Electrical Discharge Treatment Research Articles

The effect of high voltage electrical discharge (HVED) treatment on small seed plants

The effect of high voltage electrical discharge (HVED) treatment on small seed plants

A solid-state pulse power sub-nanosecond SiC DSRD-based generator with high-voltage and high repetition frequency for pulse discharge water treatment

Water treatment is one of the most important issues for all walks of life around the world. The unique advantages of the solid-state power electronic pulses in water treatment make it attractive and promising in practical applications. The output voltage, rising time, repetition rate, and peak power of output pulses have a significant impact on the effectiveness of water treatment. Especially in pulse electric field treatment and pulse discharge treatment, the pulse with fast rising time achieves the advantage of generating plasma without corona, which can avoid water heating effect and greatly improve the efficiency of the pulse generator. High repetition rate can significantly reduce the peak power requirement of the pulse in water treatment application, making the equipment smaller and improving the power density. Therefore, the study developed a high-voltage high frequency sub-nanosecond pulse power generator (PPG) system for wastewater treatment. It adopts SiC DSRD (Drift Step Recovery Diode) solid-state switches and realize modular design, which can achieve high performance and can be flexible expanded according to the requirements of water treatment capacity. Finally, an expandable high-voltage PPG for water treatment is built. The output parameters of the PPG include output pulse voltage range from 1 to 5.28 kV, rise time <600 ps (20%–90%), repetition up to 1 MHz. The experiment results of PPG application for pulse discharge water treatment is presented. The results indicate that the proposed generator achieves high-efficiency degradation of 4-Chlorophenol (4-CP), which is one of the most common chlorophenol compounds in wastewater. From experiment, the homemade system can degrade 450 mL waste water containing 500 mg/L 4-CP in 35 min, with a degradation rate of 98%. Thereby, the requirement for electric field intensity decreased. Through the further quantitative analysis, the impact of frequency, voltage, and electrode spacing on the degradation effect of 4-CP is confirmed.

ENERGY EFFICIENCY INCREASING OF ORE ENRICHMENT WASTES’ PROCESSING BY ELECTRICAL DISCHARGE METHOD

A promising and accessible raw material, comparable in terms of gold and silver content to natural ore deposits, is the lying tailings of ore flotation. Currently, billions of tons of ore tailings have been accumulated, the content of valuable components in which sometimes exceeds those in natural deposits. The processing of ore tailings from tailings for the extraction of non-ferrous metals in most cases requires complex beneficiation schemes, and in terms of technical and economic indicators and the quality of concentrates, they are uncompetitive compared to products of natural raw materials. An electric discharge method of disintegration of ore beneficiation waste to increase the number of available target components, based on the rational organization of crushing and grinding processes in relation to beneficiation tasks, was experimentally investigated. The pressure values of the compression waves generated by the electric discharge were determined to calculate the radius of effective selective influence on the studied waste samples of flotation beneficiation of copper-zinc ores. The necessary conditions for the effective operation of the technological part of the equipment are established: in the volume of the disintegrator, the pressure, created by the electric discharge, should not be less than the tensile strength of the processed material and at the same time should not exceed the strength of the disintegrator’s material. The use of the electric discharge method ensures the selectivity of disintegration of the material along the interphase boundary "dead rock - mineral inclusion", this circumstance allows to achieve a significant increase in the amount of mined valuable metals and simultaneously reduction of energy consumption by 2 - 4 times. Increasing energy efficiency is considered by the way of example with copper-zinc ore concentration’s waste. The increase in the number of target metals available in wastes of flotation concentration of copper-zinc ore after their electric discharge treatment is shown. The increase in the amount of copper extracted from copper-zinc ore enrichment waste was from 40 to 93% by mass, extracted zinc - from 39 to 94% by mass, silver extracted - from 16 to 50% by mass.

