Effects of Potassium, Ammonium, and Calcium Chlorides on the Sorption of Metamitron in Soil
Paweł Muszyński1, Marzena S. Brodowska2
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1Department of Chemistry, University of Life Science, Lublin, Poland
2Department of Agricultural and Environmental Chemistry, University of Life Science, Lublin, Poland
Pol. J. Environ. Stud. 2014;23(6):2125–2135
The effects of three electrolytes (KCl, NH4Cl, and CaCl2) on the sorption of the herbicide metamitron in a loamy soil was studied. The sorption of metamitron was measured using the batch equilibrium technique. The experimental data were fitted to the Freundlich and Dubinin-Radushkevich isotherm equations. It was noted that the fraction of metamitron sorbed in soil decreased with the increasing initial concentration of the herbicide in soil solution. In soil with organic matter removed, the sorption of metamitron was lower than in the original soil. The soil-herbicide solution contact time ranging from 60 to 720 minutes and had only a slight effect on metamitron sorption. In soil with the addition of KCl and NH4Cl, significantly higher sorption of metamitron was observed than in the soil system without these electrolytes. The extent of sorption increased with increasing concentrations of aqueous KCl or NH4Cl solutions, but the increase of sorption in the presence of NH4Cl was lower compared to the presence of KCl. A similar effect of the two electrolytes on the sorption of metamitron was observed in the soil with organic matter removed. In the single-component systems with CaCl2, a decrease of metamitron sorption was observed in the original soil. Whereas the presence of CaCl2 in the two-component systems KCl+CaCl2 and NH4Cl+CaCl2 limited the extent of sorption of metamitron in relation to that obtained in the single-component systems with KCl or NH4Cl, the adsorbed amount of metamitron was still much higher than in soil systems with no electrolyte.