This project seeks to develop plasma gas-liquid reactors to produce chemical disinfectants (e.g., hydrogen peroxide and hydroxyl radicals) through plasma formation. Previous support from NSF has provided knowledge of the basic chemical reactions and the mechanisms for the formation of reactive species including hydroxyl radicals and hydrogen peroxide in small laboratory scale reactors where non-thermal plasma contacts with liquid water. The research team has discovered that higher efficiencies can be obtained when plasma formed in the gas phase contacts a flowing liquid film or an aerosol of water droplets and used this to develop a reactor system. The reactor system developed is quite simple, durable, and robust. While it is currently of relatively small laboratory scale, we expect that the scale up can be addressed so that the system can have a potential impact on the market for small processing plants and perhaps personal use where portability and low unit expense are needed.
The development of new technologies for disinfection, water cleaning, and chemical oxidation can address many public health and environmental problems as well as improve industrial efficiency. Small scale efficient gas-liquid plasma reactors may find wide use in a variety of such applications.
The goal of this project was to investigate the potential for commercialization of a non-thermal plasma technology developed under previous NSF supported research. The specific non-thermal plasma technology uses an electrical discharge in a flowing gas that contacts a flowing liquid water stream to form useful chemical species such as hydrogen peroxide and, in the case of a carrier gas containing nitrogen (e.g., air), nitrates and other nitrogen containing compounds. During the course of the project more than 100 interviews with potential users, partners, clients, and competitors for this technology were conducted. Through these interviews, applications in agriculture were identified as having the most direct market potential for this technology. It was further discovered that organic agriculture has a particular need for a technology of this kind due to restrictions on the types of chemicals that can be used in the production of organic foods. Direct application of dilute hydrogen peroxide solutions to plants is currently one of the only effective ways to prevent crop loss on organic farms. Additionally, organic fertilizers lack highly bioavailable nitrogen sources, thereby causing lower growth rates of organically produced crops in comparison to non-organic practices. Thus, the "green" production of hydrogen peroxide (as a fungicide or bactericide) in conjunction with a readily available nitrogen source (nitrate) from air and water is of significant interest to organic farmers. While other competing technology using plasma for this market has been identified, the given process seeks to develop portable, smaller scale, devices that can be easily operated and used by farmers for the point-of-use production and application of these chemicals. The broader impacts of this work pertain to the potential for reduced cost and environmental impact of organic food production. In addition, this project accomplished the training of a PhD graduate student and faculty member in entrepreneurial activities and company formation. Several undergraduate engineering students were also trained in laboratory experiments related to plasma chemical reactor operation. The intellectual merit relates to enhanced understanding of the potential applications of non-thermal plasma for agriculture use and plasma reactor design and scale-up. One US patent application was also prepared based upon this work.
