Interelectrode Distance Research Articles

Nonlinear spatio-temporal filter to reduce crosstalk in bipolar electromyogram

Objective. The wide detection volume of surface electromyogram (EMG) makes it prone to crosstalk, i.e. the signal from other muscles than the target one. Removing this perturbation from bipolar recordings is an important open problem for many applications. Approach. An innovative nonlinear spatio-temporal filter is developed to estimate the EMG generated by the target muscle by processing noisy signals from two bipolar channels, placed over the target and the crosstalk muscle, respectively. The filter is trained on some calibration data and then can be applied on new signals. Tests are provided in simulations (considering different thicknesses of the subcutaneous tissue, inter-electrode distances, locations of the EMG channels, force levels) and experiments (from pronator teres and flexor carpi radialis of 8 healthy subjects). Main results. The proposed filter allows to reduce the effect of crosstalk in all investigated conditions, with a statistically significant reduction of its root mean squared of about 20%, both in simulated and experimental data. Its performances are also superior to those of a blind source separation method applied to the same data. Significance. The proposed filter is simple to be applied and feasible in applications in which single bipolar channels are placed over the muscles of interest. It can be useful in many fields, such as in gait analysis, tests of myoelectric fatigue, rehabilitation with EMG biofeedback, clinical studies, prosthesis control.

A Finite Element Approach for Forearm Neuromodulation: Impact of Electrode Size on the Current Density

Electrical impedance myography is a transcutaneous neuromodulation method for assessing muscle conditions through the application of a high-frequency, low-intensity current to the muscle region of interest (ROI). It has been shown that the mechanisms underpinning these findings are controversial as studies showed that the current reaching the target structure may not be enough to activate tissue due to various factors. It has been shown that anatomical properties as well as non-anatomical factors including electrode shape and size, inter-electrode distance may affect the outcome. This study was conducted to investigate the impact of the different sizes of the electrodes on the current density of the ROI. It may not be feasible to investigate these parameters impact on the outcome using experimental procedures. Alternatively, the computational methos have been used as a tool to study electrical stimulation of bio-computational models. The neuromodulators can be designed and developed using such advanced methods. This study investigates the impact of the electrode size on the current distributions. The fundamental anatomical layers of the human forearm were generated based on standard dimensions using concentric shapes. A sinusoidal bipolar current pulse was applied on the different sizes of electrodes to simulate current distribution within the associated anatomical layers. It was shown that the electrode size has a significant impact on the induced current density of the target anatomical layer.

Laboratory study of the silica removal in water by electro-Fenton method: Effect of operational parameters

The objective of this study is to investigate the effectiveness of the removal of silica from water, when using the electro-Fenton (EF) advanced oxidation process. In this laboratory study, tests were carried out varying the following parameters: pH, current density, reaction time, monopolar system vs bipolar system, inter-electrode distance. A percentage removal as high as 95% at near neutral pH was obtained after 40 min operating time using a bipolar arrangement of the electrodes. Desilication was found to increase with the increasing applied current density. Maximum removal of silica was observed at near neutral pH.

Achieving efficient clonal beta cells transfection using nanostraw/nanopore-assisted electroporation.

The prospect of being able to efficiently inject large plasmids in insulin-producing beta cells is very attractive for diabetes research. However, conventional transfection methods suffer from high cytotoxicity or low transfection efficiency, which negatively affect their outcome. In contrast, nanostraw electroporation is a gentle method that can provide a high transfection efficiency while maintaining high cell viability. While nanostraw electroporation has gone through some method optimization in the past, such as tuning the pulse frequency, amplitude, and duration, the effect of other parameters has not been thoroughly investigated. Here, we demonstrate efficient transfection of clonal beta cells and investigate the effect of voltage at a fixed inter-electrode distance, cell density, and cargo solution conductivity on transfection efficiency. We used GFP-encoding DNA plasmids stained with an intercalating dye to enable immediate analysis and assessment of the electrophoretic transport of cargo. Moreover, we ran simulations to assess how cargo buffer conductivity impacts the transfection efficiency by affecting the voltage drop on the nanostraws and cell membrane during electroporation. Both experiments and simulations show that MilliQ water as the cargo buffer yields the best transfection efficiency. We also show that the cell density should be adjusted to maximize the number of cells interfacing the nanostraws and avoid cell stacking. Finally, we compared the transfection efficiency when using nanostraws and nanopores. Whereas the amount of GFP plasmids injected using nanostraws is larger than for nanopores, the outcome in terms of GFP fluorescence 48 h after transfection was worse than for nanopores. Moreover, when using nanostraws, fewer cells were found on the substrate 48 h after transfection compared to when using nanopores. This suggests that injecting substantial amounts of plasmids in cells can affect their proliferation and/or viability, and that nanopore electroporation, as a simpler method, is an interesting alternative to nanostraws in achieving efficient and gentle clonal beta cell transfection.

