Fenton process is a viable and cost effective method commonly used in oxidative dehalogenation of non-biodegradable organic contaminants in wastewater. The conventional Fenton process is usually carried out under acidic conditions (pH 2-4) due to very low solubility of Fe under alkaline conditions. Alternative to sulfuric acid, organic ligands can be used as Fe-chelating agents to increase Fe solubility and thus extend the application pH range for Fenton process above pH 4.  Here, the effects of organic ligands (citrate and tartrate) on oxidative degradation of various chlorophenolic compounds (e.g.,  4-CP, 2,4-di CP) with modified Fenton process using pyrite as source of Fe catalyst were investigated in batch systems under variable chemical conditions (e.g., pH, ligand concentration). Our results show that the organic ligands had an adverse effect on CP degradation with modified Fenton process and the rate of CP degradation decreased with increasing ligand concentration despite the fact that ligands enhanced Fe solubility from pyrite surface. The decrease in CP degradation with pyrite-Fenton process in the presence of organic ligands can be explained through competitive effect of organic ligands for hydroxyl radical consumption against CP compounds.  Spectroscopic measurements (XPS and SEM-EDS) confirm that while Fe-oxides accumulated on pyrite surface during CP oxidation with modified pyrite Fenton process in the absence of organic ligands, the addition of organic ligands significantly enhanced Fe solubility and thus prevented the accumulation of Fe(III)-surface precipitates on pyrite surface. <br/>

Effect of organic ligands on oxidative degradation of chlorophenolic compounds (CP) with modified-Fenton process using pyrite as the catalyst

255th National Meeting (2018)

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