Membrane Electrochemical Reactor Research Articles

Enhancing membrane distillation efficiency in treating high salinity organic wastewater: A pressure-driven membrane electrochemical reactor approach

Fouling of membranes continues to be a prominent challenge in the membrane distillation (MD) treatment of high salinity organic wastewater (HSOW). Although membrane electrochemical reactor (MER) can effectively inhibit the membrane fouling of MD, the high cost of the proton exchange membrane (PEM) used in MER limits its widespread application. In this study, cost-effective pressure-driven membranes were employed as a substitute for PEM to establish pressure-driven membrane electrochemical reactors for HSOW pre-treatment. By using ultrafiltration membrane (UFM) and reverse osmosis membrane (ROM), UFMER and ROMER were developed, respectively. Due to the superior electrochemical performance of UFM, UFMER saved 43 % of energy compared to PEMER with the highest removal rate of organics (~85 %) in the simulated HSOW treatment. In practical applications, using UFMER significantly reduced the amount and size of complexes in the real nanofiltration concentrate (NC) of landfill leachate. This contributed to the superior specific flux maintenance (97 %) with a salt rejection (>99 %) and the highest recovered specific water flux (99.6 %) in MD cases. UFMER reduced ~27 % of energy compared to PEMER in MER pre-treatment, and saved the most energy (~39.6 %) in MD post-treatment. Hence, this strategy is potential for forthcoming applications, notably in lowering the membrane cost of MER and energy consumption of both MER and MD.

Feasibility of replacing proton exchange membranes with pressure-driven membranes in membrane electrochemical reactors for high salinity organic wastewater treatment

Membrane electrochemical reactor (MER) shows superiority to electrochemical oxidation (EO) in high salinity organic wastewater (HSOW) treatment, but requirement of proton exchange membranes (PEM) increases investment and maintenance cost. In this work, the feasibility of using low-cost pressure-driven membranes as the separation membrane in MER system was systematically investigated. Commonly used pressure-driven membranes, including loose membranes such as microfiltration (MF) and ultrafiltration (UF), as well as dense membranes like nanofiltration (NF) and reverse osmosis (RO), were employed in the study. When tested in a contamination-free solution, MF and UF exhibited superior electrochemical performance compared to PEM, with comparable pH regulation capabilities in the short term. When foulant (humic acid, Ca2+ and Mg2+) presented in the feed, UF saved the most energy (43 %) compared to PEM with similar removal rate of UV254 (∼85 %). In practical applications of MER for treating nanofiltration concentrate (NC) of landfill leachate, UF saved 27 % energy compared to PEM per cycle with the least Ca2+ and Mg2+ retention in membrane and none obvious organics permeation. For fouled RO and PEM with ion transport impediment, water splitting was exacerbated, which decreased the percentage of oxidation for organics. Overall, replacing of PEM with UF significantly reduce the costs associated with both the investment and operation of MER, which is expected to broaden the practical application for treating HSOW.

Electrochemical hydrogenation of oxidized contaminants for water purification without supporting electrolyte

Electrocatalytic hydrogenation enables the efficient treatment of oxidized contaminants in water under mild conditions, but its application has been greatly hindered by the need for a supporting electrolyte and the large amounts of unsafe intermediate products. Here we report the development of a rhodium nanoparticle-modified palladium membrane electrochemical reactor (Rh NPs-PdMER) for the hydrogenation of oxidized contaminants in drinking water and industrial effluents. The Rh NPs-PdMER not only enabled the hydrogenation of 12 different oxidized contaminants to safe products with ≥99% conversion and ≥95% yield in water without a supporting electrolyte, but also required a very low operating voltage of only 1.4 V. The performance of the Rh NPs-PdMER can be attributed to the specific reactor configuration and the unique adsorbability of the hydrogenated intermediates of the oxidized contaminants to the Rh nanoparticles.

