Triazine Herbicides Removal from Water with Granular Activated Carbon

Abstract

Abstract The general characteristics of triazine herbicides and their negative effect on environments and human health are described in this article. Triazine herbicides currently account for more than half of all pesticide formulations. They are intensively used for the protection of field crops, orchards and vineyards, but they are also used in the removal of undesirable stands on non-agricultural land (railway embankments, playgrounds, handling areas, etc.), in water management (in coastal management, destruction of growths in irrigation canals), in forestry, etc. Regular application of herbicides increases their content in the aquatic environment and agricultural products. Their occurrence in water is relatively common and it follows that these substances are used in large quantities. Residues of these substances can persist in soils for 1 to 2 years. Due to their good solubility in water, they are easily transported from the soil to aquifers. Several methods can be used to remove pesticides from water, e.g. coagulation, filtration, precipitation, ozonation, adsorption, ion exchange, nanofiltration, reverse osmosis and advanced oxidation processes. Their effectiveness varies considerably and depends mainly on the chemical nature of the pesticide being removed. This article studies adsorption on the two granular activated carbons Filtrasorb 400 and Norit 1240 W. Model solution of the pesticides, with concentration of approximately 1 µg/L, was prepared by mixing 50 mL of the pesticide’s standards with approximately 5 L of drinking water. The pH of drinking water was neutral, and this solution was then properly mixed and was used in the experiments. The experiments were performed in the glass bottles with the volume of 200 mL pesticide solution. On the analytical scales weighed out 200 mg granular activated carbon was used and then it was added to the bottles. Subsequently these bottles were regularly stirred, and the samples were taken out at times 0, 30, 60, 90, 120, 180, 240 and 360 minutes. Samples were taken by pipette into the 40 ml glass vials with added thiosulfate for preservation. After the experiments, these vials were sent to the analytical laboratory, which performed the analysis of the concentration of pesticides. The performed analytical methods were consistent with US EPA 535 and US EPA 1694. Concentration was determined by liquid chromatography using an internal standard method. The triazine herbicides detection analysis results after adsorption process in drinking water spiked with standard of pesticides shows, that the efficiency of selected triazines removal and adsorption capacity for two granular activated carbons used varied. Filtrasorb F400 proved to be a better sorption material than Norit 1240. The efficiency of this material ranged from 18 to 60%, while the efficiency of Norit 1240 was significantly lower.