Electrolyte Current Density Research Articles

Electrolysis-enhanced coagulation process for highly emulsified oily wastewater treatment: Floc diameter, oil removal performance and mechanism

Electrocoagulation (EC) is one of the most effective processes for highly emulsified oily wastewater (HEOW) treatment. However, the demulsification efficiency depends on the amount of aluminum or iron ions released from the conventional sacrificial metal anode, leading to challenges such as rapid anode dissolution and short lifespan. To address these issues, this study presents a novel electrolysis-enhanced coagulation (EEC) process, replacing conventional Al electrodes with dimensionally stable titanium anodes coated with ruthenium-iridium oxide and supplementing the electrochemically released Al³+ with externally added AlCl3.This process was assessed using the Turbiscan LAB Expert to measure the variation in floc diameter under various electrolysis times, AlCl3 concentrations, and current densities. At a current density of 5 mA/cm2 and AlCl3 dosage of 50 mg/L, the mean floc diameter increased from 32.4 ± 1.7 µm to 630.3 ± 76.9 µm as the electrolysis time extended from 0 to 4 min. Under optimal conditions, the oil removal efficiency of 96.7%±0.2% and residual oil concentration in the effluent of 66.3 ± 3.5 mg/L were achieved. The energy consumption of this process was 0.17 kWh/m³, which was a relatively low value compared with conventional EC techniques. Moreover, as electrolysis time increased, a greater proportion of dissolved and suspended Al transformed into species incorporated within the floating oil. These findings demonstrate the potential of the EEC process to replace EC in treating HEOW, providing an effective and durable solution.

Application of novel Dy0.06Gd0.02Er0.02Bi1.9O3 oxide ion electrolyte for intermediate-temperature reversible solid oxide cells

Bismuth-based oxides are promising electrolyte materials for Reversible Solid Oxide Cells (RSOCs) due to their high ion conductivity and rapid surface oxygen exchange kinetics. In this work we propose a multi-element doping strategy to obtain a novel Dy0.06Gd0.02Er0.02Bi1.9O3 (DGESB) quaternary oxide bismuth material whose ionic conductivities and crystal structure are characterized by AC impedance and X-ray diffraction technique in the temperature range from 600 to 700 °C. Along with promising structure stability and durability, our novel DGESB showed a remarkable ionic conductivity that is 65 times higher than the commercial yttria-stabilized zirconia (YSZ) electrolyte at 700 °C. With composite electrode of DGESB + LCN (LaCo0.6Ni0.4O3) and DGESB/YSZ bilayer electrolyte consisting of RSOC symmetric cell, which achieves a high peak power density (PPD) of 1.62 W/cm2 in fuel cell mode which is 2.7 times higher than that of YSZ single-layer electrolyte, while the electrolysis current density is as high as 1.66 A/cm2 at 1.3 V under H2/H2O:50/50 in electrolysis mode at the same operation temperature of 700 °C. The electrochemical performance measurements revealed a certain stable operation for 200 h in fuel cell mode. The performance degradation can be attributed to the microstructure evolution at the interface between electrolyte and electrodes. The high ionic conductive DGESB proves to be an excellent intermediate electrolyte layer for improving cell performance in RSOCs

An active and stable PrOx-modified open-straight pore (La0.8Sr0.2)0.98MnO3-δ-Sc0.18Zr0.82O2-δ air electrode for reversible solid oxide cells

Air electrode supported reversible solid oxide cells (RSOCs) have drawn increasing attention for the capability of fuel flexibility and well bonding between the air electrode and electrolyte. However, the high concentration polarization and sluggish oxygen reduction/evolution reaction (ORR/OER) has significantly restricted the practical applications. Herein, finger-like (La0.8Sr0.2)0.98MnO3-δ-Sc0.18Zr0.82O2-δ (LSM98-SSZ) air electrode supported symmetrical and single cells are successfully fabricated by phase inversion tape-casting technology. The open-straight pores formed on the air electrode support can facilitate the gas transport and catalyst impregnation. The ORR/OER activity of LSM98-SSZ air electrode is largely increased with the introduction of impregnated PrOx nano catalyst, showing a low polarization resistance (Rp) of 0.06 Ω cm2 and great stability for 550 h at 700 °C. Furthermore, the LSM98-SSZ supported cell with PrOx modification shows a remarkable peak power density of 1.0 W cm−2 and electrolysis current density of 1.09 A cm−2 at 1.3 V at 750 °C. The enhanced performance is primarily ascribed to the facilitated oxygen surface exchange.

