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A simple and generalized method for calculating the composition of the Type I clathrate gas hydrates is discussed. It is suggested that the use of additive terms in the known temperature dependent molar volume values of hexagonal ice is useful in calculating the molar volume of the empty clathrate cage. Since the molecular weight of the gas hydrate is dependent on the occupation, the degree of occupation can be expressed by using the experimental density values of each hydrate. The results so obtained are in fair agreement with the results calculated from experimental density and X-ray lattice constants, and with the values of the experimentally measured compositions.

[Tetraamminecadmium(II)] bis(permanganate) (1) was prepared and its crystal structure was elucidated with XRD-Rietveld refinement and vibrational spectroscopic methods. Compound 1 has a cubic lattice consisting of a 3D hydrogen-bonded network built as four by four distorted tetrahedral blocks of [Cd(NH3)4]2+ cations and MnO4– anions, respectively. The other four permanganate ions are located in a crystallographically different environment, placed in the cavities formed by the attachment of the building blocks. A low-temperature (≈100 °C) solid phase quasi-intramolecular redox reaction producing ammonium nitrate and amorphous CdMn2O4 could be established. Neither solid phase nor aqueous solution phase thermal deammoniation of compound 1 can be used to prepare Cd(MnO4)2 and [Cd(NH3)2(MnO4)2]. During deammoniation of compound 1 in aqueous solution a precipitate consisting of Cd(OH)2 forms. Additionally, solid MnO2 and ammonium permanganate (NH4MnO4) forms. The solid phase deammoniation reaction (toluene used as heat convecting medium) with subsequent aqueous leaching of the ammonium nitrate formed has proved to be an easy and convenient technique for the synthesis of amorphous CdMn2O4+x type NOx and MeSH sensor precursors. The 1-D perdeuterated complex was also synthesized to distinguish the N–H(D) and O–H(D) fragment signals in the TG-MS spectra and to elucidate the vibrational characteristics of the overlapping Mn–O and Cd–N frequencies.

2þ cations. The other four MnO � 4 anions are located in a crystallographically different environment, namely in the cavities formed by the attachment of the building blocks. A low-temperature quasi-intramolecular redox reaction producing NH4NO3 and amorphous ZnMn2O4 could be established occurring even at 1008. Due to H-bonds between the (Zn(NH3)4)2þ cation and the MnOanion, a redox reaction took place between the NH3 and the anion; thus, thermal deammoniation of compound 1 cannot be used to prepare (Zn(NH3)2)(MnO4)2 (contrary to the behavior of the analogous perrhenate (ReO � 4 ) complex). In solution-phase deammoniation, a temperature-dependent hydrolysis process leading to the formation of Zn(OH)2 and NH4MnO4 was observed. Refluxing 1 in toluene offering the heat convecting medium, followed by the removal of NH4NO3 by washing with H2O, proved to be an easy and convenient technique for the synthesis of the amorphous ZnMn2O4.

Among the known three pyridine complexes of silver permanganate, i.e. [Agpy2]MnO4 (1), [Agpy2.25]MnO4 or 7[Agpy2]MnO4[Agpy4]MnO4 (2) and [Agpy2]MnO40.5py (3), compounds (1) and (2) were studied by means of thermal analysis and TG-MS methods. Presuming identical structural motifs for the Agpy2MnO4 blocks in (1) as it has been found in its solvate (3) by single-crystal diffraction, α-C–H...O–Mn H-bonded structures are responsible for a thermally induced low-temperature intramolecular redox reaction observed for the first time between the [Agpy2]+ cation and permanganate anion.

Compositions and chemical identities of compounds formed in silver–permanganate–pyridine–water systems, as well as of their recrystallization products obtained from benzene–acetone solutions, have been elucidated. Three compounds: Agpy2MnO4(1), 7Agpy2MnO4*Agpy4MnO4 (Agpy2.25MnO4) (2) and Agpy2MnO4 * 0.5py (Agpy2.5MnO4) (3) were isolated. The compositions of the products obtained by a method described previously [1] for the preparation of ‘Agpy2MnO4’ (1*) and ‘Agpy2.5MnO4’ (2*) were determined and the constituent compounds identified. It has been established that the instability of compound (3) is due to the presence of the benzene, substituting for pyridine at the solvate sites. The benzene, however, is released at room temperature, disrupting the crystal lattice of (3), and the whole process leads to the loss of the solvate pyridine and to the formation of (1).

