DRAFT TANZANIA STANDARD TBS/CDC-7(2903) P2- Sodium silicate for industrial use - Specification (Revision of TZS 219:1984) 0
TANZANIA BUREAU OF STANDARDS 1
0 Foreword This Draft Tanzania Standard is being developed by the Industrial and Laboratory Chemicals Technical Committee under supervision of the Chemical Division Standards Committee and it is in accordance with the procedures of the Bureau. This seconsecondd edition after being finalized will cancels and replaces the first edition (TZS 219: 1984 Sodium silicate for industrial use Specification). This draft Tanzania Standard has been prepared with assistance drawn from: i) IS 381: 1999) - Specification for sodium silicate; published by Bureau of Indian Standards; and ii) BS 3984: 2011) Specification for sodium silicate; published by Bureau of British Standards Institution. Formatted: Numbered + Level: 1 + Numbering Style: i, ii, iii, + Start at: 1 + Alignment: Left + Aligned at: 0.63 cm + Indent at: 1.9 cm Formatted: Numbered + Level: 1 + Numbering Style: i, ii, iii, + Start at: 1 + Alignment: Left + Aligned at: 0.63 cm + Indent at: 1.9 cm In reporting the test results of a test or analysis made in accordance with this standard, if final value, calculated or observed is to be rounded off, it shall be done in accordance with TZS 4: Rounding off numerical values. 2
DRAFT TANZANIA STANDARD TBS/CDC7 (2903) P2 Sodium silicate for industrial use - Specification 1 Scope This draft Tanzania Standard specifies requirements, sampling and methods of tests for sodium silicate for industrial use. It does not specify requirements for sodium silicate for pharmaceutical industries. 2 Normative references The following referenced document is indispensable for the application of this document; the latest edition of the referenced document (including any amendments) applies;, Not Bold Formatted: Normal, Not Bold Formatted: Normal TZS 59: Water - Distilled quality - Specification 3 Requirements 3.1 Forms There shall be two forms of sodium silicate, namely the liquid and the solid. 3.2 Categories Each form of sodium silicate shall be of the following two categories: a) Neutral and b) Alkaline. 3.2 Types 3.2.1 Liquid, neutral sodium silicate for use as adhesive. 3.2.2 Liquid, Alkaline sodium silicate shall be of the following three types; Type 1 Type 2 Type 3 3.2.3 Solid, Neutral, sodium silicate 3.2.4 Solid, alkaline sodium silicate All three types are for use in soaps, detergents, textile, welding electrode and cement industries., Pattern: Clear (Yellow) Formatted: Pattern: Clear (Yellow) 3
3.3 General requirements 3.3.1 Sodium silicate shall be clear, free from dirt and other visible impurities and shall satisfy the requirements in Table 1. 3.3.2 Sodium silicate liquid shall be thick, viscid, translucent mass of waterwhite or slightly grey in colour. 3.3.3 Sodium silicate solid shall be in the form of glassy lumps of pale grey to green colour. The particle size shall be specified as agreed to between the purchaser and the supplier. 3.4 Specific requirements Table 1: Requirement for Sodium Silicate Requirement Liquid S/N Parameter Alkaline o. Neutral Type Type Type 1 2 3 i) Matter insoluble in water, % by ii) iii) iv) wt., max. Specific gravity at 15/15 C Total soluble silicates, % by wt., min. Ratio of total alkalinity (as Na2O) to total soluble silica (as SiO2) (Na2O:SiO2) v) Loss in wt. on ignition, % by wt., max. vi) Iron (as Fe), % by wt., max. Neutral Solid Alkalin e Method of test 0.2 0.2 0.2 0.2 4.0 1.5 A.3 1.39-1.41 1.69-1.71 1.54-1.56 1.34-1.36 NA NA A.4 38 54 45 30 95 98 A.5 1:3.2 ± 0.1 1:2.0 ± 0.1 1:2.0 ± 0.1 1:2.0 ± 0.1 1:3.2 ± 0.1 1:2.0 ± 0.1 A.8 NA NA NA NA 1.0 0.5 A.9 0.02 0.02 0.02 0.02 0.04 0.04 A.10 Note: N/A = Not applicable; stands for parameters which are not tested for particular grade Formatted Table 4
4 Sampling The method of drawing representative samples of the material, the number of tests to be performed and the method of finding out the criteria of conformity of the material to the requirements of this specification shall be as prescribed in Annex B. 5 Packing and Marking 5.1 Packing The material shall be packed in airtight container of capacity as agreed between the purchaser and the supplier 5.2 Marking Each container shall be securely closed, and shall bear legibly and indelibly the following information: a) Name, category and form of the material; b) name of the manufacturer and recognized registered trade mark, if any; c) net mass of the material; d) lot or batch number, in code or otherwise; e) year of manufacture f) safety precautions such as hazard signs f)g) country of orign Commented [u1]: Language requirement is missing Formatted: Normal, Left Formatted: Font: Not Bold 5