Enhancing electrochemical reactions in organic synthesis: the impact of flow chemistry.

Utilizing electrons directly offers significant potential for advancing organic synthesis by facilitating novel reactivity and enhancing selectivity under mild conditions. As a result, an increasing number of organic chemists are exploring electrosynthesis. However, the efficacy of electrochemical transformations depends critically on the design of the electrochemical cell. Batch cells often suffer from limitations such as large inter-electrode distances and poor mass transfer, making flow cells a promising alternative. Implementing flow cells, however, requires a foundational understanding of microreactor technology. In this review, we briefly outline the applications of flow electrosynthesis before providing a comprehensive examination of existing flow reactor technologies. Our goal is to equip organic chemists with the insights needed to tailor their electrochemical flow cells to meet specific reactivity requirements effectively. We also highlight the application of reactor designs in scaling up electrochemical processes and integrating high-throughput experimentation and automation. These advancements not only enhance the potential of flow electrosynthesis for the synthetic community but also hold promise for both academia and industry.

Efficiency of electrocoagulation for simultaneous treatment of As and Mn in neutral mine water

Despite the efficiency and ease of implementation of electrocoagulation (ECG), its industrial application for the treatment of contaminated mine water is limited due to high energy and electrode consumption. The main objective of the present study was to identify the most performant ECG conditions using Fe–electrodes for the simultaneous removal of As(III) and Mn(II) from synthetic and surrogate neutral mine water, while limiting energy and electrode consumption. Treatability tests were performed on i) single synthetic effluents containing only 3.5mg/L As (SAs) or 4.5mg/L Mn (SMn), ii)binary synthetic effluents containing both As and Mn (SAs+Mn), and iii) surrogate mine water (Elow and Ehigh). The effect of current density (CD), ionic strength, and retention time were first evaluated for the treatment of SAs, SMn, and SAs+Mn. Then, the most performant conditions were used to treat Elow and Ehigh. The toxicity to Daphnia magna of Elow and Ehigh was evaluated before and after ECG treatment. The results showed that the increase of CD from 0.25 to 10 mA/cm2 greatly improved the removal of Mn and to a lesser extent of As, as well as energy and electrode consumption. Despite a negligible effect on the removal efficiency of As and Mn, the ionic strength (from 0.25 to 2.5mS/cm) and inter-electrode distance (from 10 to 50 mm) strongly affected the energy consumption. Results showed that ECG efficiently removed As (>97 %) from SAs at low CD (0.5 mA/cm2), while Mn required a 3.3-fold higher CD to achieve satisfactory removal (>60 %) from SMn. For the treatment of SAs+Mn, As removal was more efficient and faster than Mn removal (99 vs. 60 % and 20 vs. 60 min, respectively) at a CD of 2.0 mA/cm2. Moreover, the simultaneous removal of As and Mn at 2.0 mA/cm2 produced a volume of sludge 3.3 times greater than at 0.5 mA/cm2. Lastly, high As (99 %) and variable Mn (40–57 %) removal efficiencies were obtained after Elow and Ehigh treatment, with potential positive effect of the presence of Ca2+ and Cl- on the removal of As, while SO42- may have negatively affected the removal of Mn. After ECG treatment, no addition of toxicity to D. magna was observed for Elow and Ehigh. The outcomes of this study may provide promising insights for the application of ECG for simultaneous removal of metal(loid)s from contaminated mine water.

