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Glyoxylic acid as an important fine intermediates in the field of pharmaceuticals, pesticides , spices , paper , daily chemical products, etc. widely used in high value-added downstream products , glyoxylic acid application prospects are very promising . Glyoxal electro-oxidation of glyoxylic acid process is of great value. Using a fixed - bed reactor alternating current oxidation of glyoxal to glyoxylic acid , good electrolytic effect can be achieved at very high current densities . When the average current density of 1343 A · m-2 Shi , of glyoxal the conversion rate of up to 90.8% a glyoxylic acid selectivity of 89.9% , the current efficiency of up to 80.5% . The main component of the electrolyte solution of glyoxal , glyoxylic acid, oxalic acid, hydrochloric acid . Electrodialysis according to the difference of the volume of its ion -ion molar mass , charge number the four component sub - step separation , the recovery of raw materials to obtain a certain purity of the glyoxylic acid product . Electrodialysis current density, flow rate , temperature , caustic , and the concentration of initial liquid investigated that , when the temperature was 30 ° C , flow rate of 4.21 cm · s -1 , to the the AHT membrane is an anion exchange membrane , an initial current density of 628.7 A · m-2, when hydrochloric through rate of about 50% , the current density is raised to 456.6 A m -2 , you can get a better separation effect . The weakly basic ion - exchange membrane AAV film has a good separation effect , when the migration of hydrochloric acid was 82.4% , glyoxylic acid loss was 5.6 % , the mass ratio of glyoxylic acid and hydrochloric acid in the glyoxylic acid solution was 7.15 . Combined electrolysis and electrodialysis , when the conversion rate was about 60% of glyoxal , glyoxylic acid selectivity reaches 95.9% , the electrolyte of oxalic acid can be basically ignored , therefore electrodialysis is mainly separated feedstock glyoxal hydrochloric acid and the product of glyoxylic acid . Found through experiments , glyoxal diffusion in HSF film under more serious , but CMF Membrane diffusion have a good inhibition of glyoxal , can be used for the separation of the glyoxal with the other components .
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