The use of machine learning methods to predict the processes and results of high-voltage electric discharge processing of titanium powder in kerosene with the implementation of volume-distributed multi-spark discharge

The possibility of using machine learning methods to predict the results of high-voltage electric discharge treatment of titanium powder in a hydrocarbon liquid is studied. Distribution surfaces for the average particle diameter of Titanium powder. The amount of Titanium carbide formed during processing, and the number of spherical particles of titanium powder depending on the interelectrode gap and the number of pulses, when using volume-distributed multi-spark discharge and with Titanium powder concentration in kerosene of 0.07 kg / dm3, pulse repetition frequency 0.3 Hz and the energy of single discharge of 1 kJ, were obtained.

Study on the effect of electric pulse treatment for disinfestation of vegetables

This paper describes a method of using pulsed discharge to control nematode diseases on tomato and cucumber rhizomes and crops grown in dacha plots. When pulsed discharges are applied to living tissue, certain chemical, physical, and biological processes occur, depending on the pulse energy, pulse discharge current, pulse discharge voltage, pulse discharge exposure time, pulse discharge impact current, and other similar factors. Electric pulses were applied to grafts of nematode-infested vegetables, tomatoes and cucumbers, to measure grafting ability. Crop yields were estimated by the total amount of produce grown on arable land, and the level of yield enhancement was determined by land sedimentation and proper placement of varieties and plant species. Proper selection of modern high-yielding varieties imported from Uzbekistan provides resistance to external adverse effects of nature and diseases. The creation of high-yielding varieties requires the discovery and cultivation of resistant hybrid varieties and the development and introduction of new progressive technological methods of plant cultivation. The objective of this study was to identify the main factors affecting the electric pulse discharge treatment of tomato and cucumber root crops infected with nematodes and their larvae. Various diseases occur in cotton, cereals, melons, vegetable crops, and indoors(greenhouses) on newly established farms in the Republic. Yields are particularly high in vegetable, melon, and greenhouse fields. In recent years, the impact of nematodes on plants has caused severe damage to crop yields. Treating crops with this formulation prevents nematode infestation of leaf veins. The economic damage caused by nematodes to agriculture is enormous. For example, in greenhouse vegetables (cucumbers and tomatoes) this indicator reaches 60% and in potatoes 80%. Therefore, the proposed method is realized in combination with an agrotechnical treatment process that is energy-saving, environmentally safe, and productive.

Intensification of the Processes of Extraction of Humic Acids from Biosubstrates under the Action of Electric Discharges

The article deals with the study of factors participating in the extraction of humic acids from plant substrates under the action of electric discharges. Using the example of the electric discharge treat-ment of the peat-water suspension, it was demonstrated that the main factor affecting the intensity of extraction is the degree of the solid phase of the biosubstrate-water suspension grinding, which depends on the pressure amplitude at a distance of the inner radius of the chamber and the number of discharge pulses. Experimental studies have shown that the amount of chemical reagents (alkalis) commonly used in the extraction of humic acids from peat can be significantly reduced due to the appearance of radicals and peroxide compounds in the peat-water suspension during the ac-tion of an electric discharge. The perspectives of a non-thermal electric discharge meth-od for intensifying the extraction of humic acids from biosubstrates are determined.

Electrochemical multi-sensors obtained by applying an electric discharge treatment to 3D-printed poly(lactic acid)

Electrochemical sensors for real-time detection of several bioanalytes have been prepared by additive manufacturing, shaping non-conductive poly(lactic acid) (PLA) filaments, and applying a physical treatment to create excited species. The latter process, which consists of the application of power discharge of 100 W during 2 min in a chamber at a low pressure of O2, converts electrochemically inert PLA into an electrochemically responsive material. The electric discharge caused the oxidation of the PLA surface as evidenced by the increment in the quantity of oxygenated species detected by FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS). Indeed, changes in the surface chemical composition became more pronounced with increasing O2 pressure. After demonstrating the performance of the chemically modified material as individual dopamine and glucose sensors, multiplexed detection has been achieved by measuring simultaneously the two voltammetric signals. This has been performed by collecting the signals in two different regions, a naked chemically modified PLA for dopamine detection and a chemically modified PLA region functionalized with Glucose Oxidase. These outcomes led to define a new paradigm for manufacturing electrodes for electrochemical sensors based on 3D printing without using conducting materials at any stage of the process.