(Digital Presentation) Synthesis and Characterization of Dispersed Zinc Oxide

Zinc oxide has the subject of numerous studies in recent years. Nearly half of the world's annual production of zinc oxide is used as an activator to speed up vulcanization in the rubber industry. It is also widely used in pharmaceutical and cosmetic industries. It is most widely used in the chemical industry not only as a starting material, but also as a catalyst and chemisorbent. Recently, zinc oxide has been very often studied as an efficient photocatalyst in advanced oxidation processes. The cheapness and availability of zinc oxide makes it possible to use it also as a white pigment. White pigments make up more than 60% of all modern dyes. They are used for the manufacture of paints and varnishes not only white, but also other colors, as well as in the production of plastics, paper, building materials, ceramics, etc.Obtaining nanodispersed ZnO opens up additional possibilities for controlling its chemical and physical properties. Today, to obtain nanostructured ZnO, chemical deposition, synthesis in colloidal solutions, hydrothermal synthesis, laser vapor deposition, electrochemical deposition, thermal methods, electrochemical deposition, etc. are used. Promising technologies that make it possible to obtain disperse products are physicochemical methods, including those using contact nonequilibrium plasma (CNP).To form nanodispersed ZnO nanoparticles, we used CNP. This method is economically attractive due to the simplicity of the synthesis process (the temperature varies from room temperature to 50°C, the low cost of equipment and consumables) and the possibility of influencing the structural and morphological characteristics of NPs.Theoretical (Pourbaix diagrams) and experimental studies (cyclic voltammograms, potentiometry, kinetic dependences, X-ray phase analysis, derivatography, electron microscopy, spectroscopy) were carried out, which made it possible to establish the possibility of obtaining zinc oxide using CNP and investigate its properties.The results of X-ray diffraction analysis show that under these conditions, a precipitate of ZnO is formed. It was found that with an increase in rarefaction in the plasma-chemical reactor and a decrease in the interelectrode distance, an increase in the degree of conversion of zinc cations into insoluble compounds is observed. To increase the degree of conversion, the effect of organic compounds on the degree of conversion was also investigated. The addition of ethanol in the ratio 50-100 mmol/mol increases the product yield to 99.8% even in dilute solutions. Studies of color characteristics showed that the resulting precipitate has a CRC of 95%, a color purity value of 6%, and a color tone corresponding to a wavelength of 584 nm. The band gap was 3.1 eV.

A Numerical and Experimental Sensitivity Analysis on Electrochemical Neutral Pickling for Stainless Steel Using Secondary Current Distribution

Electrochemical neutral pickling (ENP) is an extended process used in the stainless steel industry to remove the oxide surface layer formed during the annealing process. The absence of strong acids such as nitric acid results in a minimum loss of base material, improve operators working conditions, and reduces the pickling environmental impact, while keeping relatively low operation and maintenance costs. However, despite its multiple benefits, ENP may become the bottleneck for integrated annealing and pickling line, especially when processing thin austenitic and duplex steels. Fortunately, there is room for improvement as the total Faradaic efficiency of the process in typical operation is in general low (around 20 – 30 % for austenitic materials) [1]–[3], while estimations of the energy efficiency are as low as to 1 - 2 % [4].This work provides guidelines to the design and operation of ENP cells to increase the oxide removal rate. We focus on the effect of the geometry and some operational parameters, using secondary current distribution. The simulations are validated against experimental, and a sensitivity analysis of the oxide removal rate with respect to the geometry and some key operational parameters is performed. The electrode-to-strip and the inter-electrode distances were found to have a determining effect on the total cell resistance and on its so-called geometric efficiency (relative current reaching the strip). Moreover, an optimal range for the ratio of these distances is proposed. In addition, the strip thickness and width were found to significantly affect the cell performance, especially for the thinnest gauges.

