Degradation of 2,4-dichlorophenol by immobilized iron catalysts

The degradation of 2,4-Dichlorophenol (from now on 2,4-DCP) has been carried out on Nafion-Fe (1.78%) in the presence of H2O2 under visible light irradiation. A solution containing 2,4-DCP (TOC 72 mg C/L)) is seen to be mineralized in approximately 1 h in the presence of H2O2 (10 mM) under solar simulated visible light (80 mW cm-2) at pH values between 2.8 and 11. Homogeneous photo-assisted Fenton reactions were capable of mediating 2,4-DCP degradation only up to pH 5.4. The degradation kinetics of 2,4-DCP on Nafion-Fe membranes was more favorable than the one observed during Fenton photo-assisted processes at pH 2.8. The degradation of 2,4-DCP was investigated as a function of the substrate, oxidant concentration and applied light intensity. The Nafion-Fe was seen to be effective over many cycles during the photo-catalytic degradation of 2,4-DCP showing an efficient and stable performance during 2,4-DCP degradation without leaching out Fe(3+)-ions into the solution. Evidence is presented that the degradation at the surface of the Nafion-Fe membrane seems to be controlled by mass transfer and not by chemical reaction of the species in solution. The approach used to degrade 2,4-DCP is shown to be valid for other chloro-carbons like 4-chlorophenol, 2,3-chlorophenol and 2,4,5-trichlorophenol.