1 Ammonia Nitrogen Experiment

1.1 Principle of the method

In the presence of sodium nitroso ferrocyanide, ammonium reacts with salicylate and hypochlorite ions to form a blue compound with maximum absorption at wavelength 697nm.

1.2 Scope of application of the method

It is suitable for the determination of ammonia nitrogen in tap water, domestic sewage and most industrial wastewater.

1.3 Instrument

732PC spectrophotometer; dropping bottle; lOmL stoppered cylinder or colorimeter; volumetric flask (lOOmL, 1000mL).

1.4 Reagents

10% zinc sulfate solution; 25% sodium hydroxide solution; ammonium standard storage solution; ammonium standard intermediate solution; ammonium standard use solution; color development solution; sodium hypochlorite solution; sodium nitroso ferrocyanide solution: weighing O.lg sodium nitroso ferrocyanide in lOmL stoppered cuvette, dissolved in water, diluted to the standard line.

1.5 Steps

1) Calibration curve drawing

2) Measurement of water samples

Take lOOmL of water sample in a cuvette, add ImLl0% zinc sulfate solution and 5 drops of 25% NaOH solution, mix well. Leave to precipitate, filter with filter paper and take appropriate amount of water sample to the colorimetric tube, dilute about 8mL with water, add l.OOmL of color developing solution and 2 drops of sodium nitrosoferricyanide solution, mix well. Then add 2 drops of sodium hypochlorite solution diluted to the standard line, mix well. 1h, at a wavelength of 697nm, measure the absorbance. (Do the blank test at the same time)

1.6 Calculation

Ammonia nitrogen (N, mg/L) = m/v

2 Results and Discussion

2.1 Effect of the dosage of sodium nitrosoferricyanide solution on the color development of water samples

After the treatment of water samples, and then add different amounts of sodium nitrite ferrocyanide solution, at this time the amount of sodium hypochlorite solution is O.lOmL, to observe the change of its color development.

From the results of the experiment, when the amount of sodium nitrite ferrocyanide solution slowly increased from low, its absorbance also gradually increased, but in the amount of sodium nitrite ferrocyanide solution is lower than 0.15mL greater than 0.20mL, the absorbance of the solution after the color development of the solution is in an unstable, and the color development of the solution was green, the only amount of the solution in the amount of 0.15-0.20mL in line with the national standard law, for the blue compounds, so the experimental Choose to use 0.20mL sodium nitroso ferrocyanide solution is the best.

2.2 The effect of the amount of sodium hypochlorite solution on the color development of water samples

After the treatment of water samples, and then add different amounts of sodium hypochlorite solution, at this time the amount of sodium nitrite ferrocyanide solution for 0.20mL, to observe the change of its color development