Synthesis of Decorated Carbon Structures with Encapsulated Components by Low-Voltage Electric Discharge Treatment

Polycondensation of complexes of chloromethanes with triphenylphosphine by the action of low-voltage electric discharges in the liquid phase gives nanosized solid products. The elemental composition involving the generation of element distribution maps (scanning electron microscopy–energy dispersive X‑ray spectroscopy mapping) and the component composition (by direct evolved gas analysis–mass spectrometry) of the solid products have been studied. The elemental and component compositions of the result-ing structures vary widely depending on the chlorine content in the substrate and on the amount of triphenylphosphine taken. Thermal desorption analysis revealed abnormal behavior of HCl and benzene present in the solid products. In thermal desorption spectra, these components appear at an uncharacteristically high temperature. The observed anomaly in the behavior of HCl is due to HCl binding into a complex of the solid anion {text{HCl}}_{2}^{ - } with triphenyl(chloromethyl)phosphonium chloride, which requires a relatively high temperature (up to 800 K) to decompose. The abnormal behavior of benzene is associated with its encapsulated state in nanostructures. The appearance of benzene begins at 650 K and continues up to temperatures above 1300 K.

Plasma assisted synthesis of cobalt-doped ZnO nanoparticles in liquid

Cobalt-doped ZnO nanoparticles were synthesized by electrical discharge treatment of a mixture of metallic zinc and cobalt micropowders (with Co atomic concentration of 10%) in distilled water. The results of the characterization of inner structure, phase composition and morphology of the prepared samples performed by means of TEM, XRD, FTIR and UV–Vis spectroscopy proved the formation of near-spherical doped ZnO:Co nanocrystals under the found optimized experimental conditions. The band gap of the Co-doped ZnO nanoparticles was estimated to be 2.88 eV in comparison to the pure ZnO – 3.28 eV. The broad luminescence band associated with the formation of defect levels in Co-doped ZnO was observed the range from 450 nm to 750 nm. The prepared Co-doped ZnO nanocrystals exhibited ferromagnetic behavior at room temperature that can be useful for their application in spintronics.

Effect of high-voltage electrical discharge treatment on multi-element content in cocoa shell and chocolates with cocoa shell

Cocoa shell is rich in bioactive components, but also contains significant amounts of micro and macro elements, but also toxic elements. In this study, we examined the contents of different elements in cocoa shell, cocoa mass and the effect of high voltage electrical discharge (HVED) on the contents of these elements in the cocoa shell. Also, dark and milk chocolates were produced with different contents of untreated and HVED treated cocoa shell for which was also conducted ICP-MS analysis of these elements. HVED treatment caused a decrease in potassium, cadmium, uranium, cobalt, nickel, iron, molybdenum, chromium, manganese and copper content. The analysis also showed that the contents of some elements were higher after HVED treatment, and the largest increase was observed for calcium. All chocolates produced with treated and untreated cocoa shells had the contents of toxic elements in a range already reported in the literature. After the addition of cocoa shell in chocolate, contents of iron and cobalt were higher than reported in the literature. This presents that, generally, chocolates with added cocoa shell could be safe for human consumption but there are also some opened questions about HVED's influence on these metals that need to be answered.

Application of High Voltage Electrical Discharge Treatment to Improve Wheat Germination and Early Growth under Drought and Salinity Conditions.

