Study On The Recovery And Utilization Of Sodium Glycolate In 2,4-D Wastewater

2,4-D is a kind of plant growth regulator that widely used in agriculture.Great amount of wastewater was produced in the 2,4-D production process which contined a lot of NaCl and sodium glycolate.The COD of wastewater was increased due to the existence of sodium glycolate.The recovery of sodium glycolate in 2,4-D wastewater was good for the environment and economy.In this paper,recovery way of sodium glycolate was studied.(1)Sodium glycollate was recycled from 2,4-dichlorophenoxyacetic acid wastewater by cooling crystallization.First,2,4-D wastewater which was evaporating was heated to 90? to dissolve its solid.Then the wastewater was cooling with the rate of 1 ? / min.Most NaCl was removed by filtering,and mother liquor continued to cool with the rate of 1 ? / min.When the temperature dropped to 15 ?,crystal grew for a period of time.Finally,Sodium glycollate was obtained by filtering.The experimental result show that purity of crystallization product reached to 99.08% when crystallization time was 2 h,temperature of removed Sodium chloride was 40 ?,crystallization times were 3.(2)N-butyl hydroxyethanoate was produced by the esterification of Sodium glycollate and butanol.Sodium glycollate and butanol were mixed,and heated to boil,and the reaction was started with the addition of sulfuric acid.The water produced by esterification was taken out the reaction system by azeotropic system of butanol and water.After the reaction,n-butyl hydroxyethanoate was obtained by vacuum distillation.The effects of molar ratio of n-butanol to sodium glycollate,the amount of sulfuric acid and reaction time on the yield of n-butyl hydroxyethanoate were studied.When the sodium salt/ butanol mole ratio was 1:3,the amount of sulfuric acid was 13.5% of total quantity,and the reaction time was 3 h,the yield of n-butyl hydroxyethanoate could reched to 87.83%.(3)N-butyl hydroxyethanoate was produced by the esterification of Sodium glycollate from 2,4-dichlorophenoxyacetic acid wastewater.First,a little chlorophenol was removed by adjusting pH,and sodium hydroxide was added to the wastewater for adjusting pH to 8~9.Sodium chloride and most of water was removed by evaporating the wastewater,then mother liquor was dried to obtain sodium glycollate,in which sulfuric acid and butanol were added directly.Finally,n-butyl hydroxyethanoate was produced by the reaction of glycolic acid and butanol.The effects of molar ratio of n-butanol to sodium glycollate,the amount of sulfuric acid,reaction time and sulfuric acid recycle number on the yield of n-butyl hydroxyethanoate were studied.When the sodium glycollate / butanol mole ratio was 1:3,the amount of sulfuric acid was 13.9% of total quantity,and the reaction time was 3h,the yield of n-butyl hydroxyethanoate could be the highest.When sulfuric acid recycle number is 5,the yield of n-butyl hydroxyethanoate was stable.(4)Feasibility analysis of producing n-butyl hydroxyethanoate with 2,4-D wastewater treatment.The scheme of producing n-butyl hydroxyethanoate was conducted,which included material balance and energy balance,selection size of major equipment and economic technical analysis,etc.