Removal of reactive dyes from textile industrial effluent using electrocoagulation in different parametric conditions of aluminum electrodes

Untreated textile industrial effluent becomes a major concern for the receiving water bodies. Extensive use of azo dyes in textile industries trigger to find latest techniques for the treatment of textile wastewater. The purpose of this study was to employ the electrocoagulation process for the effective removal of dyes from textile wastewater. The optimization of parameters was performed using the Taguchi method to analyze the conditions of electrode for efficient dye removal. The effects of different parameters including synthetic dye initial concentration, initial pH, applied voltages, interelectrode distance and contact time were studied. Different electrode pairs combination with iron to iron, iron to aluminum and aluminum to aluminum were investigated. The electrode combination of aluminum to aluminum performed better in terms of dye removal. The removal efficiency of methylene blue was achieved to 82% under optimum conditions having pH of 8, 15 V voltage, 60 min contact time and 2 cm aluminum interelectrode distance. Similarly, the optimum conditions for decolorization of methyl orange was performed and achieved 81% of removal efficiency. After the optimization of electrode and parametric conditions, real textile wastewater was treated and removal efficiency of 81% was achieved. At optimal conditions (pH 7–8, 15 V, 60 min contact time, and 20 min settling time), COD, TDS, TSS, and discoloration removal efficiencies were 79%, 91%, 75%, and 86%, respectively. The result of this study indicates the significance of EC process and its future scope for integration of this technology at industrial scale.

Finite Modeling and Simulation of the Effects of Neutral Electrolytic Pickling Process Parameters on EN 1.4404 Steel Strips

Surface treatment via neutral electrolytic pickling (NEP) aims to remove oxide layers and scaling from stainless steel. The objective of this study was to investigate the factors that affect the energy efficiency of the process. This study developed a COMSOL Multiphysics model for the distribution of current across a bipolar steel strip by controlling the following parameters: Na2SO4 concentration, temperature, electrode-to-strip distance, and inter-electrode distance. Full factorial measurements of the electrolyte’s conductivity as well as the steel strip’s and the electrode’s polarization were conducted to provide data for the NEP model. Galvanostatic pulse measurements were performed to calculate transient times during pickling. According to the model, an applied voltage of less than 11 V was insufficient to polarize the steel strip to the potentials needed on both the anodic and cathodic sides. A higher voltage of 11–15 V resulted in anodic current densities of 600–1600 A m−2 and cathodic current densities of 700–2000 A m−2 on the steel strip. These current densities are within the range of previous experimental studies and industrial practices. The model showed that when a steel strip acts as a bipolar electrode, the current’s efficiency decreases, as only a fraction of the strip facing the anodes or cathodes is polarized sufficiently. The galvanostatic tests showed that anodic polarization of the steel strip is easier than cathodic polarization. The slow polarization in the cathodic direction can be improved by using a higher current density. The time needed to polarize stainless steel indicates that the strip’s velocity should be less than 1 m s−1 to give enough time for polarizing the steel strip.

Instability of steady states with inhomogeneous field in electron–positron plasma diode

Instability features of steady states of the plasma diode with electron and positron counter flows are studied. There are several types of such states for each value of the inter-electrode distance. The case when charged particles moving in the diode plasma are not reflected from potential extrema is considered. We have solved an equation for the amplitude of the electric field perturbation for steady states with an inhomogeneous field distribution. Studying the dispersion equation has shown that all considered solutions are unstable. We have also confirmed this result when simulating small perturbation evolution of a steady-state solution.