The environmentally friendly, physical method of high voltage electrical discharge (HVED) was developed to improve the drought and salinity tolerance of two wheat genotypes. Unlike other plasma technologies, HVED treatment involves the discharge of electricity in water. In this study, the effect of HVED pretreatment on wheat germination and early vegetative growth under drought (0%, 15%, 20% and 30% PEG) and salinity (0, 90, 160 and 230 mM NaCl) stress conditions was investigated. HVED-exposed seeds showed altered seed surfaces and became more permeable to water uptake, resulting in higher germination percentages, germination index values, and shoot and root growth under the control and all drought and salinity concentrations. Moreover, the electrical conductivity of the water medium increased significantly, indicating HVED-induced reactions of ionization and dissociations of water molecules occurred. In addition, HVED pretreatment in the salt experiment improved the tolerance index values of the shoots and roots. The most pronounced genotypic variations occurred under the highest stress levels (30% PEG or 230 mM NaCl) and varied with the stress intensity and growth stage. The study results indicate that HVED pretreatment has the potential to improve drought and salt tolerance in wheat.

Development of a new diamond-like carbon surface treatment method with electric discharge for short running-in and friction reduction

The present paper proposes a new treatment method for diamond-like carbon (DLC) coatings using electric discharge. DLC coatings exhibit excellent mechanical and tribological properties due to their unique carbonaceous structure. Several surface treatment methods were presented to achieve short running-in and low friction. However, in-situ surface treatment is needed to extend the life of machines and maintain their performance. Here, we propose an electric discharge treatment with a simple electrical circuit. As a result, the friction coefficient drastically drops from 0.3 to 0.11. Interestingly, the drop starts shortly after the discharge starts. Consequently, the running-in is shortened to about 6-m sliding compared to no discharge condition, which does not show any running-in more than 68-m sliding. Raman analysis reveals that a transfer layer on the ball surface is composed of carbonaceous material and the structure exhibits graphite-like characteristics. However, there is visible damage on the DLC surface. Another friction test shows a very low friction coefficient of 0.04 using a transfer layer-covered ball and a new DLC disk with a smooth surface. In conclusion, the combination of a transfer layer and smooth DLC surface is needed to exhibit excellent tribological performance, indicating the importance of less damage treatment. Next, pulse discharge treatment is demonstrated to achieve less damage to the DLC coating. As a result, the pulse discharge method reduces friction and surface damage. In conclusion, the proposed treatment methods using electric discharge not only show the potential for reducing friction, but also the feasibility of in-situ treatment during machine operation.

Exposure of starch to combined physical treatments based on corona electrical discharges and ionizing radiation. Impact on physicochemical properties

The paper deals with the investigation of the effects of corona electrical discharge (CED) treatment in conjunction with electron beam irradiation (EBI) on starch physicochemical properties. Acidity, paste clarity, gel consistency, apparent and intrinsic viscosities of corn starch subjected to the combined treatments were investigated and compared to the corresponding single treatment. The findings showed that the combined treatments based on CED and EBI, respectively, are able to modify the technological properties of starch, depending on the application sequence of CED, as a consequence of the degradation phenomenon. The degradation rate constant proved clearly that the combined CED/EBI treatment had the greatest efficiency in the changing of starch properties among all studied treatments. Also, this study revealed that the use of CED as a pre-treatment to EBI of starch can reduce the minimum irradiation dose required for certain industrial application by influencing more the sensitivity of starch to radiation.

