Mesh Anode Research Articles

Integrated Autothermal Reformer, Heat Exchanger and Solid Oxide Fuel Cell in Single-Stack for Aircraft Gas-Turbine Applications

To take advantage of carbon-neutral aviation fuels such as synthetic liquified natural gas, aircraft engines must increase their efficiency through novel approaches, such as hybrid electric gas-turbine/solid oxide fuel cells (GT/SOFCs). To date, most hydrocarbon-fueled SOFC stack designs utilize rigid architectures and independent pre-reformers that require complex manifolding and rigid sealing. To enable SOFCs to operate effectively and robustly within an aircraft GT engine flow path upstream of a combustor, our team is developing an innovative integrated SOFC stack with an inline autothermal reformer/heat exchanger (ATR/HX) to provide adequate operating conditions for high-power (W/cm2) performance. The ATR/HX, integrated upstream of the stack, provides preheating of the cathode air through mildly exothermic reforming of the fuel with a bleed of combustor air and recycling of some anode exhaust. The exothermic ATR provides adequate heat to the cathode air to allow intermediate-temperature SOFCs, with either gadolinium-doped ceria (GDC) electrolytes or thin-film yttria-stabilized zirconia (YSZ) electrolytes, to operate on GT compressor outlet temperatures just above 400 °C. To enable rapid thermal response of the integrated ATR/HX/SOFC, the stack design eliminates rigid seals to mitigate the risks of SOFC failure due to thermomechanical stresses. This paper presents the design and preliminary testing of the integrated ATR/HX/SOFC under rapid heating conditions to suggest the potential for SOFCs for next generation hybrid-electric aircraft application.The ATR/HX/SOFC stack design is supported by 441 stainless steel plates with electrochemically etched, air-flow channels through the upstream HX and the SOFC cathode. The plates also include a pocket for the ATR, which consists of a woven metal-mesh with an Al2O3-washcoat supported Pt catalyst that can light off with CH4/bleed air/H2O inlet temperatures of 400 °C. The SOFC membrane electrode assembly (MEA), 10 cm*10 cm with 81 cm2 active cathode area, rest within a frame that supports the MEA as well as a silver mesh cathode collector and a nickel mesh anode current collector. The cell is sealed by compressing a thermiculite seal that extends over the full area of the stack and compresses on the exposed electrolyte area bordering the cathode. Testing at operating temperatures indicated minimal leakage (<1%) from the anode and from the cathode to the external environment. This design, which lacks rigid seals or confinement of the MEA, enables ease of assembly and disassembly and minimizes external stresses on the MEA to enable rapid heating during ATR light-off.Integrated ATR/HX/SOFC stack has been initially incorporated into a low-pressure test facility shown in Figure 1a), which provides steam generation for the ATR inlet and premixing and preheating for the ATR inlet and air-side HX inlet flows. The ATR/HX/SOFC stack is preheated to 400 °C or more to achieve rapid light-off that rapidly preheats the SOFC inlet to desirable temperatures. For a 3-cell ATR/HX/SOFC short stack, light-off test to SOFC operating temperatures of 550 °C for thin-film YSZ-electrolyte MEAs from Elcogen are achieved in < 1 h. Such start-up times are expected to be reduced for larger ATR/HX/SOFC stacks with reduced heat loss per stack volume. Tests to date have only achieved maximum MEA power densities of 0.26 W/cm2 at 0.65 V/cell operating on the ATR outlet. Simulated performance shows pathway to higher power densities > 1.0 W/cm2 with higher temperature operation that will be achieved with coated interconnect materials. Tests to date show that the thin-film YSZ cells avoid cracking after undergoing multiple assembly and disassembly cycles, as well as high-temperature ATR light-off and fuel cell testing. These results indicate that both mechanical and thermal stresses remain sufficiently low to prevent cell cracking throughout start-up, normal operation, and shut-down processes, thus affirming the robustness and reliability of our integrated stack design. Figure 1

