2.4- Dinitrophenol maximum concentration

In River R a pollution cloud of 2,4-dinitrophenol (see Illustrative Example 25.2) of duration At = 1 h and concentration Cin =50 ng L-1 is passing by Groundwater System S. Calculate the maximum concentration reached at the wells for the three regimes. Compare these values to the maximum concentrations reached 3 m away from the river. 

One day, measurements in the river suddenly show rather high concentrations of 2,4-dinitrophenol. Further observations show that the values vary on a weekly basis and reach maximum concentrations Cmax = 3.5 pg L during the week and minimum concentrations Cmin = 1.3 pg L"1 over the weekend. Calculate the maximum concentration of 2,4-dinitrophenol to be expected at the drinking-water well. The pH in die infiltrating water is 7.8. 

The procedure of simultaneous extracting-spectrophotometric determination of nitrophenols in wastewater is proposed on the example of the analysis of mixtures of mono-, di-, and trinitrophenols. The procedure consists of extraction concentrating in an acid medium, and sequential back-extractions under various pH. Such procedures give possibility for isolation o-, m-, p-nitrophenols, a-, P-, y-dinitrophenols and trinitrophenol in separate groups. Simultaneous determination is carried out by summary light-absorption of nitrophenol-ions. The error of determination concentrations on maximum contaminant level in natural waters doesn t exceed 10%. The peculiarities of application of the sequential extractions under fixed pH were studied on the example of mixture of simplest phenols (phenol, o-, m-, />-cresols). The procedure of their determination is based on the extraction to carbon tetrachloride, subsequent back-extraction and spectrophotometric measurement of interaction products with diazo-p-nitroaniline. 

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