Performance of Solar-based Electrochemical System as Post-treatment of Hospital Wastewater Contaminated with Ciprofloxacin

T his research evaluated performance of a solar-based electrochemical system as a post-treatment of hospital wastewater contaminated with Ciprofloxacin (CIP), an antibiotic drug. Two laboratory-scale electrochemical units, and consisting of 2-5 anode and 1-4 cathode plates, were employed. Two types of electrode plates, aluminum (Al) and stainless steel (Ss), were installed in the units and their treatment efficiencies were investigated. Optimum conditions of the electrochemical system were determined by using a synthetic wastewater containing 0.01-20 mg/L of CIP (batch system); these experimental results were validated by using an actual hospital wastewater and a solar-based electrochemical system (continuous system). The experimental results of the batch system showed that the maximum CIP removal of 69% could be achieved at 10 minutes of hydraulic retention time (HRT), 18 volts in a voltage of power source (VPS), 83 A/m2 of current density (CD), and 1 cm of inter-electrode distance (IED) on Al plates. Similar results in the continuous system were obtained when the electrochemical system was fed with hospital wastewater containing CIP of about 350 ng/L. Application of solar-based energy in the electrochemical system showed similar efficiency of CIP removal, suggesting the applicability of the clean energy system for post-treatment of hospital wastewater containing antibiotic drugs

Improving omnipolar electrogram reconstruction: an animal model study

Abstract Background Cardiac arrhythmias are a significant cause of morbidity and mortality worldwide. The characterization of cardiac tissue's electrophysiological substrate is crucial for the diagnosis and treatment of these conditions. High-density (HD) electrode arrays, such as the Advisor™ HD Grid Mapping Catheter and Sensor Enabled™ (SE), are commonly used to examine cardiac tissue locally and create activation maps. However, the current method for reconstructing omnipolar EGMs, a novel technique claimed to be orientation-independent, has limitations. The enhancement of this reconstruction methodology has the potential to improve the accuracy and reliability of electrophysiological mapping. This, in turn, can have a positive impact on patients suffering from cardiac arrhythmias, ultimately leading to better clinical outcomes. Purpose We propose a novel reconstruction method to estimate omnipolar EGM that overcomes the angle dependence weakness of the current method to enhance the reconstruction of electrophysiological signals. Methodology Prior experiments were conducted on isolated rabbit hearts using a 128-electrode array with electrodes spaced 1mm apart over the ventricular epicardium. Four-electrode cliques were designed from these experiments, with different inter-electrode distances as depicted in Figure 1A, to reconstruct the current and novel omnipolar configurations. Metrics were designed to assess the quality of the electrogram signals, including the bipolar loop area and the ratio of the bipolar components of the omnipole (see fig. 2). The bipoles were calculated from unipolar electrograms, and the signal was corrected with a 45º offset in the cross. The propagation angle was then detected, and the local activation time (LAT) was estimated. Results In the bipole plots, it was observed that the morphology of the bipolar loop becomes distorted with an increase in the inter-electrode distance, becoming thinner for distances less than 2mm. There is a direct relation between the areas in the bipolar loop and the inter-electrode distance (see Figure 2A). Furthermore, the values of the area in the cross are always comparable to the best-performing triangular clique. For the ratio of bipoles, the relation is inversely related to distance (see Figure 2B). Similarly, the performance of the cross is comparable to the best-performing triangular omnipole. Conclusion This study highlights the importance of accurate reconstruction of omnipolar EGMs for the diagnosis and treatment of cardiac arrhythmias. To achieve precise reconstruction, inter-electrode distances smaller than 2mm are recommended. The proposed reconstruction method based on the cross configuration is more accurate and robust to wavefront propagation, provided that the recommended distance criterion is met. This study opens up new possibilities for the design of new devices and practices in the clinic.Figure 1Figure 2

Polymer micro-ring modulator on silicon nitride platform

The development of silicon nitride (SiN) waveguide platforms has enabled the realization of photonic circuits with unprecedented performance. Despite the exciting progress, SiN suffers from intrinsic material properties that block it for high-speed electro-optic (EO) modulators. Here, we present an approach to heterogeneously integrate organic EO polymer on SiN for high-performance modulators. We utilize the high resistivity of SiN to achieving a strong overlap between the optical and electrical field. Furthermore, sol–gel SiO2 side-claddings inserted in waveguides shorten the inter-electrode distance and increase the EO activity to a much higher level. As a result, the fabricated micro-ring modulator exhibits an electrical tunability of 10 pm/V, corresponding to an in-device EO coefficient as 60 pm/V. High frequency tests in the device show a 3-dB bandwidth of 32 GHz and a data rate of 40 Gbps. The proposed approach will enable efficient mass-production of the micro-footprint modulators and promote the development of integrated SiN photonics.

