Dimethyl silicone oil, due to itsExtremely low surface tensionandhydrophobicityOnce mixed with water, it will form a very stable lotion or film, which is difficult to separate by natural standing.

There are several methods to remove moisture from dimethyl silicone oil, which can be selected according to your specific needs (such as purity requirements, equipment conditions, etc.) for reference:

1 Physical methods (applicable to situations with small amounts of water or mild emulsification)

Heating evaporation method

Principle:The boiling point of water (100 ° C) is much lower than that of dimethyl silicone oil (usually much higher than 200 ° C). By heating, water can be evaporated, while the silicone oil itself is basically unaffected.

Operation Method:

Pour the silicone oil containing water into an open, heat-resistant container (such as a beaker or evaporating dish).

placeElectric heating sleeveoroil bathModerate slow heating（Never use open flamesAlthough silicone oil is not flammable, it is still a combustible material.

Control the temperature 105 - 120°CContinue stirring left and right until no bubbles (water vapor) are produced.

Advantages:Simple operation and low cost.

Disadvantages:If the moisture is in an emulsified state, it may not be completely removed; Long term high temperature may oxidize a small amount of silicone oil (although silicone oil has good thermal stability).

Vacuum dehydration method (combining heating and vacuum)

Principle:In a vacuum environment, the boiling point of water will significantly decrease. For example, under a vacuum degree of -0.095 MPa, the boiling point of water can drop below 40 ° C. This enables efficient removal of moisture at lower temperatures, making it particularly suitable for applications that are sensitive to heat or require deep dehydration.

Operation Method:needRotary evaporatororvacuum drying oven.

Rotary evaporator:Add silicone oil to the flask, set the water bath temperature (such as 60-80 ° C), evacuate, and rotate the flask to expand the evaporation area. This is a commonly used and efficient method in the laboratory.

Vacuum drying oven:Spread the silicone oil flat in an open container, place it in a vacuum drying oven, set the temperature and vacuum degree, and dry for a long time.

Advantages:脱水good effectHigh efficiency and minimal impact on the sample.

Disadvantages:We need professional equipment.

Freeze centrifugation method

Principle:Water freezes at low temperatures, and the freezing point of dimethyl silicone oil is extremely low (usually<-50 ° C). First freeze the water to freeze, then use high-speed centrifugation to separate the ice residue by utilizing the density difference.

Operation Method:

Place the silicone oil containing water into a centrifuge tube andRefrigerator freezer compartment（-18°C）Leave it in the middle for a few hours to freeze the water.

Immediately put it in after removalPre cooled centrifugePerform high-speed centrifugation (e.g10000 rpm， 10 minutes).

After centrifugation, the ice residue will settle at the bottom of the tube. Carefully pour out the supernatant (dehydrated silicone oil).

Advantages:Very suitable for handling silicone oil that becomes turbid due to emulsification, it can effectively break down emulsions.

Disadvantages:Need for cryogenic centrifuge equipment; fuckIt's a bit cumbersome to do.

II Chemical methods (not commonly used, with specific risks)

Principle:The most typical use of chemical desiccants that can react with water and generate gas issodiumSodium reacts with water to produce sodium hydroxide and hydrogen gas, thereby removing water.

Operation Method:Add a small piece of metallic sodium (cleaned with kerosene) to silicone oil, heat and stir until no more hydrogen gas bubbles are produced.

Warning:This methodExtremely dangerousSodium is a highly reactive metal that reacts violently with water, posing a risk of combustion and explosion. Meanwhile, the sodium hydroxide generated by the reaction will contaminate the silicone oil.Unless there are special requirements and professional chemical operation skills, it is strongly not recommended to use this method.

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