Cadmium Ion Concentration Research Articles

Development of immunoassay methods based on monoclonal antibody and its application in the determination of cadmium ion

Owing to the threat of cadmium (Cd2+) to public health, it is an urgent demand to develop effective, sensitive, and rapid methods for the detection of cadmium. In this study, indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and immunochromatographic test strips (ICTS) were established for the determination of Cd2+ based on the obtained mAb with high specificity and high affinity (Kaff = 3.0 × 109 L/moL). The linear range of ic-ELISA detection was 0.03–1.11 ng/mL and 50% inhibitive concentration (IC50) of cadmium ion was determined to be 0.15 ng/mL. The visual limit of detection (vLOD) of the AuNS-based strip was 0.375 ng/mL. The vLOD of AuNF-based strip using higher intensity reporter determined to be 0.03 ng/mL, which was enhanced 12 times compared to the traditional strip. In summary, the developed immunoassays based on mAb shows great potential for monitoring the cadmium ion in environmental samples.

IMPACT OF CADMIUM SALT CONCENTRATION ON CdS NANOPARTICLES SYNTHESIZED BY CHEMICAL PRECIPITATION METHOD

In this study, cadmium sulfide (CdS) nanoparticles (NPs) were synthesized via chemical precipitation, a facile and cost effective method. The effects of various cadmium salt concentration on the characteristics of CdS NPs has been analyzed to understand the structure properties relationship for optoelectronics applications. XRD, FESEM, Raman Spectra, and UV–Vis has been used to characterize the prepared samples. The optical measurement indicates that there is a direct transition in accordance to energy band gap among 2.36 as well as 2.4 eV. The XRD diffract grams verify that all the films deposited have been polycrystalline of cubic as well as hexagonal structure with superior orientation (111). Analysis of EDX displayed that certain films have been stoichiometric with a small deficiency in sulphur. By optimizing the molar concentration of cadmium ions, the optoelectronic properties of the CdS NPs can be tuned accordingly.

Vegetation engineering structure for heavy metals absorption

The treatment of contaminated water is a pressing issue. As a solution it is proposed to use a biological engineering construction with the aquatic vegetation - a bioplato. The process of water purification takes place at the expense of the natural capacity of a number of living organisms and plants to transform and absorb contaminants [1]. The phytoremediation method helps to extract heavy metals from water and makes it suitable for consumption and use. However, in order to be most effective, it is necessary to choose the planting method and optimal environmental conditions. Therefore, several types of bioplato were created and tested during the experiment: with different planting methods (bare root, container grown) and in the presence of microorganisms (Pseudomonas fluorescens and Rhodococcus erythropolis).The contaminants were water-soluble salts of lead (II) acetate and cadmium chloride. Iris pseudacorus and Typha gracilis were selected for the experiment, as the plants are capable of significant heavy metals accumulation. The sampling was carried out according to GOST R 56237-2014 «Drinking water. Sampling at water preparation stations and pipeline distribution systems» and GOST 31861-2012 «Water. General requirements for sampling». The samples were analyzed using an atomic emission spectrometer with inductively bound plasma iCAP 6300 Duo.Studies have shown that the purification rate of plants in both planting methods is quite high - more than 92 %. In bare root samples, purification is more efficient (99% in the solutions with the cadmium ions concentration 20 times above the threshold limit value (TLV). The use of microorganisms contributed to the reduction of Pb2+ absorption by 18% in the bioplato with bare root planting method. However, a bioplato with container grown planting method in the presence of micro-organisms is 8,7% better at purifying water from Cd2+ ions

Application of Taguchi Method for Optimization Cadmium Separation by Emulsion Liquid Membrane

A study was carried out to remove cadmium ions from a hydrochloric medium at a concentration of 100 ppm using the emulsified liquid membrane (ELM) technique. Emphasis was placed on assessing process parameters and their effect on changing the concentration of cadmium ions in the hydrochloric solution. To study the performance characteristics of the process, Taguchi method was used with analyzing of signal/noise ratio. Five parameters that affect performance such as (pH of the external phase (1-4), surfactant concentration in the organic layer (4% -10% v / v), carrier concentration in the organic layer (4% -10% v / v), speed of Emulsification (5800-24000) rpm and emulsion volume ratio / outer phase ratio (Eml./Ext ratio) was studied, taking into account the change in the concentration of cadmium ions in the external phase. To obtain the lowest concentration of cadmium ions in the external stage, the values ​​of the optimum parameters were: pH = 3, Surfactant conc. = 4%, Carrier conc. = 8% emulsification speed = 19700 rpm, and Eml./Ext. ratio = 18%. Results of the present work suggested that Eml./Ext. ratio had a major effect on the concentration change, followed by a pH in the outer phase, the emulsification velocity, carrier concentration, and the surfactant concentration respectively.

