Steel Mesh Electrodes Research Articles

Removal of Freshwater Microalgae by Flocculation-Enhanced Electro-flotation Using Stainless Steel Mesh Electrode

This study was conducted to explore the possibility of increasing the efficiency of electro-flotation in two ways: (1) by using an appropriate electrode capable of generating more microbubbles and (2) by introducing flocculation. The generation of more microbubbles was achieved by using an electrode with higher surface area. To further increase the removal efficiency, two inorganic $$[\hbox {Al}_{2}(\hbox {SO}_{4})_{3}$$ and $$\hbox {Fe}_{2}(\hbox {SO}_{4})_{3}]$$ and two polymer coagulants (PAC and polymer anion) were used as enhancements to electro-flotation. The results showed that 3 out of the 4 coagulants used have the capacity to remove 95% of microalgae in 1 L of suspension by using electro-flotation. By retrofitting flocculation into electro-flotation, the coagulant dose was significantly decreased in comparison with conventional flocculation process. Moreover, 95% removal of microalgae suspension from local eutrophic river (Nakdong river) was achieved also with PAC by enhanced electro-flotation. The results of this study also showed that the current method tremendously decreased the coagulant consumption as compared to other removal methods such as flocculation and flotation by DAF as mentioned in the later section of this study. Hence, it is an economical microalgae removal method and at the same time an efficient way to reduce water contamination due to excessive doses of coagulant.

Optimization of parameters of electrocoagulation/flotation process for removal of Acid Red 14 with mesh stainless steel electrodes

Abstract Dyes are persistent compounds that are not easily biodegraded and are considered as carcinogenic. Electro-coagulation and electro-flotation method, due to its adaptability and compatibility with the environment, is regarded as one of the appropriate methods for the treatment of industrial wastewater containing dye. In this study in which stainless steel mesh electrodes with a horizontal arrangement are used, the most important parameters affecting the performance of the simultaneous system of electro-coagulation and electro-flotation, including electrodes area, of distance between electrodes, electrical conductivity of the solution, type of electrolyte, and initial pH were examined. The effect of every one of these parameters in color removal efficiency of Acid Red 14 from artificial wastewater, energy consumption and anode was determined and their values were optimized. The area of the electrode equals 20.5 cm2, the distance between the electrodes is 0.5 cm, electrical conductivity 3,600 μS/cm, and initial pH 7 were selected as the optimum values, and dye removal efficiency of 99% with initial concentration of 150 mg/L and electric current density 40 mA/cm2 (0.8 A) were obtained under optimum conditions and within 20 minutes. The advantages of this method are low energy and material consumption, and low sludge production.

Investigation and improvement of a novel double-working-electrode electrochemical system for organic matter treatment from high-salinity wastewater

ABSTRACTThe novel double-working-electrode electrochemical system with air diffusion cathode (ADC) and Ti/SnO2-Sb anode (TSSA) has shown higher efficiency and lower energy consumption for the degradation of organic pollutant from high-salinity wastewater, compared to the traditional single anode system. To further investigate and improve this system, in this work, firstly the effect of vital factors of the double-working-electrode electrochemical system including initial methyl orange (MO) concentration, NaCl concentration and initial pH value of organic solution were investigated, using MO as the targeted organic pollutant, carbon black ADC (CBAC) as cathode and stainless steel mesh electrode (SSME) as control. Besides, for the further improvement of removal performance, a novel home-made activated carbon-ADC (ACAC) was studied as cathode with the same investigation process. The results showed that, in the experiments studying the effect of both initial MO and NaCl concentrations, the removal performance was in the order of TSSA-ACAC > TSSA-CBAC > TSSA-SSME in all conditions of initial MO and NaCl concentrations. However, with the pH value reduced from 6.0 to 3.0, the performances of three systems turned to be much closer to each other. Besides, ACAC played a synergistic role in MO removal by greatly improving the MO removal performance and enhancing its adaptability to the reactor parametric variation. ACAC created a weak acidic environment for accelerating the indirect electro-oxidation of MO on TSSA. The MO degradation pathways in the three systems were the same but the TSSA-ACAC system gave a higher degradation kinetics order.

