trihydroxide hexahydrate Na₉[Al(OH)₆]₂(OH)₃ · 6H₂O (4.5 Na₂O Al₂O₃ · 13.5 H₂O) (up to now described as 3 Na₂O · Al₂O₃ · 6H₂O, 4Na₂O · Al₂O₃ · 13 H₂O and [3 Na₂O · Al₂O₃ · 6H₂O] [xNaOH · yH₂O], respectively) was solved. The X-ray single crystal diffraction analysis (triclinic, space group P1 , a = 8.694(1) Å, b = 11.344(2) Å, c = 11.636(3) Å, α = 74.29(2)°, β = 87.43(2)°, γ = 70.66(2)°, Z = 2) results in a structure, consisting of monomeric [Al(OH)₆]^3? aluminate anions, which are connected by NaO₆ octahedra groups. Furthermore the structure contains both, two hydroxide anions only surrounded by water of crystallization and OH groups of [Al(OH)₆]^3? aluminate anions and a hydroxide anion involved in three NaO₆ coordination octahedra directly and moreover connected with a water molecule by hydrogen bonding. The results of ²⁷Al and ²³Na-MAS-NMR investigations, the thermal behaviour of the compound and possible relations between the crystal structure and the conditions of coordination in the corresponding sodium aluminate solution are discussed as well.     

Solid-state Al and Si NMR characterization of hydrates formed in calcium aluminate-silica fume mixtures

Partially deuterated Ca₃Al₂(SiO₄)_y(OH)_12−4y-Al(OH)₃ mixtures, prepared by hydration of Ca₃Al₂O₆ (C₃A), Ca₁₂Al₁₄O₃₃ (C₁₂A₇) and CaAl₂O₄ (CA) phases in the presence of silica fume, have been characterized by ²⁹Si and ²⁷Al magic-angle spinning-nuclear magnetic resonance (MAS-NMR) spectroscopies. NMR spectroscopy was used to characterize anhydrous and fully hydrated samples. In hydrated compounds, Ca₃Al₂(OH)₁₂ and Al(OH)₃ phases were detected. From the quantitative analysis of ²⁷Al NMR signals, the Al(OH)₃/Ca₃Al₂(OH)₁₂ ratio was deduced. The incorporation of Si into the katoite structure, Ca₃Al₂(SiO₄)_3−x(OH)_4x, was followed by ²⁷Al and ²⁹Si NMR spectroscopies. Si/OH ratios were determined from the quantitative analysis of ²⁷Al MAS-NMR components associated with Al(OH)₆ and Al(OSi)(OH)₅ environments. The ²⁹Si NMR spectroscopy was also used to quantify the unreacted silica and amorphous calcium aluminosilicate hydrates formed, C-S-H and C-A-S-H for short. From ²⁹Si NMR spectra, the amount of Si incorporated into different phases was estimated. Si and Al concentrations, deduced by NMR, transmission electron microscopy, energy dispersive spectrometry, and Rietveld analysis of both X-ray and neutron data, indicate that only a part of available Si is incorporated in katoite structures.     

Interaction Mechanisms Between Anionic Surfactant Micelles and Different Metal Ions in Aqueous Solutions

In its using or eliminating processes, surfactant solutions usually exhibit different behaviors because of the different species or concentrations of the encountered metal ions. Interactions between anionic surfactant (SDS) micellar solutions and several familiar metal salt solutions (Al₂(SO₄)₃, FeCl₃, CaCl₂ and MgCl₂) were investigated. Precipitates were formed in all systems except SDS‐MgCl₂ visually. Stoichiometric analysis reveals that, in SDS‐Al₂(SO₄)₃ system, the precipitation phenomenon is mainly owing to the effect of adsorption‐charge neutralization between Al³⁺ ions and SDS micelles; in SDS‐FeCl₃ system, bridge connection effect of Fe(OH)²⁺ ions among SDS micelles becomes the dominant mechanism; while in SDS‐CaCl₂ system, all SDS micelles are decomposed and solubility product of Ca(DS)₂ crystal results in the precipitation. SEM photographs of the precipitates can serve as additional vivid proofs of the above conclusion.     

Aus der Chemie von Uranhexachlorid und Uranpentachloridazid

On the Chemistry of Bauxite Extraction. III. Studies in the System Na₂O? MgO? CaO? Al₂O₃? TiO₂? H₂O The formation of crystalline compounds in the system Na₂O? MgO? CaO? Al₂O₃? TiO₂? H₂O was studied at 100°C and atmospheric pressure. Magnesium titanates or magnesium aluminates were not detected in the investigated range of concentrations. In the presence of Ca(OH)₂ the same compounds are formed as in the system Na₂O? CaO? Al₂O₃? TiO₂? H₂O. In addition, sodium aluminates are formed at high sodium and aluminium concentrations.     

