ANALYSIS OF P & M ALKALINITY OF WATER IN POWER PLANT

ANALYSIS OF P & M ALKALINITY OF WATER

Preparation of standard solution

• Sulphuric Acid (N/1) : Mix 115 cc. of AR (Analytical Reagent )grade H2SO4 with demineralised water and make up to 4 litres (2.12 gms of Na2CO3) shall consume 40cc. of N/1 H2SO4).
• Sulphuric Acid N/50) : Mix 81 cc. of N/1 H2SO4 with demineralised water and dilute to 4 litres (0.0424 gms of Na2CO3 in 50 ml. of water shall consume 40cc. of N/50 H2SO4).
• Dissolve 2gms. of phenolphthalein indicator in 1000 cc. of methanol.
• Dissolve 1gm. of Methyl orange indicator in 200c c. of demineralised water.

ANALYSIS

• Take 100 cc. of the water sample to be tested in a 250 cc. conical flask and add three drops of phenolpthalein indicator.
• If the solution turns red in colour, titrate it with N/50 H2SO4 till it becomes colourless. If the original water sample is colourless after the addition of the indicator, report the P alkalinity as Nil.
• Calculate the P alkalinity as per the following equation:
• P Alkalinity in ppm = vol.of N/50 H2 SO4  in ml. X 10.
• To the above soln. add 2 drops of methyl orange indicator soln. and titrate the soln. against N/50 H2 SO4 till the soln. becomes orange red.
• Calculate the M alkalinity as per the following equations:
• M alkalinity in ppm = vol. of N/50 H2SO4  in ml. X 10.

MEASUREMENT OF pH OF WATER

• Standard Buffer Solution of 7.0 pH 
• Take 100 cc. condensate water in a small plastic container and dissolve the buffer powder of 7.0 pH value.
• Prepare other Standard Buffer Solution of pH 4.0 and 9.2 in the same way as in 2.1.1

Calibration of pH meter

• Rinse the electrode of pH meter with demineralised water and carefully wipe it with filter paper.
• Take the std. buffer solution of 7.0 pH and measures temperature with a thermometer.
• Dip the electrode into buffer solution.
• Set the temperature control knob at the measured temperature of the buffer solution.
• Put on the pH meter and select the switch If the value is not 7.0 pH  then adjust and bring the pH value to 7.0  by rotating another knob provided on the meter.
• Repeat in the same manner with 9.2 pH standard solution. If this time the meter shows 9.2 pH, it means the meter is calibrated. For lower pH check with 4.0 pH Standard Buffer Solution.
• Now wash the electrode with demineralised water and wipe it with filter paper. Take the sample in a plastic beaker and measures the temperature with a thermometer.
• Now dip the electrode in this sample and adjust the temperature as above. Then by selecting proper scale note the pH value of the sample.

MEASUREMENT OF CONDUCTIVITY OF WATER.

Instrument required:

1. Digital conductivity Meter
2. Conductivity Cell and Thermometer

Standard Conductivity Solution:

• Dissolve 0.7455 gm. of dried KCL crystals in demineralised water and make the volume to 1000 cc. This solution shall give conductivity 1408.8 mho/cm at 25oC.
• Take the standard solution in a 100 ml. plastic beaker and adjust the cell constant in the scale reading which is provided on the cell.
• Take the temperature of standard solution 
• Rinse the cell thoroughly several times with demineralised water and then with standard solution.
• Dip the cell in the beaker of the standard solution. Read the conductivity. This is converted to 25 C by multiplying with temperature factors given in the chart in Annexure # 1.
• Take the sample in a 250 cc plastic beaker.
• Note the temperature of the sample.
• Rinse the cell thoroughly several times with demineralised water and then with the sample.
• Dip the cell in the sample  beaker and read the conductivity .
• Conductivity = Meter reading x Temp. factor.

ANALYSIS OF PHOSPHATE IN WATER

Ammonium Molybdate Solution .

a)Dissolve 8 gms of Ammonium Molybdate in 50 ml of demineralised water.

b)Mix 63  ml of conc. H2SO4 in 100 ml of demineralised water and 1 ml of conc. HNO3. 

Mix (a) and (b) then make up the volume to 250 ml.

Amino Napthol Sulphuric Acid (A.N.S.)

a)Grind 0.190 gms of A.N.S. and 10.5 gm of sodium sulphidte well and mix with 50 ml of demineralised water.

b)Dissolve 17.5 gm of sodium bisulphite in 200 ml of demineralised water. Mix (a) and (b) solutions.

Take 25 ml of water sample and 25 ml of demineralised water in  a 100 ml beaker.

Add 1 to 2 drops of phenolphthalein indicator to see if it is alkaline. Neutralize it with dil H2SO4 till it is colourless.

Add 2 ml of Ammonium molybdate solution (7.1.1) and wait for 2 minutes.

Add 2 ml of A.N.S. solution (7.1.2) shake gently and wait for 4 minutes.

Measures the colour intensity with a photo colorimeter at a wave length of 650 mm and compare against the obtained intensities on standard phosphate solutions.

DETERMINATION OF AMMONIA IN WATER

Standard Stock Solution:

Dry Ammonium sulphate for 1 hour at 100oC.Weigh accurately 4.718 gm into a 1 litres measuring flask and dissolve in 1 litre of demineralised water (D.M. water) and mix well by shaking the measuring flask.

Standard Solution (1ml = 0.01 mg NH3):

Take 1 ml of stock solution prepared in 5.1.1 in a 100 ml measuring flask and dilute to the mark with D.M. water and mix.

Prepare 50% Rochelli’s salt (Sodium Potassium Tartarate) solution in D.M. water.

Nessler’s Reagent:

• Dissolve 31.25 gm of Pottasium Iodide (kl) in 125 ml of D.M. water and add saturated solution of mercuric chloride (HgCl2) with stirring till red precipitate appears. Add this mixture to a cool solution of 80 gm Sodium Hydroxide (NaOH) dissolved in 75 ml of D. M. water. Dilute this mixture to 500 ml and leave for two days. Decant the solution into a glass bottle and keep in a cool place.
• Take 50 cc of water sample in a 100 cc beaker.
• Add two drops of Rochellis salt prepared vide point no 5.2 by dropping bottle.
• Add 2ml  of NESSLER’S reagent prepared vide point no 5.3 by burette.
• Leave the solution for 15 minutes for complete colour development.
• Develop the colour in the same way as above with known standard solutions.
• Measurement by Spectronic 20 D:
• Select 425 mm wave length using wave length control .
• Set the mode to Transmittance by pressing MODE select control until the transmittance L.E.D. is lit.
• With sample compartment Empty and cover closed, adjust zero control so that the reads 0.000T.
• Set the mode to Absorbance by pressing mode select until the absorbance L.E.D is lit . Insert test tube filled with D.M. water in the sample compartment and close the cover. Adjust the absorbance to 0.000 A by Absorbance Control Knob. 
• Set the mode to concentration by pressing mode select until the absorbance L.E.D. is lit. Insert the test tube filled with known value standard solution and developed as in 5.3 and use the increase or decrease keys to set known value of standard in meter display.
• First, rinse the test tube with the solution to be measured and then fill the test tube and insert in the measuring compartment and close the cover and read the value in meter display directly.

Report:

Report the meter reading which comes in display directly to concentration of Ammonia in parts per million (p.p.m.).