Patent ID: 7718833

Claim:
A method of purifying crude glycerin, comprising the steps of: a) providing an alkaline admixture comprising glycerin, soap, a fatty acid ester, and at least one other alcohol, said other alcohol having a lower boiling point than glycerin; b) adding a sufficient amount of water so that the admixture includes from about 0.8 to about 5 parts by weight water per 100 parts by weight of the admixture; c) after adding the water, distilling the admixture under conditions effective to strip away substantially all of the other alcohol; d) after stripping the other alcohol, lowering the pH of the admixture with aqueous acid under conditions effective to convert the soap to free fatty acid and to form a first organic phase comprising the free fatty acid and the fatty acid ester and a second aqueous phase comprising the glycerin; and e) separating the organic and aqueous phases.