Continuous flow experiments were performed to investigate the effects of citrate and tartrate on 2,4-dichlorophenol and 2,4,6-trichlorophenol removal in pyrite packed columns under variable chemical conditions (e.g., citrate concentration) using Fenton reaction.  The experiments were performed at an initial input solution pH of 4, chlorophenol (CP) concentration of 100 mg/L, hydrogen peroxide concentration of 0.02 M and ligand concentration ranging from 0 to 0.001 M. Effluent samples were taken at certain time intervals, and analyzed for Fe(II), total Fe, CP concentration, TOC, ligand concentration and pH. Our results show that, unlike batch systems, both citrate and tartrate significantly improved CP removal relative to non-ligand containing systems. The increase in CP removal with organic ligands could be explained through higher solid/liquid ratios and enhanced Fe dissolution in pyrite packed columns, which, in turn, led to the prevention of surface passivation with Fe-oxides as well as an increase in number of reactive sites (high solid/liquid ratio in columns) on pyrite surface. The analysis of effluent samples for Fe suggests that, in systems containing citrate and tartrate, the total effluent Fe concentration was higher compared to non-ligand containing systems, indicating the dissolution of surface Fe(III) oxides due to formation of soluble Fe(III) and ligand complexes. While all of Fe in the effluent was in Fe(II) form in the absence of organic ligands, in systems containing citrate and tartrate, nearly 80 % of Fe was Fe(II) and the remaining 20 % was in Fe(III) form in experiments involving organic ligands. In experiments with citrate and tartrate, no ligands were observed in the effluent samples, suggesting that the hydroxyl radicals produced in Fenton reaction were sufficient enough to oxidize both the ligands and CPs due to high solid/liquid ratio.

Effects of citrate and tartrate on 2,4-dichlorophenol and 2,4,6-trichlorophenol removal in pyrite-packed columns under continuous flow conditions using heterogeneous Fenton reaction

255th National Meeting (2018)

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