Optimization of Cadmium Adsorption by Magnetic Graphene Oxide Using a Fractional Factorial Design.

Graphene materials have attracted increasing interest in water remediation. In this study, magnetic graphene oxide (MGO) was prepared through the modified Hummers method and the adsorption behaviors of cadmium were investigated. Firstly, the sorption kinetics, isotherms, as well as the effects of pH were investigated. Then, fractional factorial design (FFD) was used to optimize the effects of pH, temperature, time, initial concentration of cadmium ion and NaCl on cadmium adsorption. The results indicate that MGO could effectively remove cadmium ions from an aqueous solution and the sorption data could be described well by pseudo-second-order and Freundlich models, showing that the adsorption rate of cadmium ions on MGO is multilayer adsorption and dominated by the chemical adsorption. According to the FFD results, the maximum adsorption capacity of cadmium ions was 13.169 mg/g under the optimum condition of pH value 8, 45 °C, contact time 60 min, initial cadmium concentration of 70 mg/L and NaCl concentration of 100 mg/L. Higher levels of the pH value, temperature and initial cadmium concentration are beneficial to the adsorption process. These results are important for estimating and optimizing the removal of metal ions by MGO composite.

Effects of cadmium ion concentration on the optical and photo-response properties of CdSe/PVP nanocomposites for white light sensing application

Cadmium selenide (CdSe) nanoparticles dispersed in the PVP matrix with varying concentrations of cadmium (Cd) ion complex have been synthesized through a low-cost chemical bath deposition technique to investigate the effects of cadmium ion concentration on its optical and photo-response characteristics. To confirm the formation of pure, stable, well dispersed, and highly crystalline spherical CdSe nanocomposites different characterization techniques such as X-ray diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy, and Fourier transform infrared spectroscopy have been used. The optical band gaps and sizes of the nanocomposites are determined from the UV–Vis data while the surface-related emission properties of the CdSe nanocomposites are obtained from the PL data. The quantum confinement on the CdSe nanocomposites increases with the decrease of Cd ion concentration. I–V characteristics measurements have been done on the samples to investigate the photo-response properties of the samples. Various optical properties such as bandgap, near bandgap emission, and impurity emission are correlated with the photo-response properties of the samples. The photoresponse properties are found to become more suitable for application in white light photosensor with the increase of quantum confinement. Mechanisms related to the enhancement of photocurrent with respect to quantum confinement are also discussed in this paper.

Effect of Cadmium Ions on Some Biophysical Parameters and Ultrastructure of Ankistrodesmus sp. В-11 Cells

Effects of low concentrations of cadmium ions on growth, photosynthesis, and cell ultrastructure of microalga Ankistrodesmus sp. B-11 were investigated. The addition of cadmium to growth medium at concentrations of 0.005–0.02 mg/L led to a significant decrease in the number of Ankistrodesmus sp. B-11 cells relatively to that in the untreated culture. The addition of cadmium at concentrations >0.05 mg/L completely stopped cell growth. Cadmium ions induced ultrastructural changes in the arrangement of thylakoids within the stroma, the detachment of thylakoid membranes with the formation of void interthylakoid spaces, and a significant increase in vacuolization of microalgal cells. Simultaneous measurements of fluorescence induction curves and redox transformations of photosystem I components on a microsecond time scale by means of a M‑PEA-2 fluorometer revealed that cadmium ions inhibit electron transport in photosystem II (PSII). The quantum yield of electron transport in PSII (φEo) and the performance index (PIABS) were found to decrease; the photoreduction of P700 pigment was decelerated, while energy dissipation (DI0/RC) and ΔpH-dependent nonphotochemical quenching (qE) increased significantly under the action of cadmium. The performance index (PIABS) was the most sensitive parameter; it can be used for the detection of early toxic effects of cadmium ions on algae.

