Competition of natural organic matter and atrazine for adsorption to preloaded granular activated carbon in drinking water treatment

The effects of preloading and competitive interaction of natural organic matter (NOM) on atrazine adsorption was studied for crushed granular activated carbon. Changes in the Freundlich adsorption parameters K_F and n demonstrated the significance of competitive interaction during adsorption. High-performance size exclusion chromatography coupled to UV and fluorescence detection in tandem, demonstrated that the competing NOM fraction is low molecular weight and refractory during water treatment. This ubiquitous NOM fraction, found in both surface water and groundwater, appears to be responsible for preloading with little difference in atrazine adsorption characteristics for the same preloading conditions. This NOM fraction is also implicated in competitive interaction, which was found to override preloading effects through drinking water treatment.