Titanium Alloy Ti-6Al-4V Electrochemical Dissolution Behavior in NaNO3 and NaCl Solutions at Low Current Density

Jet electrochemical micromilling (JEMM) exhibits significant potential for high-efficiency and high-quality machining of titanium alloy microstructures. However, during the JEMM process, the machined surface of the workpiece inevitably experiences stray current attacks at low current levels. Due to the formation of a dense passive film on the surface of the titanium alloy under electrochemical action, stray corrosion occurs on the machined surface. Hence, the electrochemical dissolution behavior of titanium alloys at low current densities directly impacts both machining efficiency and quality. This study first analyzed the effects of electrolyte composition and current density on the transpassive potential, breakdown of the passive film, current efficiency, and the dissolved surface on Ti-6Al-4V. The transpassive potential and electrochemical impedance of Ti-6Al-4V were found to be lower in NaCl solution than in NaNO3 solution. In addition, lower current densities enabled higher current efficiency and resulted in a more uniform and flat dissolution surface. Subsequent experiments used these two solutions for JEMM of complex-shaped microstructures on Ti-6Al-4V. The findings demonstrated that, compared to the NaNO3 solution, the use of NaCl solution increases the material removal rate by approximately 30%, enhances the aspect ratio by about 26%, and reduces surface roughness by roughly 58%. This indicates that employing NaCl solution can lead to superior machining efficiency and quality.

Investigation of the effect of current density and ZrO2 bath concentration on electrodeposited Ni-P/ZrO2 composite coatings

In this study, Ni-P/ZrO2 nanocomposite coatings were deposited on St-37 steel substrates using the electroplating method with varying ZrO2 concentrations and current densities. To investigate the effects of electrolyte components and current density on coating properties, analyses were performed regarding microhardness, wear performance, and surface morphology. As a result of the analyses, it is observed that different bath concentrations and current densities significantly affect properties such as morphology, hardness, and wear performance. It is seen that the surface morphologies of the obtained coatings are generally smooth, but it is understood from the optical images that the surfaces of all nanocomposite coatings are rougher. While adding ZrO2 nanoparticles to the main matrix increases microhardness by approximately 40% compared to pure nickel, a similar but higher hardness value was obtained with the increase in current density. When examined in terms of wear performance, an average friction coefficient value of 3.15 times higher than that of pure nickel nanocomposite coatings was obtained.

Highly active and stable oxygen electrode PrBaCo2O5+δ-Ba2CoWO6 enabled by In Situ formed misfit dislocation interface for reversible solid oxide cell

The energy conversion efficiency and durability of the reversible solid oxide cell (RSOC) is restricted by the development of highly active and stable oxygen electrode. Herein, an in-situ formed composite PrBaCo2O5+δ-Ba2CoWO6 oxygen electrode is proposed, which consists of a highly active A-site double perovskite (A-DP) phase and a stable B-site double perovskite (B-DP) phase. Misfit dislocation interface is formed between these two phases, exerting lattice tensile stress on the A-DP phase, which enhances catalytic activity and inhibits Ba segregation. Additionally, the B-DP phase suppresses lattice expansion of A-DP phase through the dislocation interface, thereby improving thermo-mechanical stability. Consequently, the composite electrode demonstrates a low polarization resistance of 0.056 Ω cm2 at 650 °C, impressive stability at 650 °C for 500 h in symmetrical cell tests, and excellent thermal-mechanical stability under 29 thermal cycles. A maximum power density of 0.75 W cm−2 and an electrolysis current density of 0.84 A cm−2 at 1.3 V were achieved at 650 °C by the composite electrode on a 260 μm-electrolyte supported cell configuration, which surpass most of the reported oxygen electrode materials. Furthermore, the cell exhibits excellent operational stability, with low degradation rates of 0.49 × 10−1 mV h−1 and 1.5 × 10−1 mV h−1 in fuel cell and electrolysis cell modes, respectively. This work offers an effective method for designing highly active and stable oxygen electrodes for RSOCs.

