István Gács

Hungarian Academy of Sciences | HAS · retired lab.head

A new type of bioreactor containing a porous permeable wall to recover the biobutanol produced in anaerobic ABE fermentation processes is presented. The ferment liquor is contacted with an organic solvent and the butanol in the fermentation liquor distributes between the organic phase and the ferment liquor. The butanol containing solvent located a...

The scarcely reactive zinc ferrite can be decomposed in solid phase to water-soluble ZnSO4 and water-insoluble Fe2O3 polymorphs by excess of solid iron(II or III) sulphates at 650°C in 4 h. Since SO3 forms in situ from the Fe2(SO4)3 as well as anhydrous Fe2(SO4)3 forms in the thermal oxidation of iron(II) sulphate, therefore the gaseous SO3 is the...

Deuterium isotope separation process takes place in the reaction of the amalgamated aluminium metal surface and water. The reaction produces hydrogen gas with ~40 ppm deuterium content and the formed aluminium hydroxide gel is enriched in deuterium. The theoretical separation factor is s=3.9. Besides the kinetic isotope effect, the key factor in th...

A simple and generalized method for calcg. the compn. of the Type I clathrate gas hydrates is discussed. It is suggested that the use of additive terms in the known temp. dependent molar volume values of hexagonal ice is useful in calcg. the molar volume of the empty clathrate cage. Since the mol. wt. of the gas hydrate is dependent on the occupati...

The minimal occupancy level (θmin) of the clathrate lattice of gas mols. is defined as the no. of guest mols. 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 w...

[Tetraamminecadmium(II)] bis(permanganate) (1) was prepd. and its crystal structure was elucidated with XRD-Rietveld refinement and vibrational spectroscopic methods. Compd. 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, resp. The other fo...

A review. Potassium permanganate is one of the most widely used chems. in chem. and chem. industry, however, the available information about the chem. of other permanganate compds. has not been reviewed. In this paper synthetic methods and reactivity of simple and complex permanganates other than the potassium salt are critically reviewed. Generali...

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Refluxing montmorillonite-contg. raw bentonite ((Na,Ca)0.33(Al,Mg)2Si4O10(OH)2) in aq. HNO3, then neutralizing it with NH3 produces NH4NO3-contg. NH4-bentonite. The NH4NO3 intercalated can be eliminated as a gaseous product (N2O and H2O) by heating at 400 °C, and the deammoniation and dehydroxylation process of the preactivated bentonite leads to f...

Transesterification of fatty acid contg. used or nonfood type vegetable oils with methanol in the presence of partially hydrated calcium oxide has been performed. The calcium soaps formed are treated with sulfuric acid without sepn. from the ester phase, and the free acids formed are immediately converted to ester with the excess of methanol and th...

Tetraamminezinc(II) dipermanganate ([Zn(NH3)4](MnO4)2; 1) was prepd., and its structure was elucidated with XRD-Rietveld-refinement and vibrational-spectroscopy methods. Compd. 1 has a cubic lattice consisting of a 3-dimensional H-bound network built from blocks formed by four MnO-4 anions and four [Zn(NH3)4]2+ cations. The other four MnO4- anions...

Two convenient methods were developed to transform KMnO4 into barium permanganate and other permanganate salts via BaMnO4 or Mn2O7 intermediates. Pure BaMnO4 was prepared by the reaction of KMnO4 with KI in the presence of BaCl2 and NaOH. Hydrothermal reaction of barium manganate with excess carbon dioxide for 1.5 h at 100 °C led to barium-permanga...

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 degrees C. These solid phase sulfatizing agents transform sodium aluminium silicates and basic sodium-compounds into water-soluble sodium sulfate without SO2 or SO3 evolution....

A convenient method for the prepn. of alkali- and chloride-free ammonium metavanadate was developed. This new process is using a hydrothermal reaction of V2O5 with ammonium hydroxide or ammonium carbonate for 2 h at 120° in a Teflon-lined stainless steel autoclave. The yields are 78 and 82%, resp.

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...

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 compo...

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 an...

A mixture of ZnFe2O4 and ZnO can easily be produced by heating fresh or sintered hot-dip galvanizing sludges at 1000 °C for 5 h. Ammoniacal leaching of this mixture with a concentrated ammonia solution at room temperature by applying a 60-fold molar excess of ammonia over the whole amount of zinc for 24 h (or using a 48-fold excess of ammonia for 7...