Elimination of pathogenic bacteria using electrochemical process containing steel mesh electrode

The main objective of this study is removal of pathogenic bacteria using electrochemical process. The bactericidal effects of electrochemical system containing steel mesh electrode were evaluated from contaminated water with E. coli, Pseudomonas aeroginosa, Staphylococcus aureous and Streptococcus fecalis at various concentrations. Effect of current density, supporting electrolyte and pathogenic bacterial concentration were studied and kinetic rate of disinfection were determined. The obtained results show, the effect of current density on disinfection efficiency was highest and then concentration of bacteria in the contaminated water and supporting electrolyte concentrations in the electrolyte have more effective. Contaminated water including 100 and 1000 bacteria/ml of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and streptococcus faecalis, compeletly disinfected using 0.088 mA/cm2 current during 5 to 60 min. The reaction rate of disinfection is directly related to current density. It is expected that experimental results could be used as a reference for the elimination of pathogenic bacteria using electrochemical process.

Characteristics of Carbon Nanotubes/Graphene Coatings on Stainless Steel Meshes Used as Electrodes for Air-Cathode Microbial Fuel Cells

Microbial fuel cells (MFCs) generate low-pollution power by feeding organic matter to bacteria; MFC applications have become crucial for energy recovery and environmental protection. The electrode materials of any MFC affect its power generation capacity. In this research, nine single-chamber MFCs with various electrode configurations were investigated and compared with each other. A fabrication process for carbon-based electrode coatings was proposed, and Escherichia coli HB101 was used in the studied MFC system. The results show that applying a coat of either graphene or carbon nanotubes (CNTs) to a stainless steel mesh electrode can improve the power density and reduce the internal resistance of an MFC system. Using the proposed surface modification method, CNTs and graphene used for anodic and cathodic modification can increase power generation by approximately 3–7 and 1.5–4.5 times, respectively. Remarkably, compared to a standard MFC with an untreated anode, the internal resistances of MFCs with CNTs- and graphene-modified anodes were reduced to 18 and 30% of standard internal resistance. Measurements of the nine systems we studied clearly presented the performance levels of CNTs and graphene applied as surface modification of stainless steel mesh electrodes.

Removing heavy metals by electrocoagulation using stainless steel mesh electrodes: a study of wastewater from soil treated with metallurgical residues: a study of wastewater from soil treated with metallurgical residues

The present work aims to study the possibility of zinc, cadmium and manganese removal from synthetic solutions simulating wastewater from washing soil by electrocoagulation process using stainless steel mesh electrodes. The influences of current density (from 10 to 40 mA cm-2), time (20 and 40 minutes) and pH (4 to 10) on removal efficiency were explored in a batch cell to determine the best experimental conditions. Under the operating conditions tested, the best result was observed at pH = 10, corresponding about 90% of heavy metals removal from solutions initially containing 15 mg dm-3 of each metal, with a power consumption of 9 kW h m-3. There are few published studies using stainless steel electrodes for the treatment of mixed heavy metals and this study newly indicated that the proposed method is adequate to remove the common heavy metals found in wastewater from heavy metals polluted soil.

Decolorization of methylene blue by the electro-Fenton process using stainless steel mesh electrodes

Aim: In this study, the decolorization of methylene blue (MB) by the electro-Fenton process using stainless steel (SS) mesh electrodes was examined. Materials and Methods: The effects of initial dye concentration, pH, and ratio of Fe: H 2 O 2 , current density, and type of electrode were studied. The kinetics of the reactions was also studied. Results: The highest removal rate 99%was obtained at pH 3 within 20 min. Kinetics experiment studies showed that removal of dye was faster at lower initial dye concentrations. The results revealed that color removal was highest at a Fe 2+ :H 2 O 2 ratio of 1:4. An increase in current density resulted in an increase in oxidation rate and faster removal of color. The results demonstrated that increasing the size of the mesh pores led to an increase in the percentage of dye removal. The highest removal percentage (94.5%) was observed in 25 min with a mesh 2 electrode. The constant rate of dye removal on steel mesh 2 was 6.6 times higher than a steel plate. Energy consumed in this state was = 1.6 kWh/m 3 , compared to 2.6 kWh/m 3 under other conditions. Conclusion: Using SS mesh electrodes was very effective in color removal for MB under optimal conditions. The present study showed that increasing the steel mesh size improved the conditions for color removal and reduced the energy consumption. Therefore, it is suggested that steel mesh be used as an electrode for electrochemical processes.

