Study Of The Separation And Extraction Of Glycolic Acid From Algal Hydrolysate

Glycolic acid was listed as a basic chemical product in our country in the 13th Five-Year Plan.The preparation route of glycolic acid has matured,while the separation and purification of glycolic acid has gradually become a major difficulty in recent years.At present,the high purity glycolic acid in the domestic market is mainly derived from imports.This article aims to break this dilemma,using solvent extraction method for the separation and purification of glycolic acid in seaweed hydrolysate,the main contents are as follows:In this experiment,the standard curve of glycolic acid was firstly drawn by high performance liquid chromatography?HPLC?,and the concentration of glycolic acid in the seaweed hydrolyzate was determined to be 39.74 g/L.Next,a series of hydrophobic DESs were prepared by heating,and methyltrioctylammonium chloride/dodecanol with the highest extraction rate of glycolic acid was selected as the best extractant to optimize the extraction conditions:phase ratio is 1.5:1,extraction temperature is 30?,magnetic stirring for15 minutes,the single-stage extraction rate is 36.35%.After 9 stages of countercurrent flow,the extraction rate reached 81.94%after dynamic equilibrium was reached.Then,a series of amides were synthesized,and i-N218 was selected as the best extractant to optimize the extraction conditions:phase ratio is 5:1,extraction temperature is 30?,magnetic stirring for 5 minutes,the single-stage extraction rate is 48.85%.After 7-stage countercurrent reaching a dynamic equilibrium,the extraction rate of glycolic acid is 87.73%.i-N218 loading is detemined to washing and back extraction after compared the two extraction process routes.The amide loading phase is explored with washing process.Phase ratio is from10 to 50.Lavation ratio decreases with the phase ratio increases.And the concentration of glycolic acid in the aqueous phase is more than 25 g/L.It was initially determined that the organic loading phase should not be washed and the stripping process should be investigated directly.Back extraction conditions:phase ratio is 3:1,stripping temperature is 70?.After countercurrent flow,The countercurrent stripping rate of five stages and seven stages is about 100%.The concentration of glycolic acid in the five-stage stripping solution is lower than that of the glycolic acid in the seven-stage stripping solution,and the purity is higher than that of the seven-stage.In this study,the extraction thermodynamics of hydrochloric acid and glycolic acid by methyltrioctylammonium chloride/dodecanol?DESs-1?was studied.On the condition that the effect of temperature on the parameter?H_m^?is neglected,we obtained the relationships between the distribution ratio and the extraction temperature,which are as follows:lnD?28?1334.56/T-6.14and lnD?28?1.84/T-10.62.The?H_m^?of hydrochloric acid and glycolic acid in DESs-1system is-11.10 kJ/mol and-1.53?10^-2kJ/mol,respectively.Low temperature is beneficial to extraction.In addition,DESs-1 of saturated seaweed hydrolyzate,DESs-1 of saturated sulfuric acid,DESs-1 of saturated hydrochloric acid,DESs-1 of saturated glycolic acid,pure DESs-1,and methyltrisine were analyzed by FT-IR spectrometry.The results of those seven organic phases showed that DESs-1extracts both inorganic and organic acids.McCabe-Thiele graphically analyzes the relationship between the operating line and the balance line of the amide extractant,the result indicates that we can increase phase ratio to decrease the concentration of glycolic acid of the raffinate solution.