Determination of dissolved oxygen and oil content in water

 DETERMINATION OF DISSOLVED OXYGEN IN WATER.

Procedure 

1.Narrow mouth ground glass stoppered dust proof  test tube of capacity 60 ml.

2.Pipette capacity 10 ml.

Indigo Carmine Solution - Dissolve 0.0108 gm of indigo carmine and 0.12 gm of dextrose in 3.0 ml of demineralized water. When completely dissolved add 45 ml. of glycerol. This reagent is stable for two weeks only.

• Pottasium Hydroxide – 5 gm KOH (Pottasium Hydroxide) is dissolved in 10ml of demineralised water.
• About half an hour before testing for dissolved oxygen add 20ml of the indigo carmine solution as prepared in the 20.2 and 5 ml of KOH to a small beaker. The solution will change colour from deep red to a lemon yellow in about 15 minutes and then it is ready for use.
• Collect the sample through the cooler filled with ice on the spot by overflowing the sample from the test tube for about 5 minutes.
• After sufficient volume of water has passed through the test tube immediately remove the test tube and insert the pipette filled with the indigo carmine reagent prepared 
• Add about 4 ml of indigo carmine solution from the pipette.
• Match the colour developed in the test tube with the colour of standards prepared in the following way.

Stock Solution 
Red Colour Standard No. CS – A : Dissolve 59.29 gm of cobaltous chloride (COCl2 . 6H2O) in 1:99 hydrochloride acid and make the volume  1 litre.

ANALYSIS OF OIL CONTENT IN WATER

Procedure

One separating funnel of 1litre capacity, concentrated sulphur acid, petroleum ether, beaker and a funnel are required.
Take 500 cc. of water sample to be analysed for oil content in a one litre separating funnel.

• Add 5 cc. of conc. sulphuric acid and shake well.
• Add 20 ml petroleum ether in the separating funnel and shake well for 5 minutes. Release the pressure formed inside the funnel cautiously by opening the stop cock after inverting the funnel.
• After shaking well keep the funnel on stand and allow the petroleum ether layer to separate from water layer.
• Take out the water from the separating funnel leaving behind the petroleum ether.
• Then filter the petroleum ether through filter paper in the funnel into a 100 cc beaker of known weight.
• Keep the beaker containing petroleum ether and oil in a drying chamber for two hours at 110oC.
• When beaker is dried take it out, cool in a desecrator to room temperature and weigh the beaker with oil.
• Weight of oil mg x 2 = oil in ppm (parts per million).

ANALYSIS OF -CN & -CNO OF SALT 

Reagents

• Dissolve 100 gms calcium Nitrate in 900 ml. of D.M. water (Deminerlised water).
• Dissolve 26.1 gm of silver Nitrate in 1 liter of demineralised water in a volumetric flask and mix well by shaking.
• Dissolve 2 gm of phenolphtalein in 1 liter of Methyl alcohol.
• Prepare 5% aqueous solution of potassium chromate (K2CrO4).

Procedure

• Crush sample in a mortor. Take 5 gms of crushed sample in a 250 c.c volumetric flask.
• Add 50 c.c D.M. water to dissolve the sample.
• Add 60 c.c. Calcium Nitrate Solution. Make the volume to 250 c.c with D.M. water and shake well to mix the contents. 
• Allow the ppt. to settle.
• Filter the solution through filter paper 
• Take 25 c.c of the filtrate. Add 5 drops of phendphtatein and Titrate against standard AgNO3 solution till the solution becomes colourless. Note the reading. (a)
• Add 5 drops of K2CrO4 to the same solution. Titrate against AgNO3 till the colour changes from yellow to brown.
• Note the reading (b).

Calculation :

ml of AgNO3 consumed (a) - CN %  = a x 1.6 CALCULATION OF - CNO (b - 2a) x 1.6 = % - CNO.

QUESTIONNAIRE 

1.Why water treatment is requred for feed-     water in Boilers?

2.Explain in brief, how demineralization of     water is done.

3.What is ‘Back wash’ and how it is done?

4.Name the various equipment in water          treatment plant.

5.Draw and explain the process flow of Dm    Plant

6.Name the various filters used in water         treatment.

7.What are the functions of Exchangers?

8.How do you check Raw water level?

9.What are the steps to be followed in   shutting down the pressure sand filter?

10.What is pressure filter and how it works 

11.In which operation of water treatment,     blowing of air is needed and Why?

12.What is the meaning of  ‘P’ & ‘M’ alkalinity of water?

13.How do you measure pH of water?

14.What are the instruments required to measure the conductivity of water?

15.What is standard conductivity solution?

16.How to analyse phosphate in water?

17.What is Nessler’s Reagent? How to prepare it? What for this is used?

18.How to analyse low silica in water?

19.What is the procedure for analysing TSS and TDS of water?

20.How to prepare elthylen Diamine Tetra Acetic Acid (EDTA)?

21.How to analyse chloride in water?

22.How to test hardness of water?

23.How to find nitrite content in water?

24.What is the procedure for analysing CO2 in Degasser water?

25.Explain the procedure for analysis of Hydrazine in water.

26.What is the procedure for analysis of iron in water?

27.How to determine zinc content in water?

28.How to analyse coper in water?

29.How to analyse - CN and – CNO of salt?

30.What is procedure for determining oil content in water?

31.How to determine dissolved oxygen in water?