RuO2/MWCNT/ stainless steel mesh as a novel positive electrode in vanadium redox flow batteries

The present work describes the preparation and electrochemical characterization of RuO2/MWCNT/Stainless Steel Mesh (SSM) electrode as compared with a MWCNT/SSM electrode in the positive half-cell of a Vanadium Redox Flow Battery (VRFB).

Study of electroflotation method for treatment of wastewater from washing soil contaminated by heavy metals

Electroflotation method (EFM) for treatment of synthetic solutions simulating wastewater from washing soil contaminated by drilling fluids from oil wells was investigated in this paper. Experiments were carried out to examine the effects of the operating conditions on the removal of lead, barium and zinc from solutions containing 15mgdm−3 for each metal representing a typical concentration of wastewater generated in the washing soil in this treatment. The experimental results showed that it is possible to remove these heavy metals by electrocoagulation/electroflotation (ECF) attaining 97% of removal using stainless steel mesh electrodes with a power consumption of 14kWhm−3. The optimal conditions of treatment were sodium dodecyl sulfate (SDS) in a molar ratio 3:1, current density around 350Am−2, ionic strength 3.2×10−3M, pH=10.0 and 20min of ECF. This study newly indicated that the proposed method is adequate to simultaneously treat the common heavy metals found in the drilling fluids oil wells.

Upflow fixed bed bioelectrochemical reactor for wastewater treatment applications

A cylindrical Upflow Fixed Bed Reactor (UFB-BER) with granular activated carbon, steel mesh electrodes and anaerobic microorganisms, was constructed for analyzing how hydrodynamic parameters affect the reactions involved during wastewater treatment processes for azo dye degradation. Dye removal percentage was not compromised by decreasing HRTm (99–90% upon changing HRTm from 4 to 1h in single pass mode). Using the residence time distribution method for hydrodynamic characterization, it was found that a higher dispersion in the reactor occurs for HRTm=1h, than for HRTm=4h. A kinetic analysis suggests that this dispersion effect could be associated to a higher specific reaction rate dependent on the azo dye concentration.

Carbon nanotube-coated stainless steel mesh for enhanced oxygen reduction in biocathode microbial fuel cells

A novel carbon nanotubes (CNTs) coated stainless steel mesh (SSM) electrode has been fabricated by a simple and scalable process and is used as biocathode in microbial fuel cell (MFC) for performance improvement. Examination by scanning electron microscope shows that CNTs are uniformly distributed over the surface of the SSM, thus forming a three-dimensional network structure. The MFC with CNT-SSM biocathode achieves higher maximum power density (147 mW m−2), which is 49 times larger than that (3 mW m−2) produced from the MFC with bare SSM biocathode. Moreover, cyclic voltammetry shows that the microorganisms on the CNTs-SSM biocathode play a major role in oxygen reduction reaction (ORR), and the CNT-SSM biocathode performes better catalytic activity toward ORR than that of SSM biocathode. Additionally, the MFC with CNTs-SSM biocathode has higher Coulombic Efficiency than that of MFC with bare SSM biocathode. In this study, we demonstrate that the use of CNTs-SSM offers an effective mean to enhance the electricity of biocathode MFCs.

Assessment of four different cathode materials at different initial pHs using unbuffered catholytes in microbial electrolysis cells

Nickel foam (NF), stainless steel wool (SSW), platinum coated stainless steel mesh (Pt), and molybdenum disulfide coated stainless steel mesh (MoS2) electrodes have been proposed as catalysts for hydrogen gas production, but previous tests have primarily examined their performance in well buffered solutions. These materials were compared using two-chamber microbial electrolysis cells (MECs), and linear sweep voltammetry (LSV) in unbuffered saline solutions at two different initial pHs (7 and 12). There was generally no appreciable effect of initial pH on production rates or total gas production. NF produced hydrogen gas at a rate of 1.1 m3 H2/m3·d, which was only slightly less than that using Pt (1.4 m3 H2/m3·d), but larger than that obtained with SSW (0.52 m3 H2/m3·d) or MoS2 (0.67 m3 H2/m3·d). Overall hydrogen gas recoveries with SSW (29.7 ± 0.5 mL), MoS2 (28.6 ± 1.3 mL) and NF (32.4 ± 2 mL) were only slightly less than that of Pt (37.9 ± 0.5 mL). Total energy recoveries, based on the gas produced versus electrical energy input, ranged from 0.75 ± 0.02 for Pt, to 0.55 ± 0.02 for SSW. An LSV analysis showed no effect of pH for NF and Pt, but overpotentials were reduced for MoS2 and SSW by using an initial lower pH. At cathode potentials more negative than −0.85 V (vs Ag/AgCl), NF had lower overpotentials than the MoS2. These results provide the first assessment of these materials under practical conditions of high pH in unbuffered saline catholytes, and position NF as the most promising inexpensive alternative to Pt.

