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To accommodate the high-frequency and low-frequency power fluctuations of renewable energy generation with a lower system cost, a multi-electrolyzer hybrid hydrogen production system demonstrated potential for application. This study achieved the integration of proton exchange membrane electrolyzers and alkaline electrolyzers through hybrid control in a photovoltaic (PV)- transformer-electrolyzer coupled system for the first time, enabling the pre-regulation of the electrolyzer power based on the LSTM forecast of the power generation of PV, to avoid the impact of sudden large power fluctuations on the electrolyzers, with a lower system cost and higher production rate. Experiment results indicate that this hybrid hydrogen production system reduces system initial investment cost by 27.2% compared to a pure PEMWE system and increases hydrogen production by 58.7% compared to a pure AWE system. • A new hybrid hydrogen production system is proposed. • Coupling of power electronic devices and multiple electrolyzers is simulated. • A high-efficiency and low-cost hydrogen production system adaptable to power fluctuations is established. • Power pre-regulation for multiple electrolyzers based on PV power prediction is established. [ABSTRACT FROM AUTHOR]

The feasibility of hydrogen production using cheese whey wastewater (CWW) in an electrolytic process is investigated. The experimental setup consists of a two-compartment electrolytic cell. Different conditions are evaluated, including several electrode materials, variable pH values, and the type of cell membrane. The optimal conditions involve a 316 stainless-steel anode, nickel foam as the cathode, an anion-exchange membrane, and CWW in both the anolyte and catholyte. It was demonstrated that when using CWW as the electrolyte in the anodic chamber or simultaneously as anolyte and catholyte, it is possible to electrolytically generate hydrogen at voltages below the theoretical value required for water splitting. A maximum hydrogen productivity of 9.78 ± 0.45 L H 2 /L-d was achieved (at 0.51 V), and the energy consumption is only 12.15 kWh/kg H 2. These results show that the electrolytic process produces significantly more hydrogen than the biological fermentative process. • H 2 was electrochemically produced from fermented cheese whey wastewater (CWW). • A maximum hydrogen productivity of 9.8 L H 2 /L-d was achieved. • Metal oxidation reactions from the anode replace the water oxidation in the anolyte. • Low energy consumption in the electrolytic H 2 production process was observed. • Carboxylic acids in the fermented CWW boost the H 2 production in the catholyte. [ABSTRACT FROM AUTHOR]

The gas purging states affect electricity output and energy storage capacity of unitized regenerative fuel cells. In this study, a model of unitized regenerative fuel cell is established. Cell voltages and operating temperatures influences on the dynamic distribution of thermal fluid during purging process and the discharge of residual liquid water in electrolytic cell mode are investigated. The motivation of the present study is better understanding the gas purging characteristics and its effect on reaction behaviors of unitized regenerative fuel cells. Simulation results reveal a significant influence of purging gas temperature on the water flooding and a great effect of operating voltage on the water diffusion. The operating temperature of electrolytic cell model almost has little effect on purging results at different cell temperature and the same purging gas temperature. When the purging gas temperature is changed, higher temperatures of cell and purging gas facilitate liquid water discharging out from the cell regions. In cell water flooding situation, when having large liquid content, the purging gas has little effects on the water expelling process. • EC temperature exhibits obscure effect on water transportation under same purging temperature. • Higher cell temperature and purging temperature facilitate expelling water from the cell. • Purging temperature hardly affects water expelling during the cell flooding processes. • Liquid water remaining in CLs is less under higher cell voltage conditions. [ABSTRACT FROM AUTHOR]