ASSESSMENT OF INFLUENCE OF RAW MATERIALS OF NATURAL ORIGIN FOR LEAD AND CADIUM CONTENT IN MODEL SOLUTIONS

The results of assessing the detoxification ability of raw materials of natural origin – propolis, buds and birch leaves (Betula pendula), buds and pine needles (Pinus sylvestris) in relation to lead and cadmium ions in in vitro experiments using the I. method. G. Mokhnacheva. The plant raw materials used in the experiment contain a large number of biologically active substances, including flavonoids (propolis, buds and birch leaves, pine buds), vitamin C (pine needles), which provide a detoxifying effect. Mass concentration of heavy metals was measured by inversion voltammetry on a TA-07 analyzer. It has been shown that raw materials of natural origin have a positive effect on the decrease in the content of lead and cadmium in model solutions. The use of pine needles caused a decrease in the level of lead to 78.4 %, pine buds to 67.4, birch leaves to 62.4, birch buds to 59.4, propolis to 57.6 %. The concentration of cadmium ions in the solution decreased under the influence of pine buds to 25.9 %, birch leaves to 19.3, propolis to 17.7 pine needles to 17.1, birch buds to 14.8 %. It has been established that the most effective lead detoxifiers are propolis, pine buds and needles; cadmium – buds of pine.

Selective detection of cadmium ions using plasmonic optical fiber gratings functionalized with bacteria.

Environmental monitoring and potable water control are key applications where optical fiber sensing solutions can outperform other technologies. In this work, we report a highly sensitive plasmonic fiber-optic probe that has been developed to determine the concentration of cadmium ions (Cd2+) in solution. This original sensor was fabricated by immobilizing the Acinetobacter sp. around gold-coated tilted fiber Bragg gratings (TFBGs). To this aim, the immobilization conditions of bacteria on the gold-coated optical fiber surface were first experimentally determined. Then, the coated sensors were tested in vitro. The relative intensity of the sensor response experienced a change of 1.1 dB for a Cd2+ concentration increase from 0.1 to 1000 ppb. According to our test procedure, we estimate the experimental limit of detection to be close to 1 ppb. Cadmium ions strongly bind to the sensing surface, so the sensor exhibits a much higher sensitivity to Cd2+ than to other heavy metal ions such as Pb2+, Zn2+ and CrO42- found in contaminated water, which ensures a good selectivity.

Application of Probiotic Preparation Based on Bacteria of the Genus Bacillus in Experimental Intoxication with Cadmium

Experimental studies show that the introduction of various heavy metals in the form of their soluble salts in laboratory animals can lead to toxic damage to the body. Taking into account the world community’s concern with acute and chronic intoxication with heavy metals, methods of detoxification of heavy metal excess, as well as their active removal from the body, are actively being developed today. A relatively new and safe method of detoxification is the use of probiotic strains that have the ability to bind heavy metals, for example, encrusting them in their cell wall, and further, withdrawing through the gastrointestinal tract. This work conducts a comprehensive assessment of the effectiveness of probiotic preparations as a means of correction of the elemental status in the intoxication with cadmium based on the study of biochemical parameters of serum, histological examination of the liver. The best effect and preservation of the structure of the main cell population of the liver – hepatocytes – was observed in samples with Vetom 2 against the background of intoxication with cadmium during all the periods of observation. There were no microcirculation violations in the liver lobule areas. Studies of the ability of bacteria of the genus Bacillus that are part of the studied probiotics to accumulate heavy metals by means of determining their concentration in tissues of laboratory animals revealed that the preparations contribute to a pronounced decrease in the concentration of cadmium ions in the tissues. At the same time, the bone and muscle tissues have the greatest accumulating ability in relation to cadmium ions. The most effective preparations in cadmium intoxication are Sporobacterin and Vetom 2.

Bakır ve kadmiyuma maruz bırakılan Sarıağız balığının (Argyrosomus regius) bazı dokularındaki metal birikimi

In this study, the metal accumulation of A. regius juveniles in muscle, liver and gill tissues was exposed to sublethal concentrations of cadmium and copper ions for 30 days. As the concentration of metal in the environment increased in the 30-day period, the accumulation of copper and cadmium in the tissues increased considerably and the difference was significant. The accumulation in both metals was mostly in the liver followed by gill and muscle tissue. This distinction between tissues in terms of metal deposition can be explained by the difference in the functions of tissues and organs.

