This research focus area deals with development and optimization of plasma-based processes for decontamination and hygiene for environmental protection, for occupational and personal Health & Safety, in food hygiene and in medical facilities. In this regard, plasma technology is used to decompose biological and chemical contaminants of surfaces gases and fluids.
Microorganisms can be specifically deactivated and even eliminated without damaging the carrier. Consequently, plasmas are particularly suitable for sterilization of thermal-labile instruments, plastic items, textiles, and even skin. For this reason, part of the research is devoted to plasma-based decontamination of sensitive materials and products from the medical sector. Made-to-measure plasma-based treatments improve hygiene and device surfaces (e.g. endoscopes), air (e.g. in an operating room) or even liquids (e.g. hospital wastewater). Moreover, use of physical plasma to remove critical contaminants in fresh foods is being investigated. Chemical decontamination through plasma is employed for example in elimination of toxic (e.g. nitric oxides) or undesired pollutants (including odors) in airflows or exhaust gas flows, which can only be decomposed with difficulty or not decomposed at all with conventional systems. In the area of wastewater treatment, plasmas can contribute to destruction of stubborn compounds, such as pharmaceutical residues (e.g. diclofenac) or radiocontrast agents (diatrizoate).
The "Clean Air" research topic is devoted to development of new plasma-based methods for decomposition of pollutants in gas flows, including air. In combination with other methods, e.g. filter systems, overall these methods aim at decomposing substances that can only be eliminated with difficulty or that cannot be eliminated at all with other methods. Plasma, as an important oxidation technology (advanced oxidation technology) is a promising approach in this area. Through high reactivity even substances that are difficult to decompose can be solubilized. In addition, plasmas have proven to be extremely efficient in the decontamination of airborne pathogens. Our research activities are directed to obtaining a deeper understanding of the elementary processes and mechanisms of non-thermal plasma chemistry as the basis for optimization of reactors and processors for exhaust air treatment and exhaust gas treatment.
The "Clean Water" research topic concentrates on microbial and chemical contamination of liquid media. In this regard a distinction is made between methods for conveying a plasma in or on the fluid, and methods for the treatment of gases. In addition other possibilities arise, such as use of pulsed electrical fields that permit efficient sterilization. Selective advanced decontamination methods will be developed on this basis. Discharges generated in and on water can be used with excellent effect for problematic contamination, for instance in the area of drinking water purification. In particular, substances such as medications or pesticides that can only be biologically decomposed with difficulty demand new, efficient approaches. In this area plasma processes are an environmentally-friendly and cost-effective alternative with which not only can microorganisms be deactivated even without use of chemicals, such as chlorine, but in addition chemical pollutants can also be solubilized.
In the "Clean Food" research topic the use of plasma in the food industry is researched. The objective is to keep transport routes and packaging in the food industry microbial clean via plasmas, and to extend post-harvest preservability of fruit and vegetables in a gentle manner. Thus, not only should harvest loss be reduced but also food hygiene should be sustainably improved overall, and infections caused by food should be prevented. The idea that is pursued is use plasma to generate efficient species with anti-microbial effect, in particular radicals and metastables. On one hand these are micro-biologically active, and on the other hand they are decomposed within process-typical times, so that a possible effect on the product is minimized and the possibility of consumer hazard can be excluded. INP is actively involved as a partner in the Plasma4Food network to drive research activities forward relative to development, manufacturing and marketing of plasma-based systems for efficient, gentle decontamination of food products, production equipment, and the packaging of food products.
The "Clean Healthcare" research topic focuses on plasma-based biological decontamination and possible sterilization of sensitive materials and medical products. For this purpose, plasma sources will be developed especially for medical requirements, such as in the field of endoscopy.
Application-oriented research in the research area of decontamination is supported through various projects, in which either physical fundamentals are the center of focus, or the feasibility of different applications is investigated.
As part of the special research area – Transregio 24 "Fundamentals of Complex Plasmas" (2005), the project includes analysis of the spatiotemporal behavior of the species and chemical processes in reactive non-equilibrium plasmas. On the other hand, interaction of such plasmas with surfaces is investigated via hydro-dynamic modeling, kinetic methods, as well as hybrid procedures.
In the funding period 2013 to 2017 theoretic investigations concentrate on molecular discharge plasmas at low pressure and atmospheric pressure that contain oxygen, nitrogen or organic silicon admixtures. Adaptation of suitable plasma-chemical models and their integration in the hydrodynamic, kinetic or hybrid procedures makes it possible to characterize plasma characteristics and analyze the influence of individual species and the reaction-kinetic processes in volumes or on the surfaces and improve the understanding of the interaction of plasma dynamics and flow dynamics.
The investigated plasmas and discharges are used in many plasma technologies, such as pollutant decomposition, ozone generation, plasma treatment of material surfaces and thin-film deposition.
Priv.-Doz. Dr. Detlef Loffhagen
Phone: +49 3834 - 554 320
Within the food production chain of vegetable foodstuffs, germ infestation can cause problems in food safety and result in harvest and storage losses. Producers and processors of fresh products, are highly interested in the direct economic consequences associated with a reduction of hazards and the corresponding reduction in losses. Additional sensitivity for this topic was aroused in 2011 through EHEC.
Inactivation of microorganisms on natural surfaces with concurrent retention of the quality-determining constituents of the vegetable matrix poses a technological challenge. Due to the immense cost pressure only relatively cost-efficient procedures can be used. The core idea of our research work in this area is to generate via plasma efficient, species with microbial effect, in particular radicals and metastables, which on one hand are micro-biologically active, and on the other hand are decomposed within times that are typical for the method, so that possible effects on the product are minimized and a consumer hazard can be excluded. The objective is to enable improved yield and simultaneously increase safety for the consumer. Other application areas are packaging, transport containers, equipment parts and medical products.
Brandenburg, R.; Kovacevic, V.-V.; Schmidt, M.; Basner, R.; Kettlitz, M.; Sretenovic, G.-B.; Obradovic, B.-M.; Kuraica, M.-M.; Weltmann, K.-D.:
Plasma-Based Pollutant Degradation in Gas Streams: Status, Examples and Outlook
DOI: 10.1002/ctpp.201310059, Contrib. Plasma Phys. 54 (2014), p. 202 – 214
Banaschik, R.; Lukes, P.; Jablonowski, H.; Hammer, M.-U.; Weltmann, K.-D.; Kolb, J.-F.:
Potential of pulsed corona discharges generated in water for the degradation of persistent pharmaceutical residues
DOI:10.1016/j.watres.2015.07.018, Water Research 84 (2015), p. 127-135
Schnabel, U.; Andrasch, M.; Weltmann, K.-D.; Ehlbeck, J.:
Inactivation of Vegetative Microorganisms and Bacillus atrophaeus Endospores by Reactive Nitrogen Species (RNS)
Plasma Process. Polym. 11 (2014), p. 110-116