Iron Effects in Advanced Alkaline Electrolyzer

Global warming, characterized by an alarming rise in the Earth’s temperature, is one of the serious impacts of industrialization. Transition towards a sustainable future requires the diversification of our energy sources by replacing fossil fuels with renewable energy such as green H2, to lower global CO2 emissions. Alkaline water electrolysis is one of the widely used affordable water splitting techniques that produces hydrogen gas. Since Fe contamination in this system is an unavoidable factor, it is important to understand the optimum Fe concentration for maximum performance. In this work, we are investigating the change in the total cell performance by spiking Fe2+ (0 to 140 ppm) solution at industrial standard conditions (6 M KOH, 80° C).In this work, we are investigating the change in the total cell performance by spiking Fe2+ (0 to 140 ppm) solution at industrial standard conditions (6 M KOH, 80° C). The KOH was purified prior to the experiment making sure the Fe limits are below the ICP-MS detection limit. To fully understand how Fe activates/deactivates the electrode performance, we chose NixCoy(O)OH coated on Ni mesh anode, commercial AWE cathode and Zirfon-220 as separator and performed testing in both 3-electrode set up and zero-gap electrolyzer set up. Our initial results show that, Fe effect on the total cell performance follows a bell curve where the maximum contribution comes from the activation of the anode. It must be noted that by spiking 40 -50 ppm Fe in the electrolyte the total cell potential is reduced by over 1V which is a huge gain. As we spike over 60 ppm the performance starts to go down. This can be explained by the deposition of FeOx on the anode which is a bad OER catalyst in comparison with NixCoy(O)OH. Our anode has a high active surface area from the nano sheet composition along with high conductivity from CoOx. At 20 ppm Fe in the electrolyte, the anode over potential reduced by 49 mV at 10 mA and by ~110mV at 250mA at 80 °C. Unlike bare Ni electrode as cathode, commercial cathodes are very resistant to Fe fouling only leading to a few millivolts of change. It is important to understand that Fe has maximum effect at low temperature, where the total cell potential was reduced by 200mV by adding 40 ppm Fe solution. As we increase the temperature to 80 °C, reaction kinetics gets improved and the optimum Fe concentration for maximum performance decreases.The activation in the anode performance at high Fe concentration has been verified by studying the surface morphology SEM imaging and by taking the EDX analysis. It has been seen that the anode gives maximum performance when we have sites of NixCoyFeO(OH) deposited on the anode catalyst. As our next step, we will be evaluating the changes in the surface morphology of the cathode along with the amount of Fe being deposited at each spiking. This will provide more information on how we should engineer the cell components to achieve the maximum output. Figure 1

Electricity-driven dealkalization of bauxite residue based on thermodynamics, kinetics, and mineral transformation.

High alkalinity content of bauxite residue is a major factor that hinders resource reutilization and pollutes the environment. Although acid neutralization is a direct and effective method, the amount of acid and secondary waste of sodium salt are still difficult problems to solve. Herein, we innovatively integrated an electric field into the acid neutralization dealkalization of bauxite residue and analyzed the dealkalization behavior by thermodynamics, kinetics, and mineral transformation. The results show that the pH of the anode chamber was maintained at the acidic levels of 3-6 after 30min of galvanostatic electrolysis, and bauxite residue can realize dealkalization by acid neutralization. In the anode chamber, Na+ was released into the leachate via the reactions of Na3Al3Si3O12 and the removal of encapsulated soluble alkali. The stainless steel wire mesh anode exhibited its superiority and decreased the Na2O content in bauxite residue from 9.48 to 3.13% through convective mass transfer driven by the electric field and steady-state diffusion under stirring. This research provides a promising method for the electricity-driven dealkalization of bauxite residue, thus facilitating the development of multifield coupling theory and the application of electric fields in the alumina industry.

An innovative electrolytic cation exchange reactor system for cleaner generation of hydrogen gas using ocean water