Integrated membrane electrochemical reactor-membrane distillation process for enhanced landfill leachate treatment

Treatment of recalcitrant landfill leachate (LFL) induces huge energy consumption and carbon emissions due to its complex composition. Although membrane distillation (MD) exhibits good potential in LFL treatment with waste heat utilization, membrane fouling and ammonia rejection are still the major problems encountered that hinder its application. Herein, membrane electrochemical reactor (MER) was coupled with MD for simultaneous membrane fouling control and resource recovery. LFL pretreatment with membrane-less electrochemical reactor (EO) and without pretreatment were also purified by MD for comparison. Results showed that the MER-MD system rejected almost all CODCr, total phosphorus, metal salts, and ammonia nitrogen (increased by 33.5%–43.5% without chemical addition), and recovered 31% of ammonia nitrogen and 48% of humic acid in the raw LFL. Owing to the effective removal of hardness (61%) and organics (77%) using MER, the MER-MD system showed higher resistance to the membrane wetting and fouling, with about 61% and 14% higher final vapor flux than those of the MD and EO-MD systems, respectively, and the pure water flux could be fully recovered by alkaline solution cleaning. Moreover, SEM-EDS, ATR-FTIR and XRD characterization further demonstrated the superiority of the MD membrane fouling reversibility of the MER-MD system. Energy consumption and carbon emissions analysis showed that the MER-MD system reduced the total energy consumption/carbon emissions by ∼20% and ∼8% compared to the MD and EO-MD systems, respectively, and the ammonia nitrogen recovered by MER could offset 8.25 kg carbon dioxide equivalent. Therefore, the introduction of MER pretreatment in MD process would be an option to decrease energy consumption and reduce carbon emissions for MD treatment of LFL.

Fabrication of tubular porous titanium membrane electrode and application in electrochemical membrane reactor for treatment of wastewater

In this study, tubular titanium membrane (TTM) /SnO2-Sb/SnO2-Sb-CeO2 porous anode was fabricated and used in continuous tubular membrane reactor for electrochemical treatment of dye wastewater. X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) were used to evaluate the morphology and microstructure of the different tubular titanium membrane. Linear sweep voltammetry (LSV) and accelerated service life test are employed to illustrate the performance of TTM/SnO2-Sb/SnO2-Sb-CeO2 porous membrane electrode. It is found that TTM/SnO2-Sb/SnO2-Sb-CeO2 active layer on titanium membrane has compact microstructure, high over-potential for oxygen evolution (2.10V vs saturated calomel electrode). The effects of pore diameter, applied voltage and flow rate on the electro-catalytic property of the tubular porous electrode were investigated. Study shows titanium membrane reactor with an optimized pore diameter of 10μm has the lowest energy consumption which is important for the practical application of electrochemical technology. The performance of titanium tubular membrane reactor is investigated by treating methylene blue (MB) wastewater under the cell voltage of 3.0–4.5V and the flow rate of 2.5–3.5Lmin−1. This continuous titanium membrane electrochemical reactor using solar cell show excellent performance in treating dye wastewater and the further potential application in electrochemical synthesis.

Decreased formation of disinfection by-products during electrochemical leachate oxidation and their post-removal by electro-adsorption

Membrane electrochemical reactor (MER) is an effective treatment system to remove recalcitrant compounds in landfill leachate but harmful byproducts can be formed during the treatment. Herein, we have investigated the formation of total halogenated organics and the associated toxicity as a side effect of leachate treatment by the MER. Those byproducts are represented by the term “disinfection byproducts, or DBPs”, because of the similar formation mechanisms. Several DBP groups were detected during the leachate treatment; however, the amount of DBP generated in the MER only accounted for 19.1 ± 4.5% of that in a membrane-less electrooxidation system (control). Likewise, the total toxicity value in the MER effluent was 26.6 × 10−3, only 15.1% of that in the control system. While trihalomethanes dominated mass concentration by 84.1% in the MER, haloacetonitriles contributed to majority of the additive toxicity due to their higher toxicity index. Increasing the initial leachate pH from 9.5 to 13 could increase the DBP concentration by 2.18 times because of less removal of humic acids. A high initial ammonia concentration of 6000 mg L−1 resulted in the increased DBP formation by 146.8%, compared to that with 2500 mg L−1, due to the increased formation of nitrogenous DBPs. A higher current density of 30 mA cm−2 doubled the DBP formation because of a faster reaction rate and a higher solution temperature. The extended treatment time caused trihalomethanes to continue forming DBP and degradation of most DBPs to some extent. With removing 67.5% of DBP mass concentration and 74.4% of the additive toxicity, the GAC-electrode system was shown more effective than GAC adsorption alone in remediating DBP from the MER effluent.