Anionic and cationic co-doping to enhance the oxygen transport property of Bi0.5Sr0.5FeO3-δ as a high-performance air electrode for reversible solid oxide cells

Reversible solid oxide cells (RSOCs) have attracted considerable interest due to their efficient energy conversion. However, the low catalytic activity of air electrodes limits the application of RSOCs. Bi0.5Sr0.5Fe0.9Ta0.1O3-δ developed in our previous work exhibits a comparatively desirable performance and is expected to be further optimized. Herein, a novel strategy of anionic F and cationic Ta co-doped Bi0.5Sr0.5Fe0.9Ta0.1O3-δ-xFx (x = 0, 0.05, 0.10, 0.15, denoted as, BSFTF0, BSFTF5, BSFTF10, BSFTF15) materials are obtained to enhance the oxygen transport property of Bi0.5Sr0.5FeO3-δ for RSOCs. The polarization resistance (Rp) of BSFTF10 (0.017 Ω cm2) decreases by 66 % compared with that of BSFTF0 (0.051 Ω cm2) at 800 °C. In fuel cell mode, the single cell with BSTF10 reaches the maximum power density of 908 mW cm−2, which is approximately 72 % higher than the only Ta-doped BSFTF0 (527 mW cm−2) at 800 °C. In electrolysis mode, the single cell with BSFTF10 exhibits a high electrolysis current density of 1679 mA cm−2, indicating an approximately 90 % increase compared to that of BSFTF0 at 800 °C and 1.5 V with 70 % CO2-30 % CO feed gas. The bulk chemical diffusion (Dchem) of BSFTF10 is up to 5.12 × 10−4 cm2 s−1, which is 4.3 times higher than that of BSFTF0. The superior oxygen transport property of BSFTF10 is attributed to the high electronegativity of F− (4.0) and low electronegativity of Ta5+(1.8), which may weaken the chemical bonding between B-site ions and O2−, generating more oxygen vacancies and accelerating the rate of oxygen transfer. The results indicate that F and Ta co-doping is an effective strategy to develop a highly catalytically active air electrode for RSOCs featuring oxygen transport properties.

Interface engineering of La0.6Sr0.4Co0.2Fe0.8O3−δ/Gd0.1Ce0.9O1.95 heterostructure oxygen electrode for solid oxide electrolysis cells with enhanced CO2 electrolysis performance

For CO2 electrolysis in solid oxide electrolysis cells (SOECs), oxygen evolution reaction in the oxygen electrode limits the electrolysis process due to its slower reaction kinetics. Composite oxygen electrodes with good uniformity and interfacial connectivity are expected to promote the charge carriers' transport effectively and thus increase the electrocatalytic performance of the cell. In this work, interface engineering is applied to promote the conventional La0.6Sr0.4Co0.2Fe0.8O3−δ-Gd0.1Ce0.9O1.95 (LSCF-GDC) composite oxygen electrode to form a heterostructure via co-synthesis method. The results prove that LSCF co-synthesized with 40 wt%GDC (LSCF/40GDC) exhibits higher conductivity and faster oxygen exchange kinetics and bulk diffusion processes. The nickel/yttria stabilized zirconia (Ni-YSZ) supported cell with LSCF/40GDC oxygen electrode could approach an impressive CO2 electrolysis current density of 2.6 A·cm−2 at 1.6 V and 800 °C. Meanwhile the cell can operate at 1.5 V and 750 °C with electrolysis current density of 1.3 A·cm−2 for more than 100 h without apparent degradation. This heterostructure enhances the interfacial bonding strength between LSCF and GDC phases, thereby providing a continuous network structure for electron and ion transport. Such an interface engineering via co-synthesis method offers a straightforward and convenient modification for oxygen electrodes, providing an alternative route for advanced materials development of CO2 electrolysis.

