Estimating Atrazine Removal and Degradation by Activated Carbon Cloth

In the U.S. Midwest, tile risers are installed to make farmed closed depressions more productive. These risers drain to nearby waterways, but they do not filter sediments. Blind inlets are an alternative conservation practice; in addition to draining the closed depressions, blind inlets also filter sediments and remove nutrients and pesticides from water. These additional benefits are due in part to the filter medium (gravel) and geotextile, which holds the materials in place. Atrazine, a commonly applied herbicide, is highly soluble in water and has been shown to sorb to pyrogenic carbonaceous materials. Textiles have been developed incorporating activated carbon that acts as a filter. The objective of this study was to determine atrazine sorption on three selected activated carbon cloths (single weave, double weave, and knit) and the geotextile used in the blind inlet (control). A sorption kinetics experiment was performed by shaking each textile at time intervals from 0.01 to 24 hrs with atrazine concentrations of 0.050 and 1 ppm. To investigate the sorption capacity of the textile during flow, a study using flow-through sorption was conducted using 1 ppm atrazine with the single weave activated carbon cloth (ACC) at retention times 0.75, 5, 10 mins collected every 10, 90, 180 mins, respectively. Also, atrazine desorption and degradation were studied by incubating single weave ACC sorbed with 1 ppm atrazine in nanopure water, 0.01 M CaCl₂solution, or methanol at 7°C and 25°C. Samples were collected at from 1 to 14 days. All samples were analyzed for atrazine and its metabolites using UPLC MS-MS. The results showed the three ACCs sorbed at minimum 95% of the atrazine by 1 hr of shaking at both concentrations, while the geotextile sorbed only 20% at the 1 ppm concentration. With flow, atrazine was found to sorb 91% at the 10 min retention time, compared to 82% and 56% at the 5 min and 45 s retention times. Preliminary results show no atrazine desorption or degradation was detected in both the nanopure water and 0.01 M CaCl₂ at either temperature, while <8% atrazine desorption, but no degradation, was observed with methanol. In placement of geotextiles in blind inlets, activated carbon cloth could be utilized in addition to other media to increase mitigation of contaminant loadings that move off farm fields and into valuable water sources.