The theoretical investigation on the distribution of chemical species obtainable as a function of the temperature of the aqueous solutions of metal complexes containing a basic ligand, altogether with the solubility relationship of the compounds to be formed, offers a simple means of planning the preparation of various types of complexes, double and single salts of the central metal cation and onium type compounds of protonated ligand of the central ion and the anion.

The hot-dip galvanizing sludges have been studied with the aim of establishing phase relations and chemical processes taking place during the thermal treatment. Phase relations in the sludge heated for 1-5 h between 100 and 1000°C were studied by infrared, powder X-ray, Mossbauer, and scanning electron microscopy methods. Dehydration and decomposition processes were also monitored by a thermogravimetry-mass spectrometry technique. Results of the investigations indicate that during the thermal treatment ZnFe 2 O 4 and ZnO were formed, while α- and γ-FeOOH (goethite) as well as the basic zinc chlorides were decomposed and finally cannot be detected in the 1000°C heat-treated samples. Because the major part of the zinc is present in the form of aqueous ammonia-insoluble ferrite, instead of ammoniacal leaching, another technique using, e.g., iron(II) sulfate, has to be used for recovering the zinc from these types of heat-treated samples.

The minimal occupancy level (θmin) of the clathrate lattice of gas molecules is defined as the number of guest molecules in the host clathrate lattice, which can stabilize the thermodynamically unstable empty cage by covering the energy demand of the transformation of hexagonal ice into empty clathrate lattice (ΔHtrans). The θmin values for chlorine hydrate were determined from the n = f(p)T=const. relationship and the average molar intercalation heat of chlorine in the type I clathrate lattice was also calculated for both type of cavities.

Nitric acid activation of bentonite has been studied with the aim of harmonizing bleaching earth and ammonium nitrate fertilizer production, where the latter is obtained from waste acid via neutralization with ammonia. In this paper, a mathematical model is described for composition measurement of the waste acid formed during the activation of the bentonite. On the basis of the results obtained from the model, the amount of concentrated nitric acid necessary for refreshing the recycled acidic solution can easily be estimated. The amounts of the products formed during ammoniacal neutralization, such as ammonium nitrate, hydroxides of hydrolizable metals, and nitrates of nonhydrolizable metals, as well as the amount of activated bentonite, can also be calculated. It is established that, with an increase in the recycling number, the activation process becomes more economical via decreasing energy and material requirements.

A study of the utilization of aqueous decomposition of sodium amalgam for the production of deuterium-depleted water is presented. In the framework of this work the correlation between the deuterium content of the hydrogen gas and the concentration of the aqueous alkali, both formed in the reaction of sodium amalgam with water, is established. The sodium amalgam is prepared via sodium chloride electrolysis. In addition to the formation of an industrial alkaline solution containing 50% w/w sodium hydroxide, hydrogen gas with a deuterium concentration of 50 ppm is obtained. This hydrogen gas is suitable (e.g., via combustion) for the preparation of deuterium-depleted water used, e.g., in cancer therapy.

A simple and sensitive sample combustion—flow-injection technique for measuring nanoequivalent amounts of organic halogens (except fluorine) is presented. The determination of volatile organic halogen (VOX) in water and total organic halogen (TOX) in air, in solid substances and in aqueous solutions is discussed in detail. The sample is subjected to high-temperature combustion in a stream of oxygen. Decomposition products containing halogen are preconcentrated from the gas stream by absorption in a capillary denuder tube coated with a 0.1–0.4 mM aqueous solution of a hydrazine monohydrohalide salt; meanwhile carbon-, sulphur- and nitrogen-containing combustion products are removed by the carrier gas. The hydrohalic acid formed in the liquid film is then eluted with a stream of the absorbent circulated through an electrolytic conductivity microdetector. The change in specific conductance due to the presence of the hydrohalic acid in the effluent stream is linearly related to the amount of halogen in the sample (e.g., up to 100 neq of chlorine). The limit if detection for VOX is 0.01 μeq l−1 and for TOX in air 0.2 μeq m−3. A simple determination takes 5 min. The precision was better than 5% (P=95%) for 3–100 neq of chlorine. The method is also suitable for the determination of total halogen (TX) in aqueous solutions and solid substances. Further, it allows the determination of the partial amounts of halogen species included in the VOX, TOX or TX content of the sample.

