Cathodic Current Efficiency Research Articles

Recovering metallic lead from spent lead paste by slurry electrolysis

Spent lead paste, the most challenging component of discarded lead-acid batteries, contains approximately 70 % Pb. Improper handling of lead-acid battery waste poses severe risks to both the environment and human health. Here, we present a novel and short process for directly recycling metallic Pb from spent lead paste by chlorine slurry electrolysis and investigate the parameters that affect Pb recovery rate and cathodic current efficiency. Our experiments showed that under optimal conditions (250 g/L NaCl, 0.8 mol/L HCl, 10 g/L Pb2+, 30 A/m2, 40 g/L pulp concentration, 65 °C, and 12 h), the Pb recovery rate and cathodic current efficiency were, respectively, 90.54 and 85.25 %. During slurry electrolysis. Cl- combined with Pb in spent lead paste in the anode chamber, converting lead oxides and insoluble PbSO4 into soluble lead chloride complexes ([PbCl3]-, [PbCl4]2-). Driven by the electric field and concentration gradient, the lead chloride complex ions then migrated to the cathode region, where they were reduced to metallic Pb with a purity higher than 99 %. The application of this cost-effective and efficient novel method can contribute to the sustainable reuse of waste lead-acid batteries and other Pb-bearing scrap.

Nickel Salt Dependency as Catalyst in the Plating Bath on the Film Properties of Cu/Cu-Ni

Metal plating frequently employs nickel (Ni) and copper (Cu) as anodes. Cu/ Cu-Ni film formed has many advantages, such as better corrosion resistance and high hardness characteristics. This study aims to assess the properties of Cu/Cu-Ni film, such as phase, surface morphology, crystallographic orientation, hardness, corrosion analysis, and contact angle, which were fabricated using electrodeposition with various Ni salt additions (0.3, 0.5 and 0.7 M). In addition, the cathode current efficiency (CCE) and deposition rate of the Cu/Cu-Ni electrodeposition were also investigated. An increase in Ni salt in the plating bath could enhance the pH, promoting higher CCE and depleting hydrogen evolution at the cathode, leading to the presenting Ni phase in the alloy. The higher concentration of Ni salt in the solution could also enhance the deposition rate due to a shift to a pH value, which affects the roughening of the surface morphology, promoting a higher contact angle. All crystal structures generated by Cu/Cu-Ni electrodeposition were FCC, with the preferred orientation of the (111) plane. Crystallite size and lattice strain depend on the deposition rate. Less crystallite size and lattice strain affect the film’s hardness and corrosion resistance. Moreover, the third bath had the resulting Cu-Ni layer with the best hardness and corrosion rate of around 136 HV and 0.081 mmpy.

Effect of Electrolysis Conditions on Electrodeposition of Cobalt-Tin Alloys, Their Structure, and Wettability by Liquids.

The aim of this study was a systematic analysis of the influence of anions (chloride and sulfate) on the electrochemical behavior of the Co-Sn system during codeposition from gluconate baths. The pH-dependent multiple equilibria in cobalt-tin baths were calculated using stability constants. The codeposition of the metals was characterized thermodynamically considering the formation of various CoxSny intermetallic phases. The alloys obtained at different potentials were characterized in terms of their elemental (EDS and anodic stripping) and phase compositions (XRD), the development of preferred orientation planes (texture coefficients), surface morphology (SEM), and wettability (water; diiodomethane; surface energy). The mass of the deposits and cathodic current efficiencies were strongly dependent on both the deposition potential and the bath composition. The morphology and composition of the alloys were mainly dependent on the deposition potential, while the effect of the anions was less emphasized. Two-phase alloys were produced at potentials -0.9 V (Ag/AgCl) and lower, and they consisted of a mixture of tetragonal tin and an uncommon tetragonal CoSn phase. The preferential orientation planes of tin grains were dependent on the cobalt incorporation into the deposits and anion type in the bath, while the latter did not affect the preferential orientation plane of the CoSn phase. The surface wettability of the alloys displayed hydrophobicity and oleophilicity originating from the hierarchical porous surface topography rather than the elemental or phase composition. The codeposition of the metals occurs within the progressive nucleation model, but at more electronegative potentials and in the presence of sulfate ions, a transition from progressive to instantaneous nucleation can be possible. This correlated well with the partial polarization curves of the alloy deposition and the texture of the tin phase.