Application of response surface methodology for optimization of cadmium removal by Aloe Vera/carboxylated carbon nanotubes nanocomposite-based low-cost adsorbent

In this research, Aloe Vera leaf powder (OAMP) was modified with carboxylated carbon nanotubes (CNTs-COOH) and the prepared nanocomposite was used as a novel low cost adsorbent for the removal of cadmium ions from aqueous solutions. The prepared OAMP/CNTs-COOH nanocomposite was characterized by fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Energy-dispersive x-ray spectroscopy (EDS) and Brunauer–Emmett–Teller (BET) analysis. The influence of operation parameters such as initial concentration of adsorbate, adsorbent dosage, contact time and pH of the cadmium solution on the cadmium adsorption process was studied by response surface methodology (RSM) optimization. The solid phase extraction (SPE) using OAMP/CNTs-COOH based-adsorbent was performed for the pre-concentration and matrix separation and inductively coupled plasma–mass spectrometry (ICP-MS) detector was used for measurement of cadmium ions concentration. The empirical adsorption data were fitted by Langmuir isotherm model. The value of maximum adsorption capacity was 46.95 mg g−1, indicating high efficiency of OAMP/CNTs-COOH nanocomposite in the adsorption process of Cd(II). The kinetic of the Cd(II) adsorption process was followed by Elovich kinetic model. The reported thermodynamic parameters designated that the adsorption of Cd(II) on the OAMP/CNTs-COOH was an endothermic and spontaneous process. The results revealed that OAMP/CNTs-COOH demonstrate enhanced adsorption performance in comparison with non-treated Aloe Vera.

Photoreduction and Removal of Cadmium Ions over Bentonite Clay-Supported Zinc Oxide Microcubes in an Aqueous Solution.

Cadmium ion is toxic to organisms and shows persistence because of its nondegradability. Photoreduction of the cadmium ion (Cd(II)) was studied using a bentonite-supported Zn oxide (ZnO/BT) photocatalyst in an aqueous medium under ultraviolet light. The prepared ZnO/BT photocatalyst was characterized by diffuse reflectance spectroscopy, field-emission scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, photoluminescence spectroscopy, transmission electron microscopy, energy-dispersive spectroscopy, and Brunauer–Emmett–Teller/Barrett–Joyner–Halenda analysis. The effects of main parameters including pH, contact time, initial concentration of cadmium(II) ion, light intensity, temperature, and the photocatalyst dosage were investigated for obtaining appreciate reduction/removal efficiency. The maximum reduction/removal efficiency of 74.8% was obtained at optimized values which were found to be at pH 5, 6 h contact time, 6 ppm Cd(II) ion, 200 W UV light, 45 °C temperature, and 4 g/L of ZnO/BT. Reduction/removal of Cd(II) was significantly affected by light intensity so that the increment in UV intensity from 0 to 200 increased the reduction/removal efficiency from 61.2 to 76.8%. This study reports an inexpensive and environmentally friendly photocatalyst for Cd2+ reduction in real samples and prospective photoelectric materials.

Investigation of Highly Sensitive Cadmium Ion Selective FET Sensors with AC Impedance Analysis

In this study, we developed a cadmium ion selective sensor which can detect cadmium ion in water, in the convenience of home/office. The ion selective membrane (ISM) FET sensor combines novel extended gate FET structure and cadmium ion selective membrane. The AC impedance measurement result is also analyzed in this research. There is an electrode pair on the epoxy substrate. One is the reference electrode (RE) and another one is the extended electrode (EE). Gate voltage is applied on the reference electrode and the extended electrode is connected to the gate of the FET. The voltage change caused by ions will be amplified by the FET. The cadmium ISM is immobilized on the electrode pair. A narrow gap between the two electrodes leads to the high sensitivity and, as well as the high gate voltage. Figure 1 shows the electrical characteristic of Cd-ISFET. From the figure we can find out that as the cadmium ion concentration increases, the drain current will also increase. The response time of the Cd-ISFET sensor only needs 15 minutes and detection limit can reach 10-11M which is comparable with laboratory based instrument like ICP-MS. This Cd-ISFET sensor has high sensitivity (71 mV/ decade [Cd2+]) which is beyond ideal Nernst sensitivity (29 mV /decade [Cd2+]). A portable device is developed in this research and makes the operation method easy, friendly and convenient in contrast with ICP-MS. We first demonstrate the methodology of our sensor and we will apply our sensor on drinking water, tea, Chinese herbal medicine, and milk etc. Figure 1