Two convenient methods were developed to transformKMnO 4 into barium permanganate and other permanganate saltsvia BaMnO 4 or Mn 2 O 7 intermediates. Pure BaMnO 4 was preparedby the reaction of KMnO 4 with KI in the presence of BaCl 2 andNaOH. Hydrothermal reaction of barium manganate with excesscarbon dioxide for 1.5 h at 100 °C led to barium-permanganatewith almost quantitative yield. Mn 2 O 7 waspreparedbymeansofthe reaction of KMnO 4 and sulfuric acid monohydrate in a two-phase (CCl 4 -H 2 SO 4 .H 2 O) system. In the presence of excess barium Introduction Barium permanganate has been in use for a long time as auseful starting material (s 75 g/L in water at 18 °C, T dec 170 °C) for the preparation of other permanganate salts [1].It has also been applied as a selective solid phase oxidantin organic chemistry [2]. In spite of the widespread appli-cation, however, its convenient synthesis has not beenachieved yet. Potassium permanganate is the only commer-cially available permanganate compounds, but its trans-formation into pure barium permanganate cannot be per-formed directly [3]. Two synthetic precursor, however, na-mely BaMnO

A convenient method for the preparation of alkali- and chloride-free ammonium metavanadate has been developed. This new process is utilizing a hydrothermal reaction of vanadium pentoxide with ammon...

Refluxing montmorillonite-containing raw bentonite ((Na,Ca)o.33(Al,Mg)2Si 4 O 10 (OH) 2 ) in aq HNO 3 , then neutralizing it with NH 3 produces NH 4 NO 3 -containing NH 4 -bentonite. The NH 4 NO 3 intercalated can be eliminated as a gaseous product (N 2 O and H 2 O) by heating at 400 °C, and the deammoniation and dehydroxylation process of the preactivated bentonite leads to formation of bleaching earth (H x (Al,Mg) 2 -ySi 4 O 10 -(OH) 2 ).

Transesterification of fatty acid containing used or nonfood type vegetable oils with methanol in the presence of partially hydrated calcium oxide has been performed. The calcium soaps formed are t...

Iron(III) sulfate or its mixture with aluminium sulfate can be used as a solid phase sulfatizing agent to destroy sodium aluminium silicates in red mud within 2 h at 200–500 °C. These solid phase s...

A convenient method for the preparation of alkali- and chloride-free ammonium metavanadate has been developed. This new process is utilizing a hydrothermal reaction of vanadium pentoxide with ammon...

An absorption/detection system is described for the determination of carbon at and below microgram detection level. The carbon dioxide formed by combustion of an organic substances (solid or in solution) is led into a simple absorption/detection system containing 2.00 cm3 of an ethanolic 2 M solution of 3-methoxypropylamine. The conductivity of the carbamate solution formed is measured by means of platinum electrodes built in the absorption tube, and the integrated d.c. voltage signal obtained is fed to a precision digital voltmeter. Detector response is linear up to 6.6 μg of carbon, and the detection limit is 2 × 10−2 μg. A single determination takes 5 min. Precision was found to be better than +− 1.0% (P-=95%) for 1–6 μg or carbon.

An automatic, rapid combustion method has been developed for the determination of tritium and14C in singly or doubly labelled organic materials by liquid scintillation counting. The sample is burned in a stream of oxygen. The water formed and its tritium content are retained from the gas stream in an absorber containing a small amount of diethyleneglycol monoethyl ether. Radioactive carbon dioxide, if included in the combustion products, is transferred into 3-methoxypropylamine. The final solutions ready for counting are obtained in less than three minutes. Quantitative collection recoveries for both tritium and14C are achieved and no cross-contamination occurs.

