Oxidative treatment of pharmaceuticals in water

Environmentally relevant pharmaceuticals were chosen according to human consumption and occurrence in the aquatic environment like sewage plant effluents, rivers and groundwater to investigate their behavior during oxidative water treatment. Derived from data compilation in literature the lipid lowering agent clofibric acid and the analgesic agents ibuprofen and diclofenac were selected. Analyses of the acidic compounds were carried out after solid-phase extraction and online derivatization in the GC injector by means of single ion monitoring (SIM) GC/MS. Oxidation experiments with the aim to degrade the pharmaceuticals were carried out in bench scale using ozone and ozone/hydrogen peroxide (advanced oxidation process). Under the specific reaction conditions only diclofenac was degraded by ozone to about 3% of its initial concentration. The combined application of ozone and hydrogen peroxide leading to OH-radical formation improved the degradation efficiency of all investigated compounds. The application of increased oxidant concentration resulted in a better degradation of all compounds to more than 90% at a concentration of 3.7 mg l−1 ozone and 1.4 mg l−1 hydrogen peroxide and to more than 98% at a concentration of 5.0 mg l−1 ozone and 1.8 mg l−1 hydrogen peroxide. At the applied conditions no reaction products could be detected by GC/MS analyses after derivatization of acidic functional groups.