The study presents a novel integrated three-compartment electrochemical continuous electrodeionization reactor that was constructed in a laboratory environment. In order to extract large amounts of carbon dioxide from naturally occurring oceanwater in the form of bicarbonate and carbonate, it develops a innovative electrolytic cation exchange process. At the same time, it produces hydrogen gas for possible hydrocarbon synthesis. The study employs the Box-Behnken experimental design approach implemented through the Design Expert software to investigate and optimize the performance of electrochemical hydrogen extraction from Ocean water from an integrated reactor. The integrated electrochemical continuous-type electrodeionization reactor comprises two cation-permeable membranes that operate as boundaries between three compartments: a central compartment and electrode compartments that house the cathode and anode, each of which may reverse polarity. These membranes are made of gel polystyrene cross-linked with divinylbenzene, which has acidic properties that allow cation transport while inhibiting anions. The integrated reactor's electrode chambers are enclosed in plexiglass end plates and contain distinct Plexiglass electrode compartments. These compartments have mesh and solid steel anode and cathode electrodes, with an electrode active area of 176.71 cm2. The influence of various factors, such as voltage and electrolyte amount, on the production of hydrogen synthesis is examined. The study results demonstrate a maximum hydrogen production rate of 2.2 mg/min and a hydrogen production efficiency of 7.82%. The lab testing was carried out using experimental equipment to determine viability. The tests included 35-min runs that measured hydrogen generation under various parameters, such as applied voltage, electrolyte concentration, and pH levels. The ocean salt solutions of 0.5M, 1M, and 2M were initially prepared and evaluated for hydrogen generation. Each concentration is assessed at a voltage range of 4–15V, with matching solution pH values ranging from 2 to 7. Optimization studies were conducted to enhance the hydrogen production rate. The results indicate that hydrogen production rises proportionally with applied voltage and electrolyte concentration but falls with pH growth. Within the Design Expert software, the statistical methods for response surface analysis and optimization are utilized accordingly.

Realizing fast plating/stripping of high-performance Zn metal anode with a low Zn loading

Zn metal batteries and capacitors (ZMBs/ZMCs) are gaining significant attention due to their low cost, high safety, and high theoretical capacity. However, the low utilization of Zn metal decreases the coulombic efficiency. Here, we present a novel approach to enhance the conductivity of host materials by utilizing a 3D conductive structural network of copper mesh. The 3D copper mesh serves as a high-conductive matrix and additionally coating it with Zn serves as a Zn source. Finally, a flexible reduced graphene oxide (rGO) was deposited on the Zn-coated copper mesh as an anode protective layer. The conductive copper mesh renders a fast plating/stripping of Zn and enables more contact of Zn with the electrolyte. The flexible rGO film deposited on Zn-coated copper mesh alleviates the local charge accumulation and inhibits corrosion. As a result, the Zn-coated copper mesh anode modified with rGO (RCZ) exhibited a longer lifespan of 200 h than the Zn-coated planar copper foil anode which cycled only for 30 h. The RCZ||AC full capacitor obtained high capacity retention of 97.9% after 9000 times cycling. The RCZ anode integrates the merits of 3D structure matrix and rGO realizing a dual-functionalized Zn metal anode. The conductive matrix strategy sheds light on other metal batteries.

Development of a novel and specialised cementitious matrix overlay for anode embedment in impressed current cathodic protection (ICCP) systems for reinforced concrete bridges

Impressed Current Cathodic Protection (ICCP) is a widely utilised method for safeguarding reinforced concrete (RC) structures, including bridges, in marine environments. However, certain ICCP systems encounter degradation of the backfill mortar caused by acid formation at the anode. The acid produced reacts with the anode backfill mortar, compromising the functioning of the cathodic protection system. Rectifying the acidification issue typically involves replacing the backfill mortar and, in some cases, even the anode when it is negatively impacted by acid attack. This paper presents, for the first time, a specialised sustainable cementitious matrix that exhibits excellent acid resistance, intended for use as the anode's backfill material in ICCP systems. The proposed mortar effectively mitigates the effects of acidification around the anode, significantly enhancing the durability of the mortar and, consequently, the service life of bridges equipped with ICCP systems. The mechanical and durability performance of the mortar in an acidic environment is evaluated through various tests, including gravimetric analysis, dimensional changes, diffusion depth, compressive strength, direct tension, slant shear, impact resistance, and interface integrity assessments. Additionally, scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques are employed to investigate the material's performance. Subsequently, the specialised mortar is applied to cover Mixed Metal Oxide (MMO) activated titanium mesh anodes of the ICCP system in a reinforced concrete bridge, while its performance is continuously monitored. The results demonstrate that the proposed mortar effectively eliminates acidification issues and improves the performance and longevity of ICCP systems in harsh marine environments.

