A comparative study on oxidative degradation of 2,4-dichlorophenol and 2,4-dichlorophenoxyacetic acid by ammonium persulfate

Abstract

The degradation of 2,4-dichlorophenol (2,4-DCP) and 2,4-dichlorophenoxyacetic acid (2,4-D) by ammonium persulfate under various activation conditions was investigated. The effect of the initial oxidant concentration, pH, temperature, and Fe²⁺ concentrations were studied. The rate of 2,4-DCP and 2,4-D oxidation was proportional to the concentration of persulfate. The optimal pH for 2,4-DCP degradation was 9.0, while for the 2,4-D, it was 3.0. The effect of temperature on the kinetics of 2,4-DCP and 2,4-D oxidation was examined, and it was demonstrated that increasing the temperature from 25 to 50°C accelerated the oxidation rate of both contaminants. The effects of Fe²⁺ concentrations and the optimal ratio of persulfate to Fe²⁺ were studied. Synergistic activation of persulfate by heat and Fe²⁺ was also investigated to enhance the oxidation of 2,4-DCP and 2,4-D. Under optimal experimental conditions, when the persulfate to Fe²⁺ molar ratio was 1:2 at 50°C, the complete oxidation of 2,4-DCP and 2,4-D was achieved after about 45 and 60 min. In any case, the 2,4-DCP was oxidized faster and more efficiently than 2,4-D.

Keywords:

• 2,4-DCP
• 2,4-D
• Oxidation
• Persulfate

Acknowledgments

This work was partially supported by project No. RMN 971/2014. We thank also Mrs Karolina Wójtowicz for technical assistance.

Notes

Presented at the 12th Scientific Conference on Microcontaminants in Human Environment 25–27 September 2014, Czestochowa, Poland