With liquid-liquid extraction technology of water and the separation of acetic acid
Acetic acid is a kind of important organic chemical raw materials, widely used in organic synthesis, medicine, basic dyes, spices, pesticides and other industries.
For a long time, the separation of acetic acid/water system problem has been brought to the attention of the people.
Not only because of acetic acid used in all kinds of industrial production of universality, but also because the acetic acid/water separation in chemical separation and the development of chemical industry environmental protection plays an important role.
Acetic acid/water while not forming the constant boiling, but not their relative volatility.
The current production is mainly adopted in the extraction method and the esterification method to deal with!
1 extraction method according to the boiling point of extractants (
Compared with the boiling point of acetic acid)
, extraction can be divided into the low boiling point extraction and high boiling point extraction.
Low boiling point extraction agent with low molecular weight of ester, alcohol, ether, acetone;
High boiling extraction agent have phosphorous extraction agent and organic amine extraction agent, such as three octyl oxygen phosphorus (
, tributyl phosphate (
, cyclohexanone, three amine.
Three of the oxygen octyl phosphate, tributyl phosphate [
The effect is better.
is shown in figure 2 of low boiling point solvent extraction is a liquid-liquid extraction of acetic acid to concentrate first w = 50%, with further enrichment azeotropic distillation.
Although low boiling point solvent extraction distribution ratio is not big, but widely used, mainly because of this kind of solvent and easy separation of acetic acid, the method is suitable for dealing with high concentration of acetic acid solution.
When treated liquid acetic acid content lower than 5%, the economic benefits of high boiling point extraction is more obvious.
the esterification method is 10% ~ 30% to add methanol or ethanol, acetic acid aqueous solution under the catalysis of inorganic acid in the esterification reaction.
Because ester and the boiling point of water is large, ester, volatile, can use ordinary distillation method to be steamed out again after hydrolysis recycling, alcohol and acetic acid.
if in acetic acid wastewater � � with inorganic acid, and then esterification method can reduce the cost of recycling, and it can avoid secondary pollution.
Such as myristic acid methyl ester via bromination, then after Ullman reaction can get treatment hepatitis of biphenyl double ester, the technological process of wastewater containing acetic acid and hydrogen bromide, about 10% of acetic acid concentration.
Using the esterification process as shown in figure 3, acetic acid in waste water recovery was 90%, the esterification products of ester content of about 80%.
After the recovery of acetic acid, column reactor in the wastewater hydrogen bromide bromine or hydrogen bromide in the form of recycling.
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