Degradation of Ibuprofen in Aqueous Solution with UV Light: the Effect of Reactor Volume and pH

The presence of trace of pharmaceutical compounds (PhACs) in groundwater and in drinking and superficial waters is a major public health concern. Recently, various advanced treatment technologies have been studied to remove these kinds of pollutants; among them, combined treatments based on UV light appear to be more eco-friendly and with very interesting removal efficiencies if properly modified. In this paper, the removal of Ibuprofen (IBP) from synthetic water streams was investigated by using a lab-scale experimental device consisting of a batch reactor equipped with a lamp emitting monochromatic UV light (254 nm; 400 mJ m−2). The IBP initial concentration (CIBP0) was 45.9 mg L−1. Two sets of experiments were carried out; the first one was aimed at studying the IBP concentration as a function of time, at different volumes of treated solution; the second one was aimed at exploring the effect of pH on IBP degradation as a function of time. The results obtained show that the concentration of IBP decreases along with treatment time, with a negative effect of the treated volume, i.e., smaller volumes, that is lower liquid heights, are more easily degraded. Moreover, the higher the pH, the better the IBP degradation; actually when pH increases from 2.25 to 5.51 and finally to 8.25, the IBP concentration, after an hour of treatment, decreases respectively to 45, 34, and 27 % from its initial value. A reaction mechanism is suggested, which well describes the effects of volume and pH on the experimentally measured IBP degradation.