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...

A simple and rapid method for trace determination of SO2 and H2S in gaseous samples by using a flow injection system with on line preconcentration on capillary denuder is described. The gaseous samples are led through a 0.4 M sulphamic acid solution, retaining nitrogen dioxide, ammonia and hydrogen chloride. The sulphur dioxide is collected from th...

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, Mössbauer, and scanning electron microscopy methods. Dehydration and decomposi...

The oxidn. or consecutive ammoxidn. reaction of benzyl alc. with solid ammonium permanganate was studied. The first oxidn. step leads to the formation of benzaldehyde, ammonia, and MnO2. The MnO2 is present in the system in a colloidal form, which facilitates the reaction between aldehyde and ammonia, and this latter reaction then yields benzonitri...

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...

A new ammoniacal leaching process for recovering zinc in hot dip galvanizing sludge is presented. Exptl. results indicate that the zinc can be efficiently leached at room temp. and atm. pressure. Two-third of the zinc could be recovered as tetraamminezinc(II)hydroxide in a one-hour extn. process if the sludge to the reagent (25%wt./wt. NH4OH) ratio...

A study of the utilization of aq. decompn. of Na amalgam for the prodn. of deuterium-depleted water is presented. The correlation between the D content of the H gas and the concn. of the aq. alkali, both formed in the reaction of Na amalgam with water, is established. The Na amalgam is prepd. via NaCl electrolysis. In addn. to the formation of an i...

Isotope sepn. under in-situ generation of hydrogen gas by a chem. reaction between a sodium amalgam reagent and natural water is considered. The efforts were directed to obtain deuterium-depleted hydrogen gas and water.

This study is focused on the speciation of selected elements in oil ash. Our efforts were directed primarily to obtain information on the various forms of vanadium, chromium and nickel. One sample was characterized via its total composition and via its capacity for releasing various elements. The latter was estimated by hot water and nitric acid ex...

A simple and sensitive flow-injection technique for measuring nanomole amounts of sulphur dioxide in gaseous atmospheres is presented. The samples are passed through 0.2 M sulphamic acid solution to eliminate constituents interfering with the final electrolytic conductivity measurement. Sulphur dioxide is preconcentrated from the carrier gas stream...

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 t...

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. T...

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...

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 diethylene...

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 a...

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 deter...

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 th...

An analytical procedure and an automatic apparatus are described for the determination of tritium in organic compounds by gas counting. The sample is pyrolysed in hydrogen atmosphere at 1000°C, then, with hydrogen, the decomposition products are rinsed through a column of molecular sieve-5A heated to 550°C. Tritium in water, hydrogen sulphide, ammo...

A new, automatic procedure developed to convert tritium in HTO into hydrogen for subsequent on-line gas counting is described. The water containing tritium is introduced onto a column prepared from molecular sieve-5A and heated to 550 °C. The tritium is transferred by isotopic exchange into hydrogen flowing through the column. The radioactive gas i...

An isotope analytical method for the simultaneous determination of35S and14C in double-labelled organic compounds by liquid scintillation counting is described. The sample is burned in a stream of oxygen. Sulfur oxides are converted to sulfuric acid and separated from other combustion products, including carbon-14 dioxide, on a heated quartz wool c...

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 hea...

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 heteroel...

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...

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 andBrger. The...

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...

Zusammenfassung Verfahren zur radiochemischen Analyse organischer Substanzen, die mit14C, Tritium bzw.35S markiert sind, wurden angegeben. Diese ähnlich der organischen Mikroanalyse durchführbaren Methoden beruhen auf Messungen der Radioaktivität in der Gasphase ohne Anwendung eines evakuierbaren Systems. Mit weichenß-Strahlern markierte organische...

A radiometric method has been developed for the quantitative determination of the hydrogen and oxygen contents of organic materials. The water is converted to carbon monoxide in the presence of radioactive carbon and its activity (after the oxidation) is measured in the gas phase. For the radiometric determination of the hydrogen content, water is...

A new method for the gas phase activity measurement of 35S labelled organic compounds is described. Organic compounds are destructively hydrogenated and the sulphur products of pyrolysis are quantitatively converted into hydrogen sulphide over a platinum catalyst. No vacuum apparatus is needed for the analysis which is similar to the procedure used...