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1.
Summary A very sensitive reaction for sulphur dioxide is proposed for use on the micro and ultramicro scales. Interference by cyanide, sulphide, and thiosulphate can be prevented. Sulphite can be distinguished from bisulphite.
Zusammenfassung Eine sehr empfindliche Reaktion zum Nachweis von Schwefeldioxid im Mikro- und Ultramikromaßstab wurde vorgeschlagen. Störungen durch Cyanid, Sulfid und Thiosulfat lassen sich vermeiden. Sulfit kann von Hydrogensulfit unterschieden werden.
Résumé On propose une réaction très sensible pour la recherche de l'anhydride sulfureux à l'échelle micro et ultramicro. On peut éviter l'interférence avec les cyanures, les sulfures et les thiosulfates. On peut distinguer les sulfites des bisulfites.相似文献
2.
The determination of sulphur in petroleum products by combustion, concentration of the sulphur dioxide in sodium tetrachtoromercurate solutions and cool flame molecular emission is described. Improvements in burner design and optimization of analytical conditions result in a minimum detectable amount of 6 ng of sulphur. The absorption of sulphur dioxide from air samples and its determination by a similar method gives a detection limit of 1.3 μg SO2 m-3. 相似文献
3.
A fibre-optic sensor for continuous measurement of sulphur dioxide is described. It is based on the dynamic quenching of the fluorescence of a polynuclear aromatic hydrocarbon [benzo(b)fluoranthene] which is immobilized in silicone polymer. Sulphur dioxide is shown to be an efficient quencher; Stern-Volmer graphs are given which describe the relation between SO2 concentration and relative fluorescence. Detection limits are about 0.01% (v/v) SO2 in air; the useful range is from 0.01–6% (v/v). Other gases likely to occur in air were found to be inert, except for oxygen which also acts as a dynamic quencher. Its interference is negligible for SO2 levels below 6% in air at constant oxygen pressure, because the quenching efficiency of SO2 is about 26 times higher than that of oxygen. For varying oxygen levels, a two-sensor technique is suggested. 相似文献
4.
Summary Studies were made of the permeation, solution, and diffusion of sulphur dioxide in polyethylene, polyamide (Nylon 11), and
polycarbonate at 25 °C and at pressures up to one atmosphere. The steady-state permeability coefficients of sulphur dioxide
in all three polymers were pressure-dependent, and the effect of pressure on the solution and diffusion processes, which together
govern the overall permeation process, account for the observed relations. Solution and diffusion in the two glassy polymers,
polyamide and polycarbonate, were strongly pressure-dependent whereas in polyethylene diffusion was pressure-dependent but
solution obeyed Henrys law. The vapour pressure isotherms of the glassy polymers obeyed a modified Langmuir expression suggesting that two concurrent sorption mechanisms were operative, the filling of microvoids within the polymer
structures and ordinary Henrys law solution. Kinetic sorption-desorption studies showed that diffusion was “Fickian” in polyethylene and polyamide over
the entire pressure range. It was also “Fickian” in polycarbonate at pressures up to approximately 25 cm Hg, but “non-Fickian”
at higher levels. For each polymer, diffusion coefficients were determined by steady-state permeation and transient sorption-desorption
methods, and the separate methods gave similar values.
