Abstract

The photochemical oxidation of a series of short-chain polychlorinated n-alkane (PCA) mixtures was investigated using H2O2/UV and modified photo-Fenton conditions (Fe3+/H2O2/UV) in both Milli-Q and lake water. All PCA mixtures, including chlorinated (Cl5 to Cl8) decanes, undecanes, dodecanes and tridecanes degraded in 0.02 M H2O2/UV at pH 2.8 in pure water, with 80±4% disappearance after 3 h of irradiation using a 300 nm light source. Degradation was somewhat enhanced under similar conditions but in natural water. The modified photo-Fenton system was more effective in degrading PCAs, with 72% and 80% disappearance of chlorinated decanes in 45 min of irradiation in pure and natural water, respectively. Carbon chain-length had minimal effect on degradation rates; however, increased degree of chlorination (from Cl5 to Cl8) resulted in slower initial degradation rates and less complete conversion after 3 h of irradiation. Three hours of irradiation in natural water/H2O2/UV resulted in 95% degradation of parent PCAs accompanied by 93% release of chloride ion. Quantitative dechlorination, which may be indicative of complete mineralization, suggests that this is an effective water remediation technique for PCAs.