BIOPLASMAS & PLASMAS WITH LIQUIDS - Joint Conference of COST ACTIONS TD1208 “Electrical discharges with liquids for future
applications” & MP1101 Biomedical Applications of Atmospheric Pressure Plasma Technology, Bertinoro, Italy, 13th-17th September 2015
Decomposition of fluorocarbons and pharmaceuticals in water by open
plasma processes
Jakob Barz1, Michael Haupt1, Christian Oehr1
1
Fraunhofer IGB, Interfacial Engineering and Material Science, Nobelstr. 12, 70199
Stuttgart, Germany
Today, the supply with pure drinking water is threatened by many hazardous anthropogenic compounds.
Amongst these compounds, perfluorinated acids and cyanides, emitted by the galvanic industry, and
pharmaceuticals, emitted by the pharmaceutical industry as well as hospitals, can be found in relevant
concentrations. Several of these substances have raised environmental concerns because of their biopersistance and toxicity levels.
For the removal of these substances, char-coal filtering or advanced oxidation processes (AOP) as quaternary
treatment step can be applied. As an alternative to UV-treatment, ozonisation and other standard AOPs,
plasma treatment of water is a very promising approach for the removal of these contaminations as plasma
comprises the formation of chemical radicals, UV radiation and other effects in a single process.
Figure 1: Schematic drawing of the DBD reactor (left); photo in action (right). © Fraunhofer IGB
In this study, we demonstrate the decomposition of perfluorohexanoic acid (PFHxA), perfluorooctanoic acid
(PFOA) and perfluorooctanesulfonic acid (PFOS) in a DBD reactor. As examples of pharmaceuticals,
Diclophenac and Carbamazepin were examined. The reactor used for the decomposition experiments is
depicted in Fig. 1. This lab-scale system has been already upscaled in the past and shown to be capable to
efficiently remove cyanide, atrazine and other hazardous substances from contaminated water [1, 2]. Here,
solutions with different initial concentrations were circulated with a gear pump through the plasma zone; as
gases, hydrogen and oxygen were used. The degradation of the fluorocarbon compounds was followed by
sampling at different times and determination of the residual amount of fluorocarbons was done by 19F
NMR and TOC analysis (TOC=total organic carbon). The reduction of pharmaceutical content was
measured by chromatography (HPLC-UV) and TOC.
Overall, the degradation of the targeted compounds was shown. The efficiency of the processes depends,
besides the choice of the plasma gas and plasma power, also strongly on the circulation velocity even when
the overall treatment time is kept constant.
[1] Hijosa-Valsero, M., Molina, R., Schikora, H., Müller, M. and Bayona, J. M.: Removal of priority
pollutants from water by means of dielectric barrier discharge atmospheric plasma; Journal of Hazardous
Materials 262 (2013), 664-673
[2] Hijosa-Valsero, M., Molina, R., Schikora, H., Müller, M. and Bayona, J. M.: Removal of cyanide from
water by means of plasma discharge technology; Water Research 47 (4) (2013), 1701-1707.