Balancing current density and electrolyte flow for improved zinc-air battery cyclability

Zinc-air batteries (ZABs), known for their high energy density and environmental friendliness, are emerging as promising solutions for sustainable energy storage. However, the irregular deposition of zinc on electrodes hinders the widespread utilization of rechargeable ZABs due to limited durability and stability. This study investigates the role of electrolyte flow in enhancing zinc electrodeposition and overall performance in zinc-air flow batteries (ZAFBs) at high current densities. We explore the interplay between current density, flow rate, and their influence on electrode surface morphology and the removal of the passivating zinc oxide layer to improve battery efficiency and lifespan. Using advanced in-situ synchrotron radiation x-ray tomography, we found that incorporating flowing electrolyte at specific current densities results in rounded dendrite tips, thinner and more uniform deposition layers, and improved zinc adhesion. Imaging and electrochemical analyses further reveal that flowing electrolyte enhances zinc morphology, reduces charge transfer resistance, diminishes passivation, and lowers galvanostatic charge/discharge polarization across various current densities, thereby improving battery cycling performance. Notably, the impact of flowing electrolyte is more pronounced at a moderate current density of 50 mA/cm2 compared to lower or higher currents. Our findings underscore the importance of electrolyte flow and current density management in developing high-performance ZAFBs, providing valuable insights for their future commercialization.

Boosting the performance of La0.5Sr0.5Fe0.9Mo0.1O3-δ oxygen electrode via surface-decoration with Pr6O11 nano-catalysts

Cobalt-free La0.5Sr0.5Fe0.9Mo0.1O3-δ (LSFM) oxide is particularly investigated as a durable and efficient oxygen electrode material for the reversible solid oxide cells (RSOCs) in this study. Pr6O11 nano-catalysts are introduced into LSFM oxygen electrode as synergistic catalysts to enhance and optimize the electrode reactions. Results demonstrate an effectively promoted oxygen reduction and evolution reaction kinetics of the Pr6O11 decorated LSFM electrode. Polarization resistances (Rp) of LSFM electrode are dramatically reduced with the increasing Pr6O11 nano-catalysts and the lowest Rp of 0.039 Ω cm2 is obtained at 800 °C, which is ∼97% lower than that of the LSFM electrode. The Pr6O11 decorated LSFM oxygen electrode also displays a superior durability under cyclic anodic and cathodic polarizations. Furthermore, both the maximum power density and electrolytic current density of the Pr6O11 decorated cell are more than 2 times that of the LSFM cell. Results make clear reliability of the Pr6O11 decorated LSFM to be a promising oxygen electrode for RSOCs.

B-site nickel tuned high active Sr and Co-free Ba0.8Ca0.2Fe0.8Ni0.2O3-δ air electrode for reversible solid oxide cells

Reversible solid oxide cells (RSOCs) have aroused wide concern as a promising technology in conversion between chemical energy and electrical power. However, the double conducting (O2−/e−) air electrode with high electrocatalytic activity and thermomechanical stability keeps a significant challenge for practical application. Herein, a perovskite Ba0.8Ca0.2Fe0.8Ni0.2O3-δ (BCFNi) oxide is synthesized and used as the air electrode material, which is experimentally and theoretically demonstrated to have excellent oxygen reduction/evolution reactions (ORR/OER) activity. The density functional theory (DFT) calculations indicate that BCFNi oxide accelerates the oxygen desorption/desorption, thus promoting the OER/ORR kinetics. The cell with BCFNi air electrode achieves a peak power density of 1.29 W cm−2 in the fuel cell (FC) mode and an electrolysis current density of 1.47 A cm−2 with 50 % H2O-H2 at 1.3 V applied voltage in the electrolysis cell (EC) mode at 800 °C. Moreover, it maintains favorable durability of 225 h in the FC, reversible, and EC modes at 750 °C, respectively. The results suggest that the Ni doping in B-site of perovskite oxide is beneficial to improve the ORR/OER activity and BCFNi material has great potential as an air electrode for RSOCs.

