Titanium Dioxide Analysis Procedure

Titanium dioxide analysis in soap by visual examination/comparison with the standard.Titanium dioxide in soap.

Take a small amount of the test sample as well as a standard sample side by side on a glass plate. Spread the samples with the help of a spatula. Compare the colour, odour, and appearance of the test sample with the standard.

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2. Solubility of Titanium Dioxide

Weigh about 1 g of the sample and transfer it to a clean and dry test tube. Add solvent to the test tube containing the sample. Shake well for 2 mins. Let it stand for 2 minutes without disturbing. Observe whether the mix is homogenous or heterogeneous. Record the observation. Repeat the process with all the specified solvents.

3. IDENTIFICATION OF TITANIUM DIOXIDE :

Reagents

(A) Anhydrous Sodium Sulphate

(B) Sulphuric Acid: 25% v/v Sulphuric Acid

(C) Strong Hydrogen peroxide solution

(D) Granulated Zinc

Method

(i) To 0.5 g of sample, add 5 g of Anhydrous Sodium Sulphate and 10 ml of water and mix. Add 10 ml of Sulphuric Acid and boil gently until clear; cool; add slowly 30 ml of a 25% v/v solution of Sulphuric Acid and dilute with water to 100 ml (Soln.` A'). To 5 ml of Soln.` A', add 0.1 ml of strong hydrogen peroxide solution, an orange-red colour is produced.

(ii) To 5 ml of Soln. `A', obtained in identification test (i), add one piece of granulated zinc; after 45 minutes, a violet-blue colour is produced.

4. CLARITY & COLOUR OF SOLUTION :

Solution `A' obtained in identification test (i) is clear to slightly opalescent and colourless.

5. ACIDITY OR ALKALINITY :

Reagents :

A. 0.01(N) HCl.

B. 0.01(N) NaOH.

C. Bromothymol blue solution - Warm 0.1 gm of Bromothymol blue with 3.2 ml of 0.05(N) Sodium hydroxide and 5 ml of alcohol (90%), after a solution is effected, and add sufficient alcohol (20%) to produce 250 ml

Method :

Shake 5.0 g of the sample with 50 ml of carbon dioxide-free water for 5 minutes and centrifuge or filter until a clear solution is obtained. 10 ml of the solution requires neutralisation of not more than 1.0 ml of 0.01(N) Sodium Hydroxide or 0.01(N) HCl, using 0.1 ml of bromothymol blue solution as an indicator.

6. WATER-SOLUBLE MATTER :

Reagents :

A. Ammonium Sulphate

Method :

Boil 10.0 g of the sample for 5 minutes with 150 ml water containing 0.5 g of Ammonium Sulphate, cool, dilute to 200 ml with water and filter until a clear solution is obtained. Evaporate 100 ml of the filtrate to dry and ignite. The residue weighs not more than 25 mg (0.5%).

7. TEST FOR ARSENIC :

Reagents :

(i) Potassium Carbonate, Anhydrous AsT.

(ii) Stannous Chloride Solution AsT - 330 g of Stannous chloride is dissolved in 100 ml of Concentrated HCl and sufficient distilled water is added to produce 1000 ml. 100 ml of this Stannous Chloride solution is mixed with 100 ml of concentrated HCl and boiled down to 100 ml, then filtered through a fine-grain filter paper.

(iii) Stannated Hydrochloric Acid, AsT :

Stannous Chloride solution AsT. --- 1 ml.

Hydrochloric Acid AsT --- 100 ml.

(iv) Potassium Iodide, AsT.

(v) Arsenic Solution, strong AsT - 0.132 g of Arsenic trioxide is dissolved in 50 ml of concentrated HCl and sufficient distilled water is added to produce 100 ml.

(vi) Arsenic Solution, dilute AsT- 1 ml of strong Arsenic solution AsT is diluted to 100 ml in a volumetric flask with distilled water. Dilute Arsenic solution must be freshly prepared, 1 ml of this solution contains 0.01 mg of Arsenic.

(vii) Mercuric Chloride paper - Smooth white filter paper, not less than 25 mm in width, soaked in a saturated solution of Mercuric Chloride, pressed to remove the superfluous solution and dried at about 60 deg C in the dark. The grade of the filter paper is such that, the weight is between 65 and 120 g per sq. mm; the thickness in mm of 400 papers is approximately equal, numerically, to the weight in gm per mm.

Mercuric Chloride paper should be stored in a stoppered bottle in the dark. Paper that has been exposed to sunlight or to the vapour of Ammonia affords a lighter stain or no stain at all when employed in the limit test for Arsenic.

(viii) Lead acetate solution soaked and dried cotton wool - Impregnate the cotton wool in a 10% w/v solution of Lead acetate in Carbon Dioxide free water and dry.