An automatic sample preparation method for the determination of35S in organic compounds by liquid scintillation counting is described. The sample is burned in a stream of oxygen and the combustion products are led onto a quartz wool column wetted with dilute hydrogen peroxide. Sulfur oxides are retained on the quartz wool as sulfuric acid, while the other acid producing combustion products are eliminated by evaporation. The residual sulfuric acid in rinsed with distilled water, the sulfuric acid solution obtained is added to a liquid scintillation cocktail and the radioactivity is measured with a liquid scintillation counter. The combustion-evaporation process runs automatically according to the operational program carried out by an electronic programmer.

In this paper an automatic apparatus designed for the radioactivity measurement of14C-labelled organic compounds in the gaseous phase is described. The labelled organic compounds are combusted in a mixture of argon and oxygen. After combustion the oxygen content of the gas is eliminated by passing it through a copper packing. The water and heteroelements present are also removed and the radioactive carbon dioxide gas is swept by argon carrier gas into a piston-type counter tube. In the counter tube the piston forming a dividing wall moves forward in accordance with the rate of combustion and sweeping, and thus sucks the gases leaving the combustion tube into the effective tube volume. The anode wire is carried by a reel located in the piston and a spring device ensures its stretched state. At the end of the sweeping period methane is fed into the counter tube and the activity of the argon—methane—carbon dioxide mixture is measured in the limited proportional region. Manual and automatic operation is possible. The piston-type counter tube provides possibility for strandardization by means of extrapolation and for measurement of absolute activities.

A sample preparation method developed for the simultaneous liquid scintillation assay of tritium and35S in doubly labelled organic materials is described. The sample is burnt in a stream of oxygen and the radioactive isotope carriers formed are collected separately for individual counting.35S content of the sample is measured as a dilute sulfuric acid solution, while the tritium is counted as water. The procedure is free of cross-contamination and memory effect, provides quantitative analytical recovery, and the final solutions ready for counting are obtained in twelve minutes.

An isotope analytical procedure and an automatic instrument developed for the determination of tritium in organic compounds and biological materials by internal gas counting are described. The sample is burnt in a stream of oxygen and the combustion products including water vapour carrying the tritium are led onto a column of molecular sieve-5A heated to 550 °C. Tritium is retained temporarily on the column, then transferred into a stream of hydrogen by isotope exchange. After addition of butane, the tritiated hydrogen is led into an internal detector and enclosed there for radioactivity measurement. The procedure, providing quantitative recovery, is completed in five minutes. It is free of memory effect and suitable for the determination of tritium in a wide range of organic compounds and samples of biological origin.

A combustion procedure is presented, in which the sulphur-containing sample is burnt in a stream of oxygen and the combustion products are led onto a small heated quartz wool column wetted with dilute hydrogen peroxide. Sulphur oxides are retained as sulphuric acid on the quartz wool, while the other combustion products are completely eliminated by evaporation. The residual sulphuric acid is rinsed off with a few ml of distilled water, then titrated with standard alkali. In the case of organic compounds labelled with sulphur-35 the sulphuric acid solution is added to a liquid scintillation cocktail for radioactivity measurement. The combustion-evaporation process takes 15 min, and provides an analytical reproducibility better than 0.3% for sulphur and 0.5% for sulphur-35.

A simple and sensitive technique for measuring both volatile organic carbon (VOC) and total organic carbon (TOC) in water is presented. The VOC fraction is stripped by a stream of oxygen and subjected to high-temperature catalytic combustion after removing the carbon dioxide, obtained from inorganic constituents at pH ⩽ 2, with lithium hydroxide. The residual non-volatile organics (NVOC) are converted into carbon dioxide by injecting an aliquot of the stripped sample directly into the combustion tube. The carbon dioxide derived from the VOC/NVOC is preconcentrated from the gas stream by absorption in a stainless-steel capillary tube coated with a 2 M ethanolic solution of 3-methoxypropylamine. The carbamate formed in the liquid film is then eluted with a stream of the absorbent circulating through a microelectrolytic conductivity detector. The change in specific conductance due to the presence of the carbamate in the effluent stream is linearly related to the amount of VOC/NVOC/TOC up to 4.5 μg of carbon. The limit of detection for VOC is 0.5 μg l−1 and for NVOC it is 100 μg l−1. A simple determination takes 5 min. The precision was better than 5% (P=95%) for 0.5–4.5 μg of carbon. The method is also suitable for the determination of total carbon and inorganic carbon in water.