Deposition of tantalum carbide on Ti6Al4V alloy by electric discharge treatment

Titanium alloys attract wide attention of researchers due to the unique combination of low density, high strength, corrosion resistance, biocompatibility, etc. Therefore, the study of new methods for processing titanium and the creation of protective coatings seems relevant. Metal-ceramic coatings were obtained by electrospark treatment of a titanium alloy Ti6Al4V in a mixture of titanium granules with tantalum carbide powder. Three mixtures of granules were prepared with a TaC content of 2.4; 4.6 and 6.7 vol.%. Coatings were deposited by rectangular pulses with an energy of 0.33 J and a frequency of 1 kHz for 8 minutes in an argon stream. The increase of the volume fraction of tantalum carbide powder in the mixture of granules from 2.4 to 6.7 vol.% does not lead to a significant increase in cathode gain. The average coating thickness ranged from 29 to 36 microns. Using scanning microscopy and energy dispersive analysis methods, it was found that the coating structure is represented by a metal Ti – Ta – C matrix with large ceramic grains. According to x-ray phase analysis, it was found that tantalum carbide TaC prevails in the coating composition. It content increases with increasing powder concentration in the mixture of granules. In addition to it, there are phases of titanium carbide and tantalum subcarbibide TaC0.6, which are the products of TaC decarburization during its interaction with the titanium melt. With an increase of the tantalum carbide concentration in the mixture of granules, the hardness of TaC/Ti coatings increased from 6.1 to 8.9 GPa, which is 2–3 times higher than that of the Ti6Al4V alloy. Coefficient of friction of coatings was in the range of 0.5–0.9. Dry sliding wear tests showed that TaC/Ti coatings had a wear rate ranging from 0.1·10–5 mm3/Nm to 1.7·10–5 mm3/Nm. Thus, the use of these coatings makes it possible to increase the wear resistance of the Ti6Al4V alloy up to 128 times.

TiO2 nanoparticle deposition on cotton fabric through pulsed electrical current in water/TiO2 solution

The present paper investigates TiO2 nanoparticle (TiO2-NP) deposition on cotton fabric through a pulsed electrical current in a water/TiO2-NP solution. The experiments used short voltage pulses with an amplitude around 1200 V, an intermediate value between those used in electrophoretic deposition (tens of V) and plasma discharge in liquids (tens of thousands of V). A sequence of pulse trains with five pulses of 1.0 μs delivered electrical energy to the mixture. The electrodes were kept 28 mm apart. An asymmetry appeared in the current waveform when the medium contained TiO2-NPs. The pieces of cotton fabric were characterized using X-ray Photoelectron Spectroscopy (XPS), X-Ray Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR). The electrical discharge treatment increased the Ti concentration on the fabric surface by as much as 6% according to XPS analysis. XRD analysis confirmed the XPS results for treated samples, indicating the presence of anatase TiO2. In the FTIR analysis, a shoulder at 800 cm−1 was observed and can be associated with coordination interactions between Ti and the OH groups of glucose. The nanoparticle adhesion was verified by observing the cotton fabric surface through field emission gun scanning electron microscopy after multiple washes. Even after 20 washing cycles, there was a considerable amount of nanoparticles on the sample surface.

Starches Modified by Combination of Phosphorylation and High-Voltage Electrical Discharge (HVED) Treatment

Starches Modified by Combination of Phosphorylation and High-Voltage Electrical Discharge (HVED) Treatment

Theoretical substantiation of the influence of electric pulse processing on the process of obtaining juice from grapes and fruits

The article presents the theoretical basis of the effect of electrical pulse processing on the process of obtaining juice from grapes and fruits. High-voltage pulsed electrical processing technology for biological products has a higher damaging effect on living cells than other electrical effects, and this can be achieved due to the passage of large discharges of current through tissues and cells in a short period of time. It has been found that high efficiency in killing living cells by secretion can be achieved as a result of a pulsed energy effect. In order to develop energy-efficient electrical technology for extracting juice from fruits and grapes, it has been found that high-voltage electric pulse discharge treatment of grapes and apples before extracting juice has a good effect. Analytical expressions between electrical impulse processing parameters (pulse energy and capacitor capacity) and juice output were determined. The degree of damage to fruit and grape cells depends on the capacitance of the capacitor, the discharge voltage, and the number of pulses.

