Fatty acid production industries use vegetable oil as one of the main sources. In the process of splitting vegetable oil, a co-product called glycerol is produced which is now a good source for making propylene glycol (via Acetol ). Fatty acids mostly converted to consumer products like soap and detergents by saponification method using sodium hydroxide or potassium hydroxide with sodium carbonate.
Biodiesel manufacturing units use the fatty acids for converting them into a fuel that is suitable to use it in place of diesel, by trans-esterification process methanol is reacted with fatty acids. Not only edible oils natural and animal fats are used to produce fatty acid because more or less their chemical structure has a glycerol molecule bonded with three fatty acid molecules. Due to this standard structure, they chemically called as triglycerides esters of fatty acids and glycerol. Hydrolysis process is one of the technologies to produce fatty acid and co-product glycerol from the edible oils/ fats.
Hydrolysis process description to produce fatty acid and co-product glycerol:
This technique is advance in controlling the separation process and high recovery of glycerol in the single process cycle. Zinc oxide catalyst is used during the hydrolysis step that takes place when water along with high-pressure steam is made contact with the counter flow of oil in a separating column. 5 Mpa pressure and 250-260oC temperature are maintained in the column. Liquid-liquid contact column is used for this operation, from its bottom the separated glycerol is removed continuously and from top fatty acids is sent to vacuum dryer and separator. Zinc oxide and the saponified fatty material is removed by the vacuum separator and to improve its quality in colour and smell.
Bottom stream from hydrolyser contains 15-20% glycerine, ZnO and partially saponified fats. Glycerin is purified by ion exchange and concentrated in triple effect evaporator to produce yellow glycerol, it is used for industrial application. It is reacted with activated carbon to obtain white USP grade glycerin with 99% concentration.
The chemical reaction in hydrolyser to produce fatty acid and co-product glycerol:
(R-COO)3C3H5 + 3H2O ↔ 3R.COO.H + C3H5(OH)3
Tri-glyceride + water ↔ fatty acid + glycerine (sweet water)
Hydrolysis process flow sheet to produce glycerol and fatty acid from any natural or animal fat/oil:
Standard analysis methods
- EN14103 for FAME test
- EN14105 for glyceride content test
- EN14104 for acid number determination