An adsorption isotherm for bromide

Bromide is often used as a conservative tracer in soils and sediments; however, it may be adsorbed onto variably charged sediments such as exist at the Savannah River Site (SRS) in South Carolina. Using a methodology simulating concentration gradients observed during field‐scale injection of anionic tracers, a series of column experiments were used to determine the nature of bromide adsorption onto and desorption from a sediment sample from SRS. Bromide concentrations ranged from <0.1 to 700 mg/L. Adsorption and desorption were reversible and repeatable; however, desorption showed tailing. Adsorption followed an apparent Freundlich isotherm (95% confidence interval) having an exponent of 0.906 lpar;±0.033). A second‐order polynomial fit provided a more accurate but less conventional model of the adsorption.