Comparison of Herbicide Sorption in Different Coal Fly Ash

Development of low cost adsorbent for pesticide retention is an important area of research in environmental sciences. Fly ash, a waste by-product of thermal power plants, was collected from seven thermal power plants and samples were evaluated for the sorption of metribuzin, metolachlor and atrazine from water. Fly ash samples from different power plants have different physicochemical properties like pH, organic carbon content, surface area, cation exchange capacity and electrical conductivity. Herbicide sorption in fly ash varied from 30% to nearly 100%. Sorption of all the three herbicide showed positive correlation with the organic carbon content of fly ash, while sorption of only metolachlor and atrazine showed positive correlation with the pH. Metribuzin sorption showed a negative correlation with cation exchange capacity of the fly ash. The study suggests that herbicide sorption capacity of the fly ash vary a lot. However, few fly ashes have potential for removal of herbicides from industrial and agricultural waste water.