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The purpose of this study is to assess the efficiency of removal of phenoxyacetic pesticides from water by means of activated carbon sorption. The sorbents used in this study (WD-extra, CWZ-22, NP-5) were produced by GRYFSKAND, Ltd., Hajn–wka. The first step of the study was the steady-state test of the suitability of selected sorbents in herbicide removal. The steady-state test was conducted according to the Chemviron Carbon methodology. Its aim was to determine the Freundlich isotherm and sorption capacity, and to select the best sorbent in static conditions. The residual concentration of the contaminant in the filtrate was determined using relevant analytical techniques. Also, the concentration of phenoxyacetic acid was identified by TLC and HPLC methods. On the basis of the results obtained it was concluded that the best sorbents of phenoxyacetic acid from water in steady-state conditions are CWZ-22 and NP-5. No significant difference was noticed in the removal process of the whole group of phenoxyacetic acids by sorption.
MCPA is the phenoxyacid herbicide widely used for weed control in cereals in Slovakia. However, little is known on the processes governing the environmental fate of MCPA in soils from Slovakia. Laboratory experiments were performed to evaluate the sorption, desorption, degradation, and leaching behavior of MCPA in two agricultural soils with high sand content and different soil organic carbon content. The extent of MCPA sorption was higher in chernitsa than that in regosol, in accordance with the higher organic carbon content of the former soil than the latter. MCPA was readily desorbed from soils with 10 mmol l⁻¹ CaCl₂ solution with the desorption rate ranging from 44.5 to 77.5% of the sorbed MCPA. The half-life values showed that the degradation of MCPA was fast in chernitsa (t1/2 = 2.2 days) and almost six times faster than in regosol (t1/2 =11.7 days). Leaching tests, performed in manually packed soil columns, indicated that MCPA was more mobile in regosol than in chernitsa with 16.44% of the applied MCPA recovered in the leachates of regosol, and 1.12% found in the leachates of chernitsa. Thus, differences in the leaching behavior of MCPA coincided well with the results of the batch sorption and degradation experiments.
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