Sequential oscillations in uncatalyzed bromate oscillator in a closed reactor

Two types of oscillatory regimes separated by a time pause occur during the oxidation of aniline with bromate in sulfuric acid (a Körös-Orbán System) in a closed, stirred batch reactor. It is most likely that sequential oscillations are due to aniline and its oxidation/bromination product.     

Relationship between the average molecular polarizabilities of polycyclic aromatic hydrocarbons and their retention indices determined on various stationary phases

The Kováts retention indices of 10 polycyclic aromatic hydrocarbons were determined on SE-30, OV-101, SE-52, OV-7 and OV-17 stationary phases. A significant correlation has been found between the retention indices and the average molecular polarizabilities of the analyzed substances. Equations were derived for the direct determination of the average molecular polarizabilities from the retention index values. The influence of the temperature on this relationship is also indicated.     

Open tube combustion method of organic samples for stable carbon isotope analysis

A simple and effective method for the conversion of organic carbon into carbon dioxide for analysis of stable carbon isotopes (delta(13)C) in samples of various organic substances, soils, sedimentary rocks, oils and volatile organic liquids is presented. The conversion of organic carbon of the samples is carried out in a quartz reactor connected to a vacuum line for CO(2) freezing and purification. A solid organic sample mixed with CuO is placed at the reactor bottom and the reactor is subsequently filled with granular CuO. One end of the CuO column is preheated to 850 degrees C while the other end of the column in contact with the sample is kept at ambient temperature. Heating of the sample (850 degrees C) and the remainder of the column is then performed. The preheated part of the column provides efficient conversion of carbon into CO(2). The reactor for the conversion of volatile liquid organic compounds is filled with granular CuO. The column of CuO is heated to 850 degrees C. Samples of volatile liquids are introduced into the reactor through a septum using a microsyringe. Complete conversion takes 10 min for solid samples and 3 min for volatile liquids. The precision of the delta(13)C analysis for solid and volatile liquid organic substances is +/-0.1 per thousand and +/-0.04 per thousand, respectively.     

Removal of humic substances from aqueous solutions with a photocatalytic membrane reactor

The process of extraction of humic substances from aqueous solutions in a photocatalytic membrane reactor is studied. It is established that, under optimum conditions, humic substances are removed almost completely. The effect of different grades and concentrations of the catalyst (TiO₂), the oxidant, UV irradiation time, and the pH value of the solution on the degree of purification is investigated. The possibility of using sunlight as the source of radiation in the process of photocatalytic purification is shown.     

Fluorescence monitoring of immobilzed microorganisms in cultures

An experimental reactor system for monitoring the fluorescence of suspended and immobilized cells is described. The growth of S. cerevisiae was monitored during batch fermentations by fluorescence of the culture. Thus, it was possible to use this intracellular parameter to study the influence of immobilization on cells. The fermentations were done under aerobic conditions with suspended and immobilized cells. A comparison of these two systems showed that the rate of ethanol consumption was significantly slower for the cells immobilized in calcium alginate. This reduced rate of oxidative decomposition may be due to mass-transfer limitations of oxygen. Pulse experiments with different substrates (glucose and ethanol) were made to monitor the changes in cell metabolism. The reactor system presented is also suitable as a “toxin guard system”, because substances toxic to cells, such as 2,4-dinitrophenol, cause clearly visible changes in the fluorescence of the immobilized cells.     

Preparation and Application of Immobilized Cells from the Fungus Mucor miehei

A laboratory bioreactor was developed for functionalizing immobilized cells of the mycelial fungusMucor miehei.The ability to use the cells to purify wastewaters from the oil-refining industry is demonstrated. With proper operation of the reactor, immobilized cells (1 g) can purify >100 l of wastewater containing 0.10-0.15% of lipid-like substances.     

Gas chromatographic method to determine formaldehyde traces in automobile exhaust gases

Summary A method for the gas chromatographic determination of traces of formaldehyde is described. The formaldehyde is detected by means of a modified FID which contains a microreactor inside the jet for the hydrogenation of formaldehyde to methane. Only a slight modification to an ordinary FID is needed with no additional gas tubes and no alteration to the existing detector heater. The additional dead volume and peak broadening is negligible. The system is calibrated by means of a gas generator. The described method is used for determining the content of formaldehyde in the exhaust gases of methanol-driven cars.Dedicated to Prof. Dr. István Halász on the occasion of his sixtieth birthday.     

A manometric method for the determination of oxygen in organic compounds

Summary A vacuum apparatus is described for the determination of oxygen in 3 to 5 mg of organic substance. The oxygen of the substance is converted to carbon monoxide by ignition in a bomb at 1050 to 1055° C. Corrections are calculated from thermodynamic data for the amounts of water and carbon dioxide not reacting at the ignition temperature.