Annex A (Normative) Methods of test for sodium silicate A.1 Quality of reagents Unless otherwise specified all reagents shall be of a recognized analytical grade. The distilled water used shall conform to TZS 59. A.2 Preparations of sample A.2.1 Sodium silicate, liquid; Weigh accurately about 20 g of the material and dissolve in freshly boiled water. Filter and thoroughly wash the filter paper with freshly boiled water. Transfer both the filtrate and the washings to a 500 ml volumetric flask and dilute up to the mark. Keep this prepared sample solution for test purposes. A.2.2 Sodium silicate, solid; This material, especially the neutral type, is very difficult to dissolve and the following methods are recommended. A.2.2.1 Alkaline silicate; Digest about 20 g of the material, accurately weighed, with 10 times its weight of water in an autoclave for two hours at a pressure of 4 kg/cm 2. Filter and thoroughly wash the filter paper with freshly boiled water. Transfer both the filtrate and the washings to a 500-mL volumetric flask and dilute up to the mark. Keep this prepared sample solution for test purposes. A.2.2.2 Neutral silicate; Crush the material fine enough to pass through 150 micron sieve. Digest about 20 g of the crushed material, accurately weighed, with twice its weight of water in an autoclave for 2 h at a pressure of 4 kg/cm 2. Filter and thoroughly wash the filter paper with freshly boiled water. Transfer both the filtrate and the washings to a 500 ml volumetric flask and dilute up to the mark. Keep this prepared sample solution for test. A.3 Determination of matter insoluble in water A.3.1 Procedure; Weigh accurately about 10 g of the material into a beaker and dissolve in freshly boiled water (for the material in the solid form, prepare the solution as under A.2). Filter into a flask through a weighed sintered crucible porosity 4 with suction. Wash the beaker and the residues free from alkali with freshly boiled water and then dry the crucible in an oven maintained at 110 C ± 5 C. Cool in a 6
desiccator and weigh. Repeat the operation of heating and cooling till constant weight is obtained. Note Filtration by Gooch crucible is not used because of the dangers involved in using asbestos; instead sintered crucible porosity 4 (or equivalent) with suction is used. A.3.2 Calculation Matter insoluble in water, Percentage by weight Where = 100 x W1 W2 W1 is the weight in g of the residue, and W2 is the weight in g of the material taken for the test. A.4 Determination of specific gravity A.4.1 Principle Specific gravity shall be determined with a hydrometer. A.4.2 Procedure; Pour the material to be tested into the clean hydrometer jar the diameter of which shall be at least 2.5 cm greater than the diameter of the hydrometer used. Remove all air bubbles that might have formed in the liquid. Keep the jar in a vertical position and in a bath maintained at 15.5 C. When the sample in the jar attains the temperature of the bath, that is, 15.5 C, lower the hydrometer gently into the material. Keep the unimmersed portion of the stem dry, as any unnecessary liquid on the stem will change the effective weight of the instrument and affect the reading obtained. Allow the hydrometer to become stationary. Remove all air bubbles that may have formed during the lowering of the hydrometer. Read the point on the hydrometer scale, to which the sample rises, with the eye placed at the principal surface of the material. This reading gives the specific gravity of the material under test. A.5 Determination of total soluble silica (as SiO2) A.5.1 Reagents A.5.1.1 Concentrated hydrochloric acid A.5.1.2 Dilute hydrochloric acid 1:1 by volume. A.5.1.3 Concentrated sulfuric acid A.5.1.4 Hydrofluoric acid About 40 percent (w/v) A.5.2 Procedure 7
