Study On Liquid-liquid Phase Equilibrium Of Hydrophilic Organic Phase/Salt Containing Aqueous System And Extraction For L-Lysine

Hydrophilic organic phase/salt containing aqueous system is a novel separation system, which can be applied to the fields of biological engineering, Sample enrichment and separation in analytical chemistry, solvent separation etc. It is a separation system of potential industrial application on account of some advantages of simple system, abundant and inexpensive raw material, non-emulsification, saving baci-extraction, low power consumption and so on.This dissertation detailedly studies on the liquid-liquid equilibrium (LLE) of two hydrophilic organic phase/ salt containing aqueous systems of water+ ethanol/isopropanol + dipotassium hydrogen phosphate, and extraction and separation for L-lysine with the system of water+ ethanol+ dipotassium hydrogen phosphate. The main contents as following:1) Phase separation ability of dipotassium hydrogen phosphate solution was investigated on the conditions of different solvent, different temperature, different pH value and little additional sodium chloride. The results indicated: isopropanol excelled ethanol in the light of separate phase ability if dipotassium hydrogen phosphate solution was fixed; temperature has a little influence on phase separation ability of the fixed systems; a small of additional sodium chloride have little influence on separation ability; phase separation ability decreases with the pH value decreasing, and it can not form two liquid-liquid system when pH value is less than 6.2) A new experimental measurement method, which was named as turbidity -density analysis method, was proposed and established to determine LLE data of hydrophilic organic phase/ salt containing aqueous system. At the constant pressure and temperature, degree of freedom is only one in the ternary saturated solution basing on the Gibbs phase law, thus the corresponding relation between solution density and concentration of any one components is unique in the solution system. According to the proposed method, the isothermal solubility was determined with "turbidity analysis" method and the destiny of ternary system was determined with density meter simultaneously, then an experiential equation, which was called density equation, was used to correlate the relation between solution density and concentration of any one components of the ternary system. Therefore, based on the density equation, the content of two liquid-liquid equilibrium system can bedetermined with the density measurement.3) According to the turbidity-density analysis method, liquid-liquid equilibrium data of water+ethanol+dipotassium hydrogen phosphate and water+ isopropanol+ dipotassium hydrogen phosphate ternary system were determined at the normal pressure and constant temperature 30 C .Those data had been predicted with Peng Qinghai's equation, but it is not very ideal. The experiential equations of Othmer-Tobias and Bancroft could accurately correlate those data.4) An experimental investigation was made on the possibility and the influencing factors of extraction and separation of L-lysine with the water+ethanol+dipotassium hydrogen phosphate. The results indicated that the distribution coefficient of L-lysine was increased with the pH values increasing, reduced with the concentration of K2HPO4 or ethanol increasing, and little influenced by the addition of sodium chloride. The distribution coefficient comes up to 18.41 when wt%(K2HPO4)=15%, wt%(C2H5OH)=20% and pH=l1.96. In conclusion, hydrophilic organic phase/ salt containing aqueous system of water+ethanol+dipotassium hydrogen phosphate may provide a new technology for the separation and extraction of L-lysine.