Carbon and hydrogen isotope fractionation of phthalates during photocatalysis reactions in aqueous solution containing Fe(III) complexes or iron minerals

The hydrogen and carbon isotope fractionation factor (82H, 813C) of dimethyl-, diethyl-and dibutyl phthalic acid ester during photosensitized degradation by artificial sunlight with Fe(III) ions and iron minerals (hematite, goethite and magnetite) in aqueous solution were examined by compound-specific isotope analysis (CSIA) in order to analyze the degradation mechanism. Hematite does not catalyze photosensitized degradation of phthalates. The correlation of 2H and 13C isotope fractionation (A = A82H/A813C) of phthalates with increasing chain length (dimethyl-; diethyl-; and dibutyl-) were compared with values of the center dot OH radical model reaction with the aromatic ring as well as acidic and alkaline hydrolysis. The A values of die photosensitized reaction of diethyl phthalate with goethite (-5.1 +/- 1.8) and magnetite (-18.9 +/- 3.9) show a large difference compared to Fe (III) solutions (4.7 +/- 0.9 to 4.8 +/- 1.0) suggesting specific reaction mechanisms. The fractionation factors determined here have potential to characterize the degradation of phthalates catalyzed by photo-induced re-action of Fe(III), goethite and magnetite in natural system and in remediation approaches.

Automated summary

The hydrogen and carbon isotope fractionation factor of phthalic acid esters during photosensitized degradation by artificial sunlight with Fe(III) ions and iron minerals were examined using compound-specific isotope analysis. The results provide important insights into the degradation mechanism.