Physical and chemical properties of deionized water and saline treated with low-pressure and low-temperature plasma
Joanna MYSTKOWSKA, Jan R. DĄBROWSKI ? Department of Materials and Biomedical Engineering, Bialystok University of Technology, Bialystok, Krzysztof KOWAL, Department of Allergology and Internal Medicine, Medical University of Bialystok, Katarzyna NIEMIROWICZ, Halina CAR ? Department of Experimental Pharmacology, Medical University of Bialystok

Please cite as: CHEMIK 2013, 67, 8, 719?724

Plasma techniques have been applied in many industries. Among the three main plasma techniques, particular attention is paid to the potential application of low temperature plasma and its modifications. Cold plasma has been used both in industry and science, as well as with the modification of physicochemical properties. In this paper, an assessment of physicochemical samples of deionized water and saline treated with low-temperature and low-pressure plasma has been made. The plasma process changed physicochemical parameters of tested fluids, which may have a beneficial importance in any biological research.

Keywords: low-temperature low-pressure plasma, deionized water, saline, physical and chemical parameters.

Introduction

Low temperature plasma, also known as cold plasma, has been used in many industries [1], including the synthesis of biomaterials, in order to improve the clinical efficacy of medical implants by a diverse modification of their surface [2]. The cold plasma process is characterized by a low degree of ionization at a low atmospheric pressure [2, 3]. In order to produce low-temperature plasma at first a compound is converted into a state of ionized gas and through the use of thermal energy in the form of direct or alternating current, radiation or laser [1, 3]. The potential applications of low temperature plasma are due to the change of surface properties, including the electrochemical reduction and the nature of the chemical groups. Therefore, properties such as hardness, physical abrasion, corrosion, and water absorption capacity and affinity to specific molecules are possible to be modified using cold plasma [4÷6]. As a result of the substance undergoing low-temperature low-pressure plasma resonance, a substantial change occurs in its physicochemical properties, yet the effects of the application of cold plasma reactor for basic physicochemical properties of liquids such as water and physiological saline are unknown. In this study, physicochemical properties of deionized water and saline were evaluated. The tests were carried out 7 days after deionization and / or operation of the low-temperature low-pressure plasma resonance in deionized water. An analysis was performed for the properties of water such as pH, conductivity, surface tension, density and dynamic viscosity. All measurements were performed at 24°C. Each measurement was repeated 6 times for a sample for all tested quantities.

The experimental part

Materials

Deionized water and saline (Fresenius Kabi Poland Sp.) have been subjected to low-temperature plasma. 0.9% NaCl solution with a volume of 0.5 litre standard production of Fresenius Kabi Poland Ltd, and deionized water by reverse osmosis were supplied in containers of 0.2 litre. Methods At the NANTES Nanotechnology Systems Ltd laboratories, deionized water and physiological saline were subjected to low-pressure low-temperature plasma with the use of a reactor at the following parameters: temperature of plasma 38°C, 5×10?3 mbar vacuum, 600 V voltage, 50 mA intensity and frequency of 280 GHz [7, 8], in the environment of residual gases, without the flow of other gases, without any change of parameters in the process. The material was placed in sealed containers with a capacity of 0.5 litre (saline) or 0.2 litre (deionized water), subject to no rotation. The impact of the plasma on the object was of a pulsatile nature with the synchronization network for 40 minutes. The pH and conductivity tests were carried out by means of suitable measuring electrodes cooperating with the multifunctional SevenMulti ionic conductivity meter from Mettler Toledo. The pH ratings were made using Clarytrode 120 electrode. The conductivity measurements were made using the InLab740 conductivity cell from Mettler Toledo with an integrated probe for measuring the temperature of the tested solution. The surface tension tests were performed using the STA1 tensiometer from Sinterface. For density tests, a pycnometer by Gay- Lussac was used. The rheological measurements (measurement of the dynamic viscosity as a function of shear rate) was carried out using a RheoStress6000 rheometer from Haake, and a Thermo Scientific cone measuring system (C35/2o TIL) ? plate (MP35) of outer solvent-trap.

The study of physicochemical properties of samples treated with low temperature plasma:

For all physiochemical measurements we used 3 specimens of water and 0.9% NaCl not treated with plasma process, and deionized water and saline, which underwent a low-temperature low-pressure plasma resonance (Tab.1). The results were analyzed statistically using the student?s t-test with the PQStat software. The results were presented as arithmetic means with the indication of the standard deviation (SD). The results were considered statistically significant at p <0.05. In order to determine the level of significance, the following indications were used: p <0.05 * p <0.01 ** p <0.001 *** in order to compare the same type of liquid treated with and not treated with plasma.

Results and discussion

The results of the measurements of selected physicochemical properties of deionized water and 0.9% NaCl showed differences between the two samples. The pH of deionized water evaluated after 7 days from the deionization was about 5.4. There was a significantly higher and statistically relevant pH value (7.85) for the deionized water after plasma process (Fig. 1). The pH (5.9) of 0.9% NaCl was slightly lower than the 0.9% NaCl treated with plasma (pH 5.99) ? however, this difference reached a statistical significance (Fig. 1). There was a significant difference in: the conductivity of deionized water was 13.53 mS/ cm-1, while of deionized water treated with plasma was 403 mS /cm-1 (p <0.001) (Fig. 2A). The conductivity of 0.9% NaCl (d=12.37 mS/cm-1 ) was lower than that of saline treated with plasma (d=13.47 mS/cm-1) (Fig. 2B). In the study [9] the conductivity of deionized water treated with a various factors was investigated. Differences were obtained in the test volume, depending on the applied medium. The electrolytic conductivity depends on the amount of the free ions in water and their ability to move. The analyzed deionized water treated with plasma had a significantly higher surface tension (g=45 mN×m-1) in reference to the untreated deionized water (g=34 mN×m-1), while physiological saline treated with plasma was characterized by statistically significantly lower surface tension (g=31 mN×m-1) than 0.9% NaCl not treated with plasma (g=44 mN×m-1). (For comparison, the surface tension of freshly distilled water according to the papers [10÷12] is respectively 72.44 and 72.49 mN× m-1. Density and viscosity of the two tested fluids have not changed significantly under the influence of plasma (Figs. 4, 5).

