water analysis method
In the water analysis method, the following substances are mainly analyzed
Water quality analysis mainly analyzes the following indicators and substances in water. The specific water analysis methods are as follows:
Calcium determination
Filter 50ml of water sample, add 3 drops of hydrochloric acid solution (1+1), and mix evenly. Heat to boil slightly for half a minute, then add 50ml of reagent water, 2ml of triethanolamine, 5ml of 20% potassium hydroxide solution, 30mg of calcein mixed indicator and titrate with EDTA standard solution against a black background until the yellow-green fluorescence of the solution disappears, and the solution is The red color is the titration end point.
Determination of total hardness
Filter 50ml of water sample, add 2ml of triethanolamine solution, 10ml of ammonia-ammonium chloride buffer solution, a little K-B indicator, and titrate with EDTA standard solution on a black background until the red turns to blue, which is the end point of the titration.
Determination of Chloride
Take 100ml of water sample, add 2-3 drops of 1% phenolphthalein indicator, if red, neutralize with sulfuric acid solution until colorless (if not red, titrate with sodium hydroxide solution to reddish, then titrate with sulfuric acid solution to colorless). Add 1ml of 10% potassium chromate indicator, and titrate with silver nitrate standard solution until orange is the titration end point.
Determination of total alkalinity
Take 100ml water sample and add 2-3 drops of 1% phenolphthalein indicator. If it appears red, titrate it with sulfuric acid standard solution until it is colorless. If it is colorless, proceed directly to the next step (it can also be judged by pH. Phenolphthalein is present when pH>8.2 alkalinity). Add two drops of methyl orange indicator, and titrate with 0.1mol/L sulfuric acid standard solution until orange red is the titration end point.
Determination of iron
A blank sample comparison is required.
Take 50ml of water sample, add 0.5ml of sulfuric acid (1+3), 5ml of potassium persulfate solution, and boil slightly to a volume of about 25ml (not less than 20ml). After cooling, transfer it to a 50ml colorimetric tube and add water to the mark. Add 1ml of hydroxylamine hydrochloride, 2ml of acetic acid-ammonium acetate buffer solution (pH3.5-5.5, preferably 4.5), 2ml of 1,10phenanthroline solution, place in the dark for 15 minutes, use a spectrophotometer at 510nm with a blank solution Absorbance was measured for reference.
Determination of Sulfate
Filter 25ml of water sample, put it into a 50ml colorimetric tube, add 2.5ml sodium chloride-hydrochloric acid mixture, 2.5ml absolute ethanol, 50mg barium chloride (weighed), shake up and down to mix, let stand for 15 minutes, and use spectrometry The absorbance was measured with a 20mm cuvette at 660nm by a photometer.
Determination of total phosphorus in circulating water
A blank sample comparison is required.
Filter 25ml of water sample (when the phosphorus content is 0-5mg/L), put it in a 100ml Erlenmeyer flask, add 1ml (1+35) sulfuric acid solution, if the pH is less than 1, add 5ml of potassium persulfate solution. Boil on low heat for almost 30 minutes (add water at any time while boiling to keep the volume between 25-30ml). Cool, adjust the pH to 3-10 with sodium hydroxide solution (80g/L or 60g/L), and transfer to a 50ml volumetric flask. Add 2ml of ammonium molybdate solution and 1ml of ascorbic acid solution, dilute to the mark with water, shake well, and place at room temperature for 10 minutes. Use a spectrophotometer to measure the absorbance at 710 nm using a 1 cm absorption cell and zeroing with a blank.