晶种协同廉价有机模板导向合成高纯度MCM-49沸石

采用廉价低毒性的环己胺（CHA）作为有机模板剂,并合理添加少量MCM-49沸石晶种,在静态水热条件下成功合成了高纯度MCM-49沸石.研究了起始凝胶组成（如Al₂O₃/SiO₂,H₂O/SiO₂,CHA/SiO₂,晶种/SiO₂,Na₂O/SiO₂）、晶化温度和时间等因素对合成MCM-49沸石的影响.通过XRD、SEM、N₂吸附、固体²⁷Al和²⁹Si MAS NMR等手段表征产物,结果表明合成的MCM-49沸石具有良好的结晶度、均匀的晶体尺寸、高比表面积和纯的四配位Al³⁺物种.热重差热分析（TG-DTA）和固体¹³C MAS NMR表征结果证实CHA是作为模板剂填充在沸石产物的孔道内.这种合成MCM-49的方法具有廉价和低毒性的特点,对其产业应用有潜在的重要价值.     

Crystal structure,thermal decomposition mechanism and catalytic performance of hexaaquaaluminum methanesulfonate

Hexaaquaaluminum methanesulfonate crystals, [Al(H₂O)₆][CH₃SO₃]₃ were synthesized by a hydrothermal reaction of Al(OH)₃ with methanesulfonic acid. Single-crystal diffraction determination revealed that Al³⁺ was coordinated by six water molecules in octahedral geometry, while the CH₃SO₃^– anion connected with Al³⁺ through coordinated water molecules by hydrogen bonds. The six-coordinate environment of Al was also determined by ²⁷Al MAS NMR measurement. Thermogravimetric analysis and Fourier transform infrared spectroscopy showed that the decomposition intermediate at 265–365 °C was Al₂(μ-OH)(CH₃SO₃)₅ and the final product was amorphous Al₂O₃ residue with about 0.8 wt% SO₃ at 520–800 °C. A pure phase of [Al(H₂O)₆][CH₃SO₃]₃ was confirmed by powder X-ray diffraction analysis. Esterification of n-butyric acid with n-butanol and ketalization of cyclohexanone with glycol catalyzed by [Al(H₂O)₆][CH₃SO₃]₃ and Al₂(μ-OH)(CH₃SO₃)₅, respectively, proceeded in 100% yield by continuously removing the produced water. In the case of tetrahydropyranylation of n-butanol at room temperature in dichloromethane, the catalytic activity of [Al(H₂O)₆][CH₃SO₃]₃ was much lower than that of Al₂(μ-OH)(CH₃SO₃)₅. Furthermore, both [Al(H₂O)₆][CH₃SO₃]₃ precursor and Al₂(μ-OH)(CH₃SO₃)₅ catalysts could be recycled.     

Infrared study of surface species arising from ammonia adsorption on oxide surfaces

Infrared spectra of ammonia adsorbed on CoO, NiO, SiO₂, CaO, MgO, ZrO₂, ZnO, TiO₂, BeO and Al₂O₃, have been studied in the NH stretching and bending vibration regions at various stages of sample dehydroxylation. Several types of adsorption were found: hydrogen bonding to surface oxygen atoms or hydroxyl groups, coordination to Lewis acid sites and coordination plus hydrogen bonding; on some oxides ammonia molecules dissociate to produce surface NH₂ and OH groups. Frequencies characteristic of the distinct adsorbed species were determined. Except for Al₂O₃, no evidence was found for Brönsted acid sites on the surface of the above oxides.     

A near-infrared study of the hydration of various ions and nonelectrolytes

The differential infrared absorption spectra of H₂O at 1200 nm and HOD/D₂O at 1450 nm have been recorded as function of temperature between 2 and 55°C. Following earlier investigations in the 1000 nm region,^(1,2) the data were interpreted on the basis of a hydrogen-bonding equilibrium invoking two states of the OH oscillators which are found to differ by a van't Hoff heat of formation of 2–3 kcal-mole^–1. The spectral changes induced by various non-electrolytes (1.0m) on the 1000 nm band have been recorded at 25°C for the following: tetrahydrofuran, tetrahydropyran, dioxane, dimethoxyethane, dimethyl sulfoxide, acetone, methyl acetate, propylene carbonate, dimethylformamide, dimethylacetamide, tetramethylurea, acetonitrile, and nitromethane. The specific influence of hydrocarbon chains on the near-IR absorption spectrum of water was further studied using a series of homologous sodiumn-alkyl carboxylates (formate to octanoate). The differential solvation spectra of three azoniaspiroalkane bromides have been obtained to compare the relative effects of cyclic and linear alkyl substituents. Finally, the study of ionic hydration effects has been extended to include the following electrolytes: NaPF₆, NaClO₄, NaBF₄, NaClO₃, NaNO₃, NaBrO₃, NaCN, NaSCN, Na₂SO₄, Na₂SO₃, Na₂CO₃, Na₂S₂O₃, MgCl₂, CaCl₂, BaCl₂, and SrCl₂. These data are discussed in terms of perturbations of the hydrogen-bonding equilibrium in water originating from one of the following: (1) direct OH... [polar group or anion] interactions, (2) structure-breaking effects due to weak OH... solute interactions, and (3) water-structure-promoting effects by alkyl groups.     