Crystallographic and electrochemical corrosion resistance analyses of cataphoretically co-deposited spinel Co>0.5Mn0.1-0.3O0.1-0.4@rGO composites over α-Fe(110) as current collector for supercapatteries

Binder free spinel Co>0.5Mn0.1-0.3O0.1-0.4@rGO composite electrode films were fabricated via galvanostatic electrochemical deposition technique over α-Fe(110) as current collector for hybrid supercapattery. Self-designed, n-MOSFET embedded ATMega328P microcontroller assisted modules were deployed to record the chronopotentiometric as well as galvanostatic charging-discharging analysis for specific capacitance (Cs) measurements. Partial, exchange as well as limiting current densities(iL) and cathodic current efficiency were estimated. Electrochemical signature was analyzed from cyclic voltammetry data. Morphology and chemical nature of the composites were scrutinized with scanning electron microscopy, X-ray photoelectron, FT-IR and Raman spectra. Indigenously designed computer simulation programs coded in Python were used to optimize the deposition parameters and to analyze the crystalline structure from XRD data. The unit cell length for the FCC crystal with an octahedral geometry was ∼ 4.28 Å. An in-depth analysis of potentiodynamic polarization as well as electrochemical impedance spectral data were carried out to scrutinize the corrosion resistance and capacitance characteristics of the composites in KOH. From the Tafel constants, Ecorr, Icorr, Ru, RCT and ZW data, it was accentuated that rGO incorporated composite films offer enhanced corrosion protection for Fe(110) substrates than their individual counterparts along with augmented specific capacitance. Estimated Cs was about 1166 F.g−1 at a scan-rate of 10 mV.s−1. Impact of time-constant (τ) and current density over Cs was analyzed via GCD technique and was about 1458.73 F.g−1 at 2 τ and at 0.5 A.g−1. And the corresponding specific energy and power density were about 183.23 W.h.kg−1 and 237.75 W.kg−1 respectively. These composite electrode films impregnated with rGO not only improved the specific capacitance but also imparts the sacrificial corrosion resistance over the α-Fe(110) as current collector in presence of OH−as electrolyte and can serve as a sustainable electrode material for supercapatteries.

Clean and efficient preparation of metallic bismuth from methane-sulfonate electrolyte in the membrane electrolysis cell

As a prevailing hydrometallurgical extraction system for bismuth sulfide concentrate, the acidic chloride solution has superior applicability to raw materials and high recovery ratio of metallic bismuth. Nevertheless, it has disadvantages of being easily volatile and strongly corrosive, as well as large energy consumption and poor deposition morphology during chloride electrolysis. Methane-sulfonic acid (MSA) solution is widely considered as the next generation of green hydrometallurgical system, due to its excellent physicochemical properties such as high metal salts solubility, low volatility, and biodegradability. In this study, membrane electrolysis technique was adopted based on the acidic bismuth methane-sulfonate leaching solution, and the influence of electrolyte composition, cathode current density (CCD), and temperature parameters on the bismuth conversion ratio (BCR) and deposition rate (BDR), techno-economic indicators and cathodic bismuth morphology were studied. The results show that the CCD affects the deposits morphology significantly, and the bismuth metal is partially dark and composed of loose ellipsoidal particles at high current density. Under the optimal conditions (70 g/L Bi3+ ions, 5 g/L Fe2+ ions, 110 g/L MSA, 35 °C, 180 A/m2), high-purity metallic bismuth (Bi 99.97 %) with silver-white luster is obtained. The BCR and BDR are 9.43 % and 0.46 kg/(h·m2), respectively. The cathodic current efficiency (CCE) reaches over 98 %, and specific energy consumption (SEC) is less than 715 kWh/t Bi. Compared with the traditional chloride system, the MSA-based membrane electrolysis medium has advantages of environmental friendliness, low occupational risks, low carbon and energy consumption, and can thus provide a sustainable green solution for bismuth hydrometallurgy.

Energy-efficient and advanced electrowinning of metallic manganese within a novel H+ exchange membrane cell using a Ti/IrO2−RuO2−SiO2 anode

Coated Titanium Anodes (CTAs) exhibit significant potential in addressing the high energy consumption challenge inherent in current manganese electrowinning processes. However, the electrodeposition of manganese dioxide (MnO2) at the anode limits the utilization of CTAs in conventional manganese electrolytic cells. Herein, a novel H+ exchange membrane (HEM) electrolytic cell was proposed and applied to manganese electrowinning employing Ti/IrO2 − RuO2 − SiO2 anode. The HEM electrolytic cell is a three-chamber electrolytic reactor consisting of cathode chamber, acidification chamber and anode chamber separated by woven terylene diaphragm and HEM. The results indicated that after 24 h of electrowinning, the cathodic current efficiency (CE) of 85.1 % was achieved, along with a specific energy consumption (EC) of 4189 kW·h/t. Compared to conventional industrial electrowinning technology, this represents an increase in CE by more than 15 % and a reduction in EC by over 1400 kW·h/t. The unique structure of the HEM electrolytic cell effectively prevents MnO2 deposition, ensuring the functionality of the CTAs and eliminating the generation of anode mud. Additionally, the H+ from the oxygen evolution reaction at the anode is collected and concentrated in the acidification chamber. This resulted in a spent electrolyte with 15.2 g/L H2SO4, enabling its reuse in extracting manganese ores. Employing the HEM electrolytic cell with a Ti/IrO2 − RuO2 − SiO2 anode for manganese electrowinning is therefore considered an energy-efficient and clean approach. It is highly recommended for saving energy and reducing carbon emissions in industrial processes.