---

Zusammenfassung Eine Vakuumapparatur für die Bestimmung des Sauerstoffes in 3 bis 5 mg organischer Substanz wird beschrieben. Der in der Substanz enthaltene Sauerstoff wird durch Erhitzen auf 1050 bis 1055° C in einem geschlossenem Quarzrohr in Kohlenmonoxid übergeführt, das dann in der Vakuumapparatur zu Kohlendioxid oxydiert und durch Absorption gemessen wird. Korrekturen werden aus thermodynamischen Daten für die bei der Verbrennungstemperatur nicht reagierenden Wasser- und Kohlendioxidmengen berechnet.

---

Résumé On décrit un appareil á vide pour le dosage de l'oxygéne sur 3 á 5 mg de substance organique. On convertit l'oxygéne de la substance en oxyde de carbone par combustion dans une bombe, á 1050–1055° C. On calcule les corrections á partir des données thermodynamiques pour l'eau et le gaz carbonique qui ne réagissent pas á cette température.

     

Optimization of conditions for the determination of the organic matter content of waters by reagentless oxithermography and its application to the analysis of natural waters

To determine the chemical oxygen demand (COD) of water by oxithermography, we studied a high-temperature reactor with two inputs of the gas flow. Such a design allowed the creation of an internal circuit of the oxygen–inert gas (argon) binary flow in the reactor for the oxidation of organic substances and the determination of COD by the decrease in the concentration of oxygen in the binary mixture. The optimum operation parameters of the instrument, affecting the analytical characteristics of the method, were determined. The detection limit for a water sample of the volume 10 µL was 3.4 mg O/L. It was shown that the oxithermograph and the proposed procedure can be used for the determination of COD in drinking and natural waters of Bryansk oblast. The approach developed has an advantage, consisting in the reagentless rapid determination of the COD of waters without preliminary sample preparation.     

Gombás pseudopotential SCF calculations for atoms

The Simplified SCF Method of Gombás, in which the orbital orthogonality conditions are replaced by statistical pseudopotentials, has been tested for the first time by accurate numerical calculations without any further approximation. Whereas the original version of the method leads to characteristic error trends, a correction factor recently introduced by Gombás into the pseudopotential expression, produces surprisingly good results.

---

Zusammenfassung Das sog. Vereinfachte SCF-Verfahren von Gombás, bei welchem die Orthogonalitätsbedingungen der Orbitale durch statistische Pseudopotentiale ersetzt werden, wird erstmalig durch saubere numerische Rechnungen getestet. Während die unkorrigierte Version der Methode Resultate mit charakteristischen Fehlern liefert, führt der kürzlich von Gombás abgeleitete Korrekturfaktor im Besetzungsverbotpotential zu überraschend guten Ergebnissen.

---

Résumé La «méthode SCF simplifiée» de Gombás, où les conditions d'orthogonalité des orbitales sont remplacées par des pseudo potentiels statistiques, a été pour la première fois éprouvée avec des calculs numériques précis sans aucune autre approximation. Alors que la version originale de la méthode conduit à des tendances d'erreurs caractéristiques, un facteur de correction récemment introduit par Gombás dans l'expression du pseudo-potential, produit des résultats remarquablement bons.

---

---

Dedicated to the memory of Professor Paul Gombás.

---

This work has been stimulated by discussions with Prof.P. Gombás. Computer time on the IBM 7090 of the GMD at Bonn is gratefully acknowledged.     

Preparation and modification of complex pyrolytic carbon-silica adsorbents

Summary The surface properties of complex adsorbents prepared through the pyrolysis of dichloromethane on the surface of silica gel were investigated. The reaction was carried out in a specially constructed reactor at 400–500°C. The construction and performance of the reactor are described. The modification of the silica gel surface by pyrogenic carbon results in its chemical but not energetical homogeneity. Such adsorbents usually show strong adsorptive properties which limits their use in chromatography. A simple method of homogenizing the porous structure and energetic properties of the adsorptive centers of such adsorbents is presented. The method consists of an additional pyrolysis of an alcohol or other substances on the surface of the carbon-silica adsorbent. Such reactions were carried out under both static and dynamic conditions. The properties of the modified adsorbent depend on the reaction conditions and on the type of the additionally pyrolysed substance.     

Fast analysis by gas chromatography

Summary The efficiency of fast GC columns depends largely on the quality of the chromatograph. A theoretical and experimental study shows the relative importance of the various phenomena involved and permits the optimization of a GC System. Extremely good performances, exceeding 2,500 plates per second have been routinely obtained.Ezzel a tanulmánnyal Halász István Professzor Urat köszöntjük 60. születésnapja alkalmából.     

Overall Kinetics of Heat Treatment of Municipal Solid Waste

A mathematical model of the overall kinetics of heat treatment of municipal solid waste was developed. The model considers the main initial substances and products of the reaction of municipal solid waste treatment at high temperatures (1300–1500°C) in a tubular flow reactor.     

