Kinetic Study of UV Peroxidation of Bis(2-chloroethyl) Ether in Aqueous Solution

The groundwater aquifer underneath a chemical manufacturing plant in Southeast Texas has been contaminated by the leachate from its landfill. Based on computer simulations, the current air flow rate used in the air-stripping unit is about 10 times higher than the calculated flow rate if bis(2-chloroethyl) ether (DCEE) is excluded. This excessive air flow rate has caused maintenance problems and a higher energy consumption. It was proposed to treat the contaminated groundwater by air stripping to remove the volatile compounds and by UV/H{sub 2}O{sub 2} oxidation to destruct the low-volatility compounds such as DCEE. Experimental data from the UV peroxidation of DCEE in aqueous solution indicated the rate equation is 0.163[DCEE]{sup 0.61}[H{sub 2}O{sub 2}]{sup 0.54}. Important intermediates identified are 2-chloroethyl acetate, an enolic tautomer of 2-chloroethyl acetate, 2-chloroethoxyethene, 2-chloroethanol, acetaldehyde, ethylene oxide, and chloroethene. All the intermediates could be reduced to undetectable levels after 30 min of irradiation when DCEE/H{sub 2}O{sub 2} initial ratio of 1/10 was used. A reaction mechanism with complex pathways through both the attack of hydroxy free radical and the direct photolysis on DCEE was proposed. Intermediate identification and the rate equation suggested that the pathways in which DCEE is attacked by hydroxy free radicals are predominant. The rate equation derived from this mechanism predicted the peroxidation of DCEE is half-order with respect to both DCEE and H{sub 2}O{sub 2} concentrations.