Synergistically coupling membrane electrochemical reactor with Fenton process to enhance landfill leachate treatment

Landfill leachate is challenging to treat due to its complex composition. Advanced oxidation processes such as Fenton process can be effective to treat leachate. Herein, a previously developed membrane electrochemical reactor (MER) was coupled with Fenton oxidation through providing synergistic benefits with the low solution pH, reduced organics, and ammonia removal/recovery. This two-stage coupled system reduced the leachate COD by 88%, much higher than that from the standalone Fenton process treating raw leachate. In addition, the usage of chemical reagents has been greatly reduced. At a dimensionless oxidant dose of 1.0, the coupled MER-Fenton system reduced the consumption of both FeSO4⋅7H2O and H2O2 by 39%, H2SO4 by 100%, and NaOH by 55%. Consequently, the sludge production was reduced by 51% in weight and 12% in volume. Despite electricity consumption by the MER, the coupled system cost $4.76 per m3 leachate less than the standalone Fenton treatment. More notably, direct Fenton oxidation removed only 21% of ammonia; in comparison the MER-Fenton system removed ammonia by 98% with the possibility for recovery at a rate of 30.6–55.2 kg N m−3 reactor d−1. Those results demonstrate that coupling MER with Fenton process could mitigate some inherent drawbacks of Fenton oxidation such as ineffective ammonia removal, high acid and chemical reagents dose requirements, and a large amount of sludge generation. This system may be moved towards practical applications by addressing a few challenges such as using renewable energy to power MER.

Removal of landfill leachate ultraviolet quenching substances by electricity induced humic acid precipitation and electrooxidation in a membrane electrochemical reactor

Persistent UV quenching substances (UVQS) in landfill leachate can affect the effectiveness of UV disinfection in domestic wastewater treatment systems when leachate is being co-treated. As a result, effective onsite leachate pre-treatment will have to be implemented to reduce the UV quenching capability. Herein, a membrane electrochemical reactor (MER) was developed and investigated for treating UV quenching organics contained in landfill leachate. Compared to a control reactor that did not have a membrane separator, the MER achieved significantly higher removals of both dissolved organic carbon (61.5 ± 4.1%) and UV254nm absorbance (63.4 ± 8.4%). This enhanced performance was likely due to the combined effects of humic acid precipitation and augmented oxidation of organics. The MER was able to remove 89.1 ± 2.9% of total nitrogen from the leachate while recovering about 51% of the influent ammonia in the catholyte, in comparison to 38.1 ± 4.4% of total nitrogen removal by the control reactor. The MER consumed significantly less electrical energy with specific energy consumption of 70.62 kWh kg−1 DOC or 33.03 kWh kg−1 sCOD, compared to that of the control reactor (211.8 kWh kg−1 DOC or 55.02 kWh kg−1 sCOD). A current density of 20 mA cm−2 was considered optimal in terms of both UVQS removal and energy efficiency. Consideration should be given to the spacing of electrodes to minimize internal resistance and also to avoid trapping of the produced gas bubbles. These results collectively suggest that the MER is a promising onsite pretreatment approach for landfill leachate and further exploration of this technology should be encouraged.

An alternative to hydrogenation processes. Electrocatalytic hydrogenation of benzophenone.

The electrocatalytic hydrogenation of benzophenone was performed at room temperature and atmospheric pressure using a polymer electrolyte membrane electrochemical reactor (PEMER). Palladium (Pd) nanoparticles were synthesised and supported on a carbonaceous matrix (Pd/C) with a 28 wt % of Pd with respect to carbon material. Pd/C was characterised by transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). Cathodes were prepared using Pd electrocatalytic loadings (LPd) of 0.2 and 0.02 mg cm−2. The anode consisted of hydrogen gas diffusion for the electrooxidation of hydrogen gas, and a 117 Nafion exchange membrane acted as a cationic polymer electrolyte membrane. Benzophenone solution was electrochemically hydrogenated in EtOH/water (90/10 v/v) plus 0.1 M H2SO4. Current densities of 10, 15 and 20 mA cm−2 were analysed for the preparative electrochemical hydrogenation of benzophenone and such results led to the highest fractional conversion (XR) of around 30% and a selectivity over 90% for the synthesis of diphenylmethanol upon the lowest current density. With regards to an increase by ten times the Pd electrocatalytic loading the electrocatalytic hydrogenation led neither to an increase in fractional conversion nor to a change in selectivity.

