3.2. Sorption
To test our hypothesis that NaN3 has a significant effect on the overall observed atrazine sorption isotherm and the calculated sorption parameters, we measured sorption of atrazine in the presence of 2-azidoatrazine (to study competition effect) and in control solution containing HgCl2 (only atrazine was present). These isotherms were measured using stock solution with initial atrazine concentration of 20 mg l−1 and 500 mg l−1 NaN3 at pH 6. The concentration ratio between 2-azidoatrazine and atrazine was 0.2 for the whole range of herbicide concentration and minimal atrazine transformation (