Influence of Atmospheric Pressure Torch Plasma Irradiation on Plant Growth

ABSTRACTGrowth enhancement characteristics of plants are investigated using an atmospheric discharge plasma. Atmospheric pressure plasma torch is consisted of alumina ceramics tube and the steel mesh electrodes wound inside and outside of the tube. The growth enhancement was observed in the length of stem and root of plants after the plasma irradiation to seeds. The stem length increases approximately 2.8 times after the cultivation time of 24 h. And the effect is found to be maintained for 40 h, after sowing seeds. The mechanism of the growth enhancement would be the redox reaction inside plant cells induced by oxygen radicals.

Electrical and optical studies of flexible stainless steel mesh electrodes for dye sensitized solar cells

Stainless steel (SS) mesh was used to fabricate anodes for flexible dye sensitized solar cells (DSSC) in order to evaluate them as replacements for more expensive Transparent Conductor Oxides (TCO's). SS mesh performance was analyzed and it was determined that oxidation of SS during the sintering of titania particles affects the transport and interface resistance of the device. Thus a thin layer of non-porous titania coating was added onto the mesh to protect the electrode from oxidation. Comparing with Fluorine doped Tin Oxide (FTO), SS mesh was found to have higher interface resistance but the overall series resistance was lower due to higher conductivity of metals. The effects of SS mesh opening size and microstructure on the performance of the device was analyzed and design strategies to obtain high efficiency flexible SS mesh DSSC are provided.

Efficient large volume electroporation of dendritic cells through micrometer scale manipulation of flow in a disposable polymer chip

We present a hybrid chip of polymer and stainless steel designed for high-throughput continuous electroporation of cells in suspension. The chip is constructed with two parallel stainless steel mesh electrodes oriented perpendicular to the liquid flow. The relatively high hydrodynamic resistance of the micrometer sized holes in the meshes compared to the main channel enforces an almost homogeneous flow velocity between the meshes. Thereby, very uniform electroporation of the cells can be accomplished. Successful electroporation of 20 million human dendritic cells with mRNA is demonstrated. The performance of the chip is similar to that of the traditional electroporation cuvette, but without an upper limit on the number of cells to be electroporated. The device is constructed with two female Luer parts and can easily be integrated with other microfluidic components. Furthermore it is fabricated from injection molded polymer parts and commercially available stainless steel mesh, making it suitable for inexpensive mass production.

Removal of Waterborne Particles by Electrofiltration: Pilot-Scale Testing

Theoretical analysis using a trajectory approach indicated that in the presence of an external electric field, charged waterborne particles are subject to an additional migration velocity that increases their deposition on the surface of collectors (e.g., sand filter). Although researchers conducted bench-scale experiments to verify the effectiveness of electrofiltration, few studies have reported on the applications of electrofiltration in larger scale facilities. In this study, a prototype pilot-scale electrofiltration unit, consisting of an acrylic tank (0.3 × 0.3 × 1.2 m) with vertically placed stainless steel mesh electrodes embedded in a sand filter was tested at a local drinking water plant. Presedimentation basin water was used as the influent with a turbidity ranging from 12 to 37 NTU. At an approach velocity of 0.84 mm/s, an electrode voltage at 8 and 12 V increased the particle removal coefficient pC* [defined as −log(Cout/Cin)] to 1.79 and 1.86, respectively, compared to 1.48 when there was no electric field. Reducing the approach velocity from 0.84 to 0.42 mm/s increased pC* from 1.48 to 1.64, when the electrode velocity was 16 V. Repetitive experiments were conducted and the results were in agreement with those calculated by a theoretical trajectory analysis. The electrofiltration process was demonstrated to be more effective for removal of smaller particles (<4 μm), the size range of many waterborne bacteria. A voltage of 8–12 V was shown to be the most cost-effective range, considering both the energy cost and filtration performance. The findings from this pilot-scale study are important for full-scale applications of the electrofiltration technology.

