Method for purification of glycerol from biodiesel production
View Patent ↗A method for purification of crude glycerol, especially crude glycerol derived from biodiesel production using alkaline catalysts. The method comprises combining the crude glycerol with acid, separating a glycerol layer, and treating the glycerol layer to decolorize it.
1. A method for purification of crude glycerol contaminated with alkaline salts; said method comprising steps of:
(a) combining the crude glycerol with at least 1 equivalent of sulfuric acid having a concentration of at least 85 wt %;
(b) separating a glycerol layer from the salts; and
(c) combining said glycerol layer with a solution of sodium borohydride and sodium hydroxide.
2. The method of claim 1 in which the crude glycerol comprises fatty acid methyl esters.
3. The method of claim 2 in which the sulfuric acid has a concentration of at least 90 wt %.
4. The method of claim 3 in which at least 1.1 equivalents of sulfuric acid are combined with the crude glycerol.
5. The method of claim 4 in which the solution of sodium borohydride and sodium hydroxide contains 8-20 wt % sodium borohydride and 35-45 wt % sodium hydroxide.
6. The method of claim 5 in which the crude glycerol is a byproduct of biodiesel production.
7. The method of claim 6 in which the solution of sodium borohydride and sodium hydroxide is added in an amount from 0.7 g to 1.5 g per 100 g of glycerol layer.
8. The method of claim 7 in which the sulfuric acid has a concentration of at least 94 wt %.
9. The method of claim 8 in which at least 1.15 equivalents of sulfuric acid are combined with the crude glycerol.