Beiträge zur Chemie des Bauxitaufschlusses. Untersuchungen im System Na2O?CaO?Al2O3?TiO2?H2O im Temperaturbereich 100–275°C

On the Chemistry of Bauxite Extraction. II. Studies in the System Na₂O? CaO? Al₂O₃? TiO₂? H₂O between 100 and 275°C The formation of crystalline compounds in the system Na₂O? CaO? Al₂O₃? TiO₂? H₂O was studied between 100 and 275°C. With caustic alkali concentrations up to 300 g Na₂O/l the calcium aluminate 3 CaO · Al₂O₃ · 6 H₂O is formed. With rising temperatures two different calcium titanates, among them perovskite, CaTiO₃, are identified. Above 200°C perovskite is formed at all concentrations investigated.     

Calcium aluminates hydration in presence of amorphous SiO2 at temperatures below 90 °C

The hydration behaviour of Ca₃Al₂O₆, Ca₁₂Al₁₄O₃₃ and CaAl₂O₄ with added amorphous silica at 40, 65 and 90 °C has been studied for periods ranging from 1 to 31 days. In hydrated samples crystalline phases like katoite (Ca₃Al₂(SiO₄)_3−x(OH)_4x) and gibbsite, Al(OH)₃, were identified, likewise amorphous phases like Al(OH)_x, calcium silicate hydrates, C-S-H, and calcium aluminosilicate hydrates, C-S-A-H, were identified. The stoichiometry of Ca₃Al₂(SiO₄)_3−x(OH)_4x (0?3−x?0.334), which was the main crystalline product, was established by Rietveld refinement of X-ray and neutron diffraction data and by transmission electron microscopy.     

Effect of Alkaline Salts on Calcium Sulfoaluminate Cement Hydration

This work analyzes the effect of the presence of 5 wt.% of solid sodium salts (Na₂SO₄, Na₂CO₃, and Na₂SiO₃) on calcium sulfoaluminate cement (CSA) hydration, addresses hydration kinetics; 2-, 28-, and 90-d mechanical strength, and reaction product microstructure (with X-ray diffraction (XRD), and Fourier transform infrared spectroscopy, (FTIR). The findings show that the anions affect primarily the reactions involved. Ettringite and AH₃, are the majority hydration products, while monosulfates are absent in all of the samples. All three salts hasten CSA hydration and raise the amount of ettringite formed. Na₂SO₄ induces cracking in the ≥28-d pastes due to post-hardening gypsum and ettringite formation from the excess SO₄^2– present. Anhydrite dissolves more rapidly in the presence of Na₂CO₃, prompting carbonation. Na₂SiO₃ raises compressive strength and exhibits strätlingite as one of its reaction products.     

Production of Granulated NaP Zeolite without Binder

Possibility was examined of synthesizing zeolites granulated without a binder with the use of a preliminary ultrasonic treatment of the suspension at a frequency of 22 kHz from mixtures of sodium metasilicate and aluminum and silicon oxides with various Si: Al ratios. It was found that, after the preliminary treatment, extrusion of grains, and calcination at 650°C, crystalline phases Na₆Al₄Si₄O₁₇, Na₈Al₄Si₄O₁₈, Na₂Al₂O₄, and Na₂SiO₃ phases are formed in the sample with Si: Al = 1. These phases are precursors for synthesis of NaA and NaP zeolites and sodalite via hydrothermal crystallization in a NaOH solution with concentration of 2 M. Upon a similar treatment of a sample with Si: Al = 2, there are crystalline phases α- and β-Na₂Si₂O₅, from which only NaP zeolite is formed in the course of crystallization. The hydrothermal crystallization in a 6 M alkali solution yields sodalite, irrespective of the Si: Al ratio. It was shown that an ultrasonic treatment gives a gel-like system at Si: Al = 1 and a powdered material at Si: Al = 2, which yields by the end of synthesis samples with cactus-like or wool-like morphology, respectively.     

Pyrolysis–gas chromatographic analysis of poly(vinyl chloride). II. In situ absorption of HCl during pyrolysis and combustion of PVC

A pyrolysis–gas chromatographic technique for measuring the amount of hydrogen chloride released during the high temperature pyrolysis of poly(vinyl chloride) resins, plastisols, copolymers and compounds containing inert fillers has been developed. The technique, which is also applicable to the analysis of chlorinated polyethylene and chlorinated poly(vinyl chloride), is based on the use of a standard precursor of HCl, poly(vinyl chloride) homopolymer. The analysis has been successfully used to measure the degree of in situ absorption of HCl during pyrolysis by certain basic fillers [K₂CO₃, CaCO₃, CaO, MgO, Al(OH)₃, Na₂CO₃, Al₂O₃ and LiOH] dispersed in a poly(vinyl chloride)–o-dioctyl phthalate matrix. Combustion of a number of combustion residues (chloride determination) revealed that the amount of HCl absorbed by the basic filler was independent of the method of degradation (pyrolysis or combustion). Flammability measurements of those matrices having the same composition indicate that in situ absorption of HCl during combustion has little effect on the overall flammability of these materials.