Complexes of metallochromic substances. IV

Summary The dissociation constants of proton complexes of 2-(o-carboxyphenylazo)-naphthionic acid and 2-(o-arsonophenylazo)-naphthionic acid were determined. The optimum conditions for the formation of complexes of these substances with Cu²⁺, and Ni²⁺ were found. The composition of the copper(II) complexes, also their formation and stability constants were estimated.

---

Zusammenfassung Die Dissoziationskonstanten der Protonenkomplexe von 2-(o-Carboxyphenylazo)-naphthionsäure und 2-(o-Arsonophenylazo)-naphthionsäure werden ermittelt. Die optimalen Bildungsbedingungen für die Komplexe dieser Verbindungen mit Cu²⁺ und Ni²⁺ wurden bestimmt. Schließlich wurden auch die Zusammensetzung sowie die Bildungs- und Stabilitätskonstanten der Cu²⁺-Komplexe festgestellt.

---

---

The author wishes to thank Miss L. Krumlová, and Miss D. Vrzalová for their technical assistance in the experimental work.

---

Part III: See Z. analyt. Chem. 207, 178 (1965)     

The effect of ring opening on the MOs of a cyclic polymer

The usual Born-Kármán boundary conditions applied in a tight-binding calculation of a cyclic polymer are relaxed by mixing the Bloch MOs of a particular band under a perturbation which creates certain states associated with the newly-formed ends of the polymer and which have energies outside the range of the particular band.     

Effect of four bentonite samples on the rare earth element concentrations of selected Hungarian wine samples

Rare earth elements (REEs) were detected and determined (except Eu, and in some cases Gd, Tb and Tm) in three Hungarian wine samples - Királyleányka, Blauer Portugieser and Merlot (2004 vintage) - from the Eger viticulture area by double focusing inductively coupled plasma sector field mass spectrometry (ICP-SF-MS) in low resolution mode (R = 300). The REE average concentrations of the samples determined after microwave-assisted digestion were in the pg cm^− 3 concentration range. According to the results, among these grapes grown on volcanic slopes, the REEs uptake by the Királyleányka and Blauer Portugieser seemed to be more inhibited. Four, commercially available bentonite samples - fibrous (Gelbenton), protein containing (Evergel), and two Na bentonites (BW200 and Tükrös) - were used for wine clarifying. Gelbenton altered the less the REE concentrations of the wine samples. The lowest increase (1.1-1.5 times) was established for the Merlot red wine sample.     

Study of the structure and thermal behaviour of intercalated kaolinites

Intercalation complexes of three different Hungarian kaolinites with hydrazine and potassium acetate were investigated by FT-IR (DRIFT) spectrometry, X-ray diffraction, and thermogravimetry combined with mass spectrometry. Differences were found in the thermal behaviour of the complexes as well as in the rehydration — reexpansion patterns of the heated intercalates. An XRD method is proposed for the distinction of kaolinite and 7.2 Å halloysite present in the same mineral.The authors wish to thank Dr. E. Máttyás for providing the kaolinite samples and for carrying out their chemical analysis. Financial support from the Hungarian Scientific Research Fund under grant No. OTKA-014179 is gratefully acknowledged.     

Partical volumes in the water-acetonitrile-tetrahydrofuran system

Summary The necessary information is given to calculate volume fractions in binary systems formed with water, acetonitrile and tetrahydrofuran, in the temperature range 20–50°C.Dedicated to Professor István Halász at the occasion of his 60th anniversary.     

Determination of tricyclic antidepressants using silica gel with a reversed-phase eluent

Summary Five common tricyclic antidepressants are separated on a silica column using an aqueous eluent. The tricyclics are concentrated from serum using an adsorption procedure on a solid phase Sep Pak^TM C₁₈ cartridge. The method appears to be adequate for monitoring therapeutic levels of these drugs.Dedicated to Professor Dr. István Halász for his 60th birthday.     

Über eine stationäre Küvette zur photometrischen Reihenmessung

Zusammenfassung Eine stationäre Durchflußküvette für photometrische Reihenuntersuchungen wird beschrieben. Füllen und Entleeren der Küvette erfolgt mit einer an der Außenseite des Meßgerätes angebrachten Injektionsspritze. Die Vorrichtung läßt sich in jedes Photometer einbauen. Für eine Messung werden 5 ml Untersuchungslösung benötigt. Pro Stunde können 350 bis 600 Einzelmessungen vorgenommen werden.

---

Summary A stationary flow-through cell for photometric series determinations is described. The cell is filled and emptied by means of an injection syringe placed on the outer side of the measuring apparatus. The device can be built into any photometer. A measurement requires 5 ml of test solution. Individual measurements can be made at the rate of 350 to 600 per hour.

---

Résumé On décrit une cuvette á écoulement stationnaire pour les expériences de photométrie en série. On la remplit et on la vide par une seringue á injection, utilisée de l'extérieur du récipient de mesure. On peut adapter le mode opératoire á tout photométre. On a besoin de 5 ml de solution étudiée pour une mesure. On peut exécuter 350 á 600 mesures individuelles á l'heure.