Sustainable water decontamination in a fluidic sequential electrochemical reactor

Here, we demonstrate an integrated fluidic sequential electrochemical system for effective water decontamination. The system consists of a Ti mesh anode deposited with nanoscale IrO2 and a CNT filter functionalized with nanoconfined Fe2O3. By conducting anodic oxygen evolution reaction (OER) and 2e– oxygen reduction reaction (ORR) sequential electrolysis, our system enables sustainable O2 generation at the anode, followed by transformation of O2 into H2O2 at the cathode, which then led to the production of 1O2 in the presence of nanoconfined Fe2O3. No chemical inputs were needed nor side products occurred during the whole sequential electrochemical processes. The effectiveness of the system was evaluated using tetracycline as a model emerging contaminant. Recirculating at 3 mL min–1, the system exhibited negligible iron and iridium leaching (≤0.01 mg L–1) and high tetracycline degradation efficiency (≥95%). Such excellent efficacy can be maintained across a wide pH range and in complicated water matrices.

Effect of 3D titanium substrates with TiO2 nanotube arrays on photoelectrocatalysis degradation of phenol

TiO2 nanotube array electrodes are coated on 3D titanium foam and mesh by the anodic oxidation procedure to investigate the effect of electrode substrates. Distribution homogeneity, crystal shape, structure, and light absorption of TiO2 nanotube are the same, orientations are different due to the planar structure of the titanium foam and the non-planar structure of the titanium mesh. However, the performance of the photoelectrocatalysis, phenol degradation, and charge transfer significantly influences by anode substrates. Although the photocurrent density of titanium mesh is 3.29 mA·cm−2, which is 1.5% lower than that of titanium foam, 96.1% ± 2% of the phenol can be degraded by the titanium mesh anode in 120 min with a degradation efficiency of 86.5% ± 3% after 4 cycles, demonstrated titanium mesh substrate is better than titanium foam. The mechanism results show that·OH and photoelectric synergy play a primary role in phenol degradation, and electrocatalysis (29.8%) increased by anode substrates, is better than photocatalysis (17.9%). The electric field enhances by electrocatalysis, resulting in accelerating electron transfer and decreasing in the recombination of electron and hole. Due to its porous structure and large specific surface area, the 3D substrate improves mass transport, providing more photocatalysts, reactants, and reaction sites for photoelectrochemical reactions, further enhancing photoelectric synergy, and ultimately promoting phenol degradation. This study confirms the role of 3D anode titanium substrate and encourages electric field enhancement to solve the recombination of electrons and holes.

Simultaneous degradation and rejection of PPCPs from wastewater in a 3DEO-FO-RO process

This study established a novel three-dimensional electrochemical oxidation coupled with forward osmosis and reverse osmosis (3DEO-FO-RO) system with the purpose to achieve simultaneous degradation and rejection of pharmaceuticals and personal care products (PPCPs) in wastewater. 18 frequently detected PPCPs were selected as the target pollutants to prepare the synthetic wastewater with a concentration of 200 μg/L for each pollutant. Ti/IrO2–Ta2O5–SnO2 mesh anode, titanium mesh cathode and Sn–Sb–Bi/γ-Al2O3 particles electrodes were integrated in the 3DEO-FO reactor. Experimental results demonstrated that degradation efficiency exceeding 98.5 % and rejection exceeding 99.4 % for each PPCP were achieved simultaneously in the 3DEO-FO-RO processes at a current density of 1 mA/cm2 after 8 h treatment. Despite variations in applied current density, the 3DEO-FO-RO processes exhibited superior PPCPs removal efficiencies, particularly for refractory compounds, compared to the 2DEO-FO-RO processes. Increased hydroxyl radical (·OH) generation in the 3D reactor was considered to be responsible for the excellent performance. Furthermore, results derived from ultraviolet (UV) absorption spectra and fluorescence excitation-emission matrix (EEM) spectra provided additional validation for the effective removal of PPCPs in the 3DEO-FO-RO processes, along with evidence indicating the decomposition of PPCPs into smaller constituents. Ultimately, the 3DEO-FO-RO process demonstrated its capacity in removing PPCPs from actual secondary effluent from a wastewater treatment plant. This integrated system coupling 3D EO with FO-RO membranes can provide an efficient approach for simultaneous degradation and rejection of trace contaminants for wastewater reuse.

