Dilute H2SO4 Solution Research Articles

Application of Sparging to the Automated Ion Selective Electrode Determination of Kjeldahl Nitrogen

Abstract An automated method has been developed for the determination of total Kjeldahl nitrogen. Sample digests are mixed with a NaOH solution and allowed to make contact with air flowing at 1000 mL/min. The mixture enters the inlet of a heating bath maintained at 75°C. On exit, ammonia gas separates from a sparging vessel and is trapped as ammonium sulfate in a dilute H2SO4 solution. An aliquot of the acid solution is resampled and made alkaline to generate ammonia, which is measured by an ammonia sensing probe. A comparison of this procedure with AOAC method 7.025 shows that the procedure is accurate and that there is no statistically significant difference between them. This procedure introduces a new approach to eliminate the interfering species present in sample digests after Kjeldahl digestion for automated ion selective electrode measurements of ammonia. Thirty samples/h can be analyzed by this method.

Effect of Gelatin on the Pitting Corrosion of Iron in Acid and Alkaline Solutions

Abstract Potentiostatic polarisation curves for iron were recorded in dilute H2SO4 solution in the presence of increasing concentrations of Cl− ion. The aggressive agent raised the active dissolution current density, and developed pits over the entire passive region. The passivation current density steadily increased with the increase of the Cl− content, and finally reached the active dissolution value. Small additions of gelatin accelerated the active dissolution of the metal. This was explained by taking both the kinetics of dissolution of iron and the catalytic properties of gelatin in acid solutions into account. The same concentrations of additive greatly reduced the tendency of the metal to undergo pitting. Larger concentrations of additive produced reverse effects, namely, a decrease in current along the active region and an increase along the passive region. This was correlated with surface blocking and an increased ratio of cathodic! anodic areas on the surface of the metal.Pitting corrosion of i...

Corrosion-electrochemical behavior of Me23C6 type carbides in sulfuric acid

Full anodic potentiostatic curves have been constructed for iron-chromium carbides in dilute H2SO4 solutions. The effects of alloying with iron, nickel, and molybdenum, temperature, and acid concentration upon the corrosion resistance of the carbides have been determined.

Polymerization of Chlorine Substitution Products of Trimeric Phosphonitrilechloride with Alkoxides of α, α' - Xylenediol and Properties of the Polymer

Chlorine substitution products of trimeric phosphonitrilechloride with alkoxides of α, α'- xylenediol P3N3Clx (X= 3 or 6) and P3N5Cl(6_2y)(OCH26F14H2O)y (Y=1-. '3) were synthesized in dioxane.Water vapor was detected by gas chromatography and polymers like plastics were obtained when P3N3(OCH26FleCH2OH)6 ortho [l], meta [2] and para [3] were heated in the temperature range from 25°C to 150°C.Then, 4 mole of water per 1 mole of [3] was found by weight loss method. Further, upon heating at about 200°C, formaldehyde was detected by gas chromatography.It was found that a part of ether bond, -Cl-12-0-CH2, changed into methylen bond, -CH, -. On the other hand, ring cleavege reaction occurred and polymers were obtained when P3N4Cl4 (0M-12-C6114: CH20) and P9N3Cl2(OCH26114H20)2 were heated at about 200°C, but no polymer was obtained with P3N3(OCH24-14H20)3.However, CO= bond absorption (IR) was observed in polymers, as a result of oxidation of a part of methylen bond. These polymers were stable toward water. Polymers having chlorine ion were unstable against dilute H2SO4, HNO3 or NaOH solutions, but they were stable toward flame. The thermal degradation of the polymers were studied by gas chromatography. It was found from the data obtained from a number of xylene, a little water and formaldehyde were detected at 320°C.

金属の疲労強度に及ぼすShot-peeningの影響（第4報）腐蝕疲労に対する効果について

It has been shown in our previous report that the surface stressing by shot-peening has a remarkable effect on the fatigue strength of steels and other metals having various types of surface weakness under non-corrosive atmosphere. In this paper, we examined the effect of shot-peening on the fatigue of Si-Mn steels under the corrosive atmosphere of distilled water and dilute H2SO4 solution. (1) The fatigue strength reduced under the atmosphere of distilled water was recovered considerably by shot-peening. For example,the fatigue limit at 107 cycles was increased from 36 kg/mm2 in the polished condition to 57 kg/mm2 in the shot-peened specimen,or about 58% in percentage. (2) In a dilute H2SO4 solution,the effect of shot-peening was reduced gradually in accordance with the increase of fatigue duration and of H2SO4 concentration,but it was still remarkable at short-time testing. (3) It was found from microscopic observation of the corrosion fatigued specimens that the propagation of fatigue cracks was prevented or delayed due to surface stressing, although the number of cracks in shot-peened specimens was much larger than in polished ones. Consequently, it is considered that the surface stressing by shot-peening is always effective in the view of prevention of fatigue failure under practical service condition which is usually accompanied by a somewhat corrosive atmosphere.

揮發酸の溜出比による鮮度判定法の研究-VI 試料の取扱について

A. Block, minced, and brayed meat prepared fresh or spoiled fish muscle were compared mutualy to determine the degree of crush for sample meats with the steam distillate method, the results are given in Table 1. In view of the practical treatment, sample meat must be brayed in a mortar. Often the brayed meat from a complete putrid fish muscle gives a large ratio than its exact value (cf. Table 2), then it must be suspended in the distilate flask liquid. And all titrating alkaline solution can be used in about 0.02N concentration. B. The preservative conditions of a sample meat in a dilute H2SO4 solution are experimented, the results obtained as follows : - Taken in 1% H2SO4 sol. 50cc., the sample meat 20g. can be preserved within 1 day at 30°C., 1-2 days at 25°C., 2 days at 20°C., 4-5 days at 15°C., 7-8 days at 10°C., 10-12 days at 5-0°C. Taken in 5 % H2S04 sol. 25cc. or 50cc., the sample meat 20g. can be preserved within 2-3 days at an ice-box temperature.