Electrolysis Duration Research Articles

Electrodeposition and characterization of Ni–TiC composite using N-methylformamide bath

Abstract Ni–TiC composite coatings containing a maximum of 14.62 wt.% TiC were obtained under optimum condition by the constant current electrodeposition of Ni and micrometer sized particles of TiC powder onto the surface of commercial grade copper substrates. A bath containing 200 g/l nickel acetate, 35 g/l boric acid and 40 g/l TiC in N-methylformamide at current density 2 A dm −2 , duration of electrolysis 30 min and bath temperature 60 °C was found to be optimum condition for electrodeposition. The composition, microstructure, hydrogen content and microhardness were investigated by AAS, EDAX, SEM, XRD and microhardness tester. The single line broadening analysis of peak shows that crystallite size decreases with increase in current density. The hydrogen content in the deposits was found to be minimal. The effect of annealing temperature on microstructure and microhardness was also examined.

Zn, Ti and Si nanowires by electrodeposition in ionic liquid

An electrochemical route for the fabrication of zinc, titanium and silicon nanowires from ionic liquid (IL) based plating solutions is presented. Thanks to the large potential window of IL and good solubility of the corresponding anhydrous chloride salts, the presented method proceeds by a kinetically controlled electrochemical decoration of step-edges at highly oriented pyrolytic graphite surface. Resulting rather crystalline nanowires are more than a few hundreds of μm long while their diameter can be controlled in the 10 to 100 nm range by the electrolysis duration.

Electrochemical depositions of palladium on indium tin oxide-coated glass and their possible application in organic electronics technology

The surface of palladium particles deposited on the (indium tin oxide) ITO coated glass by means of pulse electrolysis of 0.01 M PdCl 2 in dimethylformamide was investigated using atomic force microscopy. It was shown that at the potential value E = -1 V, pulse duration (τ on ) of 6 ms and pause duration (τ off ) of 300 ms the discrete cone-shaped nano-sized particles are formed, which almost uniformly cover the substrate s surface. The size of palladium particles increases with the increase in electrolysis duration. The absorption spectra in visible range of palladium deposited on ITO coincide with the spectrum of ITO. The study of the photoluminescence (PL) of ITO/Pd/Alq 3 structure [Alq 3 is aluminium tris(8-hydroxyquinoline)] confirmed that with the increase of palladium particles size the quenching of PL of the vacuum-deposited organic semiconductor Alq 3 takes place.

An experimental study of indigo carmine removal from aqueous solution by electrocoagulation

This paper presents an experimental study on the removal of Indigo Carmine dye from aqueous solutions using a batch stirred electrocoagulation reactor. The experimental tests were carried out in a discontinuous system provided with steel electrodes. The main purpose was to investigate the effects of the operating parameters, such as pH, initial concentration, electrolysis duration, current density, and electrolyte support concentration, on the treatment of a synthetic wastewater containing indigo carmine dye in the batch electrocoagulation process. The batch electrocoagulation reactor was operated at various current densities ranging from 5.46 to 54.57 A⋅m − 2 . Initial concentration of the dye was ranged between 25 and 100 mg⋅L −1. The initial value of pH was varied from 5 to 9, while the concentration of the electrolyte support ranged from 0.2 to 4.5 g⋅L −1. It was shown that pH control during electrocoagulation process is not beneficial in case of Indigo Carmine removal. The values of the rate constant were determined according to the pseudo first-order kinetic model that fits the experimental data. The highest rate constants were achieved for a current density of 54.57 A⋅m − 2 , an initial dye concentration of 25 mg⋅L − 1 , an initial pH of 8, and a background electrolyte concentration of 77 mM.

Formation of palladium nanoparticles under pulse current in a dimethylformamide solution

The morphology of palladium deposited by pulse electrolysis from dimethylformamide solutions of PdCl2 on the surface of graphite and ITO glass was studied. The effect of the value of cathode potential and electrolysis duration on the sizes of particles and their distribution in the substrate was investigated. It was shown that, on the substrate surface, deposits with particle sizes of 30–350 nm are formed.

Electrodeposition of Ni–SiC Composite from a Non-Aqueous Bath

Electrodeposited Ni–SiC composite deposits with SiC were produced on copper substrate using a non-aqueous organic solvent. -Methylformamide was found to be the most suitable solvent as it has a high dielectric constant (182) that allows high tolerance of the electrolyte in the bath, which is ordinarily not obtained in other solvents. The optimum condition arrived for deposition was nickel acetate , boric acid , SiC , current density , duration of electrolysis , and bath temperature . Satisfactory bright composite deposits were obtained, which were quite adherent to the copper base. Scanning electron microscope, energy-dispersive analysis by x ray, and X-ray diffraction studies have been performed to characterize the composites. Effect of current density on composition and microhardness of the composite deposits was investigated. Also, the effect of annealing on the microhardness of the deposits was studied.