Mesoporous cobalt oxide/nickel foam (NF) is got by a simple chemical method, and a glycerin-based electrolytic cell is rationally assembled with CoO/NF, in which glycerin-KOH aqueous solution is used as electrolyte. Herein, the influence of anodic glycerin oxidation on cathodic hydrogen production is investigated mainly. At 1.35 V vs. reverse hydrogen electrode (RHE), CoO/NF electrode exhibits a current density of 235.71 mA cm−2 for glycerin oxidation, which is about 2.5 times higher than that over Co 3 O 4 /NF. For glycerin oxidation, the Tafel slope (189 mV dec−1) over CoO/NF is much lower, compared to that (286 mV dec−1) over Co 3 O 4 /NF, demonstrating the robust electrocatalyic reaction kinetics over CoO/NF. For glycerin-contained electrolytic cell, a cell voltage (1.672 V) is needed to reach 50 mA cm−2, which is obviously lower than that (1.975 V) for conventional electrolytic cell. It is obvious that for glycerin-contained electrolytic cell, the required cell voltage has obviously decreased by 0.303 V. This work demonstrates that the substitution of glycerin oxidation for sluggish four-electron OER reaction can greatly promote water electrolysis to hydrogen production. Moreover, this design can not only degrade environmental pollutants, but also produce clean energy, and the reported strategy is obviously environment-benign and cost-effective. Image 1 • Electrolytic cells are assembled with glycerin. • Cell voltage is 0.303 V lower than conventional one at 50 mAcm−2. • The HER potential with glycerin is lower than that without glycerin. • The design can not only degrade pollutants, also produce clean energy. [ABSTRACT FROM AUTHOR]

• A critical review on the influence of reactor design for electrochemical CO 2 reduction. • The feature, advantage and disadvantage of all types of electrolytic cells are compared. • H-type cell, flow cell and DEMS cell are emphasized with good potentials. • Perspectives and challenges for electrochemical cells are discussed. Transmute CO 2 to value-added chemical products by electrochemical reduction is a potential candidate and a highly providential route to mitigate CO 2 levels in atmosphere and meet the energy and global warming crisis. Recent reported studies have focused on advancement of novel electro-catalysts with outstanding performance, but unfortunately, little attention has been paid to the influence of reactor design. In this contribution, we for the first time comprehensively review all types of electrolytic cells reported in literatures and compare their features, advantages and disadvantages for CO 2 electro-reduction. To date, H-type cell is still the well-known typical reactor for CO 2 RR, typically for screening electro-catalysts. Based on H-type cell, a similar modified sandwich-type cell is designed to reduce system resistance. However, for industrialization, the flow cell in which the reactants and products are continuously transferred to and away from the electrodes, need further advancement because of its efficient mass transfer efficiency. Besides, the DEMS cell is an effective way to detect products efficiently in real time and analyze reaction process, which is useful for seeking reaction mechanism. The perspectives and challenges for the development of electrochemical cells are also addressed. We hopeful, this review should provide researchers with a clearer understanding of reactor selection, and impart important, timely and valuable insights into the design of advance electrolytic cells and its practical applications for CO 2 reduction. [ABSTRACT FROM AUTHOR]

• Carbon dioxide reduction in a microfluidic electrochemical cell is modeled. • Gradient or double-layers porosity in the gas diffusion electrode is investigated in. • The effects of porosity on fluid flow, diffusion and reaction sites are considered. • Optimized porosity has greater current density and Faraday efficiency. • Structural variation in the cell is investigated under different operating conditions. To obtain better electrical behavior, the linear or double-layers porous electrode is set in microfluidic electrochemical cell for CO 2 diffusion, which couples Tafel's law and Ohm's law with the flow equation and species transport equation for numerical calculations. This research analyzes the effects of linear or double-layer porosity, the thickness of double-layer porosity, and electrode structure in the electrode on current density, CO 2 conversion, and Faraday efficiency under different working conditions. The higher current density and CO 2 conversion occur in the case with smaller porosity in the electrode due to more reactive sites, and poor gas transport is observed simultaneously. Optimizing linear or double-layers porosity distribution results in higher current density, CO 2 conversion, and Faraday efficiency. The Faraday efficiency can reach 91.54% in the case of stepwise increasing porosity from 0.3 to 0.9 in the electrode. Poor electrical behavior occurs as linear increasing porosity compared to stepwise porosity due to different porosity distributions, and the opposite is the case for decreasing linear porosity. Setting the double-layer porosity along the electrode thickness direction results in larger Faraday efficiency as a thickness ratio of 1:1 and larger current density and CO 2 conversion as a thickness ratio of 4:1 in the case of porosity from 0.3 to 0.9. Better electrochemical behavior occurs with electrode thickness to length ratio of 10–20 and the CO 2 gas channel to electrode thickness ratio of 1:1–4:1, and optimized electrode porosities tend to show higher Faraday efficiencies during electrode structural changes. [ABSTRACT FROM AUTHOR]

