Bulletin of the American Physical Society
68th Annual Gaseous Electronics Conference/9th International Conference on Reactive Plasmas/33rd Symposium on Plasma Processing
Volume 60, Number 9
Monday–Friday, October 12–16, 2015; Honolulu, Hawaii
Session TF1: Plasma Interaction with Liquids III |
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Chair: David Go, University of Notre Dame Room: 301 B |
Friday, October 16, 2015 10:00AM - 10:15AM |
TF1.00001: Measurement of OH Radical in an Atmospheric Plasma Generated on Water Surface Brandon Byrns, Alex Lindsay, Kris Ford, Steve Shanno, Detlef Knappe Hyrdoxyl radicals are a well-known oxidizing agent that has many uses in the removal of contaminants from materials in both liquid and gas phases. To this end, an atmospheric plasma, operated at 162MHz, is used for the production of dissociated reactive species through plasma enhanced vaporization, ionization and the functionalization of liquid precursors via non-thermal plasma treatment. A coaxial source is used that has all components DC grounded allowing for the flow of water through the device creating a layer of water on the surface of the powered electrode. The plasma can be completely sustained through the evaporation of water from the electrode without the need for noble gases or any other feedgas. Air can also be flown through the device with little effect on OH densities but can be used to change the shape of the discharge at the exit of the device, which could be desirable for different applications. The emission spectrum of the discharge is completely dominated by the emissions of the hydroxyl radical. Spatially resolved absorption spectroscopy is performed using a broadband white light source that only requires a single pass through the plasma. OH concentrations have been calculated to be 10$^{\mathrm{14}}$-10$^{\mathrm{16}}$ cm$^{\mathrm{-3}}$. [Preview Abstract] |
Friday, October 16, 2015 10:15AM - 10:30AM |
TF1.00002: Gas flow rate dependence of the production of reactive oxygen species in liquid by a plasma-jet irradiation Giichiro Uchida, Atsushi Nakajima, Toshiyuki Kawasaki, Kazunori Koga, Kosuke Takenaka, Masaharu Shiratani, Yuichi Setsuhara Atmospheric nonequilibrium plasma jets have been widely employed in biomedical applications. For biomedical applications, it is an important issue to understand the complicated mechanism of interaction of the plasma jet with liquid. The main purpose of this study is to clarify the effects of the gas flow rate on the production of reactive oxygen species (ROS) in liquid by the plasma-jet irradiation. For this purpose, we performed plasma-jet experiments using the detection medium for oxidation reaction with KI and starch under the various gas flow rates [1]. In the KI-starch solution system, the absorbance of KI-starch solution near 600 nm behaves linear to the total amount of the ROS, and we could relatively estimate the total amount of the ROS from the solution absorbance. The 569-nm absorbance of the KI-starch solution after the irradiation of a plasma jets for 60 s increases from 0.41 to 0.52 when the He gas flow rate is increased from 3 to 9 slm. Our experiment demonstrates that the gas flow rate strongly affects the total amount of the ROS in liquid in the plasma-jet system. \\[4pt] [1] T. Kawasaki \textit{et al}., IEEE Trans. Plasma Sci. 41, 2482 (2014). [Preview Abstract] |
Friday, October 16, 2015 10:30AM - 10:45AM |
TF1.00003: Generation Mechanisms of Hydroxyl Radical and Hydrogen Peroxide in Plasma Generated over Solution Nozomi Takeuchi, Naoto Ishibashi, Daichi Shiraki Plasmas in contact with liquid have been used in many applications such as water treatment using OH radical, generation of hydrogen peroxide, and so on. The understanding of the generation mechanisms of OH radical and hydrogen peroxide is necessary to improve the time and energy efficiencies in these applications. In this study, plasma generated over a solution was used to investigate the mechanisms. A needle electrode was placed 1 mm above a solution and DC or pulsed voltage was applied to the needle whereas the bottom of the solution was grounded. The concentrations of OH radical and hydrogen peroxide were measured while changing experimental conditions. It was revealed that one of the key mechanisms is OH radical generation in gas phase by dissociation of water molecule in the vicinity of the solution, and the other is OH radical generation in liquid phase followed by irradiation of positive ions to the solution. [Preview Abstract] |
Friday, October 16, 2015 10:45AM - 11:00AM |
TF1.00004: In-water plasma generation and its performance using a coaxial DBD device and compact power supply Shin-ichi Imai, Y. Sakaguchi, Y. Miyamoto, A. Odagwa, Tatsuru Shirafuji This paper describes in-water plasma generation and its characteristics using a coaxial tungsten electrode and a compact power supply. In-water plasma is formed in an air stream supplied from outside by an air pump. The power supply circuitry, which is based on LC series resonance, was designed using SPICE simulation. We were able to reduce the volume of the power supply to 1.5 liters. The behavior of the in-water plasma and voltage waveform generated by our device and the power supply were simultaneously observed using a high-speed camera system in conjunction with an oscilloscope. The device performance was estimated using the decoloration of indigo carmine during Plasma ON and OFF. The radicals and species in in-water plasma were measured using an ESR-spin-trap method. It was found that O2- and OH radicals are generated during Plasma ON, and OH radicals remain after Plasma OFF. [Preview Abstract] |