An investigation on pulsed electric fields technology using new treatment chamber design

A pulsed electric field (PEF) system was designed and constructed using modern IGBT technology. The main focus of this work was to design a new PEF treatment chamber that operate at high electric field intensities with limited increase in liquid temperature and limited fouling of electrodes. Four multi-pass treatment chambers were designed consisting of two stainless steel mesh electrodes in each chamber, with the treated fluid flowing through the openings of the mesh electrodes. The two electrodes are electrically isolated from each other by an insulator element designed to form a small orifice where most of the electric field is concentrated. Dielectric breakdown inside the chambers was prevented by removing the electrodes far from the narrow gap. The effect of PEF treatment on the inactivation of gram-negative Escherichia coli ATCC 25922 suspended in simulated milk ultra-filtrate (SMUF) of 100%, 66.67% and 50% w/w was investigated. Treatments with the same electrical input power but with higher electric field strengths provided larger degree of killing. The effect of PEF treatment using suspensions at different flow rates and different pulse frequencies was also investigated. In general, the inactivation rate of E. coli increased with increasing electric field strength, treatment time and processing temperature. More than 6 log reductions in E. coli suspended in SMUF was achieved using electric field intensity in the range of (37.2–49.6 kV/cm) with a treatment temperature not exceeding 38 °C.

Reduction of hexavalent chromium by polypyrrole-modified steel mesh electrode

Adherent polypyrrole (ppy) films were electropolymerized from a para-toluenesulfonic sodium (PTS) solution on stainless steel mesh (SSM). Reduced ppy-modified SSM electrode can transfer Cr(VI) to Cr(III) effectively. Lower pH (<2) or higher temperature (>35 °C) is beneficial for the removal of Cr(VI). Electro-reduction achieved 90% removal efficiency after 21 min by cyclic voltammetry. The removal efficiency is 96–56% for one–six contact cycles between ppy and Cr(VI). SEM shows that ppy films on SSM have regular morphology with small nucleus of less than 1 μm in diameter.

Preparation of YBCO superconducting thick film by electrophoresis

The thick films of YBa 2Cu 3O x (YBCO) superconductor were prepared by electrophoretic deposition, using pre-sintered YBCO powder dispersed in acetone solution. The alumina (Al 2O 3) ceramic plate, coated with Ag, was used as the cathode substrate and the stainless steel mesh electrode was used as the counter electrode in suspension for electrophoresis. The conditions of applied voltages and temperatures, contents of iodine additives, and deposition times for electrophoretic deposition of YBCO thick films were studied in detail. As a result, the optimum value of iodine content in acetone was 200 mg/l, the applied electrical potential for electrophoresis was 200–300 V for 10 mm electrode gap, and the content of YBCO powder was 10–20 g/l in acetone suspension solution. The critical temperature was determined at 91 K by AC susceptibility curve and the critical current density, J c, was measured by a four-point prove method at the value of 700 A/cm 2 deposited on the Ag coated Al 2O 3 substrate and 1456 A/cm 2 deposited on the Ag wire (77 K, 0 T).

Chloride Extraction and Realkalization of Reinforced Concrete Stop Steel Corrosion

Chloride extraction and realkalization are nondestructive, electrochemical treatments to halt and prevent corrosion in chloride-contaminated and carbonated concrete, respectively. The process actually removes chloride ions from the contaminated concrete by the principle of ion migration while at the same time raising the pH of the carbonated concrete through electro-osmosis. Concrete to be treated is first tested to determine the level of chloride contamination. Then, after preparing the surface, a steel or titanium mesh electrode is attached to the structure. The electrode is embedded in a nontoxic biodegradable electrolytic media. Next, electric contacts are established between the attached electrode and the steel reinforcement bars (rebars) inside the concrete. When an electric field is applied, chloride ions migrate away from the rebars and towards the externally attached electrode, eventually ending up in the temporary electrolytic media, which is then discarded. Simultaneously, alkali ions migrate from the electrolyte into the concrete, raising its pH to the original levels. The passivating layer of the rebars is thus reestablished to protect them from corrosion.