Intensified treatment of kitchen wastewater in a filter- press type electrochemical reactor

Commercial kitchen wastewater (KW), characterized by a high load of bio-refractory organics, can be effectively treated by electrochemical methods for non-potable applications. This work explores the electrochemical degradation of KW in a batch recirculation type flow reactor consisting of mixed metal oxides coated titanium mesh anode and stainless steel cathode. The effect of operating factors such as current density, supporting electrolyte concentration, initial pH, and recirculation flow rate on chemical oxygen demand (COD) reduction was examined by following one-factor-at-a-time method. The %COD reduction increased with an increase in electrolyte concentration and current density. The optimum current density and electrolyte concentration were found to be 2 A/dm2 and 2 g/L, respectively. The treatment was intensified by incorporating mechanical stirring and ultrasound irradiation in the reservoir. The results showed about 99 % COD reduction, and the kinetic model proposed predicted the experimental data satisfactorily.

Scaling up of MFC technology using cost effective electrodes for treatment of kitchen wastewater

The current study aims to scale up Microbial Fuel cell (MFC) system for power generation and treat kitchen wastewater using a low-cost material. One MFC with stainless steel mesh as both anode and cathode and another MFC with carbon veil as anode and stainless-steel mesh as cathode with a natural clay as membrane was selected for this study. Ten cells, each with an anodic chamber of volume 275 mL and cathodic chamber of volume 90 mL were externally connected to perform the treatment. COD removal and power generation of the cells were monitored and the performances of electrically combined cells in series, parallel, series–parallel and parallel-series combinations were also studied. MFC with carbon veil as anode generates an open circuit voltage (OCV) of 476 mV, power density of 0.397 W/m3 and current density of 0.26 A/m2 which is higher than the system with stainless steel as the anode. The comparative study of the various electrical combinations concludes that the parallel combination shows a maximum power density of 0.55 W/m3. This study reveals that the best electrode material and electrical connection for a scaled up MFC were carbon veil as anode and stainless-steel mesh as cathode and a natural clay-based membrane connected in parallel combination.

MnO2/La2O3/rGO composite catalyst prepared by electrodeposition as corona discharge anode for electrocatalytic cracking of toluene

To achieve the purification of coke oven gas and pyrolysis gas under oxygen-free conditions, the MnO2/La2O3/rGO composite catalyst was innovatively loaded directly onto the surface of porous titanium mesh anode by electrodeposition in this study, together with corona discharge for toluene cracking. During the catalyst preparation, the effects of potential and pH on the catalyst were verified in combination with cyclic voltammetry (CV) curves. The results showed that the toluene cracking rate reached 90% at 7 kV when the electrolyte concentrations of Mn2+, La3+ and rGO were 0.1 mol/L, 0.05 mol/L and 0.005 g/L, respectively. In addition, in this study, the distribution and changes of potential and electron temperature inside the reactor were simulated by COMSOL, and the concentration and change pattern of positive and negative ions at 7 kV were calculated. The results showed that both the plasma and the catalyst play a very significant role in this process.

An Electric Self‐Sensing and Variable‐Stiffness Artificial Muscle

Soft robots have better flexibility than their rigid counterparts thus offering greater adaptability to changing environments. These robots made from flexible materials are generally with low stiffness and have limited capability to perform tasks that require the application of large forces. Soft artificial muscles (AMs) with variable stiffness are promising solutions for soft robots to handle larger payloads. However, the existing actuators need to overcome their small range of stiffness variation and slow response. Further, it is difficult to integrate self‐sensing into existing actuators. Herein, a novel electric AM with variable stiffness and self‐sensing referencing smooth muscle contraction in nature is proposed. The AM consists of two pieces of soft anode mesh, a flexible cathode and a polyvinyl chloride (PVC) gel dielectric layer, where the cathode is also a resistive sensor. The stiffness variation is induced by the friction change caused by electrostatic adsorption. Compared with the existing PVC gel actuation technology, the new design integrated the dielectric and the cathode layers and combined the sensing function. Also, the rigid anode and cathode are replaced by the soft ones, respectively, which makes the AM suitable for soft robotics or wearable devices.