Apparatus

A wide-mouthed bottle capable of holding about 120 ml is fitted with a rubber bung through which passes a glass tube. The latter, made from ordinary glass tubing, has a total length of 200 mm and an internal diameter of exactly 6.5mm (external diameter of about 8 mm). It is drawn out at one end to a diameter of about 1 mm and a hole not less than 2 mm in diameter is blown in the side of the tube, near the constricted part. When the bung is inserted in the bottle containing 70 ml of liquid, the constricted end of the tube is above the surface of the liquid, and the hole in the side is below the bottom of the bung. The upper end of the tube is cut off square and is either slightly rounded or ground smooth. Two rubber bungs (about 25 mm x 25 mm ), each with a hole bored centrally and true, exactly 6.5 mm in diameter are fitted with a rubber band or spring clip for holding them tightly together.

Preparation of the test solution 

Mix 1.25 g of sample, intimately with 2 g of Potassium Carbonate and ignite in a muffle furnace at about 950 deg C for thirty minutes. Allow to cool, break up the mass, transfer to a flask, add 0.1 ml of Stannous Chloride AsT and 30 ml of HCl (constant boiling composition) AsT, attach a condenser to the flask, heat at just below the boiling point for one hour, and then distil 16 ml to the distillate, add 45 ml of water and 0.1 ml of Stannous Chloride solution AsT.

Standard Stain 

The solution is prepared by adding 50 ml of water, 10 ml of stagnated HCl AsT and a quantity of dilute arsenic solution AsT 1.0 ml. The resulting solution when treated as described in the method yields a stain on the mercuric chloride paper referred to as the standard stain.

Procedure 

The glass tube is lightly packed with cotton wool, previously moistened with a solution of Lead acetate and dried so that, the upper surface of the cotton wool is not less than 25 mm, below the top of the tube. The upper end of the tube is then inserted into the narrow end of one of the pairs of rubber bungs, either to a depth of about 10 mm or when the tube is flush with the larger end of the bung. A piece of Mercuric Chloride paper is placed on the top of the bung, and the other bung is placed over it and secured by means of the rubber band or spring clip, in such a manner that the borings of the two bungs meet to form a true tube of 6.5 mm dia interrupted by a diaphragm of mercuric Chloride paper.

The test solution is placed in the wide-mouthed bottle and in another 50 ml water, 10 ml standard hydrochloric acid AsT and 1.0 ml dilute Arsenic solution AsT are placed. Then in both the bottles, 1 gm Potassium Iodide AsT and 10 g Zinc AsT are added and the prepared glass tube is placed quickly in position. The action is allowed to produce for forty minutes in dark at nearly 40 deg C. The yellow stain which is produced on the mercuric Chloride paper, if arsenic is present in the test solution is compared by daylight with the standard stains. The comparison is made immediately at the completion of the test. The colour of the mercuric chloride paper in the test solution should not be more intense than the colour obtained from the standard solution.

Notes :

1. The mercuric chloride paper should remain quite dry throughout the test.

2. The most suitable temperature for carrying out the test is generally about 40 deg C.

3. The tube must be washed with hydrochloric Acid AsT, rinsed with distilled water and dried between successive tests.

8. TEST FOR BARIUM :

Reagents :

(i) Hydrochloric Acid

(ii) Dilute Sulphuric Acid

Shake 20 g of the sample for one minute with 30 ml of Hydrochloric Acid, add 100 ml of water and boil. Filter while hot, through a hardened filter until a clear filtrate is obtained. Wash the filter with 60 ml of water and dilute the combined filtrate and wash to 200 ml with water. To 10 ml of the resulting solution, add 1 ml of dilute Sulphuric Acid; the solution remains clear for not less than 30 minutes.

9. TEST FOR HEAVY METALS :

Reagents

(i) Thio acetamide reagent - Add 1 ml of a mixture of 15 ml of 1.0(N) Sodium Hydroxide, 5 ml of water, add 20 ml of glycerine to 0.2 ml of a 4% w/v solution of thioacetamide in water. Heat on a water bath for 20 seconds and cool. Thioacetamide reagent should be prepared immediately before use.

(ii) Acetate buffer pH 3.5 - Dissolve 25 g of Ammonium Acetate in 25 ml of water and add 38.0 ml of 7(N) HCl. Adjust the pH to 3.5 with either 2(N) HCl or 5(N) Ammonia and dilute with water to 100 ml.

Dilute 10 ml of the solution prepared in the test for Barium to 20 ml with water. To 12 ml of the solution, add 1.2 ml of thioacetamide reagent and 2 ml of acetate buffer, pH 3.5, mix, and allow to stand for 2 minutes. Any brown colour produced is not more intense than that produced by similarly treating a mixture of 10.0 ml of Lead Standard Solution (2ppm) in a similar manner in place of the solution being examined.

Lead Standard Solution (0.1% Pb): Dissolve 0.400 g of Lead Nitrate in water containing 2 ml of Nitric Acid and add sufficient water to produce 250.0 ml.

Lead Standard solution (100ppm Pb): Dilute 1ml of Lead Standard Solution (0.1% Pb) to 10 ml with water.

Lead Standard Solution (20ppm Pb): Dilute 1 ml of Lead Standard Solution (100 ppm Pb) to 5 ml with water.

