According to the principle that oil and water are insoluble and the boiling point of water is lower than oil, water can be removed by heating and static separation.Heavy H2SO4 oxidation is used to remove organic substance, and clay is used to adsorb pigment and filter out mechanical impurities.

The following five steps are generally required for motor oil decolorization:


Collect the used motor oil into the oil collecting tank and put it in the oil refining tank after dehydration,Stop heating after temperature rise to 70 ~ 80 ℃,static separation for 24hours ,discharging the surface water.
And then slowly heat up to 120 ℃(when the oil temperature is close to 100 ℃, slowly heating, prevent oil boiling overflow) . With the water evaporating, don’t stir the oil in about 2 hours ,the process finished when the black gas steamed out from the oil surface.

2.Acid pickling

When the oil is cooled to normal temperature, sulfuric acid is added slowly under stirring (the concentration is about 92 ~ 98%),the amount of acid is usually 5-7% of the oil(It depends on how dirty the oil is).After adding the acid, continue stirring for half an hour, and then leave for about 12 hours to discharge the acid residue.

3.Alkali washing:

Heat up the oil temperature to 80℃ after acid pickling,add sodium carbonate during stirring,leave the oil for 1 hour after full stirring.When it is tested to be neutral with the test paper, leave the oil for more than 4 hours to discharge the alkali residue.

4.Activated clay adsorption

Heat up the oil temperature to 120 ~ 140 ℃, adding activated clay(which amount is 3.5% of the oil) under constant temperature and stirring.After adding the activated clay, continue to stir in half an hour, leave it on constant temperature of 110 ~ 120 ℃ overnight, filter out while it’s hot on the next day.


Oil filter can be used to filter the oil, we can get the qualified oil after filtering .If there is no oil filter, the cloth bag lifting filter method can also be adopted.