Zusammenfassung Permeation, L?sung und Diffusion von Schwefeldioxid in Poly?thylen, Polyamid (Nylon 11) und Polycarbonat wurden bei 25 °C und Drucken bis zu einer Atmosph?re untersucht. Die station?ren Permeationskoeffizienten von Schwefeldioxid waren in allen drei Polymeren druckabh?ngig, und es erwies sich der Einflu? des Druckes auf die den Permeationsvorgang bestimmenden L?sungs- und Diffusionsvorg?nge als verantwortlich für die beobachteten Beziehungen. L?sung und Diffusion in den beiden glasigen Polymeren, Polyamid und Polycarbonat zeigen eine starke Druckabh?ngigkeit, w?hrend die Diffusion im Poly?thylen zwar druckabh?ngig war, der L?sungsvorgang jedoch dem Henryschen Gesetz gehorcht. Die Dampfdruckisothermen der glasigen Polymeren gehorchen einem modifizierten Langmuirschen Ausdruck, womit sie andeuten, da? zwei Sorptionsmechanismen gleichzeitig wirksam sind: die Auffüllung der Mikrohohlr?ume im Inneren des Polymergefüges und eine normale Henrysche L?sung. Kinetische Sorptions-Desorptionsuntersuchungen haben gezeigt, da? es sich bei Poly?thylen und Polyamid im ganzen Druckbereich um eine Ficksche Diffusion handelt. Das gleiche gilt für Polycarbonat bei Drucken bis zu etwa 25 cm Hg, jedoch nicht für h?here Drucke. Für jedes Polymer wurden die Diffusionskoeffizienten mit Hilfe von station?ren Permeationsund nichtstation?ren Sorptions- und Desorptionsverfahren ermittelt, wobei die Verfahren ?hnliche Werte ergaben.相似文献
5.
The generator is based on permeation of sulphur dioxide through silicone rubber tubes immersed in a buffered, thermostated solution of sodium hydrogensulphite. The generator contains three (or more) permeation tubes of different lengths immersed simultaneously in the generation solution. The tubes can be connected stepwise to the carrier gas source, so that three (or more) different concentrations of SO2 in the carrier gas can be obtained from a single solution. The tested generator produced 1.25–25.4 ng s?1 SO2, depending on the hydrogensulphite concentration in the solution. Long-term stability was tested for the production of 10.49 ng s?1 over 50 h; the relative standard deviation was 1.57%. The experimental conditions affecting the production of SO2 are discussed. An equation is derived for estimating the SO2 production for various solution compositions and surface areas of the permeation tubes. 相似文献
6.
An operationally inexpensive and sensitive spectrophotometric procedure for sulphur dioxide is proposed. The reagent 5,5-dimethyl-1,2,3-cyclohexanetrione-1,2-dioxime-3-thiosemicarbaz one is used to determine trace amounts of sulphur dioxide indirectly by means of the reduction of Fe(III) to Fe(II). The method can determine down to 0.032 microg/ml of sulphur dioxide in the final solution and recoveries are better than 98%. The method can be applied to the determination of atmospheric SO(2) provided that interfering gases such as nitrogen dioxide and hydrogen sulphide are eliminated. 相似文献
7.
We have demonstrated the formation of a reactive species from ketene and sulfur dioxide and have investigated some of its reactions. The 3 + 2 ← 5 cycloaddition reactions of this intermediate with benzylideneaniline and its derivatives gave the corresponding 2,3-diphenylthiazolidin-4-one 1,1-dioxides. The reduction of 2,3-diphenylthiazolidin-4-one 1,1-dioxide with lithium aluminum hydride yielded the corresponding thiazolidine. Aniline and its derivatives reacted with the ketene-sulfur dioxide adduct to give thioaceto-1,3-dianilide 3-oxide. o-Phenylenediamine gave [2,1,5]benzothiadiazepin-4-one 2-oxide, a derivative of a new ring system, [2,1,5]benzothiadiazepine. o-Aminophenol yielded [1,2,5]benzothiazepin-4-one 2-oxide. 相似文献
8.
The formation of VC-SO2 and VC-(SO2)2 complexes in liquid mixtures of vinyl chloride (VC) and sulphur dioxide has been shown by (a) the freezing point composition diagram and (b) chemical shifts in the PMR spectrum of VC over the complete composition range. It is postulated that SO2 can associate with the CC bond and the Cl atom. These complexes may be involved in the copolymerization and influence the composition and stereochemistry of the product. PMR spectra of VC-SO2-ethane(E) mixtures with [SO2] ? [E] ? [VC] gave Kv = 2·0 ± 0·5, 1·5 ± 0·1 and 1·1 ± 0·3 at 232·6, 272·6 and 301·3 K with ΔHf0Hf = ?6·6 ± 1·4 kJ mol?1 for the VC -(SO2)2 complex. The chemical shift of the trans β-proton was twice that of the other two protons. indicating that SO2 adopts an asymmetric orientation to the double bond. 相似文献
9.