Electro-oxidation of ammonia using a continuous system equipped with RuO2@Ti mesh anode: Optimization of the design parameters with a focus on energy consumption and removal efficiency

In this study, the influence of the main parameters, such as electrode distance, flow rate, electrode numbers, electrode arrangements, initial pH, and alkalinity on ammonia removal and energy consumption was investigated in a continuous electrochemical system. The optimal distance, the number of the anode, and electrode pairs were 2 cm, 1 anode, and 2, respectively. The comparison between electrode arrangements showed that the lowest energy consumption was achieved using the monopolar parallel arrangement (160–254 kWh/kg TN). The pH is neutral and slightly alkaline between the electrodes, which increases the rate of ammonia reaction. The highest removal and anode efficiency were observed at the initial pH of 6.5 to 9.0, and the optimal alkalinity was 50–200 mg/L as HCO3–. The results showed that the optimization of design parameters has a significant impact on energy consumption and ammonia removal in the continuous reactor, bringing the technology closer to real-world application in wastewater treatment.

Polarity reversal for enhanced in-situ electrochemical synthesis of H2O2 over banana-peel derived biochar cathode for water remediation

The fabrication of a cost-efficient cathode is critical for in-situ electrochemical generation of hydrogen peroxide (H2O2) to remove persistent organic pollutants from groundwater. Herein, we tested a stainless-steel (SS) mesh wrapped banana-peel derived biochar (BB) cathode for in-situ H2O2 electrogeneration to degrade bromophenol blue (BPB) and Congo red (CR) dyes. Furthermore, polarity reversal is evaluated for the activation of BB surface via introduction of various oxygen containing functionalities that serve as active sites for the oxygen reduction reaction (ORR) to generate H2O2. Various parameters including the BB mass, current, as well as the solution pH have been optimized to evaluate the cathode performance for efficient H2O2 generation. The results reveal formation of up to 9.4 mg/L H2O2 using 2.0 g BB and 100 mA current in neutral pH with no external oxygen supply with a manganese doped tin oxide deposited nickel foam (Mn-SnO2@NF) anode to facilitate the oxygen evolution reaction (OER). This iron-free electrofenton (EF) like process enabled by the SSBB cathode facilitates efficient degradation of BPB and CR dyes with 87.44 and 83.63% removal efficiency, respectively after 60 min. A prolonged stability test over 10 cycles demonstrates the effectiveness of polarity reversal toward continued removal efficiency as an added advantage. Moreover, Mn-SnO2@NF anode used for the OER was also replaced with stainless steel (SS) mesh anode to investigate the effect of oxygen evolution on H2O2 generation. Although Mn-SnO2@NF anode exhibits better oxygen evolution potential with reduced Tafel slope, SS mesh anode is discussed to be more cost-efficient for further studies.

Novel application of electrochemical chloride extraction fixing polymer-modified conductive repair mortar as anode

Electrochemical chloride extraction (ECE) technique provides an effective technique to remove the chloride ions from concrete and realize reinforcements performance recovery. In this study, a novel type of polymer-modified conductive repair mortar (PCRM) was developed as the anode of ECE system, while the impacts of electrochemical parameters, anode types and reinforcements layout on the chlorides extraction efficiency were investigated, in addition, an innovative method is also proposed to further enhance the ECE efficiency. The results highlight that PCRM can be successfully fabricated with proper initial/final setting time, which presents the similar extraction efficiency compared with PC-based repair mortar and stainless-steel mesh anode. Furthermore, reinforcement cages provide target concrete with lower extraction efficiency inside the cage, and the efficiency can be remarkably increased by pulse current. Most importantly, the chloride extraction efficiency of PCRM anode is increased from 45.1% to 59.6% (electrochemical parameters), 53.7% (reinforcements layout), 60.2% (pulse current), respectively.

