Effect of humic acid on the oxidation of phenolic endocrine disrupting chemicals by permanganate

Abstract

The effect of dissolved humic acid on the oxidation of phenolic endocrine disrupting chemicals (EDCs) by potassium permanganate was studied. It was found that the degradation of phenolic EDCs is promoted to various extents by the addition of humic acid. Results show that the removal rate of estrone by permanganate within 3 min of reaction time is increased from approximately 10% in control experiments to 68% when 0.08 mg l 21 of humic acid is present in the reaction system. The oxidation experiment of nine types of phenolic EDC by permanganate confirms that the promotion induced by the addition of humic acid varies in the cases of different EDCS. Results also indicate that the promotion induced by the presence of humic acid takes effect under acidic and neutral pH conditions, while the effect of pH plays a dominant role for the degradation of phenolic EDCs under alkaline conditions. Additionally, it was found that the oxidation of estrone by permanganate is promoted through the addition of humic acid to natural waters.

Reinvestigation of the Role of Humic Acid in the Oxidation of Phenols by Permanganate

“…In addition, the HA-induced improvement in the oxidation of phenols by permanganate was strongly dependent on the amount and position of chlorine substituents on the aromatic ring. Shao et al also reported that the promotive effects of HA on the oxidation of phenolic EDCs by permanganate were dependent on the structure of EDCs, consistent with our observations. Figure also reveals that the presence of HA slightly decreased the oxidation rate constants of phenols at pH ≥8.0, indicating that HA played a role under alkaline conditions different from that under acidic and/or neutral conditions.…”

“…1 Jiang et al 19,20 also reported that the presence of HA can improve the oxidation of TCS by permanganate at pH 5.0−7.0 and the oxidation of BPA by permanganate at pH <7.0, and the improvement was greater at lower pH. Shao et al 25 confirmed that the presence of HA could facilitate the oxidation of nine EDCs by permanganate at pH 5.8 to different extents, depending on the structure of EDCs. Our previous studies elucidated that the high-molecular weight subunits, carbon− carbon double bonds, π-electrons, and long conjugated bonds in HA contributed to its positive influence on the oxidation of phenol and/or chlorophenol by permanganate.…”

“…23 Surprisingly, compared to the oxidation kinetics obtained in synthetic water under the same condition, tap water, filtered natural water, and wastewater accelerated the oxidation of BPA, TCS, and estrone by permanganate, although they had natural permanganate demand. 19,24,25 Humic substances (HS) are ubiquitous in natural waters, and their presence may cause the gap between the oxidation behavior of phenolic compounds in pure water and that in natural waters.…”

Kinetics study on the oxidation of chlorophenols by permanganate

“…humic acid (HA), phosphate, and EDTA, could accelerate the reaction between phenolic compounds and permanganate [28,35]. It was also confirmed in our previous study that HA could greatly promote the permanganate oxidation of nine kinds of phenolic endocrinedisrupting chemicals over a wide pH range [36]. HA is the major component of natural organic matter (NOM) that consisted up to 90% of DOC in surface waters.…”

“…All these previous studies confirmed that the presence of HA facilitating the formation of in situ MnO 2 contributes to the enhancement of the oxidation of phenols by permanganate. In addition, the promotive effect of HA is not only dependent on pH of the aquatic system but also associated with the structures of phenolic compounds [35,36]. The oxidative ability of the in situ formed MnO 2 decreases with the increase in pH and takes effect for oxidation of phenols by permanganate under acidic and neutral pH conditions, while it decays and even shows no effect under alkaline conditions.…”