Take 50 ml of the prepared sample solution (see A.2) in a 150 ml porcelain evaporating dish, add 25 ml concentrated hydrochloric acid and evaporate to dryness on a water-bath. Moisten the residue with 10 ml dilute hydrochloric acid and again evaporate to dryness on a water-bath. Heat the dish for one hour on a hot plate maintained at 110 º C ± 5 º C. To dissolve the soluble salts, add 10 ml of dilute hydrochloric acid and 20 ml of water to the residue and digest for 5 minutes on the water-bath. Filter the residue, which is mainly silica, through a Whatman filter paper and wash the residue on the filter paper with hot water till it is free from chlorides. Keep the residue on the filter paper and collect the filtrate and washings in original dish. A.5.2.1 Evaporate to dryness the filtrate and washings on the water-bath; moisten the residue with 10 ml dilute hydrochloric acid and again evaporate to dryness. Heat at 110 º C ± 5 º C for one hour, add to the residue 10 ml of dilute hydrochloric acid and 20 ml of water and digest as before to dissolve the soluble salts. Filter any additional silica separated on a separate filter paper and wash it free from chlorides as before. A.5.2.2 Transfer both the filter papers and the residues as obtained under A.5.2 and A.5.2.1 to a platinum crucible previously ignited and weighed without cover. Ignite it in a muffle furnace, slowly raising its temperature until free from carbon. Cover the crucible with a platinum cover, heat to the highest temperature of blast burner for 15 minutes. Cool in a desiccator and weigh without the crucible cover. A.5.2.3 Add sufficient water just to moisten the contents of the crucible and add 2 to 3 drops of concentrated sulfuric acid. Slowly add 10 ml of hydrofluoric acid. Evaporate to a small volume on the water-bath; add another portion of about 10 ml of hydrofluoric acid and evaporate to fumes of sulfuric acid. Heat the crucible gently at first over an open flame to drive off sulfuric acid and finally at a red heat. Cool in a desiccator and weigh. Repeat the heating, if necessary, till constant weight is obtained. A.5.3 Calculation Total soluble silica (as SiO2), Percentage by weight = 1000 x A - B W Where A is the weight in g of the residue and crucible as obtained under A.5.2.2, B is the weight in g of the residue and crucible after treatment with Hydrofluoric acid (see A.5.2.3), and W is the weight in g of the material of taken for the prepared Sample solution A.6 Determination of total alkalinity (as Na2O) 8
A.6.1 Two methods, namely, Method A and Method B, have been prescribed for the determination. Method B shall be used only when xylene cyanol FF is not available. A.6.2 Method A A.6.2.1 Reagents a) Standard hydrochloric acid 0.5 N. b) Indicator Dissolve 0.2 g of methyl orange and 0.28 g of xylene cyanol FF in 100 ml of 50 percent rectified spirit. A.6.2.2 Procedure Transfer 50 ml of the prepared sample solution by means of a pipette into a conical flask and titrate with standard hydrochloric acid, using the above indicator, till the colour changes from green to grey. A.6.2.3 Calculation Calculate the total alkalinity (as Na2O) on the basis that 1 ml of normal hydrochloric acid is equivalent to 0.031 g of sodium monoxide. A.6.3 Method B Total alkalinity (as Na2O), Percent by weight = 31 x AN W Where A is the volume in ml of standard hydrochloric acid required for the titration, N is the normality of standard hydrochloric acid, and W is the weight in g of the material taken for the prepared sample solution. A.6.3.1 Reagents a) Phenolphthalein indicator solution Dissolve 0.5 g phenolphthalein in 100 ml of 60 % rectified spirit, which has previously been neutralized to the indicator. b) Standard sulfuric acid 0.5 N. c) Standard sodium hydroxide solution. A.6.3.2 Transfer 50 ml of the prepared sample solution by means of a pipette into a conical flask and add a few drops of phenolphthalein indicator. Add in excess a known volume of standard sulfuric acid. Warm the mixture, taking care that no spurting takes place, and titrate the excess acid with standard sodium hydroxide solution until a delicate pink colour persists for one minute. A.6.3.3 Calculation 9