Enhancing Direct Eectrochemical CO2 Electrolysis By Introducing a-Site Deficiency for Dual-Phase Pr(Ca)Fe(Ni)O3-Δ Cathode

High-temperature CO2 electrolysis via solid oxide electrolysis cells (CO2-SOECs) has drawn special attention due to the high energy convention efficiency, fast electrode kinetics, and great potential in carbon cycling. However, the development of cathode materials with high catalytic activity and chemical stability for pure CO2 electrolysis is still a great challenge. In this work, A-site cation deficient dual-phase material, namely (Pr0.4Ca0.6)xFe0.8Ni0.2O3- δ (PCFN, x=1, 0.95, and 0.9), has been designed as the fuel electrode for a pure CO2-SOEC which presents superior electrochemical performance. Among all these compositions, (Pr0.4Ca0.6)0.95Fe0.8Ni0.2O3- δ (PCFN95) exhibited the lowest polarization resistance of 0.458 Ω cm2 at open circuit voltage and 800℃. The application of PCFN95 as the cathode in a single cell yields an impressive electrolysis current density of 1.76 A cm-2 at 1.5 V and 800℃, which is 76% higher than that of single cells with stoichiometric Pr0.4Ca0.6Fe0.8Ni0.2O3- δ (PCFN100) cathode. The effects of A-site deficiency on materials’ phase structure and physicochemical properties are also systematically investigated. Such an enhancement in electrochemical performance is attributed to the promotion of effective CO2 adsorption, as well as the improved electrode kinetics resulting from A-site deficiency.

Stability and energy consumption of solid oxide electrolysis cells under wide fluctuating and stable conditions

The combination of solid oxide electrolysis cells (SOECs) with renewable electricity has enormous potential, but this requires the cells to be able to adapt to strong fluctuation conditions. This work directly combines fluctuating actual wind power with flat-tube Ni-YSZ/YSZ/LSCF-GDC SOECs to study the operational stability and energy consumption under wide fluctuation and constant current electrolysis. The results indicate that under an average electrolysis current density of 0.26 A cm−2, there is little difference in stability between fluctuation and constant current electrolysis. At a high current density of 0.58 A cm−2, the cells operating for 375 h under fluctuation conditions exhibit a larger degradation rate. The current density is dynamically switched between 0 and 0.93 A cm−2 to simulate actual wind turbine power fluctuations from 0 to 100 %. After rapid large-scale current switches for 2000 times in 375 h, little change is observed in the cell structure. Under fluctuating electrolysis, the minimum energy consumption for power-to-gas conversion in SOEC is 2.84 kWh/Nm3, while under constant current electrolysis, the lowest energy consumption is 2.67 kWh/Nm3. In summary, SOECs can efficiently and stably consume and store highly fluctuating renewable power and can also dynamically respond to wide power ranges from 0 to 100 %.

In-situ construction of Ni–Fe alloy nanoparticles on perovskite surface for CO2 direct electrolysis

Perovskite (ABO3) materials are commonly used as cathodes for solid oxide electrolysis cells (SOECs), but their electrochemical performance is poor due to the low CO2 adsorption and conductivity. Herein, we design an A-site deficient (La0.5Sr0.5)0.95Fe0.85Mn0.1Ni0.05O3-δ (95LSFMNi) perovskite cathode with rich oxygen vacancy and Ni–Fe alloy to enhance the CO2 adsorption. The surface precipitated Ni–Fe alloy nanoparticles introduce more oxygen vacancies into the matrix and increase the active sites for CO2 adsorption, enhancing the electrochemical reduction reaction for CO2 (CO2RR). Fe element exsolution was stimulated after the Ni reduction, and Fe content in the nanoparticles increased with the reduced time. The 95LSFMNi with in-situ dissolved Ni–Fe particles exhibits a doubled conductivity than the parent La0.5Sr0.5Fe0.9Mn0.1O3-δ (LSFM) at 800 °C and 5%H2/Ar. In addition, the electrolysis current density at 1.6 V and 800 °C reaches 1.09 A cm−2, representing a 28.2% increase compared to the LSFM. These findings demonstrate that the in-situ precipitated nano Ni–Fe particles are highly effective in enhancing the catalytic ability of CO2RR.

