A Quantitative Study of Fluorine Distillation

Dahle, Dan; Wichmann, H J

doi:10.1093/jaoac/19.2.313

Cited by 4 publications

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“….23 °Aliquots of standard sodium fluoride solutions were used. 6 Silica was added in the form of a clear solution of NazSiOa. e Approximately the SiOz equivalent of the fluorine as HzSiFe.…”

Section: Separation Of Fluorine From Interferingmentioning

confidence: 99%

“…distillate of 0.1 gram of the rock was evaporated to 45 to 50 ml. 6 National Bureau of Standards standard sample. 6 Distilled in the presence of KMnOi.…”

Section: Separation Of Fluorine From Interferingmentioning

confidence: 99%

“…of 60 per cent perchloric acid and 5 ml, of water were added to distilling flask. 6 All titrations were made in a volume of 10 ml. of aqueous solution.…”

Section: Samplementioning

confidence: 99%

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Determination of Fluorine

Reynolds¹,

Hill²

1939

Ind. Eng. Chem. Anal. Ed.

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H E determination of fluorine in most materials requires T its separation from other constituents of the sample.For this separation volatilization (or distillation) methods, being relatively rapid, have been favored whenever the fluorine-bearing constituents were readily soluble in acid, whereas fusion with alkali compounds with subsequent separation of the fluorine by rather cumbersome precipitation methods has been the rule with acid-insoluble materials. The chief carrier of fluorine in natural phosphates is apatite ( l a ) , and calcium fluoride has been identified in a few instances as a constituent of phosphate rock. Fortunately, both compounds can be treated successfully by distillation methods. On the other hand, fusion with alkali fluxes is not very effective in decomposing apatite (2%').The volatilization method (65, 27) used prior to about 5 years ago was not entirely satisfactory. One of the principal difficulties arose from the interfering effect of gelatinous zirconium salt from the indicator used for titrating very small amounts of fluorine. Because of the greater sensitivity of the simplified indicator to changes in the pH of the solution during titration, it was not satisfactory for the titration of several milligrams of fluorine in a slightly buffered solution (20), such as was used a t that time. Later, the advent of the use of a buffer solution (16) to control the pH during titration made the addition of a zirconium salt to the indicator unnecessary for the titration of the larger quantities of fluorine. The almost constant attention required to maintain the temperature of distillation within the permissible range by the frequent additions of small quantities of water to the distilling flask was overcome by means of a form of steam distillation (24).With the foregoing improvements the Willard and Winter method has been used in this laboratory on a wide variety of natural phosphates and phosphatic products. A number of silica, which renders the method inapplicable to materials that contain acid-decomposable silicates (23). Furthermore, the method of Reynolds and Jacob @a), involving fusion and acid extraction of the sample with subsequent precipitation of the fluorine as lead chlorofluoride, was very tedious and gave low results on some types of phosphate rock, such as Tennessee blue rock and Florida waste-pond phosphates.The publication of a volumetric method by Willard and Winter (28) in 1933 marks a great forward step in the analysis of fluorine-containing materials. I n simplicity of requisite a p p a r a t u s , ease of manipulation, speed, and quality of results, this is far superior to any other known method for the analysis of a wide variety of materials.I n the original procedure fluorine is (1) separated from the sample (fused with alkali carbonate if the fluorine compounds are not decomposed by acid) by distillation with sulfuric acid or perchloric acid and (2) determined in the neutralized distillate, after the addition of an equal volume of ethyl alcohol, b y t i t r a t i o n with ...

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Section: Separation Of Fluorine From Interferingmentioning

confidence: 99%

“…distillate of 0.1 gram of the rock was evaporated to 45 to 50 ml. 6 National Bureau of Standards standard sample. 6 Distilled in the presence of KMnOi.…”

Section: Separation Of Fluorine From Interferingmentioning

confidence: 99%

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Determination of Fluorine

Reynolds¹,

Hill²

1939

Ind. Eng. Chem. Anal. Ed.

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“…With the recent modifications in the distillation method, some of the objections have been overcome, but the procedure still is not entirely foolproof. [1][2][3][4][5][6]…”

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confidence: 99%

Automatic Fluoride Distillation

Bellack¹

1961

Journal AWWA

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Distillation of water samples prior to fluoride analysis, although often a necessary procedure, has remained a disagreeable laboratory operation. With the recent modifications in the distillation method, some of the objections have been overcome, but the procedure still is not entirely foolproof. This article discusses the direct distillation method, conversion to automatic operation, and apparatus and procedure.

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“…T H E basic technology of fluoride distillation has been little changed since Willard and Winter (1) reported it in 1933. Many of the conditions of distillation, including both mechanical and chemical considerations, have been thoroughly studied by a number of investigators (2,3). Several modifications have been suggested with the aim of providing greater ease or less time consumption in the distillation process; among these is the use of temperature-controlling devices and compressed air to replace the steam or distilled water normally used to drive over the fluoride (4)(5)(6).…”

mentioning

confidence: 99%

Simplified Fluoride Distillation Method

Bellack¹

1958

Journal AWWA

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A Quantitative Study of Fluorine Distillation

Cited by 4 publications

References 0 publications

Determination of Fluorine

Determination of Fluorine

Automatic Fluoride Distillation

Simplified Fluoride Distillation Method

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