Analysis Of Fluorinated Organic Compounds In Waste Water With High Salt And Hydrofluoric Acid

At the beginning of 2017,with the increasing pressure on environmental protection and safety,some of the small and medium fluorine chemical enterprises have had shutdowns inevitably.At the same time,some of the large corporations on the scale are faced with pollutant discharge pressure.Therefore,it is the only way to improve the competitiveness of the fluorine chemical industry by improving the safety management and environmental protection ability.Objective to seek efficient detection methods of the fluorinated organic acids and their salts in the high salt waste water,and the volatile organic compounds in the hydrofluoric acid waste water in the fluorine chemical industry.It has been established successively RP-HPLC method,headspace gas chromatography,and the substitute method using silver nitrate.Furthermore,the paper has made a preliminary exploration of the COD contribution to the perfluoro organic acid,and discussed the effectiveness of the supervision and control measures in the fluorine chemical industry in the actual control of the emission of fluorinated organic compounds.The main work and results of this article are as follows:1.A reversed-phase high performance liquid chromatography(RP-HPLC)method was developed for the determination of trifluoroacetic acid,pentafluoropropionic acid,heptafluorobutyric acid and their salts in high salt water simultaneously.The sample was diluted or dissolved with water.The assay was carried out on a SHIM-PACK VP-ODS C18 column(4.6mm × 150mm,5?m)with a column temperature at 50?.The mobile phase was a mixture of acetonitrile-40 mmol·L-1 KH2PO4(pH 3.0)with flow rate 0.6 mL·min-1.The ratio of acetonitrile to KH2PO4 was controlled by a gradient elution program.The detection wavelength was set at 195nm.All the correlation coefficients(r)were no less than 0.9992.The linear range was 2?1000 ?mol·L-1 and the detection limit rate was 0.002?0.01 ?mol·L-1.The recovery rate was 96.2%?109.4%.Verified by the methodology,the method was simple,rapid and with high specificity.It is suitable for the determination of trifluoroacetic acid,pentafluoropropionic acid,heptafluorobutyric acid and their salts in high salt water and will supply reference evidence for the monitoring of organic acid and their salts which containing fluoride in industrial waste water.2.Establishing a method for the simultaneous determination of 8 volatile organic compounds in hydrofluoric acid waste water by headspace gas chromatography,which were VOCs were methane,ethane,ethylene,propylene.fluoromethane.trifluoromethane.dimethyl ether and methanol.The sample vas diluted by water and was heated at 85? for 45 minutes in order to reach the vapor-liquid equilibrium state.The method was carried out on the HP-POLT Q capillary column and used the hydrogen flame ionization detector(FID).At the same time the method was quantified by the external standard method.All 8 organic compounds were in good linearity within the specified range(R>0.9993).The detection limit of the method met the application requirements which was between the range of 0.013 mg/L to 0.54 mg/L and the recovery rate was within 94%?118%.Verified by the methodology,the method is simple,rapid and with high specificity.It is suitable for the determination of volatile organic compounds in hydrofluoric acid waste water which is from the process of the preparation of fluoromethane.And it also can provide guidance for the quantitative detection of volatile organic compounds in industrial waste acid.3.In this paper,the COD value in high salt water body was tested by silver nitrate substitute method in standard potassium dichromate method and the validity and accuracy of the method were also determined.The COD contribution of perfluoroorganic acid was preliminarily studied by the current national standard.The conclusion was that trifluoroacetic acid,pentafluoropropionic acid,heptafluorobutyric acid and other substances were not fully digested and oxidized in the process of COD determination by potassium dichromate method.It is clear that the current waste water discharge standards in fluorine chemical industry can not accurately monitor the emission of waste water containing fluorinated organic compounds.