Shen ChangHong Water quality monitoring is a process of monitoring and measuring the types of pollutants in water, the concentration and change trend of various pollutants, and evaluating the water quality. The monitoring range is very wide, including the uncontaminated and polluted natural water (river, river, lake, sea and groundwater) and various industrial drainage. There are several kinds of water commonly used in the laboratory or laboratory:
1、 Distilled water
Distilled water is a kind of pure water commonly used in water quality analysis experiments. It can remove most of the pollutants in tap water in the production process, but volatile impurities cannot be removed, such as carbon dioxide, ammonia, silicon dioxide and some organic matters. The fresh distilled water is sterile, but the bacteria are easy to reproduce after storage; in addition, the storage containers are also very particular, if the non inert substances, the ions and the plastic substances of the containers will precipitate and cause secondary pollution, but because the requirements of the normal sewage / waste water quality analysis and detection are not very high, the distilled water can meet the daily use of water quality detection and analysis.
2、 Deionized water
The use of ion exchange resin to remove anions and cations in water, but there are still soluble organics in water, which can pollute the ion exchange column and reduce its efficiency. After the deionized water is stored, it is also easy to cause bacterial reproduction. Generally, it can be used for routine test, preparation of standing solution, cleaning of glassware, etc.
3、 Reverse osmosis water
The principle of its formation is that the water molecules become pure water through the reverse osmosis membrane under the action of pressure, and the impurities in the water are trapped and discharged by the reverse osmosis membrane. Reverse osmosis water overcomes many shortcomings of distilled water and deionized water. It can effectively remove dissolved salts, colloids, bacteria, viruses, bacterial endotoxin and most organic matters and other impurities in water by using reverse osmosis technology. The bottled water we usually drink is produced by the principle of reverse osmosis membrane.
4、 Ultra pure grade water
Ultrapure water is the water produced by distillation, deionization, reverse osmosis or other appropriate supercritical fine technologies for the development of ultrapure materials (semiconductor raw materials, nano fine ceramic materials, etc.), whose resistivity is greater than 18 m Ω * cm, or close to the limit value of 18.3 m Ω * cm (25 ℃). To put it simply, water is removed from almost all atoms except oxygen and hydrogen. Ultra pure water is usually used in chemical process water, chemicals, cosmetics, etc.
For the above laboratory water, the most commonly used water for water quality detection and analysis is distilled water, because its price is relatively low, the production process is relatively simple, and it is easy to purchase, and it can meet the experimental requirements.