Recovery of boron and zinc from wastewater via electrodialytic metathesis

With the development of industrial civilization, large amounts of wastewater containing boron and zinc are being produced. Such wastewater poses a great threat to human health if discharged without treatment. In this study, an integrated technology of electrodialytic metathesis (EDM) and a hydrothermal process was utilized to recover boron and zinc from wastewater in the form of zinc borate (Zn2B6O11·3H2O). Experimental results showed that electrolyte concentration, current density, and initial boron and zinc concentration clearly affected the recovery ratios for B4O72− and Zn2+ and their corresponding specific energy consumption and current efficiencies. Under the optimal experimental conditions (an electrolyte concentration of 1.0 mol/L in the recycling compartment in the experimental setup, a current density of 15 mA/cm2, initial ZnSO4 and Na2B4O7 concentrations of 0.1 mol/L, and a flow rate of 20 mL/min), the recovery ratio, specific energy consumption, and current efficiency were 85.6 %, 6.5 kW·h/mol, and 12.3 %, respectively, for recovering B4O72− and 80.6 %, 1.7 kW·h/mol, and 45.7 %, respectively, for recovering Zn2+. When one recovery compartment was employed, the current efficiencies for recovering B4O72− and Zn2+ were 12.3 % and 45.7 %, respectively, and these values were 11.4 % and 43.8 %, respectively, when two recovery compartment were used. After B4O72− and Zn2+ concentrated by EDM were treated via a hydrothermal process, a white precipitate was produced. The results of X-ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analyses showed that this precipitate exhibited physicochemical properties similar to those of commercial Zn2B6O11·3H2O. Thus, the integrated technology can be regarded as an effective method for recovering boron and zinc from wastewater.

Constructing high-performance micro fuel electrodes for reversible proton ceramic electrochemical cells

Reversible proton ceramic electrochemical cells (R-PCECs) are of great interest as efficient energy conversion device. Optimization of structural design can enhance the mechanical properties and gas transport of the cells, resulting in improved electrochemical performance. In this study, we developed a 7-channel micro-monolithic R-PCEC for the first time, with uniform channel distribution and smaller gas diffusion pathway length using phase inversion/extrusion technique. The assembled cell with Ni-BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (Ni-BZCYYb, fuel electrode support) | BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb, electrolyte) | PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF, air electrode) structure showed a peak power density of 0.94 W cm−2 at 700 °C in fuel cell mode and electrolysis current density of 2.17 A cm−2 at 700 °C with an operating voltage of 1.3 V. Additionally, electrochemical impedance spectroscopy (EIS) further indicated that the diffusive polarization of the structured cell was effectively reduced compared to single-channel counterpart.

Critical Challenges in the Anodizing Process of Aluminium–Silicon Cast Alloys—A Review

The microstructure of the substrate plays a crucial role in the anodizing process. Anodizing cast aluminum alloys is quite challenging due to the higher levels of alloying elements present compared to pure aluminum. Elements such as silicon, iron, and copper significantly impact the growth and quality of the anodic layer. Additionally, anodizing parameters such as electrolyte composition, current density, and temperature are critical in determining the morphology and thickness of the anodic film. The casting process, surface condition, and post-treatment also affect the properties of the anodic layer. Optimizing these parameters is essential to achieve a durable and high-quality anodic layer. This work aims to provide a comprehensive understanding of the various factors affecting the anodizing of cast aluminum alloys and the properties of the anodic layer, including its thickness, corrosion resistance, and wear resistance.

Influence of plasma electrolytic oxidation coating on reducing the corrosion rate of dissimilar FSW joint between AA5052 and AZ31 alloys by minimizing effect of different galvanic couple types

