EVALUATING ATRAZINE SORPTION BY CHAR-LIKE MATERIAL

Atrazine is the second most used herbicide in the U.S. Midwest for weed control in corn (Zea mays). Although the recommended management practices, e.g. buffer zones and recommended application rates, are implemented during the atrazine applications in the U.S. Midwest, the off-site transport of this herbicide from agricultural fields to nearby waterways is still observed. Thus, additional conservation practices, including contaminant removal structures with target-specific media, are needed to improve water quality. This medium should be cheap, easily accessible, and efficient to remove the target contaminant. This study investigates the efficiency of hardwood charcoal, from a hardware store, to remove atrazine in solution at the lab scale using the kinetic and the batch sorption approaches. For the kinetic sorption study, 1 mg L^-1of atrazine solution and hardwood charcoal (32:1 v/w ratio) was shaken from 1 to 24 h. For the batch sorption experiment, a 32:1 ratio (v/w) of atrazine solution (concentrations ranging from 0.01 to 5 mg L^-1) /hardwood charcoal was shaken for 24 h for the sorption step; then, the supernatant was decanted; and a sequential desorption was performed to the sorbed atrazine using a solution of 0.01 M CaCl₂ (desorption 1) and 50% methanol solution (desorption 2). Three replicates were used per each time (kinetics) and concentration (batch), including the control (no hardwood charcoal). After shaking in each approach, the atrazine in equilibrium was determined by liquid chromatography with mass detection, and the amount of atrazine sorbed by the hardwood charcoal was calculated by difference. For the kinetic sorption study, the order of sorption reaction and equilibrium sorption were determined, whereas the adsorption-desorption distribution coefficient was determined for the batch sorption isotherm. The results of this study will help to evaluate a cheap and easily available medium that can be used in contaminant removal structures.