Spatial and temporal regulation of homogeneous nucleation and crystal growth for high-flux electrochemical water softening

Electrochemical softening is an effective technology for the treatment of circulating cooling water, but its hardness removal efficiency is limited because that nucleation and growth of scale crystals depended on cathode surface. In this study, a novel method was proposed to break through this limit via spatiotemporal management of nucleation and growth processes. A cube reactor was divided into cathodic chamber and anodic chamber via installing a sandwich structure module composed of mesh cathode, nylon nets, and mesh anode. Using this continuous-flowing electrochemical reactor, OH ̄ generated by water electrolysis was rapidly pushed away from cathode surface by water flow and hydrogen bubbles movement. As a result, a wide range of strongly alkaline regions was rapidly constructed in cathodic chamber to play a nucleation region, and homogeneous nucleation in liquid phase replaced heterogeneous nucleation on cathodic surface. Furthermore, the growth process of scale crystals in alkaline regions was monitored in situ. It took only 150 s of residence time to grow to 500 nm, which may be easily separated from water by a microfiltration membrane. With this new method, the precipitation rate was 290.8 g/(hˑm2) and corresponding energy consumption was 2.1 kW·h/kg CaCO3, both were superior to those reported values. Therefore, this study developed an efficient electrochemical softening method by spatial and temporal regulation of homogeneous nucleation and crystal growth processes.

Influence of various parameters on the current distribution and protection degree of impressed current cathodic protection for reinforced concrete with TiMMO mesh anodes

Impressed current cathodic protection (ICCP) is an effective technique to control reinforcement corrosion in concrete structures. The efficiency and design of an ICCP system with titanium mixed metal oxide (TiMMO) anodes in a mortar overlay is strongly influenced by the current distribution to the different reinforcement layers of a reinforced concrete element. An in-depth experimental study is performed to investigate the effect of various parameters on the current distribution and degree of corrosion protection: (i) chloride content, (ii) cement type, and (iii) reinforcement configuration. 24-hour depolarization measurements (EN ISO 12696:2022) indicate that an increase in chloride concentration in the concrete, related to an increase in the rate of reinforcement corrosion, leads to a general decrease in the degree of protection. The use of a CEM III/A cement leads to a large increase in concrete electrical resistivity compared to concrete with an ordinary Portland cement (CEM I). This causes a lower total current output to the reinforcement and a less uniform distribution of current. Finally, a lower steel reinforcement density resulted in a larger current density, as the total current is distributed over a smaller steel surface area, causing higher depolarization values.

Structure of Filter Cakes during the Electroassisted Filtration of Microfibrillated Cellulose

Microfibrillated cellulose (MFC) is a biobased material with unique properties that can be used in a multitude of applications. Water removal from the dilute product streams is, however, challenging and hinders its commercial attractiveness. One possible method of improving dewatering is the use of electroassisted filtration, in which an electric field is applied across part of the filter chamber. In this work, a bench-scale dead-end filter press, modified to allow for electroassisted filtration, was used to dewater a suspension of MFC produced via 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-mediated oxidation. A filter cake was produced with a channeled structure related to the design of the anode mesh, indicating that the cellulose microfibrils were aligned in the direction of the electric field. This was investigated, qualitatively and quantitively, using scanning electron microscopy and wide-angle X-ray scattering, which showed a preferred orientation on a microscopic level but only a partial orientation on a molecular level (fc between 0.49 and 0.57). The influence of the density of the anode mesh, in terms of the structure/permeability of the filter cake and dewatering rate, was also evaluated using two different anode mesh densities (5 × 5 and 10 × 10 mm). It was not, however, found to have any major impact on the dewatering rate.

HF RADIATION PULSE SOURCE LOCATING IN DIN-2K ACCELERATOR

Experiments aimed at locating the source generating an HF pulse during the opening of the plasma switch and leading to explosive electron emission at the cathode were performed on DIN-2K pulse accelerator. It is demonstrated that certain lamps glow during the explosive electron emission pulse. This may point to the possible HF pulse generation during the opening of a plasma switch or radial interruption of current. In order to locate the radiation source the FR-2 dielectric insert was introduced into the vacuum diode and Ne lamps were placed over the anode mesh. The thickness of this insert was chosen to be larger than the electron penetration depth. The lack of Ne indicator lamps glow when the anode was shielded by an FR-2 insert was observed as opposed to the case of operation with the vacuum diode as a load. The virtual cathode caused by the explosive emission from the cathode is shown to be the source of HF radiation.