Size-selective Electrochemical Preparation of Alcohol Ionic-liquid-stabilized Palladium NPs

We have successfully synthesized morpholinium ionic-liquid-stabilized palladium nanoparticles by electrochemical reduction. The palladium nanoparticles (NPs) were characterized by using transmission electron microscopy and X-ray diffraction. The sizes of the particles produced could be controlled by adjusting the current density and the duration of the electrolysis. The particle sizes increased with decreasing current density and increasing electrolysis duration. X-ray diffraction of the resulting NPs indicated that the particles had a crystalline structure.

Electrodeposition of carrier-free 57Co on rhodium as an approach to the preparation of Mössbauer sources

Electrodeposition of carrier-free (57)Co on a rhodium matrix as the first step of preparing Mössbauer sources was studied. To optimize the plating parameters, the influences of current density, volume and pH of the electrolyte solution, shape, thickness, and surface area of the rhodium cathode, mode of cathode pretreatment, concentration of (57)Co and duration of electrolysis were investigated.

Catalytic activity for nitrate electroreduction of nano-structured polypyrrole films electrochemically synthesized onto a copper electrode

Polypyrrole film was synthesized electrochemically onto a copper electrode in oxalate, oxalic acid and salicylic acid solutions. The electrochemical oxidation of pyrrole to form polypyrrole film and the electroreduction of nitrate and nitrite ions at synthesized Ppy modified copper electrodes (Ppy/Cu) in potassium chloride aqueous solutions were studied by cyclic voltammetry. Polypyrrole nano-porous film formation and the activity of the modified Ppy/Cu electrode for nitrate reduction were found to be dependent on the synthesis medium and conditions: pH; content and concentrations of the electrolytes; pyrrole concentration; electrode potential; electrolysis duration; drying time and temperature for finishing the Ppy/Cu electrode and immersion time in water for storing the Ppy/Cu electrode before use. High catalytic activity for nitrate reduction was found for composite electrodes with nano-porous structured Ppy films. The Ppy/Cu electrodes prepared in oxalate buffer and salicylic acid solutions perform more stable catalytic activity for nitrate reduction; their service life is about ten times longer than for an electrode prepared in oxalic acid solution.

Preparation of nickel oxyhydroxide by a new electrolysis method using spherical β-Ni(OH) 2

This paper introduces a novel electrolysis method to prepare NiOOH by oxidizing spherical Ni(OH) 2 in a dilute alkaline solution (pH = 8–13). The effects of preparation conditions, including KCl concentration, pH, constant voltage, temperature and oxidation time, on the synthesis of NiOOH were systematically investigated. The results show that the electrolytic efficiency and reaction rate are superior and the electrolyte can be conveniently re-utilized. The physical properties and electrochemical performance of NiOOH samples were also studied. The results show that the NiOOH, prepared by this electrolysis method, is pure β phase, even if the electrolysis duration is fully prolonged. The spherical NiOOH sample not only possesses excellent electrochemical activities, providing discharge capacities of 256.5 and 199.1 mAh g −1, and volume capacities of 625.86 and 485.80 mAh cm −3 at rates of 0.2 C and 3 C, respectively, but also has the high tap density of 2.44 g cm −3. Moreover, the synthesis process of the new electrolysis method is environmentally friendly, cost saving, and efficient for a large-scale production.

Treatment of high-strength pharmaceutical wastewater by electrocoagulation combined with anaerobic process

This article discusses a combined treatment system comprising electrocoagulation (EC) as a pre-treatment followed by anaerobic fixed film fixed bed reactor (AFFBR) for treatment of high strength pharmaceutical wastewater. The effect of various operating parameters such as pH, current density and electrolysis duration on COD, BOD and colour removal was studied. The maximum removals for COD, BOD and colour under optimal operating conditions i.e. pH 7.2, current density (CD) of 80 A/m(2) and electrolysis time of 25 minutes were 24%, 35% and 70.25% respectively. Increase in current density has resulted in decrease in electrolysis duration with marginal improvement in treatment efficiency. The efficiency of removal is discussed in terms of kg COD(r) A(-1)m(-2)h(-1) and energy consumption as Wh kg(-1)COD(r). The effluents obtained after EC were treated by AFFBR at various organic loading rates (OLRs) and hydraulic retention times (HRTs). The results indicated removals in the range of 80-90% for COD and 86-94% for BOD respectively, at OLRs between 0.6 to 4.0 Kg COD/m(3) d at an HRT of 2 days. The total gas quantity increased with increase in both HRT and OLR up to a loading of 6 Kg COD/m(3)/d but it did not commensurate with organic load. The results indicated that the combined treatment option is competitive and can be used effectively for high strength wastewaters.

