Photochemical degradation of atenolol, carbamazepine, meprobamate, phenytoin and primidone in wastewater effluents

The photochemical degradation of five pharmaceuticals was examined in two secondary wastewater effluents. The compounds, which included atenolol, carbamazepine, meprobamate, phenytoin and primidone, were evaluated for both direct and sensitized photolysis. In the two wastewaters, direct photolysis did not lead to significant compound degradation; however, sensitized photolysis was an important removal pathway for the five pharmaceuticals. Upon solar irradiation, hydroxyl radical (HO center dot) was quantified using the hydroxylation of benzene and singlet oxygen (O-1(2)) formation was monitored following the degradation of furfuryl alcohol. Degradation via sensitized photolysis was observed following five-day exposures for atenolol (69-91%), carbamazepine (67-98%), meprobamate (16-52%), phenytoin (44-85%), and primidone (34-88%). Varying removal is likely a result of the differences in reactivity with transient oxidants. Averaged steady state HO center dot concentrations ranged from 1.2 to 4.0 x 10(-16) M, whereas the concentrations of O-1(2) were 6.0-7.6 x 10(-14) M. Partial removal due to presence of HO center dot indicates it was not the major sink for most compounds examined. Other transient oxidants, such as O-1(2) and triplet state effluent organic matter, are likely to play important roles in fates of these compounds. (C) 2014 Elsevier B.V. All rights reserved.