Lead Standard solution (2 ppm Pb): Dilute 1 ml of Lead Standard Solution (20 ppm Pb) to 10 ml with water.

10. TEST FOR IRON

Reagents

(i) Bromine water - A freshly prepared saturated solution obtained by shaking occasionally during 24 hours, 3 ml of Bromine with 100 ml of water, and allowing it to separate.

Storage - Store in solution over an excess of Bromine.

(ii) Potassium Thiocyanate solution - A 9.7% w/v solution of Potassium Thiocyanate in water.

(iii) 20% w/v solution of Sulphuric Acid.

(iv) Standard Iron solution - Weigh accurately 0.1726 g of Ferric Ammonium Sulphate and dissolve in 100

ml of 0.1(M) Sulphuric Acid and sufficient water to produce 1000 ml. Each ml of the solution contains 0.02 mg of Fe.

To 8 ml of solution A obtained in identification test A, add 4 ml of water and one drop of Bromine water. After 5 minutes, remove the excess Bromine by passing a current of air and add 3 ml of Potassium Thiocyanate solution and shake. After 5 minutes, any red colour in the solution is not more intense than the colour obtained by treating 0.4 ml of standard Iron solution and 8 ml of a 20% w/v solution of Sulphuric acid in the same manner.

11. Loss Drying Titanium Dioxide:

Carry out the loss by drying 2 g of the sample in an oven at 105 deg C for 3 hours.

Calculation :

(W1 - W2) x 100

L.O.D % w/w = --------------------

W

W = Wt of the sample

W1 = Wt of Petri-dish and sample

W2 = Wt of Petri dish and sample after drying

12. LOSS ON IGNITION Titanium Dioxide 

Weigh accurately about 2.0 g of sample, previously dried at 105 deg C for 3 hours and ignite at 800 +/-25 deg C to constant weight.

Calculation:-

                  (W1 - W2) x 100

L.O.I % w/w = ----------------------

                      W

W = Weight of the sample in g.

W1 = Weight of the crucible and sample.

W2 = Weight of the crucible and sample after ignition.

13. Assay of Titanium Dioxide 

Reagents :

(i) Sulphuric Acid

(ii) Ammonium Sulphate

(iii) Strong Ammonia solution

(iv) Strong Hydrogen Peroxide solution

(v) 0.05 (M) Disodium EDTA solution - Dissolve 18.6 g of Disodium EDTA in sufficient water to produce 1000 ml and standardise the solution as follows :

Weigh accurately about 0.8 g of granulated Zinc P.S; dissolve by gentle warming in 12 ml of dilute Hydrochloric acid and five drops of Bromine water. Boil to remove excess Bromine, cool and add sufficient water to produce 200 ml. Pipette 20 ml of the resulting solution into a flask and neutralise with 2(N) Sodium Hydroxide. Dilute to about 150 ml with water, and add sufficient Ammonia buffer pH 10 to dissolve the ppt. and add 5 ml in excess. Add 50 mg of Mordant Black II mixture and titrate with the Disodium EDTA solution until the solution turns green. Each 0.003269 gm of granulated Zinc is equivalent to 1ml of 0.05 (M) Disodium EDTA.

(vi) Sodium hydroxide solution - A 20% w/v solution of Sodium Hydroxide in water.

(vii)Hexamine

(viii)0.05 (M) Zinc Sulphate solution - The 0.05 (M) solution is prepared by dissolving 14.4 g of Zinc Sulphate in water and diluting it to 1000 ml.

(ix) Xylenol Orange solution - Shake 0.1 g of Xylenol orange with 100 ml of water and filter if necessary.

Method of Titanium Dioxide :

Weigh accurately about 0.3 g of sample, transfer it to a beaker, and add 20 ml of Sulphuric acid and 8 g of Ammonium Sulphate. Mix and heat until white fumes appear, and continue heating over a strong flame until a solution is affected. Cool and carefully dilute with 100 ml of water. Heat gently and bring to a boil with continuous stirring. Cool, filter and wash with several quantities each of 10 ml of water. Combine the filtrate and washings, add 10 ml of strong Ammonia solution, cool and dilute to 200 ml with water. Pipette 50 ml of the resulting solution into a flask, add 100 ml of water and 4 ml of strong Hydrogen Peroxide soln. Cool and add 50 ml of 0.05(M) Disodium EDTA. Allow standing for five minutes. Adjust the pH of the solution to 5.0 with Sodium hydroxide solution., add 5 gm of Hexamine and titrate with 0.05(M) Zinc Sulphate using Xylenol856orange solution as an indicator.

Calculation of Titanium Dioxide:-

                   (50 - V) x F x 0.003995 x 4 x ( 100 - M )

Assay (% w/w) = -------------------------------

                               W

V = Volume of 0.05(M) Zinc Sulphate solution required for titration.

F = Factor of 0.05(M) Zinc Sulphate solution.

W = Weight of the sample taken.

M = % w/w loss on drying of Titanium Dioxide.

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