Electrochemical pretreatment of distillery wastewater using aluminum electrode

Electrochemical (EC) oxidation of distillery wastewater with low (BOD5/COD) ratio was investigated using aluminum plates as electrodes. The effects of operating parameters such as pH, electrolysis duration, and current density on COD removal were studied. At a current density of 0.03 A cm−2 and at pH 3, the COD removal was found to be 72.3%. The BOD5/COD ratio increased from 0.15 to 0.68 for an optimum of 120-min electrolysis duration indicating improvement of biodegradability of wastewater. The maximum anodic efficiency observed was 21.58 kg COD h−1 A−1 m−2, and the minimum energy consumption observed was 0.084 kWh kg−1 COD. The kinetic study results revealed that reaction rate (k) decreased from 0.011 to 0.0063 min−1 with increase in pH from 3 to 9 while the k value increased from 0.0035 to 0.0102 min−1 with increase in current density from 0.01 to 0.03 A cm−2. This study showed that the COD reduction is more influenced by the current density. The linear and the nonlinear regression models reveal that the COD reduction is influenced by the applied current density.

Electrochemical degradation of specialty chemical industry effluent

Conventional wastewater treatment techniques are inefficient to manage large quantities of refractory organics discharged by specialty chemical industries. It is aimed in the present investigation to compare overall performance of the basic electrochemical reactor configurations such as batch, batch recirculation and continuous recycle reactors, in removing the organic part of wastewater from a medium-scale, specialty chemical industry. The effects of current density, supporting electrolyte concentration, electrolysis duration and fluid flow rate on the pollutant removal and energy consumption performances were critically evaluated. Continuous recycle reactor is found to be the better configuration, because of its flexibility of operation. Circulation flow rate and withdrawal flow rate enable control on transfer coefficients and treatment duration respectively. The ability of artificial neural network (ANN) in predicting the performance of the batch electrochemical treatment has also been demonstrated.

Electrochemical Degradation of Remazol Black B Dye Effluent

AbstractThis study focused on the electrochemical degradation of hydrolyzed Remazol Black B (CI Reactive Black 5), a common diazo reactive dye, in aqueous solution. In the presence of various auxiliary dye chemicals, a typical Remazol Black simulated exhausted dyebath liquor was treated electrochemically in various basic electrochemical reactor configurations such as batch, batch recirculation and single pass systems. The effect of current density, supporting electrolyte concentration, electrolysis duration, specific electrode surface and fluid flow rate on pollutant removal and energy consumption performance of the systems was critically evaluated. Batch studies show the following operating parameters, current density: 2.5 A/dm2, electrolysis duration: 6 h, and supporting electrolyte concentration: 3 g/L, were optimal for good overall performance of the system. Color removal was complete by 3 h of treatment for all combinations of parameters studied. The pollutant removal performance of the batch recirculation system was found to have improved considerably by increasing the flow rate. Performance of the batch recirculation system was comparatively better than the other rector configurations studied, with respect to capacity utilization and energy consumption.

The current efficiency of barium during the electrolysis of chloride and oxide-chloride melts with liquid cadmium and zinc cathodes

The influence of the current density (i) and the duration of electrolysis on the current efficiency of barium (CEBa) in the alloy with zinc and cadmium has been investigated during the electrolysis of melts (K-Na)Cleq-26 mol % BaCl2 containing up to 0.4 mol % BaO dissolved at T = 973 K. It is determined that the dependence of CEBa on the current density passes through a maximum: at i = 0.18 A/cm2, the value of CE Ba in the alloy with Zn is 86%; with cadmium it is 74%. An increase in the electrolysis time and the presence of barium oxide in the melt decrease the current efficiency of barium in melts.

Electrochemical degradation of pulp and paper industry waste‐water

AbstractBACKGROUND: Conventional biological waste‐water treatment techniques are insufficient to degrade large quantities of dissolved lignin discharged by small‐scale paper mills. The current investigation is aimed at comparing the overall performance of basic electrochemical reactor configurations such as batch, batch recirculation, recycle and single pass systems, in removing the organic part of waste‐water from a small‐scale, agro‐based paper industry. The effect of current density, supporting electrolyte concentration, duration of electrolysis, specific electrode surface and fluid flow rate on the removal of pollutants and energy consumption are critically evaluated. The improvement in biodegradability of the effluent during treatment is also noticed.RESULTS: The batch recirculation mode of operation was found to be superior in comparison with a batch system using the same specific electrode surface for both COD removal (73.3 vs. 64%) and capacity utilization (rate constant 1.112 × 10−3 vs. 1.049 × 10−3 cm s−1). The pollutant removal performance of the batch recirculation system improved considerably with increase in the circulation flow rate. At the best operating point in the recycle system, 59% of COD was removed, corresponding to a current efficiency of 68.9% and specific energy consumption of 18.46 kWh kg−1. The biodegradability index of the waste‐water was improved from 0.18 ± 0.01 to 0.36 ± 0.01.CONCLUSION: A recycle reactor was the best configuration, because of its flexibility of operation. Circulation flow rate and withdrawal flow rate enable the control of transfer coefficients and treatment duration respectively. Electrochemical treatment not only removes the bulk of the organic matter, but also makes the remaining pollutants more easily biodegradable. Copyright © 2009 Society of Chemical Industry

