Modeling of Fe(II)-activated persulfate oxidation using atrazine as a target contaminant

• A kinetic model is built from reactions and parameters in literature.
• An optimum molar ratio of Fe2+ and PS at 1:1 was favorable for ATZ degradation.
• SO4− is the predominant radical species in Fe2+/PS system.

In this paper, a mathematical model on Fe(II)-activated persulfate oxidation of atrazine (ATZ) was tested using the rate constants from literature, and the degradation kinetics and mechanism of ATZ degradation in Fe(II)/persulfate (Fe2+/PS) system were investigated to verify the model. Some influence factors were taken into consideration in this model, including molar ratio of Fe2+ and PS, initial ATZ concentration, natural organic matter (NOM) concentration, tertiary butanol (TBA) and methanol (MeOH) concentrations. Corresponding experimental data could be predicted accurately according to this model. Both experimental data and predicted results implied that a molar ratio of Fe2+ and PS at 1:1, low initial ATZ and NOM concentrations were favorable for ATZ degradation. Besides, the radical species were determined via evaluating the effect of TBA and MeOH, and results confirmed that both sulfate radical (SO4−) and hydroxyl radical (OH) existed in this system. To investigate the predominant radical in Fe2+/PS system, nitrobenzene (NB) was used as a probe compound which only react with OH. According to the degradation efficiency of NB and ATZ in Fe2+/PS system, it could be concluded that only small amount of OH were produced and SO4− made a major contribution to ATZ degradation in Fe2+/PS system. Experimental data, as well as the mathematical model in this study, improved our understanding on the effect of operating parameters for ATZ degradation in Fe(II)-based advanced oxidation processes.

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