Treatment of a Waste Water Pharmaceutical by Fenton Oxidation - Paracetamol contaminated Waste Water treated by the Heterogeneous Dark- and Photo-Fenton Oxidation

摘要

A study in waste water treatment has been performed, using advanced oxidation processes, namely the heterogeneous dark- and photo-Fenton. The applied catalysts were two iron doped zeolites, ZSM-5 (Fe/MFI) and Beta (Fe/BEA).Methods of analysis: the degradation of the paracetamol molecule was analyzed by HPLC, the concentration of aqueous organic pollution was evaluated with total organic carbon (TOC), the oxidant consumption by permanganate titration, the activity of leached iron by homogeneous Fenton and the magnitude of leached iron with inductively coupled plasma (ICP).Three major events were proposed to occur; the oxidation of the aqueous and adsorbed organic molecules, the continuously changing equilibrium between aqueous and adsorbed phase, and the formation of iron-organic-intermediate complexes.A complete degradation of the paracetamol molecule was obtained in every experiment within 5 to 180 minutes, while the degree of mineralization reached 20-70% in five hours. When going from dark- to photo-Fenton an increase in TOC conversion was observed for both zeolites. The magnitudes were between 15-40% for the Fe/MFI and 14-19% for the Fe/BEA. On the other hand, the increase of oxidant (H2O2) concentration affected the TOC concentration of the zeolites differently. For the Fe/MFI the TOC conversion increased between 20-30% while it had a slight decrease in TOC conversion (between 1-5%) for the Fe/BEA. The activity of the leached iron was of a larger magnitude for the Fe/BEA zeolite than for the Fe/MFI zeolite.The highest degree of mineralization based on the liquid phase was found to be 68% for the photo-Fenton reactor setup using the Fe/MFI as catalyst at 30°C and an oxidant amount of two times the stoechiometry for full mineralization (27.7mmolL-1). When including the remaining adsorbed organic pollutant the highest degree of mineralization was 60%. This was obtained with the photo-Fenton using Fe/MFI as catalyst at 30°C and ten times the stoechiometry of oxidant (138.5mmolL-1).