Intensification of the chlor-alkali process by using a spinning disc membrane electrolyzer

A zero-gap spinning disc membrane electrochemical reactor (SDMER) is presented for the intensification of the chlor-alkali process at high current densities up to 20kA/m2. Two configurations of the SDMER, namely rotor-stator (RS) and thin-film (TF), are investigated and compared with a conventional parallel plate (PP) cell. The cell voltage as a function of current density is virtually identical for both SDMER configurations, and lower when compared to PP cell. The effect of the rotational speed on the cell voltage shows a decrease of 0.9V at 6kA/m2 when the rotational speed is increased from 40 to 60rad/s. The estimated membrane permselectivity, increases with increasing current density to values between 0.95 and 0.98. The intensification of the chlor-alkali process was successful with the SDMER by obtaining an approximately three times higher production compared to the PP cell when increasing the current density from 6kA/m2 to 20kA/m2.

PERFORMANCE ASSESSMENT OF A POLYMER ELECTROLYTE MEMBRANE ELECTROCHEMICAL REACTOR UNDER ALKALINE CONDITIONS − A CASE STUDY WITH THE ELECTROOXIDATION OF ALCOHOLS

A novel polymer electrolyte membrane electrochemical reactor (PEMER) configuration has been employed for the direct electrooxidation of propargyl alcohol (PGA), a model primary alcohol, towards its carboxylic acid derivatives in alkaline medium. The PEMER configuration comprised of an anode and cathode based on nanoparticulate Ni and Pt electrocatalysts, respectively, supported on carbonaceous substrates. The electrooxidation of PGA was performed in 1.0M NaOH, where a cathode based on a gas diffusion electrode was manufactured for the reduction of oxygen in alkaline conditions. The performance of a novel alkaline anion-exchange membrane based on Chitosan (CS) and Poly(vinyl) alcohol (PVA) in a 50:50 composition ratio doped with a 5wt.% of poly (4-vinylpyridine) organic ionomer cross-linked, methyl chloride quaternary salt resin (4VP) was assessed as solid polymer electrolyte. The influence of 4VP anionic ionomer loading of 7, 12 and 20wt.% incorporated into the electrocatalytic layers was examined by SEM and cyclic voltammetry (CV) upon the optimisation of the electroactive area, the mechanical stability and cohesion of the catalytic ink onto the carbonaceous substrate for both electrodes. The performance of the 4VP/CS:PVA membrane was compared with the commercial alkaline anion-exchange membrane FAA −a membrane generally used in direct alcohol alkaline fuel cells- in terms of polarisation plots in alkaline conditions. Furthermore, preparative electrolyses of the electrooxidation of PGA was performed under alkaline conditions of 1M NaOH at constant current density of 20mAcm−2 using a PEMER configuration to provide proof of the principle of the feasibility of the electrooxidation of other alcohols in alkaline media. PGA conversion to Z isomers of 3-(2-propynoxy)-2-propenoic acid (Z-PPA) was circa 0.77, with average current efficiency of 0.32. Alkaline stability of the membranes within the PEMER configuration was finally evaluated after the electrooxidation of PGA.

High Performance of Alkaline Anion-Exchange Membranes Based on Chitosan/Poly (vinyl) Alcohol Doped with Graphene Oxide for the Electrooxidation of Primary Alcohols

Mixed matrix membranes (MMM) based on chitosan (CS) and poly (vinyl) alcohol (PVA) with a 50:50 w/w ratio doped with graphene oxide (GO) are prepared by solution casting and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), water uptake, alcohol permeability, ion exchange capacity (IEC) and OH− conductivity measurements. The SEM analysis revealed a dense MMM where the GO nanosheets were well dispersed over the entire polymer matrix. The incorporation of GO increased considerably the thermal stability of the CS:PVA membrane. The GO-based MMM exhibited a low conductivity of 0.19 mS·cm−1 in part because the GO sheets did not change the crystallinity of the CS:PVA matrix. The reinforced structure created by the hydrogen bonds between the GO filler and the CS:PVA matrix resulted to be a good physical barrier for alcohol permeability, achieving a coefficient of diffusion of 3.38 × 10−7 and 2.43 × 10−7 cm2·s−1 after 60 and 120 min, respectively, thus avoiding additional alcohol crossover. Finally, the electrochemical performance of the GO-based MMM in the electrooxidation of propargyl alcohol was investigated in a Polymer Electrolyte Membrane Electrochemical Reactor (PEMER) under alkaline conditions, through the polarization curve and the electrolysis reactions, showing a performance comparable to anion-exchange commercial membranes.