• A two-phase simulation in a unitized regenerative fuel cell is performed. • Relative humidity effect on purging is studied under severe water flooding condition. • Purging result shows diverse effects on cell start-up performance in fuel cell mode. A unitized regenerative fuel cell is a typical gas–liquid two-phase system that consumes oxygen and hydrogen in a fuel cell mode and liquid water in an electrolytic cell mode. Liquid water removal is crucial for a successful cell start-up after the electrolytic cell mode ends. However, investigations on two-phase transfer mechanisms for liquid water removal are limited during mode switching. To fill this research gap, a three-dimensional two-phase full-cell model is developed to describe charges, gas mixtures and liquid water transfer corresponding to operational modes of electrolytic cell, gas purging and fuel cell. The cell is assumed to being in the isothermal state. Numerical model is analyzed by using COMSOL Multiphysics 5.3a software. Furthermore, experimental and simulated results are compared to validate the proposed model. Results show that more than 84.0% of pore volume is occupied with liquid water on porous layers in an electrolytic cell mode. Although pre-switching for water removal can decrease the volume fraction of liquid water within the porous layers from 0.88 to 0.50 in a short time, more time is required for liquid water being carried away under a low level of water flooding. Purging result presents diverse influences on start-up performance in a fuel cell mode. Liquid water distribution, which is similar to that in a fuel cell mode, formed in a purging mode is encouraged for promoting a quick and stable start-up in a fuel cell mode. [ABSTRACT FROM AUTHOR]

Hydrogen production from the sulfur–iodine water splitting cycle integrated with solar or nuclear energy has been proposed as a promising technique. Bunsen reaction is one of the three main steps in the cycle and electrochemical method has been applied to this reaction. In present work, a three-dimensional numerical study of the electrochemical Bunsen reaction was conducted. A three-dimensional, steady state, laminar and isothermal mathematical model of electrolytic cell was developed and verified by experiments. The spatial maldistribution of species concentration was found between electrodes and proton exchange membrane (PEM). The electric power drives most H 2 SO 4 and I 2 to the anode and cathode surface, respectively, while the proton attraction contributes to HI enrichment on the surface of PEM. At the high inlet H 2 SO 4 concentration of 50 wt%, the transformation of flow channel from single serpentine to single entry & double serpentine with the same inlet flow rate cannot solve the insufficient problem of SO 2. But the increase of the overall inlet flow rate in the double entry & double serpentine flow channel make SO 2 sufficient for anode reaction. Further decreasing the inlet H 2 SO 4 concentration to 40 wt% and 30 wt% make the initial SO 2 sufficient for overall reactions. The single serpentine channel gives the highest SO 2 conversion rate, followed by the single entry & double serpentine and double entry & double serpentine flow channels. The single serpentine flow channel at the H 2 SO 4 inlet concentration of 40 wt% is found optimal for achieving a high electrochemical Bunsen reaction performance. • Three-dimensional study of electrochemical Bunsen reaction was first conducted. • A 3-D, steady state, laminar and isothermal model of EC was developed. • Transformation of flow channel and key initial conditions were analyzed. • Single serpentine flow channel at inlet H 2 SO 4 of 40 wt% was optimal. [ABSTRACT FROM AUTHOR]

• The AEC-PEMFC system shows greater flexibility and cost compared to an HP system. • A 16–20 h load prediction horizon is found effective for operation optimization. • MPC using load interval prediction optimizes and generalizes well. • RL using load point prediction optimizes better, but is risky in generalization. Low carbon energy systems are dependent on renewable power sources, which present challenges in controllability compared to conventional sources. This poses difficulties in maintaining grid balance. To address these challenges, demand response mechanisms and low-carbon technologies are being implemented, particularly in the residential sector, which is a significant consumer of electricity and heat. In this respect, on-site hydrogen production by alkaline electrolytic cell (AEC) and proton exchange membrane fuel cell - combined heat and power (PEMFC-CHP) systems are of particular interest for their potential to improve grid flexibility. For uncovering the flexibility and techno-economic gaps of the hydrogen based system, this study compares the performance of an AEC-PEMFC-CHP system with a market-competitive heat pump (HP) system for a residential community scenario. Results from a two-step capacity-operation optimization using advanced methods demonstrate that the AEC-PEMFC-CHP system offers greater flexibility but at the expense of higher power consumption and lower efficiency. In detail, the cost of the AEC-PEMFC-CHP system is 2.3 times higher than that of the typical HP system, implying that it would require a 0.6 times higher efficiency and a 1/10th lower equipment cost to compete. Furthermore, load prediction plays a critical role in optimizing both systems, with a longer prediction horizon of 16–20 h proving effective even with larger prediction errors. [ABSTRACT FROM AUTHOR]

Lithium rechargeable batteries have been used for lithium extraction in recent years. Here, we report on a highly selective lithium recovery system that consists of a LiMn 2 O 4 positive electrode, a Li 1-x Mn 2 O 4 negative electrode and a monovalent selective anion-exchange membrane. The effect of potential, temperature and coexisting ions on lithium extraction were investigated in this paper, and the lithium recovery system was applied to extract lithium from brine and concentrated seawater. The extraction capacity of Li + reached 34.31 mg· (1 g LiMn 2 O 4 ) −1 at 1.2 V. With higher reaction rate and lower energy consumption, 25 °C (room temperature) was considered as the appropriate temperature. The system still remained high selective for Li + even in the presence of impurity ions (K + , Na + , Mg 2+ , Ca 2+ ). With simulated brine and concentrated seawater as source solutions, the concentrations of Na + , Mg 2+ and Ca 2+ were reduced more than 300, 70 and 100 times, consuming 18–19 W h per mole of lithium recovered. And the electrodes still had high separation coefficients of Li + and Me n+ (Na + , Mg 2+ , Ca 2+ ) after five cycles although a slight drop was existing. [ABSTRACT FROM AUTHOR]

An electrostatic-induction potential-superposed hydrogen electrolytic cell for the synthesis of stoichiometric H 2 –O 2 fuel for fuel cells has been developed for use of the hydrogen energy cycle to produce electric power. This hydrogen electrolytic system works on a mechanism, where the power used is theoretically 17% of the total electrical energy required, while the remaining 83% is provided as electrostatic energy. A combined cycle of H 2 –O 2 fuel cell and this type of electrolyser is introduced to achieve the highest energy efficiency for a fuel cell and full sustainability for the fuel. Part of the power delivered by the fuel cell is returned to the electrolyser, while the remaining represents the net power output. According to theoretical calculations, the net power output can exceed 70% of that delivered by the H 2 –O 2 fuel cell, without violating the laws of thermodynamics. [ABSTRACT FROM AUTHOR]

• DD was coupled with electro-reduction to remove nitrate from groundwater. • Environmental impacts are reduced by electro-chemically treatment of DD waste. • Nitrate flux of 63 mmol/m2 h was reached at RT of 40 min of Donnan dialysis. • Electro-reduction of nitrate in DD waste consumed 0.03 kWh/mmol NO 3 –. • 65% N 2 -selectivity and no NH 3 formation was obtained using Cu-DSA electrode pair. In this study, Donnan dialysis (DD) was applied to denitrify synthetic groundwater and electro-reduction was utilized as a post-treatment to remove the nitrate from the secondary waste generated during the DD process. Combined experiments were performed under continuous operating mode using a synthetic solution mimicking nitrate-contaminated groundwater found in agriculturally intensive regions of Italy. The influence of residence time on thie removal efficiency of nitrate in each reactor was studied. The effects of nitrate concentration, accompanying ions, and by-product formation were tested in the electrolyzer. In DD, nitrate, along with the accompanying ions bicarbonate and sulfate, was transported through an anion exchange membrane into a 100 mM NaCl receiving stream. Higher removal efficiencies were obtained with prolonged residence time, up to 65% at RT of 120 min. A maximum of 60% electro-reduction of nitrate , using a Cu-DSA electrode pair, was achieved at a residence time of ≥90 min. The specific energy consumption did not change significantly with the electrolysis RT ranging from 40 to 120 min. An increase in the nitrate concentration resulted in higher removal efficiency and reduced energy consumption. During the electrolysis of the DD waste, no ammonia was formed and 100% N 2 -selectivity was obtained. [ABSTRACT FROM AUTHOR]

The SO 2 -depolarized electrolysis (SDE) is one of the main processes in the hybrid sulfur cycle for hydrogen production, the microscopic characteristics of which are still not clear. In this work, a numerical analysis of SDE was conducted. The steady-state, laminar and incompressible 2D model of the electrolytic cell (EC) for carrying out SDE was first developed and verified. Physical field characterization indicated that the velocity was almost uniformly distributed in the flow channel, but higher pressure drops and pumping power consumption existed in the anode channel than in the cathode channel. Meanwhile, the continuous conversion of SO 2 to H 2 SO 4 at anode and generation of H 2 at cathode along the channel length were determined. Further exploring the impacts of three main operating parameters implied that an appropriate higher electrolytic potential, lower inlet flow rate (not less than 0.005 m/s) and operating temperature were favorable for improving the SDE. After comprehensive consideration of SDE performance and energy consumption, a feasible operating condition of 0.8 V, 303 K, and 0.005 m/s was proposed for SDE process. The developed model and microscopic characterization of SDE will favor the design and optimization of EC for SDE process. [Display omitted] [ABSTRACT FROM AUTHOR]

Highlights: [•] 4% CO2 concentration in the flue gas is the most economical and technical configuration for CO2 capture. [•] The waste heat recovery allows to reduce by 58% the cost of capture. [•] In the most favorable case, the capture cost is 100.15$/ton Al (4.86% increase on the aluminum price). [•] With thermal integration and incomes from tax, the capture represents 2.06% increase on its actual production cost. [ABSTRACT FROM AUTHOR]

Abstract: A numerical model for a microfluidic electrolytic cell (MEC) for CO2 utilization and fuel production is developed and validated against experimental data in literature. Mass transfer and electrochemical characteristics at the cathode of the MEC are studied. Limiting factors to the cell performance are found to be (i) low diffusivity of CO2 in the porous electrode, (ii) competing hydrogen evolution reaction (HER) at the cathode and (iii) dilution effect of hydrogen. Parametric effects are also studied to find strategies to optimize the cell performance. [Copyright &y& Elsevier]

Abstract: An electrolytic cell (EC), composed of two ruthenium-plated titanium electrodes separated by cation-exchange membranes, was fabricated and evaluated for online postcolumn derivatization in ion chromatography (IC). Folic acid (FA) and methotrexate (MTX) were preliminarily used as prototype analytes to test the performance of EC. After separation by an anion exchange column, FA and MTX, which emit very weak fluorescence when excited, were electrochemically oxidized online in the anode chamber of the EC. The compounds with strong fluorescence, which are oxidation products, were detected by the fluorescence detector. The phosphate buffer solution (100mM KH2PO4) served as an optimal eluent for anion exchange chromatographic separation and a suitable supporting electrolyte for electro-oxidation, leading to ideal compatibility between IC separation and the postcolumn electrochemical derivatization. For the presently proposed method, the linear ranges were from 0.01mgL−1 to 5mgL−1 for both FA and MTX. The detection limits of FA and MTX were 1.8and 2.1μgL−1, and the relative standard deviations (RSD, n =7) were 2.9% and 3.6%, respectively. The method was applied for the simultaneous determination of FA and MTX in the plasma of patients being treated for rheumatoid arthritis. The determination of MTX in the urine of the patients of diffuse large B cell lymphoma was also demonstrated. [Copyright &y& Elsevier]

Abstract: Hygrometers for monitoring of water vapour (moisture) in natural gases have been investigated with respect to influence from methanol co-exposure, during a total of 34 days of experiments. The tested hygrometers are based on capacitor sensor, quartz crystal microbalance (QCM), electrolytic cell, fibre-optic sensor and conversion of water to ethyne with calcium carbide (CaC2-GC), respectively. In the latter technique ethyne was quantified by a gas chromatograph (GC). While monitoring moisture at the level of 45μmol/mol, the hygrometers were exposed to approximately (10, 170 and 750)μmol/mol gaseous methanol. The experiments were performed in the laboratory, using nitrogen as the matrix gas. Exposure to approximately 10μmol/mol methanol demonstrated no clear effect on the tested hygrometers. At the higher levels of 170μmol/mol and 750μmol/mol methanol, the readings from several hygrometers were affected. Taken into account the specified uncertainty of the hygrometers, only the electrolytic cell and one of the two tested capacitor sensors (Capacitor B) were significantly affected during the test period. They demonstrated severe misreading as a result of methanol exposure. The readings from the fibre-optic sensor drifted slowly upwards during exposure to the higher methanol levels. The drift speed increased with increasing methanol concentration. However, despite the drift, the readings from the fibre-optic sensor stayed within its specified uncertainty (±2°C) during the test period. The QCM made a minor shift to higher readings when exposed to 750μmol/mol methanol. Similar shifts were noticed for the two different brands of capacitor sensors tested. Both capacitor sensors also demonstrated a permanent downward drift during the experiments, one of them increasing the drift speed upon increased methanol concentration. The CaC2-GC did not show any clear influence from methanol. The results imply that methanol exposure should be taken into consideration when choosing equipment for moisture monitoring and when determining a quality control strategy for the monitoring. [Copyright &y& Elsevier]

Abstract: Hygrometers for monitoring of water vapour (moisture) in natural gases were compared with respect to accuracy, long term stability and response time. The hygrometers were based on capacitor sensor, quartz crystal microbalance (QCM), electrolytic cell, fibre-optic sensor and conversion of water to ethyne with calcium carbide (CaC2-GC), respectively. In the latter technique, ethyne was quantified by a gas chromatograph (GC). Monitoring of water vapour concentrations between 20μmol/mol and 120μmol/mol was carried out in the laboratory, using nitrogen as the matrix gas. The capacitor hygrometers and the electrolytic cell hygrometer tested in this work showed a tendency to drift, which reduced their accuracy. The QCM, fibre-optic and CaC2-GC hygrometer showed good accuracy and long term stability. The QCM hygrometer had the overall shortest response times. The results demonstrated the need for careful quality control of the hygrometers, and monitoring systems which are thoroughly fitted to the requirements of individual natural gas applications. [Copyright &y& Elsevier]

Abstract: The removal of nitrate and potassium from wheat leachate solution was studied using an electrolytic cell in batch recirculation mode. High nitrate and potassium removals were obtained at 5, 6, 7, 8 and 9V. Anions removals over 90% were obtained after 200min of operation at these constant applied voltages. A maximum nitrate and potassium removal of 100% and 99.82%, respectively, was obtained at 9V. During the electrolytic cell operation, the removal of monovalent anions was found to be higher than divalent and trivalent ones. This is different from the selectivity of monovalent and divalent cations found when cation-exchange membrane is used where the removal of monovalent and divalent cations is very similar. [Copyright &y& Elsevier]

Abstract: In the present investigation, a vertical disc electrode was vibrated in a rectangular electrolytic cell. The cell consisted of equimolal potassium ferricyanide and ferrocyanide electrolyte with excess indifferent electrolyte, sodium hydroxide. The mass transfer data were obtained on the disc electrode by varying the amplitude of vibration (0.033 to 0.089m), frequency of vibration (2.93 to 16.16Hz) and diameter (0.0125 to 0.0315m) of the disc electrode. The mass transfer coefficient was increased with the decrease in the diameter of the disc electrode. The mass transfer coefficient was enhanced from 12 to 52 fold due to vibration. [ABSTRACT FROM AUTHOR]

Abstract: An innovative, nanostructured composite, anode electrocatalyst, material has been developed for the electrolytic splitting of (100%) H2S feed content gas operating at 135 kPa and 150 °C. A new class of anode electrocatalyst with general composition, RuO2–CoS2 has shown great stability and desired properties at typical operating conditions. This configuration showed stable electrochemical operation over the period of 24 h and also exhibited a maximum current density of (0.019 A/cm2). The kinetic behaviors of various anode-based electrocatalysts demonstrated that, exchange current density, which is a direct measure of the electrochemical reaction, increased with RuO2–CoS2-based anodes. Moreover, high levels of feed utilization were possible using these materials. Electrochemical performance, current density, and sulfur tolerance were enhanced compared to the other tested anode configurations. The structural, microstructural and surface behavior of RuO2–CoS2 anode electrocatalyst was investigated in detail. [ABSTRACT FROM AUTHOR]

Abstract: Systematic experiments were performed on an electrolytic cell using different ionic species and covering a large range of concentration values. Experimental data indicate that cell impedance is well described by a series combination of discrete circuit elements different from that originally proposed by Randles. A first-principle model describing diffusion and migration of the ionic species excited by an applied electric field was able to describe our data. This model relates the spectral decomposition of the measured impedance to spatially distributed sample properties, and opens the possibility of getting information concerning sample structure using this experimental technique. [Copyright &y& Elsevier]

Abstract: Slaughterhouse wastewaters contain varied and high amounts of organic matter (e.g., proteins, blood, fat). In order to produce an effluent suitable for stream discharge, electrochemical techniques have been particularly explored at the laboratory pilot scale for organic compounds removal from poultry slaughterhouse (PS) effluent. Electrocoagulation (EC) process was tested using either mild steel or aluminium electrodes arranged in bipolar (BP) or monopolar configuration system. Results showed that the best performance was obtained using mild steel BP electrode system operated at a current intensity of 0.3A, through 60 or 90min of treatment. Under these conditions, removals of 86±1% and 99±1% were measured for BOD and oil and grease, respectively, whereas soluble COD and total COD were removed by 50±4% and 82±2%, respectively. EC is also efficient for decolorization (red-color) and clarification of the PS effluent. Removals of 89±4% and 90±4% have been measured for total suspended solids and turbidity, respectively. Electrochemical coagulation operated under the optimal conditions involves a total cost of 0.71 USD $ per cubic meter of treated PS effluent. This cost includes energy and electrode consumptions, chemicals, and sludge disposal. [Copyright &y& Elsevier]

The effects of the presence of copper on the photooxidation of phenol and 4-chlorophenol and of the presence of the phenols on the recovery of copper by electrodeposition are studied in three systems: a photolytic cell in the presence and absence of TiO2 as a catalyst or H2O2 as an oxidant; an electrolytic cell and a combined photolytic–electrolytic system. The optimum system for the simultaneous removal of copper and destruction of the phenols which overcomes the effects of copper–phenol reactions is a combined system with concentrator electrode technology incorporated into the electrolytic cell. This combined system achieves >99% removal of copper and destruction of phenol or 4-chlorophenol in an 8 h period. [Copyright &y& Elsevier]

Mass transfer data have been obtained for copper microelectrodes fixed flush with the surface of a rectangular perspex electrode support firmly fixed in an electrolytic cell. Circular cylindrical promoters were inserted at the bottom of the cell. The electrolyte was equimolal potassium ferricyanide, potassium ferrocyanide and excess sodium hydroxide. The mass transfer data were obtained for the reduction of ferricyanide ion. The mass transfer coefficient increased with increased flow rate of the electrolyte and diameter of the promoter and decreased with increase in spacing between the promoters. [Copyright &y& Elsevier]

A pilot scale sodium hypochlorite (NaClO) continuous generator is described in this paper, which was used for anti-microbial applications, basically for cleaning-in-place (CIP) or sterilizing-in-place (SIP), in food industry. The electrolytic cell was constructed as a tubular electrochemical reactor with a nylon net membrane between the electrodes and with a layer of rare-earth metallic oxide, RuO2, as catalytic coating on the titanium-anode surface. The performance of this sodium hypochlorite continuous generator was analyzed from a reaction engineering view point. The electric current efficiency was above 82% and the consumption of sodium chlorine was 2.7 kg for producing 1 kg of available chlorine (Cl2). The sterilizing water production rate ranged from 810 to 1080 l per hour with an available chlorine concentration of 200–150 ppm. [ABSTRACT FROM AUTHOR]

A comparison study of an electrolytic, adsorption, and a novel hybrid method towards the removal of malachite green (MGD) dye from the aquatic environment utilizing agricultural biomass, Eucalyptus globulus seeds was examined. The synthesized material has been characterized by thermogravimetric analysis, SEM, FTIR, and XRD. The acid-modified biosorbent developed a microporous structure suggesting a suitable removal process of MDG. The hybrid method was carried in an indigenously designed three-phase three-dimensional electrolytic reactor with varying applied voltage (6, 9, and 12 V) with biosorbent serving as particle electrode. The hybrid method gave the highest removal rate at a voltage of 12 V, compared to other methods. Moreover, the dye removal capacity increased with increased voltage, and contact time was optimized at 15 min. The adsorption isotherm was well fitted with Freundlich isotherm and kinetic data represented pseudo-second-order. Intra particle diffusion studies suggested no interference with gradual adsorption from macropores to micropores. The removal efficiency of particles electrodes for 6, 9, and 12 V were 95, 97, and 99.8%, respectively. The higher removal of MDG towards the hybrid system may be assigned to the synergistic effect of electrolytic and adsorption systems. Regeneration studies indicated that the biosorbent can be reused up to ten times without appreciable loss of efficiency. [Display omitted] • Eucalyptus globulus seeds was utilized as a particles electrode in hybrid system. • In hybrid system, adsorption is dominated. • The highest dye removal rate was achieved at 12 V and at 15 min. • Particle electrode has heterogeneous surface followed pseudo-second order kinetics. • Particle electrode showed excellent regeneration behaviour up to 10 cycles. [ABSTRACT FROM AUTHOR]

Porous separators have been widely used in classical alkaline electrolysers. The development of an advanced separator with low ohmic resistance and hydrogen permeability is essential for operating a high-rate alkaline electrolyser in a dynamic mode. In this study, we report the synthesis of a Zirfon-type separator with a reduced ohmic resistance of 0.10 Ω cm2 and hydrogen permeability of 0.2 × 10−12 mol cm−1 bar−1 sec−1 measured in 30 wt% KOH electrolyte solution at ambient conditions while exploring the effects of coagulation temperature, poly(vinylpyrrolidone) addition, and separator thickness. This separator was employed in the single cell of a lab-scale water electrolyser with non-noble metal catalysts demonstrating a stable cell voltage of 1.83 V at a current density of 1000 mA cm−2, temperature of 80 °C, and 30 wt% KOH concentration in the electrolyte solution during 300 h of operation. The anodic hydrogen content at a low current density of 50 mA cm−2, differential pressure of 0.3 bar, and temperature of 80 °C was only 1.2%, while the corresponding value obtained for a Zirfon PERL separator exceeded 2%. These results are comparable with the cell parameters previously achieved using anion exchange membranes combined with noble metal-based catalysts. • A separator with low ohmic resistance and hydrogen permeability is synthesised. • A durability test is conducted to evaluate the separator thermal stability. • Polarisation characteristics of the cell containing the new separator are studied. • Effects of electrolyte circulation flow modes on separator properties are examined. [ABSTRACT FROM AUTHOR]