Removal of Cadmium Ions from Aqueous Solutions Using Acid-Activated Cockle Shell Powder

In Vietnam, heavy metal removal from aqueous solution has been the subject of great attention in the last few years. There are several methods have been developed to reduce heavy metal pollution problems and adsorption technique has been widely used due to the versatility and effectiveness. Cockles are marine bivalve mollusks, whose shell are discharged as wastes by many marine product manufacturers and restaurants. Cockle shell can be economically used as adsorbent for the wastewater treatment. In this study, acid-activated cockle shell was used as an adsorbent material for divalent cadmium ion removal from waste water. The experiments in this work used batch mode adsorption. Experiments were designed by response surface methodology (RSM) and a quadratic model was used to predict the removal efficiency of cadmium. The input to the model was varied as initial cadmium ion concentration from 600 to 1000 mg/L, contact time from 30 to 90 minutes, adsorbent dosage from 0.5 g/L to 1.5 g/L. Analysis of variance was incorporated to judge the adequacy of the models. The predictions of the model were in good agreement with experimental results and the optimal condition is then estimated from the model. Other properties of obtained materials were also investigated using XRD, BET, TGA, SEM analysis methods. The results show that the simple acid-activated cockle shell can be used as a low cost and effective adsorbent for cadmium ion removal.

Emulsion Stability Tes and Effect of HNO3 Concentration in the Internal Phase on Cadmium Ion Extraction using Liquid Membrane Emulsion Technique

Study on the emulsion stability and cadmium ion extraction tests was performed using the liquid membrane emulsion technique. This study aimed to determine the emulsion stability between the membrane phase and the internal phase with the variation of the ratio (2:1, 1:1, 2:3, and 1:2), and to determine the maximum conditions of cadmium ion extraction in a solution including the various concentration of HNO3 solution 1, 1.5, 2, and 2.5 M. This study is a laboratory experimental method using benzoyl acetone compound as cation carrier, kerosene as membrane phase, HNO3 solution as the internal phase, span-20 and span-80 as surfactants, and cadmium solution as the sample solution. Cadmium ion concentration in the external phase was determined by UV-VIS spectrophotometer. The result showed that the emulsion stability test which produced the most stable emulsion was in the ratio of the membrane phase and the internal phase 1:1. In addition, the concentration of the HN03 solution resulted in a maximum extraction percentage of 1.5 M with an extraction percentage was 95.28%.

The inhibitor-evoked shortage of tocopherol and plastoquinol is compensated by other antioxidant mechanisms in Chlamydomonas reinhardtii exposed to toxic concentrations of cadmium and chromium ions.

One of the major mechanisms of heavy metal toxicity is the induction of oxidative stress. Redox-active heavy metals, like chromium, can induce it directly, whereas redox-inactive metals, like cadmium, play an indirect role in the generation of reactive oxygen species (ROS). Living organisms defend themselves against oxidative stress taking advantage of low-molecular-weight antioxidants and ROS-detoxifying enzymes. Tocopherols and plastoquinol are important plastid prenyllipid antioxidants, playing a role during acclimation of Chlamydomonas reinhardtii to heavy metal-induced stress. However, partial inhibition of synthesis of these prenyllipids by pyrazolate did not decrease the tolerance of C. reinhardtii to Cr- and Cd-induced stress, suggesting redundancy between antioxidant mechanisms. To verify this hypothesis we have performed comparative analyses of growth, photosynthetic pigments, low-molecular-weight antioxidants (tocopherols, plastoquinol, plastochromanol, ascorbate, soluble thiols, proline), activities of the ascorbate peroxidase (APX), catalase and superoxide dismutase (SOD) and cumulative superoxide production in C. reinhardtii exposed to Cd2+ and Cr2O72- ions in the presence or absence of pyrazolate. The decreased α-tocopherol and plastoquinol content resulted in the increase in superoxide generation and APX activity in pyrazolate-treated algae. The application of heavy metal ions and pyrazolate had a pronounced impact on Asc and total thiol content, as well as SOD and APX activities (the latter only in Cd-exposed cultures), when compared with algae grown in the presence of heavy metal ions or pyrazolate alone. The superoxide production in cultures exposed to heavy metal ions and pyrazolate decreased when compared to the cultures exposed to either heavy metal ions or an inhibitor alone.

