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Advanced oxidation processes have become an important part of research due to their capacity to degrade many environmental pollutants during water treatment. Especially the heterogeneous photocatalysis is a promising method because it often results in a full mineralization of many hazardous compounds. Incomplete degradation reactions can result in transformation products due to oxidative conditions. The transformation products may have a higher toxicity than the precursor substances and are often only partly removed during water treatment. Since a lot of these compounds are still unknown, transformation products are not detected by target analysis used in sewage treatment plants and are often released into the aquatic ecosystems. Therefore, extensive and effective non-target analytical methods are necessary for the monitoring and identification of the transformation products which can be generated during waste water treatment.
Titanium dioxide (TiO2) is the most frequently used photocatalyst because of its inexpensiveness, non-toxicity, chemical stability and its high photocatalytic activity. If TiO2 is irradiated electron-hole pairs are generated on the surface of the TiO2, resulting in the formation of active oxidized species such as hydroxyl radicals which can react with environmental pollutants.
A model system has been developed to simulate photocatalytic reactions in a laboratory scale. The commonly used pharmaceuticals metformin and gabapentin were selected as model substances because of their high input in waste water and the little information about their fate during water treatment. Metformin is the drug of choice for treating type 2 diabetes. More than half of the total amount of pharmaceuticals in the environment are the antidiabetic agent metformin and its major transformation product guanylurea. Gabapentin is used as antiepileptic drug and for the treatment of neuropathic pain. It is found in waste water influent in the high ng/L range.
First results of the optimization of the photocatalyst and its application are shown.
In recent years advanced oxidation processes have become an important part of research due to their capacity to degrade many environmental pollutants during water treatment. Especially the heterogeneous photocatalysis is a promising method because it often results in a full mineralization of many hazardous organic compounds. However incomplete degradation reactions during this process can result in transformation products due to the oxidative conditions. The transformation products may have a higher toxicity than the precursor substances and are often only partly removed during the waste water treatment. Since a lot of these compounds are still unknown, the transformation products are not detected by target analysis used in sewage treatment plants and are often released into the aquatic ecosystems. Therefore, extensive and effective non-target analytical methods are necessary for the monitoring and identification of the transformation products which can be generated during waste water treatment. Among various semiconductors, titanium dioxide (TiO2) is the most frequently used photocatalyst because of its inexpensiveness, non-toxicity, chemical stability and its high photocatalytic activity. If TiO2 is irradiated with light of an energy higher than the band gap of the semiconductor, electron-hole pairs are generated on the surface of the TiO2, resulting in the formation of active oxidized species such as hydroxyl radicals which can react with environmental pollutants. To study photocatalytic reactions, a model system has been developed to simulate environmental relevant conditions for photocatalytic reactions of organic substances on a laboratory scale. The commonly used pharmaceuticals metformin and gabapentin were selected as model substances because of their high input in waste water and the little information about their occurrence, behavior and fate in the environment. Metformin is the drug of choice for treating type 2 diabetes. The drug therapy for diabetes mellitus has increased significantly in recent years. More than half of the total amount of pharmaceuticals in the environment are the antidiabetic agent metformin and its major transformation product guanylurea. Gabapentin is an analogon of the neurotransmitter γ-aminobutyric acid (GABA) which is used as antiepileptic drug and for the treatment of neuropathic pain. Gabapentin is found in waste water influent in the high ng/L range.
First results of the optimization of the photocatalyst and its application are shown.
Untersuchung der Transformation von umweltrelevanten Schadstoffen am Beispiel von 4-n-Octylphenol
(2015)
For years there have been more and more reports on the presence of drugs in the aquatic environment. Due to the demographic change, the consumption of pharmaceuticals has risen sharply. After taking the drugs, they are partly metabolized in the human body. However, the metabolism is not complete so that both the metabolites and non-metabolized amounts of the parent compounds are excreted. These compounds reach the waste water and afterwards the sewage treatment plants. In sewage treatment plants transformation products can be formed by the oxidative conditions during wastewater treatment processes. The transformation products may have a higher toxicity than the actual environmental pollutants and are often only partly removed during the waste water treatment. Since a lot of these compounds are still unknown, the transformation products are not detected by target analysis used in sewage treatment plants and are often released undetected in the aquatic ecosystems. The released substances may be subject to additional transformation processes in the environment. Pharmaceuticals produced in high amounts can be already detected in the μg/L range in water bodies worldwide.
Metformin and its major transformation product guanylurea are one of the main representatives. Metformin is the drug of choice for treating type 2 diabetes. The drug therapy for diabetes mellitus has increased significantly in recent years. In the year 2015 1500 tons of metformin were prescribed in Germany (for statutory insured persons). Metformin is not metabolized in the human body and is excreted unchanged therefore concentrations between 57 μg/L and 129 μg/L are found in German waste water treatment plants influents.
In this work the transformation of the antidiabetic drug metformin is investigated. The degradation of metformin is initialize by commercial water treatment techniques like UV-radiation or noncommercial techniques like heterogenous photocatalysis based on titanium dioxide. The degradation of metformin and resulting transformation products are analyzed by LC-MS/MS and LC-HRMS.
Due to the favorable properties of polymers, their production and thus their input into the environment has increased significantly in recent decades. Currently, FTIR or Raman spectroscopy are mainly applied for the analysis of microplastic particles (MP) in environmental samples. However, these methods have great difficulties in determining metrologically traceable MP values, especially with regard to the limiting values, as preferred in regulation. Therefore, we developed a systematic and fast thermoanalytical method called TED-GC-MS (thermal extraction desorption gas chromatography mass spectrometry), which determines mass contents. Now the current goal is the determination of its process parameters.
This poster illustrates the theoretical requirements for MP analysis (left side) and contrast them with the current state of research (right side).Unexpected practical problems are presented and the relatively new method is discussed concerning the quality requirements of well-established methods such as LC-or GC-MS.
Das Ziel dieses Projektes ist die Entwicklung neuer Materialien, um den Rückhalt von Mikroplastik-Partikeln (MP) aus verschiedenen urbanen Eintragspfaden (Kläranlagenablauf, Mischwasserüberlauf und Straßenabfluss)zu optimieren.
Die im Rahmen des Projekts entwickelten Materialien sollten auf ihre Rückhaltefähigkeit von MP aus dem Kläranlagenklarlauf getestet werden. Für die Probenahme sowie für die Analytik wurden die entwickelten und optimierten Probenahme- sowie Analysetechniken angewendet.
Das Ziel des OEMP-Projektes ist die Entwicklung neuer Materialien, um den Rückhalt von Mikroplastik-Partikeln (MP) aus verschiedenen urbanen Eintragspfaden (Kläranlagenablauf, Mischwasserüberlauf und Straßenabfluss) zu optimieren. Grundlage für die Bewertung ist die Entwicklung von geeigneten Untersuchungsverfahren (Probennahme, Probenaufbereitung, Detektion) zur Qualifizierung und Quantifizierung von MP in den relevanten Umweltmatrices. Diese Verfahren müssen zeiteffizient und zuverlässig sein.