For the naval field there are two major problems related to the existence of microorganisms: the deposition of Biofouling and the treatment of ballast water. The first problem is strictly related to corrosion with an important economic impact on maintenance costs. In accordance with new IMO (International Maritime Organization) regulations, different green technologies have been proposed for solving this particular issue, among them being also considered the technology based on plasma discharge produced at low pressure. The proposed study concerns the opportunity of atmospheric plasma treatment for naval steel preparation or conditioning. Five different treatments, with three types of plasma working under different gases, have been used. Their effects were evaluated based on microbiological analysis. These analyses concern the biological contamination of each sample by bacteria control at 2 different moments of time. For this purpose, the Gram-negative bacteria Escherichia coli has been used, because it is one of the most important microbial indicators according to Ballast Water Performance Standard D2 (http://www.imo.org). Three different types of electric discharges were used as non-thermal plasmas for the surface treatment.
Improving corrosion resistance represents a highly interesting topic in the maritime field, having important economic consequences by reducing the maintenance costs or increasing the life expectancy of the final products and by imposing significant environmental impact. In accordance with new IMO (International Maritime Organization) regulations, different new clean technologies have been proposed for solving this particular issue, among them being also considered the technology based on plasma discharges, generally produced at reduced pressure. The proposed study concerns the opportunity of atmospheric plasma treatment for naval steel preparation or conditioning. Five different treatments, with three types of plasma working under different gases, have been used. Their effects were evaluated based on surface modification analysis. These analyses concern the roughness of the samples and the surface hydrophobicity at two different moments of time. There were used three types of reactors producing non-thermal plasma: GlidArc, Gliding Spark and Minitorch.
This paper aims to analyze the functionality of different types of power supplies producing laboratory controlled electrical discharges using pulsed power supplies for DBD discharge. The analysis includes measured electrical parameters and simulated electrical parameters using PROTEUS ISIS software. Also in this paper DBD types of plasma discharges will be simulated with two different power supplies in order to approximate functionality. Laboratory electrical discharges that produce non-thermal plasma are used more and more for microbiological decontamination, surface treatment and depollution by the means of decomposing some complex molecules or in the field of modern medicine. Each application requires a power supply particularly adapted to each type of the plasma reactor. If the first applications of these discharges were designed mostly for reactor types with high volume discharge capabilities, and the power supplies were simple and robust generating high power using industrial frequencies, in time the reactors decreased significantly in size and the power supplies used were working on higher frequencies. This trend was adopted on one hand out of the need for energy optimization of the power supplies used, and on the other hand to get a better homogeneity of the treatment. This paper aims to provide a comparison for pulsed power supplies working at different frequencies, with respect to the electrical parameters, from the point of view of power supplies themselves for DBD discharges. In order to optimize the non-thermal plasma treatment for different applications, the parameters of the electric discharges producing the plasma must be considered. Consequently, it is necessary to carry out a simulation starting from an equivalent electric schematic with parameters as close as possible to those of the discharge. This discharge is produced in non-thermal plasma DBD reactors. The analysis is done on simulated electrical parameters using PROTEUS ISIS software in order to assess the parameters in functionality of the power supplies.
Treatments with atmospheric pressure non-thermal plasma are easy to implement and inexpensive. Among them gliding
arc (GlidArc) remains rarely used in surface treatment of polymers. However, it offers economic and flexible way to
treat quickly large areas. In addition the choice of carrier gas makes it possible to bring the active species and other
radicals allowing different types of grafting and functionalization of the treated surfaces, for example in order to apply
for anti-biofouling prevention.
This preliminary work includes analysis of the surface of epoxy resins by infrared spectroscopy: the different affected
chemical bonds were studied depending on the duration of treatment. The degree of oxidation (the C/O ratio) is obtained
by X-ray microanalysis and contact angle analysis have been performed to determinate the wettability properties of the
treated surface. A spectroscopic study of the plasma allows to determine the possible active species in the different zones
of the discharge.