Chitosan:poly (vinyl) alcohol composite alkaline membrane incorporating organic ionomers and layered silicate materials into a PEM electrochemical reactor

Mixed matrix membranes (MMM) are prepared from equivalent blends of poly (vinyl alcohol) (PVA) and chitosan (CS) polymers doped with organic ionomers 4VP and AS4, or inorganic layered titanosilicate AM-4 and stannosilicate UZAR-S3, by solution casting to improve the mechanical and thermal properties, hydroxide conductivity and alcohol barrier effect to reduce the crossover. The structural properties, thermal stability, hydrolytic stability, transport and ionic properties of the prepared composite membranes were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), water uptake, water content, alcohol permeability, thickness, ion exchange capacity (IEC) and OH− conductivity measurements. The addition of both organic and inorganic fillers in a CS:PVA blend polymer enhances the thermal and ionic properties. All the membranes are homogenous, as revealed by the SEM and XRD studies, except when UZAR-S3 stannosilicate is used as filler, which leads to a dual layer structure, a top layer of UZAR-S3 lamellar particles bound together by the polymer matrix and a bottom layer composed mostly of polymer blend. The loss of crystallinity was especially remarkable in 4VP/CS:PVA membrane. Thus, the 4VP/CS:PVA membrane exhibits the best ionic conductivity, whereas the UZAR-S3/CS:PVA membrane the best reduced alcohol crossover. Finally, the performance of the CS:PVA-based membranes were tested in a Polymer Electrolyte Membrane Electrochemical Reactor (PEMER) for the feasibility use of alkaline anionic exchange membranes in electrosynthesis under alkaline conditions, showing the 4VP/CS:PVA and UZAR-S3/CS:PVA membranes the best performances in PEMER.

Electrochemical synthesis at pre-pilot scale of 1-phenylethanol by cathodic reduction of acetophenone using a solid polymer electrolyte

The pre-pilot scale synthesis of 1-phenylethanol was carried out by the cathodic hydrogenation of acetophenone in a 100cm2 (geometric area) Polymer Electrolyte Membrane Electrochemical Reactor. The cathode was a Pd/C electrode. Hydrogen oxidation on a gas diffusion electrode was chosen as anodic reaction in order to take advantage of the hydrogen evolved during the reduction. This hydrogen oxidation provides the protons needed for the synthesis. The synthesis performed with only a solid polymer electrolyte, spe, has lower fractional conversion although a higher selectivity than that carried out using a support–electrolyte–solvent together with a spe. However, the difference between these two cases is rather small and since the work-up and purification of the final product are much easier when only a spe is used, this last process was chosen for the pre-pilot electrochemical synthesis of 1-phenylethanol.

Electrocatalytic hydrogenation of acetophenone using a Polymer Electrolyte Membrane Electrochemical Reactor

The use of a solid polymeric electrolyte, spe, is not commonly found in organic electrosynthesis despite its inherent advantages such as the possible elimination of the electrolyte entailing simpler purification processes, a smaller sized reactor and lower energetic costs. In order to test if it were possible to use a spe in industrial organic electrosynthesis, we studied the synthesis of 1-phenylethanol through the electrochemical hydrogenation of acetophenone using Pd/C 30wt% with different loadings as cathode and a hydrogen gas diffusion anode. A Polymer Electrolyte Membrane Electrochemical Reactor, PEMER, with a fuel cell structure was chosen to carry out electrochemical reduction with a view to simplifying an industrial scale-up of the electrochemical process. We studied the influence of current density and cathode catalyst loading on this electroorganic synthesis. Selectivity for 1-phenylethanol was around 90% with only ethylbenzene and hydrogen detected as by-products.