Removal of fluoride from ground water by electrocoagulation method: investigation of process parameters, kinetic analysis, and operating cost

In the current study, aluminum electrodes have been employed in electrocoagulation (EC) to remove fluoride ions from groundwater. The effects of various operating process variables of EC, including pH, salt dosage, stirring speed, inter-electrode distance, and current density have been studied, as well as the operating cost and kinetics of the process. The most favorable values of the EC process parameters have been observed, which are effective for the removal of 97.6% fluoride, such as an initial value of pH 7.0, a current density value of 105.86 A/m2, an IED of 1 cm, a dose of salt of 0.33 g/L, a rotating speed of 700 RPM, and a time 40 min. The operating cost for the removal of fluoride (97.6% efficiency) from groundwater by EC was found to be 0.27 US$/m3. The effectiveness of the EC process in the removal of turbidity and TDS from different operating circumstances have also been investigated. First-order kinetics was observed in the kinetic study. The reaction rate constant k increases with CD increase, k decreases with IED increase, and k decreases with initial concentration increase. EDX analysis and FTIR spectra of the sludge confirm the availability of trace amounts of fluoride in the sludge produced. The EC process can effectively reduce the fluoride concentration from synthetic water as well as real groundwater up to below 1.5 mg/L as per WHO recommendations for drinking water.

Effects of Circular Hydraulic Jump on the Material Removal Characteristics of Jet Electrochemical Machining

Jet electrochemical machining (Jet-ECM) is a potential precision machining method. Due to the advantages of non-stress-free machining and high flexibility, it is widely used in surface finishing and complex structural machining. However, the “w” shaped removal profile and wide removal range caused by inappropriate process parameters reduce the stability and localizability of Jet-ECM. In this paper, the material removal characteristics of Jet-ECM were investigated both theoretically and experimentally. A multi-physics field simulation model for Jet-ECM was established, and the overall shape of the circular hydraulic jump (CHJ), current density distribution and workpiece deformation were calculated. The effects of CHJ on the material removal characteristics were investigated by experiments with jet flow rate and inter-electrode gap (IEG) distance. The results reveal the qualitative relationship between CHJ states and process parameters and give the range of parameters that can form a stable CHJ and ensure a Gaussian shaped removal profile and a narrower removal range. This study provides theoretical guidance on the process parameters of Jet-ECM to improve its processing stability and localizability, which is significant for the accuracy of surface finishing and the controllability of complex structural machining, promoting the further application of Jet-ECM.

Integrated electroflocculation-membrane process for pre-concentration of domestic wastewater: Filtration performance, organics recovery and membrane fouling characteristics

A novel electroflocculation-membrane (EFM) reactor for pre-concentrating domestic wastewater (DWW) is proposed in this study, using a conventional direct membrane filtration (DMF) reactor as a control. The results showed that under the operating conditions of a current density of 5 A/m2, an electrolysis time of 2.5 h and an inter-electrode distance of 25 mm, an obviously higher organics recovery efficiency of 72.92 % can be achieved in EFM, while only 55.14 % was obtained in DMF. Concentrate with chemical oxygen demand (COD) concentration of 4391.50 mg/L and 3322.88 mg/L was finally got by EFM and DMF, respectively. The higher retention effect of the dissolved organics remained key to the enhanced organics recovery capability of the EFM. Membrane fouling was also mitigated with EFM in continuous operation, with transmembrane pressure (TMP) increasing rate of 0.15 kPa/h (1.27 kPa/h for DMF). The loose and porous floc structure and small size distribution of the supernatant in EFM were the main contributors for reducing the resistance of the cake layer to mitigate membrane fouling. This study provides a new perspective on future wastewater resource recovery.

Mechanism Analysis of Discharge Energy in the Electrostatic-Field-Induced Electrolyte Jet Micro-EDM.

