1, increase the flow of water sample to be tested, and take 5- 10L water sample. Immediately add 5- 10mL aluminum sulfate solution (calculated by 1mL per liter of water), shake well, and add 5- 10mL sodium carbonate solution (also calculated by 1mL per liter of water).
2. Pour 100mL carbon tetrachloride into the sampling bottle, and thoroughly clean the oil stains on the bottle wall of the sampling bottle. Transfer carbon tetrachloride to a separatory funnel.
3. Shake well, extract the oil from the acidified solution and let it stand. After layering, filter the carbon tetrachloride layer at the bottom with Jess Zhang ashless filter paper, transfer the filtered carbon tetrachloride solvent to an evaporating dish with constant weight of 100ml, then rinse the separating funnel and filter paper with 10ml carbon tetrachloride, and add the washing liquid to the evaporating dish with constant weight.
4. Put the evaporating dish on the water bath, evaporate the carbon tetrachloride in the fume hood, then put the evaporating dish in (110 5)℃ and bake it repeatedly for 30 minutes, then cool it, weigh it, and so on, until the weight is constant. In addition, put 100mL carbon tetrachloride into another constant weight evaporating dish for blank test.
Precautions for detection:
1. It is suggested to add the extractant used in the method immediately after sampling, or to carry out on-site extraction.
2. In order to preserve the water sample, 5mL sulfuric acid solution (1+ 1) can be added to each liter of water sample to make the pH value of the water sample.
Forms of oil in water:
1, oil slick:
The particle size dispersed in water is generally larger than 100μm, and it can float up quickly after standing, forming a continuous oil film on the water surface.
2, dispersed oil:
The particle size of the dispersion in water is 10 ~ 100 micron, which is unstable as tiny oil droplets suspended in water, and often forms an oil film after standing for a certain period of time.
3, emulsified oil:
The particle size dispersed in water is less than 10μm, generally 0. 1 ~ 2μ m, and oil droplets often form a stable emulsion because water contains surfactants.