Differential determination of sulfur dioxide and sulfuric acid mist by using heated sodium chloride

Since a mist of sulfuric acid reacts with heated sodium chloride producing hydrogen chloride whereas sulfur dioxide does not virtually, the process was used for the differential determination of a mixture of them. The sample mixture was allowed to react with sodium chloride at about 500°C, and the r...

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Published inBUNSEKI KAGAKU Vol. 23; no. 4; pp. 356 - 364
Main Authors YOSHIMORI, Takayoshi, NONOMURA, Makoto
Format Journal Article
LanguageJapanese
English
Published Tokyo The Japan Society for Analytical Chemistry 1974
Japan Science and Technology Agency
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Summary:Since a mist of sulfuric acid reacts with heated sodium chloride producing hydrogen chloride whereas sulfur dioxide does not virtually, the process was used for the differential determination of a mixture of them. The sample mixture was allowed to react with sodium chloride at about 500°C, and the resulting product was introduced into a 1% solution of hyrdogen peroxide. Both hydrochloric and sulfuric acids thus produced were determined alkalimetrically and argentometrically. In order to produce the definite amount of a mist of sulfuric acid, the following method was recommendable. An aliquot of a standard solution of potassium hydrogen sulfate was taken in a platinum boat, and was evaporated to dryness. Then the boat was placed in a silica tube heated at about 300°C, and the temperature of the tube was raised gradually up to 800°C. Pure nitrogen was used as the carrier gas of the mist. As a source of sulfur dioxide, a standardized gas mixture of the dioxide and nitrogen were preferable, and were also utilized as the carrier gas of the mist. The absorbent of sulfuric acid mist was preliminarily investigated in conjunction with the usefulness of potassium hydrogen sulfate as the standard for the production of the mist (Table I). An aqueous solution of 80% isopropanol which was sometimes preferred as the absorbent of the mist was not recommendable. As Fig. 1 shows, a combination of the aqueous solution of 1% hydrogen peroxide with the electrostatic precipitator was most satisfactory for the complete absorption of the mist. About 3φ60% of the mist was deposited on the inner surface of the "cap" in Fig. 1. No effective absorption of the mist could be expected by any solution used. The reactions both sulfuric acid mist and sulfur dioxide with heated sodium chloride were next investigated. Ninety per cent of the mist and 3.3% of the dioxide were converted to hydrogen chloride by the reaction at 500°C (Table II). These values were used to correct the results of the titrations. It was considerable to be the reason for the lower results from the mist that sodium hydrogen sulfate was produced and was not decomposed completely at the reaction temperature. The conversion ratio of the dioxide was negligible if the dioxide content was small. The mixtures of the mist and the dioxide were analyzed by this method with satisfactory results (Table III). This method was applied to analyze the mist and the dioxide in the flue gases produced at an ore-sintering furnace and a water boiler furnace by using the apparatus illustrated in Fig. 2, and the results obtained were shown in Table IV.
ISSN:0525-1931
DOI:10.2116/bunsekikagaku.23.356