The discharge energy determines the machining resolution, minimum processable feature size, and surface roughness, which makes it a hot research topic in the microelectrical discharge machining (EDM) field. In this paper, a kind of novel discharge-energy-generation method in micro-EDM is investigated. In this method, the opposite induced charges on the electrolyte jet and workpiece serve as the source of the discharge energy. The operating mechanism of this discharge energy is revealed by analyzing the equivalent discharge circuit. The unique discharge current and voltage between the electrolyte jet and the workpiece are sampled and investigated. In contrast with the pulsating energy in conventional EDM, this study shows that the direct current (DC) voltage source can automatically generate a continuously periodical pulsating discharge in the electrostatic-field-induced electrolyte jet (E-Jet) EDM process. After further analyzing the electric signals in a single discharge process, it can be found that the interelectrode voltage experienced a continuous sharp electric breakdown, a nearly unchanging process, and a fast exponential recharging process. The discharge frequency increases as the electrolyte concentration and interelectrode voltage increase but decreases as the interelectrode distance increases. The discharge energy per pulse increases with the increasing interelectrode distance and electrolyte concentration but with the decreasing interelectrode voltage. Finally, the electrostatic-field-induced discharge-energy generation and change mechanisms are revealed, which provides a feasible method for micro-EDM with continuous tiny pulsed energy only using the DC power supply.

Valorizing the Steel Industry Off-Gases: Proof of Concept and Plantwide Design of an Electrified and Catalyst-Free Reverse Water-Gas-Shift-Based Route to Methanol.

Conversion of steel industry off-gases to value-added chemicals enabled by renewable electricity can significantly reduce the environmental burden of the steelmaking process. Herein, we demonstrate that CO2 reduction by H2, both contained in steel mill off-gases, to form syngas via the reverse water-gas-shift reaction is effectively performed by nanosecond pulsed discharges at atmospheric pressure. The experimental results suggest the following: (i) An optimum interelectrode distance exists, maximizing CO2 conversion. (ii) CO2 conversion at constant SEI follows a nonmonotonic trend with H2 excess. CO2 conversion increases with H2 excess up to H2:CO2 = 3:1 upon shifting the chemical equilibrium. At larger H2:CO2, both gas cooling, promoted by the high H2 content, and hindered CO2 collisions in a highly diluted stream hamper CO2 conversion. (iii) SEI enhances CO2 conversion, but the effect decreases with increasing SEI due to equilibrium limitations. A stoichiometric H2:CO2 feed ratio in the plasma reactor is recommended for higher energy efficiency. Intensifying MeOH productivity via SEI elevation is not advised as a 2-fold SEI increase results only in 17% higher MeOH throughput.

Biodegradability enhancement of waste lubricating oil regeneration wastewater using electrocoagulation pretreatment.

As a sustainable management of fossil fuel resources and ecological environment protection, recycling used lubricating oil has received widespread attention. However, large amounts of waste lubricating-oil regeneration wastewater (WLORW) are inevitably produced in the recycling process, and challenges are faced by traditional biological treatment of WLORW. Thus, this study investigated the effectiveness of electrocoagulation (EC) as pretreatment and its removal mechanism. The electrolysis parameters (current density, initial pH, and inter-electrode distance) were considered, and maximal 60.06% of oil removal was achieved at a current density of 15mA/cm2, initial pH of 7, and an inter-electrode distance of 2cm. The dispersed oil of WLORW was relatively easily removed, and most of the oil removal was contributed by emulsified oil within 5-10μm. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that effective removal of the biorefractory organic compounds could contribute to the improvement of biodegradability of WLORW. Thus, the 5-day biochemical oxygen demand/chemical oxygen demand ratio (BOD5/COD) was significantly enhanced by 4.31 times, which highly benefits future biological treatment. The routes of WLORW removal could be concluded as charge neutralization, adsorption bridging, sweep flocculation, and air flotation. The results demonstrate that EC has potential as an effective pretreatment technology for WLORW biological treatment.