Calculate the total alkalinity (as Na2O) on the basis that 1 ml of normal sulphuric acid is equivalent to 0.031 g of sodium monoxide. Total alkalinity (as Na2O), Percentage by weight = 31 x (AN1 BN2) W Where A is the volume in ml of standard sulfuric acid required for added, N1 is the normality of standard sulfuric acid, B is the volume in ml of standard sodium hydroxide solution required to neutralize the excess acid, N2 is the normality of standard sodium hydroxide solution, and W is the weight in g of the material taken for the prepared sample solution. A.7 Determination of total soluble silicates A.7.1 Determine (as SiO2) and total alkalinity as under A.5 and A.6 respectively, and add the percentages of these two components to obtain the percentage by weight of total soluble silicates. A.8 Determination of ratio of total alkalinity (as Na2O) to total soluble silicate (as SiO2) Determine the total soluble silica and total alkalinity as under A-5 and A-6 respectively and find out the ratio of these two components. A.9 Determination of loss on ignition A.9.1 Procedure Weigh accurately about 5 g of the material into a clean tarred platinum crucible. Heat the crucible with a low flame until the material melts. Increase the heat gradually as water is driven off, taking care to avoid spattering. Continue heating till constant weight is obtained. Cool in a desiccator and weigh. A.9.2 Calculation Loss in weight on ignition, Percentage by weight = 100 x (W W1) W Where W is the weight in g of the material taken for the test and W1 is the weight in g of the residue after ignition. A.10 Determination of iron (as Fe) A.10.1 Apparatus - Nessler cylinders 50 ml capacity. 10
A.10.2 Reagents A.10.2.1 Concentrated nitric acid A.10.2.2 Ammonium persulphate Solid. A.10.2.3 Butanolic potassium thiocyanate Dissolve 10 g of potassium thiocyanate in 10 ml of water; add sufficient n-butanol to make up to 100 ml and shake vigorously until the solution is clear. A.10.2.4 Dilute sulfuric acid Approximately 10 percent (v/v). A.10.2.5 Standard iron solution Weigh 0.702 g ferrous ammonium sulphate [FeSO4 (NH4)2SO4.6H2O] and dissolve in 10 ml of dilute sulfuric acid. Dilute with water to make up the volume to 1000 ml. Transfer 10 ml of this solution and again dilute with water to make up the volume to 100 ml. One millilitre of this solution is equivalent to 0.01 mg of iron (as Fe). A.10.3 Procedure Take about 5 g of the sample accurately weighed, dissolve it in water as prescribed in A-2 and make up the solution to exactly 100 ml. Take 10 ml aliquot of this solution, add 1 ml of concentrated nitric acid and then boil. Cool to room temperature, transfer the solution to a Nessler cylinder and add 30 mg of ammonium persulphate and 15 ml butanolic potassium thiocyanate solution. Shake for 30 seconds and allow the liquid to separate. Carry out a control test in the other Nessler cylinder, adding slowly from a burette a quantity of the standard iron solution in place of the material and the same quantities of the other reagents in the same total volume of the reaction mixture until the colours of butanol layers in the two cylinders are exactly matched. A.10.4 Calculation Iron (as Fe), percent by weight = 0.001V W Where; V is the volume in ml of standard iron solution required in the Control test, and W is the weight in g of the material present in the aliquot of prepared sample solution. A.11 Alternative method for the determination of total soluble silicates and ratio of total alkalinity to total soluble silica A.11.1 Reagents A.11.1.1 Standard hydrochloric acid 1 N 11
A.11.1.2 Sodium fluoride Solid A.11.1.3 Rectified spirit A.11.1.4 Methyl red indicator solution Dissolve 0.1 g of methyl red in 100 ml of 60% rectified spirit. A.11.1.5 Methyl red-xylene cyanol FF indicator solution Dissolve 0.8 g of methyl red and 0.2 g xylene cyanol FF in 1 000 ml of 60% rectified spirit. A.11.1.6 Standard sodium hydroxide solution 1 N A.12.2 Procedure Transfer 50 ml of the prepared sample solution to a 250 ml beaker and add about 0.5 ml of methyl red indicator solution. Titrate with standard hydrochloric acid to the first colour change. Then, add to it about 5 g of sodium fluoride and dissolve as much of it as possible by agitation. Add 25 ml of ethyl alcohol and continue titration till the colour of the solution is definitely red (an excess of about 2 ml of 1N hydrochloric acid is sufficient). At this point, add about 0.5 ml of methyl red-xylene cyanol FF indicator solution and