An external lamp, annular photocatalytic reactor with titania immobilized on a quartz tube was used to degrade two @entity2555 ( @entity2556 ), viz. @entity11966 ( @entity815 ) and @entity9435 (PYR) from a dilute water stream. The thin film geometry was used to obtain both the mass transfer coefficients and intrinsic reaction rate constants for the two compounds on immobilized titania (Degussa P-25) particles. Beyond a feed velocity of 7 cmmin(-1), the conversion was solely reaction rate controlled and was not subjected to mass transfer limitations from the aqueous phase to the immobilized titania film. The overall reaction rate constant was independent of the feed concentration as large as the saturation aqueous solubility of the two compounds. However, the conversion was dependent on the ultraviolet (UV) light illumination intensity at the reactor. The quantum efficiency ranged from 3.7 x 10(-5) to 2.7 x 10(-4) which was somewhat low because of the very low aqueous concentrations of the chemicals. The overall reaction rate constant was 1.6 times larger for @entity9435 than for @entity11966 . Seven reaction intermediates were identified for the conversion of @entity11966 , while for the degradation of @entity9435 two intermediates were identified. The presence of the @entity5243 as an intermediate product in the degradation of both @entity2556 indicates the presence of a @entity3276 in both cases which degrades to the products @entity515 and @entity2507 , along with other stable intermediates. Mass balance in a batch reactor showed that only 28.6-40.1% of @entity11966 is mineralized to @entity515 in 1-3h of reaction although 35-67% of the parent compound has disappeared, confirming that a substantial fraction of the parent compound has been converted to stable intermediates that remain in the reactor. A plausible mechanism based on these observations is proposed.

A titania thin film annular photocatalytic reactor for the degradation of XXXX in dilute water streams.

@entity3276 :: ('MESH:C004532', 'Chemical') :: ['quinone'] @entity2555 :: ('MESH:D011084', 'Chemical') :: ['polycyclic aromatic hydrocarbons'] @entity515 :: ('CHEBI:29334', 'Chemical') :: ['CO(2)'] @entity2556 :: ('CHEBI:33848', 'Chemical') :: ['PAHs'] @entity5243 :: ('CHEBI:35484', 'Chemical') :: ['phthalate ester'] @entity2507 :: ('CHEBI:33813', 'Chemical') :: ['H(2)O'] @entity9435 :: ('MESH:C030984', 'Chemical') :: ['pyrene'] @entity815 :: ('CHEBI:28044', 'Chemical') :: ['PHE'] @entity11966 :: ('MESH:C031181', 'Chemical') :: ['phenanthrene']
@entity2555 :: (MESH:D011084,Chemical) :: ['polycyclic aromatic hydrocarbons']