Polypyrrole Modified Copper Electrode for Nitrate and Nitrite Reduction in Neutral Solutions

Conducting polypyrrole (Ppy) film was synthesized electrochemically onto a copper electrode in oxalate, oxalic acid and salicylic acid solutions. The electrochemical oxidation of pyrrole to form polypyrrole film and the electroreduction of nitrate and nitrite ions at synthesized PPy modified copper electrodes (Ppy/Cu) in potassium chloride aqueous solutions were studied by cyclic voltammetry. Polypyrrole film formation and the activity of the modified Ppy/Cu electrode for nitrate and nitrite reduction were found to be dependent on synthesis medium and conditions: pH, content and concentrations of the electrolytes; pyrrole concentration; electrode potential; electrolysis duration. The finishing and storage conditions of the prepared Ppy/Cu modified electrodes, such as drying duration and temperature; soaking duration in water before use, also affect their catalytic activity for nitrate and nitrite reduction. The highest reduction currents of nitrate and nitrite were obtained for the nanoporous structured Ppy film prepared in salicylic acid solution. Nitrate and nitrite reduction occurred at cathodic potentials of ca. -0.70 V and -0.85 V (Ag/AgCl) respectively, and the peak potentials ranged from -1.00 V to -1.15 V (Ag/AgCl). In the potassium chloride aqueous solution the reduction of nitrate and nitrite ions on the Ppy/Cu electrode was found irreversible.

Current efficiency of strontium deposition into an alloy with zinc and cadmium in electrolysis of chloride and oxide-chloride melts

Effect of the current density and electrolysis duration on the cathodic current efficiency by strontium was studied in chloride and oxide-chloride melts.

Electrochemical treatment of skim serum effluent from natural rubber latex centrifuging units

Electrochemical treatment of raw and anaerobically treated skim serum effluent from natural rubber latex centrifuging units was investigated using different electrodes like aluminium, stainless steel, mild steel, and cast iron in the presence of chloride ions. Experimental results were assessed in terms of the removal of COD, biochemical oxygen demand (BOD), TKN, ammoniacal nitrogen, turbidity, sulphides and phosphates. The effect of operating factors such as supporting electrolyte, duration of electrolysis, pH, concentration of effluent and the presence of Fenton's reagent as chemical oxidant were studied. The influence of these factors on the biochemical constituents and population of total bacteria were also investigated. Aluminium anode was found to be more effective to remove pollutants and maximum removal of BOD took place within 30 min of electrolysis. After electrochemical treatment phosphate removal efficiency was 99.5% and complete removal of sulphide was observed from the anaerobically treated effluent. Electrochemical treatment is effective in removing biochemical constituents and total bacteria in the presence of Fenton's reagent.

An investigation of the effect of the electrolyte composition on the consumption of fired anodes during electrolytic aluminum production

The effect of adding CaF2, AlF3, and KF into electrolyte on the consumption of fired anode during aluminum electrolysis is investigated. The CaF2 content varied from 5 to 10 wt % in the electrolyte of the industrial composition. Correspondingly, the concentration of AlF3 and KF varied from 4 to 10 and from 0 to 4.7 wt % in the modified electrolytes. Based on the procedure used, the total consumption of carbon and the amount of carbon transported into the gas phase (m g) and foam (m f) were determined. Electrolysis duration was 12 h, the distance between the poles was 40 mm, the temperature was 960°C, and the current density was 0.85 and 1.2 A/cm2. It is established that adding CaF2 and AlF3 increases the consumption of anode, while adding KF decreases it. For CaF2, ∂m f/∂[CaF2] is larger than ∂m g/∂[CaF2], 15.4 and 6.6 kg/(tAl wt %) CaF2, respectively. For AlF3, ∂m f/∂[AlF3] is also larger than ∂m g/∂[AlF3] and equals 6.8 and 4.2 kg/(tAl wt %) AlF3. For KF, ∂m f/∂[KF] is smaller than ∂m g/∂[KF], being −11.3 and −8.1 kg/(tAl wt %) KF.