titrate back with standard sodium hydroxide solution till the end point is reached. (The end point is an intermediate grey colour immediately after the disappearance of pink and before the appearance of green). A.11.3 Calculation Total soluble silica (as SiO2), percent by weight = (BN1 CN2) x 15.02 W Total alkalinity (as Na2O), percent by weight = 31 x AN1 W Where B is the volume in ml of standard hydrochloric acid after the addition of sodium fluoride and rectified spirit, N1 is the normality of hydrochloric acid, C is the volume in ml of standard sodium hydroxide solution used for the back titration, N2 is the normality of standard sodium hydroxide solution, W is the weight in g of the material taken for the prepared sample solution, and A is the volume in ml of standard hydrochloric acid required to reach first methyl red end point. A.11.3.1 Determine total soluble silicates by adding the percentage of total soluble silica and total alkalinity. Find out the ratio of total alkalinity to total soluble silica as obtained in A.11.3. 12
ANNEX B (Normative) Sampling of sodium silicate B.1 General requirements of sampling B.1.0 In drawing, preparing, storing and handling samples, the following precautions and directions shall be observed. B.1.1 Precautions shall be taken to protect the samples, sampling instruments and the containers for samples from contamination. B.1.2 In case of sampling liquids from drums, the material shall be thoroughly mixed before drawing the sample. In case of solids, the material shall be sampled without breaking the lumps, which are included in the sample drawn. 13
B.1.3 The samples shall be placed in suitable, clean and dry containers with proper closures. B.1.4 Each sample container shall be closed air-tightly after filling and marked with full details of sampling. B.2 Scale of sampling B.2.1 Lot All containers in a single consignment of the material of one category, form and drawn from a single batch of manufacture shall constitute a lot. If a consignment is declared or known to consist of different grades, types or batches of manufacture, the containers shall be suitably separated and grouped to form lots as defined above. B.2.1.1 Samples shall be tested from each lot for ascertaining conformity of the material to the requirements of the specification. B.2.2 The number (n) of drums to be chosen from a lot shall depend on the size of the lot (N) and shall be in accordance with column. 1 and 2 of Table 2. Table 2: Number of drums to be selected Lot size Number of drums to be selected N n Up to 10 3 11 20 5 21 30 7 31 50 10 51 and above 15 B.2.3 The drums to be selected for sampling shall be chosen at random, preferably with the aid of random number tables. B.3 Preparation of test samples and number of tests B.3.1 Draw with an appropriate sampling equipment a small portion of sodium silicate (solid) from different parts of the drum selected according to B-2. The total quantity of the solid drawn shall be approximately 500 g. In the case of liquid, the sample weighing approximately 300 g shall be withdrawn after mixing the content of the drum thoroughly and set aside. B.3.2 Transfer the portions collected from each drum to separate sample containers. These filled containers are termed as individual samples. B.3.3 Out of each of the individual samples, collect equal quantities and mix thoroughly to form a composite sample weighing about 300 g. From this composite sample, sample solution shall be prepared as prescribed in A.2. In 14
case sieving is necessary, the portions from individual samples shall be sieved separately and the composite sample shall be prepared only out of the sieved material. B.3.4 Tests for total soluble silicates and the ratio for total alkalinity shall be carried out on any three of the individual samples drawn under B-3.2. The same samples should be used for both tests. The preparation of sample solution shall be done in accordance with A-2. B.3.4.1 Tests for all the other characteristics shall be done on the composite sample. B.4 Criteria for conformity All the test results on individual as well as composite sample(s) shall satisfy the requirements given in Table 1 if the lot is to be declared acceptable under this specification. 15
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