The biosynthesis of cadmium selenide quantum dots by Rhodotorula mucilaginosa PA-1 for photocatalysis

CdSe quantum dots (QDs) are semiconductor materials and possess unique optical and electronic properties, therefore being increasingly used in many fields. Biosynthesis of CdSe QDs has several advantages over the chemical synthesis route. In this study, the CdSe QDs were biosynthesized using a yeast Rhodotorula mucilaginosa PA-1 under the aerobic condition. The regulation of QDs biosynthesis was achieved by changing the concentration of precursors and the pH of the medium. The concentration of cadmium ions but not selenium ions determined the synthesis of CdSe QDs. Synthesized CdSe QDs with a narrow size distribution (3.2 ± 0.4 nm) exhibited great photocatalytic activity under ultraviolet and visible light using a dye malachite green (MG) as a model pollutant. The photocatalytic degradation efficiency of MG was 86.5 % and 94.28 % after 60 min irradiation under ultraviolet and visible light, respectively, which is comparable for those catalyzed by various nanomaterials through chemical synthesis.

Высшие грибы как сорбенты ионов кадмия

It is known that fungal chitin exhibits high sorption properties with respect to heavy metal ions, while it is practically not absorbed in the human body, which makes it a promising sorbent. The aim of this work was to evaluate the sorption abilities of the mushrooms of Agaricus bisporus and Russula atropurpurea with respect to cadmium ions. The use of the potentiometric method for measuring the potential of the ion-selective electrode, which depends on the concentration of cadmium ions in solution, made it possible to register in detail in real time the kinetic curves of sorption of cadmium ions by mushrooms. During the experiment, it was found that the kinetics of sorption of cadmium ions from a solution with initial concentrations (0.2-2.0)·10-5 M by the preparations of fruit bodies of mushrooms A. bisporus and R. atropurpurea is well described by the pseudo-second order equation, according to which the limiting stage of the process is chemical interaction of sorbent and sorbate (1:1 ratio). At relatively low initial concentrations of cadmium ions in solution ((0.2-0.6)·10–5 M), the sorption rate was 1.5-2.5 times higher for R. atropurpurea compared to A. bisporus. At higher concentrations of cadmium ions in solution ((0.8-2.0)·10-5 M) the speed and capacity of sorption were very close for different types of mushrooms. Moreover, the rate of sorption by mushrooms exceeds 5-10 times the rate of sorption of activated carbon and micromycetes of the genus Fusarium. It was revealed that the sorption isotherm of cadmium ions by mushrooms is well described by the Dubinin-Radushkevich equation, according to which R. atropurpurea is characterized by the highest sorption compared to A. bisporus. Thus, R. atropurpurea has the highest sorption activity with respect to cadmium ions.

Optimization of the electro coagulation process for the removal of cadmium from aqueous solution using RSM

A certain of industrialized wastewater streams include heavy metal ions, should be efficiently removal before the reuse or discharge of treated waters could occur. In this work, the removal of cadmium from aqueous solution was carried out by electro coagulation using aluminum electrodes as anode and cathode. Electro coagulation cell of 1litter was used in this research. Several operating parameters on the removal efficiency of cadmium were investigated, such as initial pH, voltage, initial cadmium ion concentration, NaCl concentration, spacing between electrodes, and type of electrode . The Cd(II) concentration (50 ,100,150,200 ppm),( stirring speed 120 rpm) at room temperature . A pH was use to be a constant best value when studied the impact of voltage values were chosen as 6,10, and 14 increasing voltage increased Cd(II) removals significantly Removal of 30.1%, 94.1%, 97.4%. The optimum removal efficiency of 97.4 % was achieved at a voltage of 14 V and pH 5 using (Al/Al.) electrodes, within 60 min of operating time. The concentration of NaCl was 0.6 g/l with a 0. 5 cm spacing between the electrodes.