Preparation of pure water in the cremation Laborat

Preparation of pure water in the laboratory

the preparation of pure water is the basis of analysis and testing. With the strong support of the state, drinking water or other relatively pure water should be selected as raw materials for the preparation of laboratory water. Generally, there are the following methods

distillation

distillation is a method widely used in laboratories to prepare laboratory water at present. Distilled water is obtained by processing and distilling raw water. Since most of the inorganic salts are nonvolatile in the test process, most of the inorganic salts are removed from the distilled water, which is suitable for general laboratory work

the water distillers currently used are small ones made of glass and larger ones made of copper. Due to the different materials of the distiller, the impurities brought into the distilled water are also different. The distilled water produced by glass still contains more Na + and SiO plasma. Distilled water produced by copper distiller usually contains more Cu, etc. Distilled water usually contains some other impurities, such as carbon dioxide and some volatile substances with low boiling point, which enter the distilled water with steam; A small amount of liquid water flies out in fog, and its stability is not as good as that of the first transmission system, which directly enters distilled water; A small amount of condenser material can also be brought into distilled water. Therefore, primary distilled water can only be used for general analysis

the distillation speed of distilled water should not be too fast. The purity of distilled water can be improved by non boiling evaporation, increasing the number of distillation, discarding the head and tail, etc. At the same time, the storage of distilled water is also very important. It should be stored in containers that are not polluted by ions, such as plexiglass, polyethylene or quartz

to make secondary distilled water in the laboratory, a hard glass or quartz distiller can be used, and a small amount of alkaline solution of potassium permanganate can be added first, in order to destroy the organic matter in the water. Discard the first quarter during distillation and collect the middle distillate. Alkali asbestos pipe shall be installed on the upper mouth of the receiver to prevent carbon dioxide from entering and affecting the conductivity of distilled water

some water for special purposes should be made by distillers made of special materials such as silver, platinum, polytetrafluoroethylene, etc