Friday, October 16, 2015 11:00AM - 11:15AM |
TF1.00005: Decomposition of n-Dodecane for Hydrogen Production using Microwave in-Liquid Plasma Method Andi Amijoyo Mochtar, Shinfuku Nomura, Shinobu Mukasa, Hiromichi Toyota, Kohji Kawamukai The purpose of this paper is to investigate the decomposing of dodecane in produce hydrogen using in-liquid plasma method. Microwave oven as a medium in generating plasma has modified and connected with the generator. The plasma was improved 1.3 times of hydrogen production when the electrode bubbles were created. The hydrogen ratio of the generated gas was created graphite concentrate that can decrease the decomposition of plasma. The steam reforming in plasma was induced the gas production rate increase 1.4 times. The generated hydrogen efficiency of alkaline water electrolysis was reached at 284{\%} and the conventional of steam reforming at 41{\%}. [Preview Abstract] |
Friday, October 16, 2015 11:15AM - 11:30AM |
TF1.00006: One Step Phenol Production from Toluene Solution Using RF In-Liquid Plasma Muhammad Agung, Shinfuku Nomura, Shinobu Mukasa, Hiromichi Toyota, Hidekazu Goto, Otsuka Kazuhiko The objective of this research is to investigate the possibility of phenol production with one step process directly from solution of toluene and pure water using plasma in-liquid method. Experiments have been conducted using 27,12 MHz Radio Frequency in-liquid plasma to decompose a solution of 30{\%} toluene. When the plasma was formed in the liquid solution, molecule water substance was decomposed to OH radicals, H$\alpha $, H$\beta $ and O by plasma energy. In phenol production using the proposed method, OH radicals play a major role during the process of direct chemical reaction with toluene. In the sample residue liquid solution, phenols spectral lines are observed by GCMS. Experimental investigations clearly show that phenol can be directly produced from toluene. [Preview Abstract] |
Friday, October 16, 2015 11:30AM - 11:45AM |
TF1.00007: Generation of Discharge Plasma in Gas-Liquid Slug Flow Kakeru Mano, Yui Hayashi, Noriharu Takada, Hideki Kanda, Motonobu Goto Discharge plasma in contact with aqueous solution has been attracted attention in the application of wastewater treatment nanoparticles generation and medicine. A lot of methods of electric discharge over aqueous solution surface were researched, but contact area between plasma and aqueous solution was small on these methods. Therefore, some methods generated discharge plasma inside bubbles to enlarge contact area of plasma. However, bubbles were difficult to control because of sheer force and buoyancy in these studies. Namely, the discharge conditions varied temporally. We proposed the discharge method using gas-liquid slug flow in the same direction to control bubbles. Slug flow had the gas phase and liquid phase and these were arranged regularly and flow forward in the same direction. Therefore, this study have potential to generate discharge plasma continuously. In the experiment, the discharge plasma was generated linearly along the inner surface of bubble continuously while flowing the gas-liquid slug. All bubbles between electrodes had plasma emission. Optical emission of feed gas (Ar, He, O$_{2}$ and N$_{2})$ were observed respectively and emission of OH radical and H$_{\alpha }$ were also observed. Especially, emissions of OH radical were intense relatively. OH radical has high decomposition ability, thus 4-nitroacetanilide was degraded. The decomposition ratio reached 80{\%} by using Ar or O$_{2}$ slug flow. However, by using N$_{2\, }$slug flow, the decomposition ratio reached only 50{\%}. [Preview Abstract] |
Friday, October 16, 2015 11:45AM - 12:00PM |
TF1.00008: Application of strong pulse electric fields for disinfecting of the water mediums Elchin Gurbanov, Arif Hashimov Now development on use of strong electric fields for water treatment represents a big urgency. In present article influence of high-voltage pulse fields for disinfecting of drinking water and sewage is considered. In researches the high voltage pulsed generator with exit tension about 100 kV and the different electrode systems are used. They promotes the non-uniform distribution of electromagnetic power lines in interelectrode distance and to development of discharge processes in gases, dissolved in water. Depending on parameters of the discharge gap and electrode system (tension polarity, radius of curvature , the bared area of potential electrode and etc.) we observe the various electro physical processes in interelectrode distance. An impact of high pulse voltage periodically cause inside of gas bubbles in water the high-frequency plasma-chemical processes with photoionization. As a result, an ultra-violet radiation and mechanical compressed waves are appeared and perniciously influencing on microorganisms in water. This process periodically proceeds to their full relaxation. Such method of treatment of liquid mediums is considered much more power effective (less energy-intensive) and environmentally clear in comparison with other appendices. [Preview Abstract] |
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