Study Of The Principle And Technology For The Determination Of Organic Pollutants In The Coking Wastewater

This thesis mainly involved the qualitative and quantitative analysis of the organic components in the coking wastewater and the wastewater in the different stages of treatment process by gas chromatography-mass spectrometry. Several sample pretreatment methods were studied systematically and applied to the analysis of coking wastewater. The highlights were as following:1) The technology of Purge and Trap was applied in the testing of the volatile organic compounds(VOCs) in the coking wastewater.18kinds of volatile components were detected such as dimethyl selenide, tetramethyl diselenide, pyridine, benzene, toluene etc with the content ranged from8.0μg/L to1.2mg/L.2) The sample pretreatment methods such as liquid-liquid extraction, macroporous adsorption resin extraction, solid phase extraction, automatic solid-phase disk extraction were studied and compared to determined the semi-volatile organic compounds(SVOCs) in the coking wastewater. All the factors which would affect the extraction efficiency in each method were studied and optimized.By using liquid-liquid extraction coupled with gas chromatography mass spectrometry, more than250kinds of semi-volatile organic compounds were detected, mainly for phenols, anilines, biphenyls, indoles and quinolines and other toxic and harmful components, ranged of1.0μg/L-100mg/L by semi-quantitative calculation. The changes, migration, degradation and produce of organic pollutants in coking wastewater and the wastewater in the different stages of treatment process were studied. The results showed that the A1/A2/O system was effective to the treatment of coking wastewater and the degradation rates of semi-volatile organic compounds reached98.5%.Solid phase extraction was compared with the liquid-liquid extraction for the analysis of semi-volatile organic compounds in the coking wastewater. The results showed that, for the original wastewater, solid phase extraction was equal to liquid-liquid extraction; for low concentration outlet water, solid phase extraction performed better than liquid liquid extraction by acquiring10%-20%additional compounds in type and amount.Automated solid-phase disk extraction was studied for the pretreatment of coking wastewater. The apparatus and method was improved according to the real condition. After the optimization of the relative factors, the results showed that this method could completely replace the solid phase column extraction, and had the advantage of less workload, high recovery rate and good automatization. Automated solid-phase disk extraction had a good application prospect in batch detection.3) The microextration technology including solid phase microextraction and liquid phase microextraction were developed to the test of the organic compounds in coking wastewater. First, solid phase microextraction was developed to enrich volatile and semi-volatile organic compounds simultaneous in the wastewater. The qualitative analysis and quantitative analysis was reached by optimization of relative conditions. Under optimal conditions, the limit of detection was down to0.1μg/L, good linearity was got in the range of5μg/L-20mg/L. Solid phase microextraction greatly simplifies the sample pretreatment steps, has the advantage of low detection limit, long linearity range, environmental friendly, small sample size, solvent-free, quickness etc.Then we developd a liquid-liquid dispersion microextraction technique, and the qualitative and quantitative analysis of main organic pollutants and polycyclic aromatic hydrocarbons in the coking wastewater were carried out. Under optimal conditions, enrichment factors the target compounds ranged from300-900times, the limit of detection was0.01μg/L. liquid liquid dispersion microextraction had the advantage of lower limit of detection, wide quantitation range, simple operation, small sample size, less consumption of reagents, and less time consuming etc.