Influence of process parameters on the effectiveness of photooxidative treatment of pharmaceuticals

ABSTRACT

In this study, UV-C/H₂O₂ and UV-C/ processes as photooxidative Advanced oxidation processes were applied for the treatment of seven pharmaceuticals, either already included in the Directive 2013/39/EU “watch list” (17α- ethynylestradiol, 17β-estradiol) or with potential to be added in the near future due to environmental properties and increasing consumption (azithromycin, carbamazepine, dexamethasone, erythromycin and oxytetracycline). The influence of process parameters (pH, oxidant concentration and type) on the pharmaceuticals degradation was studied through employed response surface modelling approach. It was established that degradation obeys first-order kinetic regime regardless structural differences and over entire range of studied process parameters. The results revealed that the effectiveness of UV-C/H₂O₂ process is highly dependent on both initial pH and oxidant concentration. It was found that UV-C/ process, exhibiting several times faster degradation of studied pharmaceuticals, is less sensitive to pH changes providing practical benefit to its utilization. The influence of water matrix on degradation kinetics of studied pharmaceuticals was studied through natural organic matter effects on single component and mixture systems.

KEYWORDS:

• Kinetics
• natural organic matter
• pharmaceuticals
• photooxidation
• response surface modelling

Funding

We gratefully acknowledge the financial support from Croatian Science Foundation through project entitled Modeling of Environmental Aspects of Advanced Water Treatment for Degradation of Priority Pollutants (MEAoWT) (IP-09–2014-7992).