Preparation of high-pure choline
Choline chloride is one of the raw materials to produce high-pure choline.The choline chloride solution contains many kinds of metal ions such as Na~+,K~+,Mg~(2+),Ca~(2+)and so on.Metal ion has a bad influence on the quality of high-pure choline.WU64-H resin was used to eliminate the metal ions in choline chloride.The effects of transformation agent,flow rate and concentration were investigated.Experimental result indicated that,the electron-grade tetramethylammonium hydroxide was the best transformation agent,the best flow rate was 5 times as bed volume rate in an hour and the optimal concentration was 2 mol·L~(-1).Under these optimal conditions,the concentrations of metal ions were significantly decreased.Choline was prepared by electrolysis.The current density was 1000 A·m~(-2)and the temperature was 50℃.After electrolysis,the contents of metal ions were below 100μg·L~(-1),and came up to the requirements.