This paper presents the GlidArc plasma effects on some metallic surfaces often used in dentistry: zirconium, titanium and nickel – chromium alloy plates. For the experiments performed, a GlidArc reactor with two planar electrodes has been used. During the tests, the gas flow has been kept constant while the treatment time and the distance between the plasma and the sample were modified. The surfaces were analyzed using atomic force microscopy (AFM) in order to determine the surface morphological modifications induced by the plasma treatment.
This paper aims to present the evolution of the construction and performances of non-thermal plasma reactors, identifying specific requirements for various known applications, setting out quality indicators that would allow on the one hand comparing devices that use different kinds of electrical discharges but also their rigorous classification by identification of criteria in order to choose the correct cold plasma reactors for a specific application. It briefly comments the post-discharge effect but also the current dilemma on non-thermal plasma direct treatments versus indirect treatments, using plasma activated water (PAW) or plasma activated medium (PAM), promising in cancer treatment.
Biofouling is the most important cause of naval corrosion. In order to reduce the Biofouling development on naval materials as steel or resin, different new methods have been tested. These methods could help to follow the new IMO environment reglementations and they could replace few classic operations before the painting of the small ships. The replacement of these operations means a reduction in maintenance costs. Their action must influence especially the first two steps of the Biofouling development, called Microfouling, that demand about 24 hours. This work presents the comparative results of the Biofouling development on two different classic naval materials, steel and resin, for three treated samples, immersed in sea water. Non-thermal plasma, produced by GlidArc technology, is applied to the first sample, called GD. The plasma treatment was set to 10 minutes. The last two samples, called AE9 and AE10 are covered by hydrophobic layers, prepared from a special organic-inorganic sol synthesized by sol-gel method. Theoretically, because of the hydrophobic properties, the Biofouling formation must be delayed for AE9 and AE10. The Biofouling development on each treated sample was compared with a witness non-treated sample. The microbiological analyses have been done for 24 hours by epifluorescence microscopy, available for one single layer.
Corrosion in marine environment is a complex dynamic process influenced mainly by physical chemical, microbiological and mechanical parameters. Times for maintenance related to corrosion are greater than 80% of the total repair. Reducing this cost would be a significant saving, and an effective treatment can reduce times related to ships repairing. Biofouling is a main cause of corrosion and its formation contains four steps. To inhibit biofouling it is proposed a treatment based on non-thermal plasma produced by GlidArc, which can be applied before the immersion of small boats in the sea, as well as cleaning treatment of the hull after a period of time. This work presents the microbiological results of treatment of metal surfaces (naval OL36 steel) with GlidArc technology, according to the first, respectively the second phase formation of biofouling. Samples of naval steel were prepared with three specific naval paints and before the treatment have been introduced in seawater. Microbiological results have been compared for two types of treatments based on GlidArc. In the first case the painted samples are submitted to direct action of non-thermal plasma. In the second case the plasma produced by GlidArc technology is used to activate a solution (plasma activated water = PAW) and then the samples are introduced into this water.
Corrosion in marine environment is an actual problem, being a complex dynamic process influenced mainly by physical, chemical, microbiological and mechanical parameters. Around 70% of the maintenance costs of a ship are associated with the corrosion protection. Times for maintenance related to this phenomenon are greater than 80% of the total repair. Reducing this cost would be a significant saving, and an effective treatment can reduce times related to ships repairing. Biofouling is a main cause of corrosion and for its reduction different methods could be applied, especially in the first part of its production. The atmospheric pressure non-thermal plasmas have been gaining an ever increasing interest for different biodecontamination applications and present potential utilisation in the control of biofouling and biodeterioration. They have a high efficiency of the antimicrobial treatment, including capacity to eradicate microbial biofilms. The adhesion microbial biofilm is mainly influenced by presence of bacteria from the liquid environment. That is why this work concerns the study of annihilation of maximum amount of bacteria from sea water, by using GlidArc technology that produces non-thermal plasma. Bacteria suspended in sea water are placed in contact with activated water. This water is activated by using GlidArc working in humid air. Experimental results refer to the number of different activated and inactivated marine organisms and their evolution, present in solution at certain time intervals after mixing different amounts of seawater with plasma activated water.
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