This study investigated the different aspects of macro/micro-galvanic corrosion behavior of plasma electrolytic oxidation coating (PEO) applied on a dissimilar joint. In this regard, AA5052 and AZ31 were joined by friction stir welding. Then, the dissimilar joints were simultaneously coated with different electrolyte conductivities and current densities through PEO process. Despite of coated samples, the stir zone (SZ) of uncoated sample was severely corroded due to macro-galvanic couple (AA5052/AZ31) and micro-galvanic couple (intermetallic compound/surrounding matrix). In the optimal coated sample (CD-350), the corrosion current density of SZ compared with uncoated sample dropped from 8.18 × 10−4 to 1.69 × 10−5 A/cm2. The ratio between corrosion current density of SZ and that of uncoupled anode that is demonstrating the severity of galvanic effect; was less than 5 (icorr SZ/iuncoupled anode = 4.17), therefore the various regions were totally compatible due to the effect of PEO coating on reducing different galvanic couple types. The corrosion rates for both heat-affected zone and base metal on each side of the coated samples were nearly identical, indicating the independence of the coating quality and properties from substrate microstructure. The findings revealed that rising electrolyte conductivity and current density led to the growth of coating thickness while the number of microspores decreased and their average diameter increased. Meanwhile, α-Al2O3, γ-Al2O3, and SiO2 amorphous formed on AA5052 side; and MgO, Mg2SiO4, and MgF2 on AZ31 side during coting process.

Obróbka dla przemysłu ekstrakcji oliwy z oliwek poprzez zastosowanie peroksy-elektroutleniania

This study aimed to assess the effectiveness of peroxy-electrooxidation (PEO) for treating wastewater from the olive pomace oil extraction industry. The response surface methodology was utilized to optimize the efficiency of the PEO process under varying conditions of electrolysis time, current density, and hydrogen peroxide (H2O2) dosage. Appling graphite/aluminum sheets as cathode/anode in the treatment process showed that the concentration of H2O2 directly affected the efficiency of total phenolic compounds (TPh) removal. It was observed that at an H2O2 concentration of 15 g L-1, the removal efficiency was less than 80%. The removal of chemical oxygen demand (COD) is mainly influenced by the dosage of H2O2 and the reaction time. The experiments conducted on the PEO processes with graphite/iron sheets showed that the highest removal of TPh was achieved with an H2O2 dosage of 30 g L-1 and an intermediate reaction time of 30 minutes. Current density also had an impact on TPh removal. Regarding COD removal, the results showed that the highest removal rates were attained with increased H2O2 concentrations, but reaction time was a positive factor, with better results obtained with 30 and 50 minutes. The PEO is recommended as a pre-treatment for TPh removal but not for COD and other treatment processes should be evaluated.

Current-Voltage (i-V) characteristics of electrolyte-supported (NiO-YSZ/NiO-SDC/ScSZ/LSCF-GDC/LSCF) solid oxide electrolysis cell during CO2/H2O co-electrolysis

Solid oxide electrolysis cells (SOECs) stabilize CO2 emissions by converting CO2/H2O into synfuel. Current-Voltage (i-V) characteristics of an electrolyte-supported button cell (NiO-YSZ/NiO-SDC/ScSZ/LSCF-GDC/LSCF) were measured as a function of temperature, water vapor concentration, and CO2 gas concentrations. The cell microstructure was characterized by the Field Emission Scanning Electron Microscope (FE-SEM). FE-SEM micrographs depict that the electrolyte layer is relatively dense, and porous fuel and air electrode layers are well adhered to the electrolyte. The i-V curves were obtained at a scan rate of 0.02 Vs−1 from 0.3 to 1.5 V. Electrolysis current density increases as the temperature increases. SOEC performance increases, but SOFC performance decreases with increased water vapor concentration. Electrolysis current densities decrease as the CO2 concentration increases. The i-V characteristics show only ohmic polarization under fuel-lean and fuel-rich conditions. At optimal conditions, current density values at 800 °C/1.5 V are -174, -187, and -195 mA cm−2 for 5 %H2O, 30 %CO2, and 30 %CO2/5 %H2O co-electrolysis. At 800 °C, open-circuit voltage (OCV) values for H2O, CO2, and co-electrolysis are 0.906, 0.891, and 0.885 V, respectively. The electrolysis area-specific resistances (ASRs) give information on the reduction of CO2 or H2O, forming CO or H2, respectively. At optimal conditions, ASR values are 3.43, 3.29, and 3.18 Ω cm2 for H2O, CO2, and co-electrolysis, respectively. Co-electrolysis has a lower ASR value than pure H2O and CO2 electrolysis, indicating that H2O and CO2 are involved in the electrochemical processes.