Survey of photochemical oxidation efficiency of 2,4-Dichlorophenoxyacetic acid using S2O8/UV from aqueous solution

2,4-Dichlorophenoxyacetic acid (2,4-D) is a widely used acidic herbicide with high toxicity. So, this study was performed with the aim of investigation of 2,4-D photochemical oxidation by persulfate and UV.
This study was performed in bench scale and batch condition. K2S2O8 was used as oxidant in presence of UV. In this study, effects of pH, oxidant concentration, contact time and initial concentration of 2, 4-D on the process were examined in batch experiments. The concentration of 2, 4-D was determined using spectrophotometer at 285 nm.
The best results were achieved at acidic conditions (pH =3). Increasing dosages of persulfate and contact time increased the degradation of 2,4-D. However, an increase in initial 2,4-D concentration resulted in decreasing of photochemical oxidation efficiency. The maximum photochemical oxidation efficiency of 2,4-D was 96 % for a 2.5 mg/l persulfate, 10 mg/l 2,4-D, pH value of 3.0 and contact time of 240 min. The degradation of 2, 4-D by persulfate is found to follow the pseudo-first-order kinetic model (R2=0.979).
In this study, 2,4-D was effectively degraded in aqueous solutions by the photochemical oxidation using S2O8/UV. From this study, it seems that photochemical oxidation with S2O8/UV can be an effective process for the treatment of contaminated water with 2, 4-D.