Chemical and photochemical degradation of acenaphthylene. Intermediate identification.

Removal of acenaphthylene from water has been carried out by means of different treatments combining UV radiation, ozone and hydrogen peroxide. Ozonation alone or in conjunction with hydrogen peroxide (10(-3) M) resulted in the highest elimination rates. Thus, conversions as high as 95-100% were obtained in less than 3 min with an ozone dose of 4.1x10(-3) mol O(3) h(-1) (flow rate 2x10(-2) m(3) h(-1)). Slightly lower efficiencies were experienced when using systems containing UV radiation. By considering the kinetics of the direct photolysis of acenaphthylene and the UV/H(2)O(2) system the photochemical reaction quantum yield φ(A) (4.0+/-0.1x10(-3) mol/photon) and the rate constant of the reaction of acenaphthylene with the hydroxyl radical k(OH,A) (8.0+/-0.5x10(9) M(-1) s(-1)) were calculated. Intermediates identified by GC/MS were in many cases similar regardless of the oxidation treatment used. Most of these by-products constituted oxygenated species of the parent compound (mainly ketones, aldehydes and carboxylic acids) that further degraded to low molecular, harmless end products.