Process for recovering glycine from sodium sulfate solutions

Abstract

Glycine can be recovered from an aqueous starting solution of glycine and sodium sulfate having a mole ratio of glycine to sodium sulfate of about 1-5:1 and a pH of about 4.5-8.5 by: (a) cooling the starting solution to precipitate a first lot of glycine and form a first mother liquor; (b) separating the precipitated glycine from the first mother liquor; (c) recovering the separated glycine; (d) precipitating a first lot of sodium sulfate from the first mother liquor by evaporating water therefrom to form a first lot of precipitated sodium sulfate and a second mother liquor; (e) separating the precipitated sodium sulfate from the second mother liquor; (f) admixing the separated second mother liquor with water and a second lot of the aqueous starting solution to form a first resulting solution; (g) cooling the first resulting solution to form a second lot of precipitated glycine and a third mother liquor; (h) separating the second lot of precipitated glycine from the third mother liquor; (i) evaporating water from the third mother liquor to precipitate a second lot of precipitated sodium sulfate and form a fourth mother liquor; (j) separating the second lot of precipitated sodium sulfate from the fourth mother liquor; (k) admixing the separated fourth mother liquor with water and a third lot of the aqueous starting solution to form a second resulting solution; (1) cooling the second resulting solution to form a third crop of precipitated glycine and a fifth mother liquor; and (m) separating the third crop of precipitated glycine from the fifth mother liquor. The separated fifth mother liquor can be concentrated to precipitate a third lot of sodium sulfate and to form a sixth mother liquor. Steps (j) through (m) can then be repeated. This procedure can be repeated indefinitely.