H. Flyger J. Fenger E. Lund Thomsen E. Lewin S. E. Gryning E. Lyck 《Fresenius' Journal of Analytical Chemistry》1976,282(4):297-300
Summary Pertinent, previous studies of the oxidation of SO2 in the atmosphere are briefly reviewed. A project dealing with the conversion in the plume from an oil-fired power station is described in greater detail. Measurements were performed from an aircraft and included continuous registration of NOx, SO2 and ozone concentrations. The possibility of using NOx as an internal tracer is discussed; also the use of the inert tracer SF6 is treated and a special detector for the continuous registration of SF6 in relative concentrations down to 10–6 ppm is described. Preliminary results indicate a half-life for SO2 in the plume of about half an hour.
Umsetzung von Schwefeldioxid in der Atmosphäre
Zusammenfassung Einschlägige frühere Studien über die Oxidation von SO2 in der Atmosphäre werden kurz diskutiert. Ein Projekt zum Studium der Umwandlung im Abrauch eines ölbefeuerten Kraftwerkes wird im Detail beschrieben. Die Messungen wurden mit Hilfe eines Flugzeuges vorgenommen und schließen die kontinuierliche Aufzeichnung von NOx-, SO2- und Ozon-Konzentrationen ein. Die Möglichkeit der Verwendung von NOx als interner Indicator wird diskutiert. Außerdem wird der Gebrauch des inerten Indicators SF6 behandelt und ein spezieller Detektor für die kontinuierliche Aufzeichnung von SF6 mit relativen Konzentrationen bis herunter auf 10–6 ppm beschrieben. Vorläufige Ergebnisse deuten auf eine Halbwertszeit von SO2 im Abrauch von etwa 30 min hin.
Presented at the 6th Annual Symposium on Recent Advances in the Analytical Chemistry of Pollutants, April 21–23, 1976; Vienna, Austria 相似文献
10.
Sulphur contents of the original sample and the sample free from sulphur dioxide were determined by ICP-AES following nitric acid digestion under high pressure (using PAAR HPA equipment), and the total sulphur content was calculated from the difference between the results obtained. With the aim of preparing a sample free from sulphur dioxide, bound sulphur dioxide was released by sodium hydroxide, then after acidifying by phosphoric acid, boiling was carried out. Relative standard deviations of the results obtained for total sulphur, the sulphur without S(IV) and total sulphur dioxide were lower than 2.5, 3.5 and 5% respectively. Various amounts of sulphur (in the form of Na2SO4), added to wine samples, were successfully recovered between 95.5 and 104.9%. Based on comparative analyses performed by a widely accepted classic method, the indirect method developed was found to be adequate for the determination of total sulphur dioxide. The procedure is suitable for serial tests. 相似文献
11.
In catalytic concentrations (10?5?10?4 mol l?1) sulphur dioxide induces polymerization of MMA, particularly on photoactivation. The effective initiating species appears to be the monomer-SO2 complex rather than free SO2. A mechanism involving biradical initiation by decomposition of the initiating species, linear propagation in two directions, and significant termination of growing chains by chain transfer with initiating species has been suggested. The initiator transfer constant is 1.6 at 40°. 相似文献
12.
《Physics and Chemistry of Liquids》2012,50(2):349-353
The solubility of sulphur dioxide in N,N-dimethylformamide, dimethyl sulphoxide, N,N-dimethyl acetamide, sulpholane, tributyl phosphate and diethanolamine has been determined. A solubility model is proposed and the solubilities calculated by the model show good agreement with experimental data. 相似文献
13.
