What are the requirements and precautions for acid value of oil products
2018/5/17 Viewers:
The regulations and precautions that must be observed when determining acid value of oil are as follows.
(1) why should the anhydrous alcohol be used without aldehydes: if potassium hydroxide is made from anhydrous alcohol containing aldehydes? Because of the dilute alkali solution, the condensation reaction occurs. With the extension of time, the potassium hydroxide will become yellow and deteriorate. For this reason, aldehyde containing ethanol must be removed first, especially when the acid value is measured by potential difference method.
(2) if the anhydrous alcohol is alkaline reaction (often bought by the star alkaline reaction), when the acid value is used, the anhydrous alcohol after boiling and the 6B indicator of the alkali orchid is slightly red, which indicates that the ethanol has phenolphthalein alkalinity (Star alkalinity). At this time, the ethanol should be added with several drops of hydrochloric acid (o.1M) before using to neutralize its alkalinity and make the ethanol a micro acid surface. Reoccupy. Otherwise, the blank of ethanol can not be detected. And the acid value is low.
(3) the acid value of the side oil is stipulated to boil 5min two times, and the principle of hot titration is: 1. In order to dispel the influence of carbon dioxide on the acid value. Because the carbon dioxide in the air at room temperature is very easy to dissolve in the ethanol (3 times larger than the solubility in the water), if the heat is not boiled, the acid value will be determined by the quick drop of heat. (2) boiling 5min is conducive to the extraction of acidic components in oil products. (3) the ethanol solution used as solvent must also be heated by titration. If it is titrated after cooling, it will also be dissolved in carbon dioxide.
(4) when the acid value is exile to the end of the end, the alkali solution should be added slowly. When the estimated difference is one, the two drops should be replaced by half drop in order to reduce the titration error.
(5) when boiling the ethanol, the temperature should not be too high.
(1) why should the anhydrous alcohol be used without aldehydes: if potassium hydroxide is made from anhydrous alcohol containing aldehydes? Because of the dilute alkali solution, the condensation reaction occurs. With the extension of time, the potassium hydroxide will become yellow and deteriorate. For this reason, aldehyde containing ethanol must be removed first, especially when the acid value is measured by potential difference method.
(2) if the anhydrous alcohol is alkaline reaction (often bought by the star alkaline reaction), when the acid value is used, the anhydrous alcohol after boiling and the 6B indicator of the alkali orchid is slightly red, which indicates that the ethanol has phenolphthalein alkalinity (Star alkalinity). At this time, the ethanol should be added with several drops of hydrochloric acid (o.1M) before using to neutralize its alkalinity and make the ethanol a micro acid surface. Reoccupy. Otherwise, the blank of ethanol can not be detected. And the acid value is low.
(3) the acid value of the side oil is stipulated to boil 5min two times, and the principle of hot titration is: 1. In order to dispel the influence of carbon dioxide on the acid value. Because the carbon dioxide in the air at room temperature is very easy to dissolve in the ethanol (3 times larger than the solubility in the water), if the heat is not boiled, the acid value will be determined by the quick drop of heat. (2) boiling 5min is conducive to the extraction of acidic components in oil products. (3) the ethanol solution used as solvent must also be heated by titration. If it is titrated after cooling, it will also be dissolved in carbon dioxide.
(4) when the acid value is exile to the end of the end, the alkali solution should be added slowly. When the estimated difference is one, the two drops should be replaced by half drop in order to reduce the titration error.
(5) when boiling the ethanol, the temperature should not be too high.
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