2,4-D abatement from groundwater samples by photo-Fenton processes at circumneutral pH using naturally iron present. Effect of inorganic ions

Abstract

This study evaluated, at laboratory scale, if the using iron naturally present (0.3 mg L) and adding 10 mg L of hydrogen peroxide was effective to remove 24.3 mgL of 2,4-dichlorophenoxyacetic acid (2,4-D) from groundwater samples by simulated solar irradiation (global intensity = 300 W m). Under these conditions, the degradation of 2,4-D reached 75.2 % and the apparition of its main oxidation byproduct 2,4-dichlorophenol (DCP) was observed. On the other hand, pH exhibited an increasing from 7.0 to 8.3 during the experiment. Experiments using Milli-Q water at pH 7.0, iron, and HO concentrations of 0.3 and 10 mg L, respectively, were carried out in order to study the effect of ions such as carbonate species, phosphate, and fluoride in typical concentrations often found in groundwater. Ion concentrations were combined by using a factorial experimental design 2. Results showed that carbonates and fluoride did not produce a detrimental effect on the 2,4-D degradation, while phosphate inhibited the process. In this case, the pH increased also from 7.0 to 7.95 and 8.99. Effect of parameters such as pH, iron concentration, and hydrogen peroxide concentration on the 2,4-D degradation by the photo-Fenton process in groundwater was evaluated by using a factorial experimental design 2. Results showed that the pH was the main parameter affecting the process. This study shows for the first time that using the photo-Fenton process at circumneutral pH and iron naturally present seems to be a promising process to remove pesticides from groundwater.

Strategies to Drive Photo-Fenton Process at Mild Conditions for the Removal of Xenobiotics from Aqueous Systems

“…Finally, in a very recent work, iron present in natural waters (0.3 mg/L) was employed to drive a photo-Fenton process at pH = 7 to remove the pesticide 2,4-dichlorophenoxyacetic acid under simulated sunlight. This experiment shows that iron present in natural effluents can be used to treat pollutants present in groundwater [24].…”

Addition of Hydrogen Peroxide to Groundwater with Natural Iron Induces Water Disinfection by Photo‐Fenton at Circumneutral pH and other Photochemical Events

“…These statements are not yet clear and further studies are required to gain more insights. The positive effect of fluoride (at 1.2 mg L −1 ) on the degradation of 2,4‐D in Milli‐Q water by photo‐induced reactions was reported involving iron and H 2 O 2 at neutral pH in the presence of bicarbonates at high concentration and phosphates .…”

Degradation of 2,4-Dichlorophenol by Ethylenediamine-N,N′-disuccinic Acid-Modified Photo-Fenton System: Effects of Chemical Compounds Present in Natural Waters

“…The presence of common inorganic ions had no substantial effect on herbicide removal when using the photo-Fenton system, but the H2O2 (oxidant) consumption of this reaction was higher than that of the same reaction where inorganic ions were absent [19]. In the process of the photodegradation of 2,4-D by the photo-Fenton reaction, carbonate has little adverse effects, fluoride has a positive effect, and phosphate has an inhibitory effect [20]. The effect of typical inorganic water constituents (carbonates and chloride ions) and organic matter was also investigated and found to be different in the UVA-UVB activation of hydrogen peroxide and persulfate for advanced oxidation processes [21].…”