《The Chemical Engineering Journal》1993,51(2):99-108
A model has been developed for the removal of sulphur dioxide from flue gas by absorption into a limestone slurry. The flue gas desulphurization unit consists of an absorber tower and an oxidation tank. Flue gas enters the absorption tower at the bottom and meets the limestone slurry. There are five important chemical reactions with a finite rate. The rate-limiting reactions are limestone dissolution, calcium sulphite precipitation and dissolution, gypsum precipitation, sulphur dioxide absorption and sulphite oxidation in the slurry. The model also accounts for the presence of chloride ions, magnesium ions and organic acids in the limestone slurry. The absorption rates of sulphur dioxide and carbon dioxide in the tower are calculated according to the two-film model. A non-uniform set of limestone particles is also included in the model. The model was tested against literature data and the agreement between the data and the model was satisfactory. A sensitivity analysis of the desulphurization process was carried out, the inputs to the model were changed and the results from the calculations were compared with the expected results. The response to the change in the inputs agreed well with the expected results. 相似文献
14.
The contour of the band of SO2 at 29937 cm?1 has been shown to be of type-c, and an approximate excited state structure derived as rSO = 1.50 Å, valence angle = 112°. For a number of reasons it is proposed that the principal bands between 3150 and 3400 Å correspond to vibronically induced B1-A1 transitions of a 1A2-1A1 forbidden electronic transition rather than to an allowed 1B1-1A1 transition. 相似文献
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16.
The merits of the nitroanilines as an alternative to p-rosaniline and fuchsine in the colorimetric determination of sulphur dioxide and sulphites have been investigated. p-Nitroaniline was found to be a stable, well-defined reagent, with which sulphur dioxide can be determined to a high level of precision, the sensitivity being of the same order of magnitude as for p-rosaniline. 相似文献
17.
食品中二氧化硫的含量测定 ,采用的是国家标准GB5 0 0 9.34 96盐酸副玫瑰苯胺法[1 ] ,但该法在实际运用中却存在着许多不足之处 ,如SO2 的吸收剂采用的是剧毒四氯汞钠试剂 ,且该试剂配制好后需放置过夜后过滤才可使用 ;而显色剂盐酸副玫瑰苯胺溶液的配制也较为麻烦 ,需时较长 ;更为严重的是 ,该法在未扣除有色试样背景干扰的情况下 ,对有色试样采取直接取样进行分析 ,这就给测定结果带来了较大的误差 ,特别是测定诸如赤砂糖这类颜色较深的物质中SO2 含量时 ,其较深的背景严重干扰测定 ,且测定结果往往还因其取样量的不同而不同 ,这就… 相似文献
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19.
A sensitive spectrophotometric method for the determination of SO2 after fixing in a new trapping solution of NaOH-citrate is described. The method is based on the redox reaction of SO2 with bromate in acid medium to liberate bromine which brominates 2,7-dichlorofluorescein (DCF) and subsequent measurement of the brominated product at 535 nm in an organic phase. Absorption characteristics of the developed trapping solution and application studies are also described. The relative standard deviation was 3.8% (10 g SO2). Interferences by NO2 and H2S were eliminated. 相似文献
20.
A new piezoelectric crystal impedance sensor for the determination of sulphur dioxide in aqueous solution is presented. It is realized using a series piezoelectric crystal device which is constructed by connecting an AT-cut piezoelectric crystal to a probe in series. The probe is filled with an internal electrolyte solution that is separated from sample solutions by a gas-permeable membrane. The present sensor exhibits a favourable frequency response to 1 x 10(-7)-1 x 10(-3) M sulphur dioxide. The detection limit is 1 x 10(-8) M. The effects of the sensor preparation are considered. Dynamic range, reproducibility, response time and selectivity of the sensor are also discussed. The proposed sensor has been used successfully for lamp sulphur determinations in petroleum samples. 相似文献