Free radical detection in water after processing by means of high voltage electrical discharges and high power ultrasound

Nonthermal processing technologies have been researched in lab scale for more than 15 years. In this study, the influence of sonification and high voltage electrical discharge—plasma treatment of water on the formation and stabilization of hydroxyl radicals has been investigated by electron paramagnetic resonance (EPR) spectroscopy and spin-trapping method. As analysis tool, an agglomerative hierarchical clustering was used in grouping samples recorded by EPR and near infrared spectroscopy (NIR) spectroscopy. Also, the multivariate analysis was performed using the principal component analysis (PCA) and Principal Regression models (PCR). Results for ultrasound-treated samples showed that number of radicals is increasing with treatment time and increase in amplitude. High-voltage electrical discharge treatment at 120 Hz resulted in the formation of the largest number of hydroxyl radicals. Developed PCR models are highly effective in prediction of NIR spectra, regardless the sample treatment what is an additional step forward in green technology. Practical applications Usage of electron paramagnetic resonance measurement can be used in laboratory and scale-up treatments by nonthermal processing. It is of outmost importance to monitor the production of free radicals, from starting of processing, in order to avoid overtreatment of foods and to avoid possible oxidation and unwanted radical chain reactions. Monitoring of processing can be used to optimize nonthermal processing and to avoid production of unwanted oxidative products and compounds.

Surface alteration of biomedical alloys by electrical discharge treatment for enhancing the electrochemical corrosion, tribological and biological performances

In the current research, the electrical discharge treated (EDT) biomedical alloys substrates such as cobalt-chromium (F90), stainless steel (316L) and titanium (Beta type) have been investigated for their in-vitro biocompatibility, corrosion resistance and tribological performance. The alloys substrates were machined by copper tungsten tool electrode in a deionized water tank at 10A current, 200μs pulse on-time, 60μs pulse off-time. To examine the corrosion rate of the substrates, the electrochemical potentiodynamic test was executed in which Tafel slopes were designed. Further, cytocompatibility and hemocompatibility tests were performed on the substrates to study the in-vitro biocompatibility. Moreover, the tribological characteristics such as wear rate and coefficient of friction were investigated on a pin-on-disc tribometer. The results revealed that the modification of the substrate was perceived to be effective in increasing the corrosion resistance of cobalt-chromium alloy, titanium alloy and stainless steel alloy by 86.39%, 62.15% and 56.21%, respectively in comparison to the unmachined substrates. Similarly, the tribological results exhibited that the altered substrates have improved friction-reducing characteristics and higher wear-resistance. The cytocompatibility and hemocompatibility outcomes validating the higher %cell viability and low RBC-lysis on treated substrates. The existence of titanium carbide (TiC), niobium carbide (NbC) and tungsten carbide (WC) phases on EDT substrates were detected from X-ray diffraction examination favors the synthesis of the hard and wear-resistant surface. Although, the formation of oxides, nitrides and phosphides during the EDT process lead to developing bio-inert surfaces and also ameliorates the corrosion resistance of the alloy. However, the F-90 cobalt-chromium alloy substrate showed improved corrosion, wear and biocompatibility responses as compared to titanium and stainless steel alloy. Therefore, the metallurgical alteration during EDT and the inherent bulk properties of base alloy contributed towards its biocompatibility and surface properties. These results promote the EDT biomedical alloys in bulk in the biomedical field.

ELECTROPHYSICAL CHARACTERISTICS OF THE COAL ASH OF THE MAYKUBEN BASIN

In this work, the temperature dependences of the electrophysical characteristics (electrical capacitance, electrical resistance, dielectric permittivity) were investigated in the range of 293-483 K for coal ash of the Maikuben basin (Kazakhstan) in its initial form, after electromagnetic (EM) and electrical discharge (ED) treatments. The temperature ranges in which the material exhibits both semiconductor properties and metallic conductivity are established. The band gap width (ΔE) was calculated for the studied samples. The measurement results showed that in comparison with the initial ash and ash after the EM treatment, the ash after the ED treatment has the highest values of electrical capacitance and dielectric permittivity and the lowest electrical resistance. Analysis of the research results showed that coal ash after ED treatment seems promising as a prepared raw material for its further thermochemical processing with the extraction of such valuable components as rare metals, silica, alumina, as well as a capacitive material (capacitor) and semiconductor.