Use of MEA technology in the synthesis of pharmaceutical compounds: The electrosynthesis of N-acetyl- l-cysteine

The electrosynthesis of N-acetyl- l-cysteine (NAC) from the electroreduction of N,N-diacetyl- l-cystine (NNDAC) using a Polymer Electrolyte Membrane Electrochemical Reactor (PEMER) has been carried out. The Membrane Electrode Assembly (MEA) was formed by a cathode with a catalyst layer made of Pb/C 20 wt% supported on Toray Paper and a catalyst loading of 0.5 mg Pb cm −2. The anode was a 2 mg Pt cm −2 gas diffusion anode fed with H 2. The main advantages of this process are: (1) the electrochemical reactor allows to carry out the electrosynthesis without supporting electrolyte, improving in this way the NAC purification and (2) a pronounced decrease of the electrosynthesis energy consumption due to both, the small internal resistance of the PEMER (electrode gap very small and electrolyte very conductive) and the choice of the H 2 oxidation as anodic reaction in stead of the oxygen evolution reaction from water oxidation. The large number of pharmaceutical applications of NAC, as well as the high versatility of the PEMER for electrosynthesis processes, makes interesting the use of MEAs for electroorganic synthesis.

Membrane electrochemical reactor for continuous regeneration of spent chromium plating baths

Membrane electrochemical reactor for continuous regeneration of spent chromium plating baths

Electrochemical Hydrogenation of Soybean Oil with Hydrogen Gas

Soybean oil has been partially hydrogenated in a proton exchange membrane (PEM) electrochemical reactor, with H2 gas as the anode feed and source of hydrogen. The reactor is similar in design to that used in a H2/O2 fuel cell, with a membrane electrode assembly composed of a Pd-black powder cathode and a Pt-black powder anode fixed to the opposite surfaces of a Nafion 117 cation-exchange membrane. The PEM reactor was operated at a moderate temperature (6090 °C) and 1 atm of pressure using commercial-grade soybean oil as the cathode feed. The effects of the current density, temperature, and oil flow rate on oil hydrogenation current efficiency and product selectivity were investigated. The oil hydrogenation current efficiency (the efficiency of electrogenerated H2 addition to fatty acid double bonds) increased with temperature, decreased with current density, and ranged from 45 to 97%. Partially hydrogenated oil products were characterized by a low percentage of trans-fatty acid isomers (which are known contributors to coronary heart disease) and a moderately high concentration of saturated stearic acid (typical of nonselective, precious metal hydrogenation catalysts). An improvement in fatty acid hydrogenation selectivity was achieved by increasing the oil feed flow rate and inserting a turbulence promoter into the oil feed channel of the PEM reactor. The use of a bimetallic cathode (Pd/Co or Pd/Fe) increased the selectivity of the hydrogenation process, at the expense of a drop in current efficiency and an increase in the trans isomer content of hydro-oil products.

Design and Modelling of a Dialysis Membrane Electrochemical Reactor (D-MER) for Oxidoreductase-Catalysed Synthesis

The study is the first step in a design of an electrochemical reactor able to process enzyme catalysed electrochemical synthesis. To develop economically efficient synthesis, the enzymes must be confined very close to the electrode surface. Here, the confinement was achieved with a dialysis membrane integrated in a classic filter-press electrochemical reactor. A simple electrochemical reaction, without enzymatic catalysis, was used to model the behaviour of the ‘dialysis membrane electrochemical reactor’ (D-MER). The values of the physicochemical parameters were determined by independent experiments, and the thickness of the reaction layer in the reactor was the only parameter to be adjusted numerically. The conditions of this adjustment were discussed. The model gave a good fit to the experimental data and consequently proved that the current design of the reactor is ready to be used with more complex reactions as enzymatic synthesis. A first example was described, based on the glucose oxidase-catalysed synthesis of gluconic acid.

Glucose oxidase catalysed oxidation of glucose in a dialysis membrane electrochemical reactor (D-MER).

The purpose of this work was to evaluate the effectiveness of a new Membrane Electrochemical Reactor (MER) for the production of gluconic acid by glucose oxidase (GOD) catalysed glucose oxidation. The GOD was confined against the electrode surface with a dialysis membrane. The role of the electrochemical step was to eliminate by oxidation the hydrogen peroxide that appeared as a by-product of the reaction and strongly inhibited and/or inactivated GOD. The dialysis MER gave a transformation ratio of 30% with an initial glucose concentration of around 300 mM. This result is significantly better than the maximum of 10% obtained when hydrogen peroxide was eliminated by addition of a large excess of catalase in solution, as is generally done. The D-MER also revealed unexpected properties of the enzyme kinetics, such as an oscillatory behaviour, which were discussed.