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ASTM D6410-99(R2020) pdf free download

ASTM D6410-99(R2020) pdf free download.Standard Test Method for Determining Acidity of Vegetable Tanning Liquors
1. Scope
1.1 This test method covers determining the acidity of tannery liquors made up from vegetable tanning materials. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.4 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
4. Summary of Test Method
4.1 An analytical solution is prepared from the sample of tannery liquor (Practice D6404). Specimen aliquots from this analytical solution are then analyzed for total acidity by one of two titrametric methods.
5. Significance and Use
5.1 This test method is used to determine one of the chemical properties of tannery liquors which are relevant for the vegetable tanning process and influence the astringency of vegetable tanning liquors. The astringency of liquors is depen- dent upon the solids and tannin content and the acidity. This test method provides a standard procedure for determining the total acidity for any sample of vegetable tanning liquor. 5.2 The specimens are aliquots from the analytical solution prepared from the sample of tannery liquor collected for this purpose. 5.3 The total acidity of the liquor sample is determined by one oftwo titrametric procedures described in this test method.
6. Apparatus and Reagents
6.1 Analytical Solution: 6.1.1 Flask, 1 L volumetric. Class Aflasks with a bulb in the neck (M.C.A. type) are especially suitable for this work. 6.1.2 Hydrometer, preferably with a Barkometer scale (that is, a scale calibrated in °Bk). The three digits to the right of the decimal point on a standard specific gravity reading are equal to the Barkometer scale reading. That is, a sp.gr. of 1.200 equals 200°Bk and a sp.gr. of 1.020 equals 20°Bk. 6.2 Acidity Determination—Method I: 6.2.1 Graduated Cylinder, glass-stoppered, graduated to contain 250 mL. 6.2.2 Gelatin Solution, 1 %, neutral to bromocresol purple. The addition of 25 mL of 95 % ethyl alcohol per litre is recommended to prevent frothing. The solution shall be ad- justed to neutrality to bromocresol purple with 0.1 N acetic acid or 0.1 N sodium hydroxide.6.2.3 Kaolin 4 , acid-washed kaolin clay which conforms to the following specifications: Suspend 1.0 g kaolin in 100 mL distilled water. The pH value should be between 4.5 and 6.0 after 5 min. A mixture of2.0 g kaolin and 200 mL distilled water are shaken for 10 min and the mixture filtered through the standard filter paper. A 100 mL aliquot of the clear filtrate should have less than 0.001 g of residue after evaporation and oven-drying in a platinum dish. 6.2.4 Alkaline Titrant, 0.1 N sodium hydroxide solution. 6.3 Acidity Determination—Method II: 6.3.1 Pipet, transfer pipette with 6 mL capacity. 6.3.2 pH Meter, with glass/calomel electrodes. 6.3.3 Alkaline Titrant, 0.1 N sodium hydroxide solution.
8. Procedure
8.1 Preparation ofthe Analytical Solution: 8.1.1 Collect the tannery liquor sample as described in Practice D6404. 8.1.2 Prepare the analytical solution for this analysis by diluting a specimen aliquot from the tannery liquor sample to the mark in a 1 L volumetric flask with distilled water. The aliquot specimen shall be of such size that, after dilution the analytical solution shall contain as nearly as possible 7.0 g total solids per litre. Follow the above procedure except where such dilution would give more than 3.5 g tannin per litre. In this case select the aliquot specimen size such that after dilution the analytical solution shall contain as nearly as possible, but not exceed, 3.5 g tannin per litre, irrespective of the solids content. 8.1.3 Dilution Procedure: When the liquor sample has a specific gravity of 65°Bk (that is, sp.gr. ≥ 1.065) or more, dilute the aliquot specimen with water at 40°C, and cool as in Test Method D4904. When the liquor sample has a specific gravity ofless than 65°Bk (that is, sp.gr. < 1.065), dilute the aliquot specimen with water at 23°C.

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