Verfahren zur radiochemischen Analyse organischer Substanzen, die mit14C, Tritium bzw.35S markiert sind, wurden angegeben. Diese ahnlich der organischen Mikroanalyse durchfuhrbaren Methoden beruhen auf Messungen der Radioaktivitat in der Gasphase ohne Anwendung eines evakuierbaren Systems. Mit weichenβ-Strahlern markierte organische Substanzen lassen sich so mit mikroanalytischer Genauigkeit mit Hilfe einer einfachen Apparatur bei einem Zahleffekt von 96 bis 98% messen.

A procedure and an automatic apparatus designed for the radioactivity measurement of tritium-labelled water in the gaseous phase are described. The method is based on the conversion of water to hydrogen, methane and carbon monoxide in a carbon-packed quartz reactor. The reaction products are swept by hydrogen carrier gas into a piston-type counter tube. Methane is fed to the radioactive gaseous mixture, and the radioactivity of the hydrogen-methane-carbon monoxide mixture is measured in the limited proportional region. The radioactivity values are correlated with the weight of the sample taken and the results are corrected for the ‘memory effect’ obtained in the measurement of inactive water samples. The standard deviation of the procedure, characteristic of its reproducibility, is lower than ±0.5% rel. at preset number of counts.

A procedure has been developed for the activity measurement of tritium-labelled organic compounds in the gas phase. The organic compounds are pyrolysed in hydrogen carrier gas at 1150° and the decomposition products are swept through a carbon packing in accordance with the principle of the oxygen determination developed byUnterzaucher andBurger. The radioactive gas mixture obtained from the sample is swept by the hydrogen carrier gas flowing continuously through the reactor into a proportional counter tube, after the addition of propanebutane counter gas. By closure of the counter tube at a suitable moment, the radioactive gas is quantitatively trapped in the counter tube. The activity is measured in the limited proportional region. No memory effect occurs. The preparation of the sample requires 12 minutes; the relative standard deviation of analysis is

Bis(pyridinium) tetrachlorocuprate monomer 1 and bis(pyridinium) octachlorodiaquatricuprate polymer 2 were synthesized and their crystal structures were determined. Both complexes contain pyridinium cations with bifurcated H-bridges. These H-bridges stabilize the monomeric structure of the tetrachlorocuprate anion together with the steric demand of the relatively large pyridinium ions in the crystal lattice of 1. Conversely, at the lower pyridinium ion:copper(II) ratio of 2, the bifurcated hydrogen bonds reduce the electron density on the chloride ions in such a way that the electron repulsion decreases and coordination spheres with more ligand interactions develop. Obviously, water may be a successful competitor for ligand sites in 2 as well. The octahedral and square-pyramidal structural units condense into polymeric chains which are stabilized by the interchain hydrogen bond networks of the water molecules. The structure motif of SP-5-[OC-6-SP-5-SP-5]-OC-6 (−CuCl5-[CuCl4(OH2)2-CuCl5CuCl5]-CuCl4(OH2)2-) were observed in 2, and the two neighboring square-pyramidal units were found to be localized in a transoid position. The IR and ESR spectroscopical characterization of complexes was also performed.

Automatic sample preparation methods for the determination of carbon–14 and/or tritium, and carbon–14 and/or sulfur–35 in dual labelled samples by liquid scintillation counting are presented. The sample is burnt in a stream of oxygen, and the combustion products carrying radioisotopes are subsequently separated and collected for radioactivity determination. Tritium is measured as water, carbon–14 as “carbamate” and sulfur–35 as sulfuric acid. The procedures run automatically, they are free of memory effect and cross contamination, and provide quantitative recovery.