Summary and conclusions

The physicochemical studies have clearly shown that the deionized water and saline subjected to low-temperature lowpressure plasma significantly changed their properties such as pH, electrical conductivity and surface tension as compared to their counterparts not treated with plasma. The procedure of processing deionized water using a low-pressure and low-temperature plasmas have been submitted to patent admission [7].

Literature
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7. Patent application. Nr P.389626
8. http://www.nantes.pl/
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Acknowledgement
This study was performed under the project ?Studying, researching, commercializing ? of the doctoral support program at UMB?, Measure 8.2.1 of the Human Capital Operational Programme, co-financed by the European Union under the European Social Fund Programme. Special thanks are directed by the authors to the company of NANTES Nanotechnology Systems in Boleslawiec for conducting the plasma processes and providing fluids for evaluation as well as covering the editorial costs.

Translation into English by the Author

Joanna MYSTKOWSKA ? Ph.D. Eng., is a graduate of the Faculty of Chemistry, Warsaw University of Technology (2003). Doctoral thesis defended at the Faculty of Materials Science and Engineering, Warsaw University of Technology. Currently, she works in the Department of Materials and Biomedical Engineering at Bialystok University of Technology. Scientific interest: biopolymers, biological fluids and biofilm. She is an author of several chapters in international scientific monographs, 29 articles in scientific-technical journals and author or co-author of 24 papers and communications presented at national and international conferences. Department of Materials and Biomedical Engineering, Bialystok University of Technology, Wiejska 45 C, 15?351 Bialystok, Poland e-mail:; phone

Jan Ryszard DĄBROWSKI ? Professor, is a graduate of the Institute of Chemistry and Technology of Moscow (1977). Defended his doctoral dissertation to the Board of the Faculty of the Technical University of Wroclaw (1981). Habilitation thesis defended to the Council of the Institute of Chemical Technology of the German Academy of Sciences (1989). In 2005, the President of Poland awarded him the title of Professor. He is currently head of the Department of Materials and Biomedical Engineering at Bialystok University of Technology. Scientific interest: tribology, biomaterials, biological fluids. He has received numerous medals and awards, including the Silver Cross of Merit and Awards of the Minister. He is a member of many organizations and scientific societies, including the German Society for Biomaterials Rhine- Westphalia (NRW eV Biomaterialien AG). He is an author or co-author of several monographs, over 200 articles in scientific and technical press and author or co-author of more than 70 papers and communications presented at national and international conferences. e-mail:; phone:

Krzysztof KOWAL ? Ph.D., is a graduate of the Faculty of Medicine (1990), Medical University of Bialystok. He completed his Ph.D. degree in 1991 at the Faculty of Medicine of the Medical University of Bialystok. During the four years received two specializations of internal diseases and allergy. In 2009, he defended his habilitation thesis in medical science. He currently works as an assistant professor in the Department of Allergology and Internal Medicine, Medical University of Bialystok. He has authored or co-authored more than 70 publications and 100 communications. He is also an author of six chapters in textbooks. His interests focus on the mechanisms of the inflammatory response, the impact of exogenous substances on the cellular response and the implementation of new therapeutic approaches including targeted therapy. e-mail:; phone:

Katarzyna NEMIROWICZ ? M.Sc., is a graduate (chemistry) of the Faculty of Biology and Chemistry, University of Bialystok (2011) and Laboratory Medicine at the Medical University of Bialystok (2012). At present she is the second year PhD student in the Department of Experimental Pharmacology, Medical University of Bialystok, Faculty of Medicine. Since February 2013 she has been a principal investigator the grant Prelude. She is also the beneficiary of a program ?I study, investigate, commercialize? ? UMB doctoral support program funded by the European Union under the European Social Fund as well as the scholar of Polpharma Science Foundation Scholarship. Research interests: organic synthesis, nanotechnology and targeted therapy. She is the author and co-author of five research papers, 13 papers and communications runs at national and international conferences, as well as a patent application. e-mail: ; phone:

Halina CAR ? M.D., Ph.D., is a graduate of the Faculty of Medicine, Medical University of Bialystok (1987). She obtained the degree of Doctor of Medicine in 1990, and defended her habilitation thesis in 2007. In the years 1987÷2010 she worked in the Department of Pharmacology, Medical University of Bialystok. For the last three years has been ahead of the Department of Experimental Pharmacology, Medical University of Bialystok. She works as Voivodshipl Consultant in Clinical Pharmacology. Research interests: learning and memory, neurodegeneration and possibilities of their therapy, tumor processes in the brain, targeted therapy. She is the author and co-author of 58 scientific articles published in the international medical journals and 80 papers and communications presented at national and international conferences, as well as a patent application e-mail: , ; phone: