双极膜成对电合成L-磺基丙氨酸和L-半胱氨酸

利用自制的CuTsPc-SA/CuTAPc-CS双极膜（CuTsPc：四磺酸基铜酞菁;SA：海藻酸钠;CuTAPc：四氨基铜酞菁;CS：壳聚糖）作为电解槽隔膜,成对电解L-胱氨酸合成L-磺基丙氨酸和L-半胱氨酸,提高了电流效率,降低了生产成本。研究表明,电解时电流密度以35mA/cm^2为宜,阴极室L-胱氨酸的初始浓度以0.65mol/L为宜。当氢溴酸浓度为3 mol/L时,阳极室电流效率达到最大值,为85.1%。     

Comparative study of hydrogen peroxide electro-generation on gas-diffusion electrodes in undivided and membrane cells

The generation of hydrogen peroxide by means of the cathodic reduction of oxygen at gas-diffusion electrodes with a near 100% current efficiency was achieved in concentrations sufficient for the mineralization of refractory organics in Fenton treatment. A decrease in current efficiency over time at high temperatures and high current densities was observed. The polarization study carried out in potentiostatic, potentiodynamic and galvanostatic modes in 0.5 M Na₂SO₄ solution at pH 3 showed that the destruction of hydrogen peroxide at the cathode of the electrochemical reactor, as well as its chemical decomposition in the bulk solution, takes place at a significantly lower rate than the oxidation of H₂O₂ at the Ti–IrO₂ anode. Preparative electrolysis in the membrane reactor showed much higher current efficiencies for H₂O₂ electro-generation in comparison with tests carried out in an undivided cell. The performance of different proton-exchange membrane in this process was studied and a membrane cell with a heterogeneous MK-40 type PEM was found to be suitable. An optimized cell design, the appropriate selection of electrodes, supporting electrolytes, and a membrane resulted in a lower voltage in the membrane cell in comparison with the undivided cell.     

HBr electrolysis in the Ispara Mark 13A flue gas desulphurization process: electrolysis in a DEM cell

The potential application of a DEM cell for the electrolysis of hydrogen bromide in the Ispra Mark 13A process for flue gas desulphurization has been tested in a number of laboratory experiments and in long-duration tests in a bench-scale plant of the process. Satisfactory electrode materials have been found, i.e. Hastelloy C 276 for the cathode and a RuO₂ coating on titanium for the anode. Both electrode materials showed a good stability during a 1500 hours experiment. Cell voltage/current density relationships have been determined during bench-scale plant operation. A typical value is 1.5V at a current density of 2.5 kA m^–2. It has been shown that in an undivided cell a cathodic back reaction occurs which causes a decrease of the current efficiency. Under normal operation conditions current efficiencies of about 90% are obtained.A simplified flow model for the DEM cell was developed which is useful in understanding the phenomena which occur during scale-up of the cell. An industrial size installation for the production of 170 kg h^–1 of bromine at a current density of 2 kA m^–2 was constructed and has been in operation since August 1989.Nomenclature a _x thermodynamic activity of the constituentx (mol cm^–3) - C bromine concentration (mol l^–1) - e _z local current efficiency - e _ov overall cell efficiency - E _a ⁰ anodic standard potential (V) - E _c ⁰ cathodic standard potential (V) - E _a ^c equilibrium anode potential (V) - E _e ^c equilibrium cathode potential (V) - F Faraday number (C mol^–1) - g _a anodic overpotential (V) - g _c cathodic overpotential (V) - G electrolyte flow rate (l h^–1) - i current density (A m^–2) - K _c cathodic back reaction rate factor (l mol^–1) - L cell width (m) - n number of electrons involved (n=2) - R gas constant (J K^–1 mol^–1) - R _cell cell resistance (ohm m²) - R _c circuit resistance (ohm m²) - w _b local cathodic back reaction rate (mol m^–2 h^–1) - w _th local theoretical reaction rate (mol m^–2 h^–1) - W _th overall theoretical reaction rate (mol h^–1) - T temperature (K) - Z cell length (m)     

Electrochemical bromination and oxidation of alkyl aromatic compounds by two-phase electrolysis

A simple, regioselective, environmentally clean and economical method for the preparation of side chain/ ring brominated aromatic compounds is reported in 70–98% yield by an electrochemical method using two phase electrolysis technique. Electrochemical reactions were carried out using aqueous 25–50 wt% sodium bromide containing catalytic amount (5 wt%) of hydrobromic acid as an aqueous phase and chloroform containing alkyl aromatic compounds as an organic phase, at a temperature of 0–30 °C in an undivided cell. The same two-phase electrolytic system can be used for the oxidation of benzylic alcohols to the corresponding benzaldehydes in 80–94% yield without over oxidation to carboxylic acids. The advantage of this very mild procedure is a room temperature reaction used with an undivided cell. Excellent conversions are observed. After completion of alcohol oxidation the electrolyte can be reused for a number of times, demonstrating “spent reagent” free electro organic reaction as an attractive one. In the case of side chain/ring bromination of alkyl aromatic compounds, the electrolyte can be reused after making up the concentration of the electrolyte with 47 wt% HBr solution. In some cases homogeneous electrolysis is applied, where the two-phase electrolysis did not work. Styrene epoxidation and α-bromination of ketones underwent homogeneous electrolysis at room temperature without any catalyst. The reaction was performed in CH₃CN-water (3: 2) using equimolar amount of NaBr as an electrolyte to get 68% of styrene epoxide. Use of an ionic liquid 1-butyl 3-methyl imidazolium bromide (Bmim) Br, instead of NaBr improved the yield and current efficiency of styrene epoxide to 86%.     

Hydrogen production from wastewater using a microbial electrolysis cell

A Microbial electrolysis cell (MEC) was designed to produce a useful and valuable product, hydrogen gas, during the wastewater treatment process. Hydrogen can be produced using the MEC with an applied voltage of over 0.4 V, and the hydrogen yields gradually increased with the increasing of applied voltage. A maximum overall hydrogen efficiency of 21.2% was achieved at an applied voltage of 1.0 V with acetate as substrate, corresponding to a volumetric hydrogen production rate of approximately 0.095 m³ H₂/m³ reactor liquid volume/day. A volumetric hydrogen production rate of 0.061 m³ H₂/m³ reactor liquid volume/day was achieved when piggery wastewater was fed to the MEC, and the chemical oxygen demand removal rate ranged from 45 to 52%. The results demonstrated that the wastewater, especially an organic-rich item such as piggery wastewater, could be feasibly treated based on this MEC system.     

A simple and inexpensive microfluidic electrolysis cell

A single channel microfluidic electrolysis cell based on inexpensive materials and fabrication techniques is described. The cell is characterised using the electrochemistry of the Fe(CN)₆³⁻/Fe(CN)₆⁴⁻ couple and its application in electrosynthesis is illustrated using the methoxylation reactions of N-formylpyrrolidine and 4-t-butyltoluene. It is shown that the reactions can be carried out with a good conversion in a single pass. The device, as described, allows the production of several mmol/hour of the methoxylated products.     

Highly stable novel inorganic hydrides from aqueous electrolysis and plasma electrolysis

After 10⁴ h of continuous aqueous electrolysis with K₂CO₃ as the electrolyte, highly stable novel inorganic hydride compounds such as KH KHCO₃ and KH were isolated and identified by time of flight secondary ion mass spectroscopy (ToF-SIMS). The existence of novel hydride ions was determined using X-ray photoelectron spectroscopy (XPS) and solid state magic-angle spinning proton nuclear magnetic resonance spectroscopy (¹H MAS NMR). A novel hydride ion formed by plasma electrolysis of a K₂CO₃, Rb₂CO₃, or Cs₂CO₃ electrolyte was also observed by high resolution visible spectroscopy at 407.0 nm corresponding to its predicted binding energy of 3.05 eV.     

A computational multi-reaction model of a Cu electrolysis cell

A computational model for quantitatively describing the behavior of four simultaneous chemical reactions taking place on two copper electrodes in a Cu–Cu electrolysis cell is formulated. The individual reaction rates, corresponding current densities and total cell current and voltage are obtained as direct model output. The model parameters are found based on cyclic voltammetry experiments done in a Cu–Cu electrolysis cell with CuSO₄ (aq) concentrations between 0.1 M and 1 M. The model is fit against the data of one experiment and compared against a series of other measurements. A full set of model parameters is given and the effect of selected parameters on the simulated current–time response is analyzed.     

The “In-cell” and “Ex-cell” Fenton treatment of phenol, 4-chlorophenol and aniline

A comparative study of phenol, 4-chlorophenol and aniline degradation with the electro-generation of H₂O₂ at gas-diffusion electrodes was carried out under three different conditions: electro-Fenton^® treatment in an undivided cell; electro-Fenton treatment in the catholyte of a membrane cell divided by a proton-exchange membrane (in-cell electro-Fenton membrane process); and a treatment of polluted solution in the cathode space of a membrane cell with the generation of H₂O₂, followed by the addition of Fe(II) salt in the other reactor (ex-cell electro-Fenton process).An optimized cell design with no gap between the membrane and the anode, along with the appropriate choice of supporting electrolytes, ensured a voltage reduction with a membrane cell in comparison with that of an undivided cell. The accumulation of hydrogen peroxide in concentrations sufficient for the almost complete destruction (90–98%) of aromatic organic pollutants was achieved in all cases but the ex-cell process with the preparative electrolysis in the pilot scale membrane reactor separated by the proton-exchange membrane MK-40 showed higher treatment efficiency and lower specific energy consumption in comparison with known technologies. Damage of the gas-diffusion layer was observed in some tests which could be caused by alkaline conditions in the pores of the gas-diffusion cathode (GDE). The pH indicator paper showed a color specific for alkaline media in contact with the GDE treated in the solution with pH 3 in the bulk. A possible explanation could be that even in acid media, hydrogen peroxide generation in pores of the gas diffusion layer proceeds with formation of HO ₂ ^? which is common for alkaline media and consecutive protonation occurs at the interface with the acid solution.     

Coproduction of sulphuric acid and hydrogen by sulphur-assisted water electrolysis process

The addition of sulphur powder to the anode compartment of the sulphuric acid-water electrolysis cell resulted in the suppression of oxygen evolution rate; at a cell voltage of 2 V, there was an acceleration of the hydrogen production rate, and the anode reaction led to the production of sulphate ion (SO ₄ ^2? ) by the oxidation of the sulphur powder. The net equation for this sulphur-assisted water electrolysis system may be written as S + 4H₂O → H₂SO₄ + 3H₂ whose stoichiometry was proved experimentally using phosphoric acid as the electrolyte. The whole process can be rationalized if the anodic oxidation of sulphur occurs at a lower potential than oxygen evolution and hence the energy consumption is lower. Thus the addition of sulphur to the anolyte helps to improve the energy efficiency of the acidic water electrolysis system and generates, simultaneously, sulphuric acid and hydrogen.     

Kolbe electrolysis of CF3COONa,CF2ClCOONa and CF2BrCOONa in acetronitrile solution—1. Product identification and Faradaïc yield

To study the influence on the Kolbe reaction of different halogene substituents, the electrochemical behaviour of CF₃COONa, CF₂ClCOONa and CF₂BrCOONa in acetonitrile solution was compared. It has been shown that in all three cases there is a one electron transfer reaction and that coupling of the radicals formed is the main reaction. However, side chemical reactions are leading to different other products: CH₃H for CF₃COONa and CF₂ClH for CF₂ClCOONa. In the case of CF₂BrCOONa we obtained several side products: CF₂BrH, CF₂Br₂ and C₂F₄. This last product is certainly formed from CF₂: and we have so an interesting new route for the preparation of difluorocarbene at room temperature.     

Water electrolysis in the presence of an ultrasonic field

The energy efficiency of water electrolysis has been considerably improved in the presence of an ultrasonic field. This was demonstrated by measuring the cell voltage, efficiency and energy consumption of the generated gas from the electrolysis. These measurements were carried out in alkaline solution using linear sweep voltammetry (LSV) and galvanostatic polarization techniques. A large reduction of the cell voltage was achieved under the ultrasonic field, especially at high current density and low electrolyte concentration. With the same current density, the cell voltage difference with and without the ultrasonic field fell as the concentration of the electrolyte was increased. The efficiency of H₂ generation was improved at a range of 5-18% at high current density in the ultrasonic field but the efficiency of O₂ generation fell a little due to the difference in the behavior of the gas bubbles. The energy saving for H₂ production by using the ultrasonic field was about 10-25% for a certain concentration of the electrolyte when a high current density was used. On the other hand, the energy consumption for O₂ production with and without the ultrasonic field was almost the same.     

Analysis of the performance of the electrodes in a natural gas assisted steam electrolysis cell

The performance of solid oxide electrolysis (SOE) cells while operating in the natural gas assisted steam electrolysis (NGASE) mode was evaluated. The SOE cells used yttria-stabilized-zirconia (YSZ) as the oxygen ion conducting electrolyte, Co-CeO₂-YSZ as the H₂-H₂O electrode, and Pd-doped as the CH₄-oxidation electrode. The cell electrochemical performance was evaluated as a function of the H₂O/H₂ ratio and the extent of conversion of CH₄. The results of this study provide insight into the factors that control electrode performance and further demonstrate the viability of an NGASE cell for the production of H₂.     

Evaluation of Cu-substituted La1.5Sr0.5NiO4+δ as air electrode for CO2 electrolysis in solid oxide electrolysis cells

Ruddlesden-Popper oxide, Cu-substituted La_1.5Sr_0.5NiO_4+δ series materials (La_1.5Sr_0.5Ni_1-xCu_xO_4+δ; denoted as LSNCu_x; x = 0, 0.1, 0.25, 0.5) are investigated as air electrodes in solid oxide electrolysis cells (SOECs) for electrolysis of CO₂. Room temperature crystal structure, electrical conductivity and oxygen exchange capacity, as well as electrochemical performance of LSNCu_x are comprehensively investigated. Among the series of samples, LSNCu_0.25 half-cell exhibits the lowest polarization resistance value of 0.179 Ω cm² at 800 °C, which decreases by approximately 86.07% compared with that of LSN. In addition, the fuel electrode-supported single cell with LSNCu_0.25 air electrode presents a high current density of 1.2 A cm^?2 at 1.5 V under 30% CO–70% CO₂ condition at 800 °C, which is 207% of LSN (0.58 A cm^?2) under the same condition. Results show that the impressive catalytic activity for oxygen evolution reaction (OER) is ascribed to the improved electronic conductivity and oxygen exchange capacity. With Cu substitution for Ni-site, the contraction of Ni–O bond in NiO₆ octahedron and increased concentration of charge carries owing to the oxidation of Ni²⁺ to Ni³⁺ are beneficial to the electron conduction. The formation of more interstitial oxygen as ionic compensation also favors the oxygen ion diffusion/exchange and greatly accelerates the charge transfer process. Furthermore, no degradation is observed for the single cell durability test at 750 °C for 50 h, which demonstrates the highly stable performance of LSNCu_0.25 air electrode for electrolysis of CO₂.     

Development of a Novel Ceramic Support Layer for Planar Solid Oxide Cells

The conventional solid oxide cell is based on a Ni–YSZ support layer, placed on the fuel side of the cell, also known as the anode supported SOFC. An alternative design, based on a support of porous 3YSZ (3 mol.% Y₂O₃–doped ZrO₂), placed on the oxygen electrode side of the cell, is proposed. Electronic conductivity in the 3YSZ support is obtained post sintering by infiltrating LSC (La_0.6Sr_0.4Co_1.05O₃). The potential advantages of the proposed design is a strong cell, due to the base of a strong ceramic material (3YSZ is a partially stabilized zirconia), and that the LSC infiltration of the support can be done simultaneously with forming the oxygen electrode, since some of the best performing oxygen electrodes are based on infiltrated LSC. The potential of the proposed structure was investigated by testing the mechanical and electrical properties of the support layer. Comparable strength properties to the conventional Ni/YSZ support were seen, and sufficient and fairly stable conductivity of LSC infiltrated 3YSZ was observed. The conductivity of 8–15 S cm^–1 at 850 °C seen for over 600 h, corresponds to a serial resistance of less than 3.5 m Ω cm² of a 300 μm thick support layer.     

Recent developments in the technology of sulphur dioxide depolarized electrolysis

The use of sulphur dioxide as an anode depolarizer in the electrolytic production of hydrogen can considerably reduce the electrical energy input to the electrolyzer. The present work deals with developments in the technology of SO₂-depolarized electrolysis. Recent achievements in electrode fabrication techniques and optimization of cell configuration have resulted in substantial improvements in both cell potential and performance stability. While operating in 50 wt% sulphuric acid at 50° C and 1 atm, the measured cell potentials at 200 and 400mA cm^–2 were 0.77 and 1.05V (including ohmic losses), respectively. A cell endurance test, performed at a constant current density of 100mA cm^–2, indicated that a stabilized cell potential of 675 mV was achieved after 80 hours of continuous operation. The resulting gas from the test cell contained 98.7 vol% hydrogen. The effect of acid concentration in the range 10–60 wt% on the performance characteristics of an SO₂-depolarized electrolyzer was also investigated. Experimental results revealed that the optimum acid concentration for operating SO₂-depolarized electrolyzers is approximately 30 wt%. The observed cell potential was only 0.71 V at 200mA cm^–2.     

Investigation of the electrochemical behavior of catechol and 4-methylcatechol in the presence of methyl mercapto thiadiazol as a nucleophile: application to electrochemical synthesis

The present study concerns the electrochemical behavior of catechol and 4-methylcatechol in the presence of 2-mercapto-5-methyl-1,3,4-thiadiazole (MMT) in aqueous medium on the surface of the glassy carbon electrode by means of cyclic voltammetry and controlled-potential coulometry. The oxidation mechanism was deduced from voltammetric and spectrophotometric data. The electro-generation of quinoid intermediates and their subsequent Michael-type reaction with MMT has been investigated as a clean and convenient strategy for the synthesis of corresponding reaction products. In addition, electro-synthesis of Michael addition products has been successfully accomplished by controlled-potential coulometry in a divided H-type cell in mild conditions that can be considered as a green procedure. The reaction products were characterized by spectrophotometric, ¹H and ¹³C NMR, and mass spectrometric methods.     

Semitransparent inverted polymer solar cells employing a sol-gel-derived TiO2 electron-selective layer on FTO and MoO3/Ag/MoO3 transparent electrode

We report a new semitransparent inverted polymer solar cell (PSC) with a structure of glass/FTO/nc-TiO₂/P3HT:PCBM/MoO₃/Ag/MoO₃. Because high-temperature annealing which decreased the conductivity of indium tin oxide (ITO) must be handled in the process of preparation of nanocrystalline titanium oxide (nc-TiO₂), we replace glass/ITO with a glass/fluorine-doped tin oxide (FTO) substrate to improve the device performance. The experimental results show that the replacing FTO substrate enhances light transmittance between 400 and 600 nm and does not change sheet resistance after annealing treatment. The dependence of device performances on resistivity, light transmittance, and thickness of the MoO₃/Ag/MoO₃ film was investigated. High power conversion efficiency (PCE) was achieved for FTO substrate inverted PSCs, which showed about 75% increase compared to our previously reported ITO substrate device at different thicknesses of the MoO₃/Ag/MoO₃ transparent electrode films illuminated from the FTO side (bottom side) and about 150% increase illuminated from the MoO₃/Ag/MoO₃ side (top side).     

Improving performance of proton ceramic electrolysis cell perovskite anode by Zn doping

As an important renewable energy, hydrogen energy becomes an important part of the future energy system. Proton ceramic electrolysis cell (PCEC) enables the efficient, clean, large-scale preparation of hydrogen, which is a new type of energy conversion device, attracting the attention of many researchers. Sr₂Fe_1.4Zn_0.1Mo_0.5O_6-δ (SFZM) anode materials were developed to investigate the effect of B-site doping of Zn on the electrochemical properties of the Sr₂Fe_1.5Mo_0.5O_6-δ (SFM) materials. The results reveal that the doping of Zn increases the concentration of oxygen vacancies and improves the electrocatalytic activity, which in turn improves the performance of the material. A current density of 408 mA cm⁻² has been achieved at 1.3 V when the SFZM-based single cell was operated in an electrolysis mode (50% H₂O in air) at 600 °C, higher than SFM-based single cells (286 mA cm⁻² at 1.3 V). In addition, the SFZM-based single cell exhibited good durability in a stability test at an electrolysis current density of 408 mA cm⁻². This work confirms that SFZM is a promising material for proton ceramic electrolysis cell anode.     

Potential distribution and electrode stability in a bipolar electrolysis cell

A computational model is presented, which enables the identification of those zones endangered by corrosion in a bipolar electrolysis cell stack. The method consists of two steps: first the potential profile in the electrolyser is computed by numerical solution of the Laplace equation using the finite difference method; then, making use of the Criss-Cobble correspondence principle, this profile is related to the potential-dependent thermodynamic stabilities of the respective metals. This may be a useful tool in the design of intermittently operating electrolysers (for example those powered by solar energy).Nomenclature A metal phase - A _i single A-phase point - B electrolyte phase - B _i single B-phase point - F Faraday constant - h mesh interval (m) - i local current density (A m^–2) - i ₀ exchange current density (A m^–2) - j local current across the double layer (A) - j _iA,j _iB tangential or normal component of the double layer current (A) - K A, B phase conductivity ratio - m molality mol kg^–1 - R gas constant - T absolute temperature (K) - U potential (V) - U ₀ water decomposition voltage (V) - U _tot end plate potential (V) - x, y cartesian coordinates - overrelaxation factor - _a, _c anodic or cathodic overpotential (V) - _A, _B electrical conductivity (^–1 m^–1) - potential (V) - _m local double layer potential, electrode end (V) - _s local double layer potential, electrolyte end (V)