Electrodeposition of Nanostructured Co–Cu Thin Alloy Films on to Steel Substrate from an Environmentally Friendly Novel Lactate Bath under Different Operating Conditions

A new lactate bath was proposed to deposit Co–Cu thin alloy films in nanostructure form onto a steel cathode. The deposition bath contained CuSO4.5H2O, CoSO4.7H2O, CH3CHOHCOOH, and anhydrous Na2SO4 at pH 10. The effects of [Co2+]/[Cu2+] molar ratios, lactate ion concentration, current density (CD), and bath temperature on cathodic polarization, cathodic current efficacy (CCE), composition, and structure of the Co–Cu alloys were investigated. The new bath had a high cathodic current efficiency of 85%, which increased with the applied CD. However, it decreased as the temperature increased. The produced coatings have an atomic percentage of Cu ranging from 19.8 to 99%. The deposition of the Co–Cu alloy belonged to regular codeposition. The Co content of the deposit increased with the amount of Co2+ ions in the bath, lactate concentration, and current density but decreased as the temperature increased. Cobalt hexagonal close-packed (HCP) and copper-rich, face-centered cubic (FCC) Co–Cu phases combine to form the polycrystalline structure of the electrodeposited Co–Cu alloy. The average crystallite size ranges between 46 and 89 nm. An energy dispersive X-ray (EDX) examination confirmed that the deposit contained Cu and Co metals. The throwing power and throwing index of the alkaline lactate bath were evaluated and found to be satisfactory.

High-speed electrolyte jet 3D printing of ultrasmooth and robust Cu microelectrodes

Electrochemical 3D printing technology built on computer numerical control platforms has enabled multi-dimensional and multi-scale manufacturing of various metal materials through layered electrochemical deposition. Compared to thermal 3D printing technology, electrolyte meniscus-confined 3D printing can manufacture Cu microstructures with fewer defects and smoother surfaces. In the meantime, it is still susceptible to unstable liquid–solid-air interfaces, low deposition rates, and limited printing geometry. This work combined jet electrochemical deposition with a portable 3-axis platform to develop a cyclic high-speed electrolyte jet (HSEJ) 3D printer. It offers a faster deposition rate of 53.4 µm/h when printing ultrasmooth Cu microelectrodes with surface average roughness down to 1.1 nm and microhardness of 3.3 GPa which is much higher than the best result of 2.4 GPa obtained by the other ECD methods. It is identified that the fluctuation of cathode current density plays a crucial role in defining the nucleation morphology on the Cu surface, while the cathode current efficiency is a reliable indicator to assess the deposition localization by reflecting the variation of diffusion percentage. HSEJ 3D printing provides a sustainable pathway for the facile recycling of waste cables into high-grade metal microelectronics with controllable surface morphology and 3D dimensions.Graphical

Influence of pulse parameters on microstructure and corrosion characteristics of electrodeposited Ni-W alloy coating

Material characterization and electrochemical performance of the pulse plated Ni-W alloy coatings were assessed by varying duty cycles (0–50%) and pulse frequencies (10–500 Hz) under relatively low applied current density (0.1 mA·cm−2). Compared to DC electroplating, the pulse plating process exhibited lower cathodic current efficiency, and the obtained coatings displayed slightly lower W content. However, the surface roughness, hardness, and anti-corrosion properties of the coatings were improved due to common characteristics, such as grain refinement, fewer defects, and enhanced surface uniformity, associated with the pulse plating process. The Ni-W alloy coating produced at a medium pulse frequency of 100 Hz with duty cycles of 10% and 50% exhibited the highest hardness (5.34±0.33 GPa) and the best corrosion resistance (corrosion current density Ic: 9.62 μA·cm−2), respectively. These properties were significantly improved compared to those for the counterparts prepared by DC electroplating (hardness: 3.13±0.58 GPa; Ic: 10.89 μA·cm−2).

Experimental study and modelling of continuous SO2-depolarized electrolysis in hybrid sulfur cycle for hydrogen production

SO2-depolarized electrolysis (SDE) is the key process in the hybrid sulfur cycle for green hydrogen production, but the detailed SDE characteristics including products generation, current efficiency variation, and side reactions are unclear. Herein, a continuous SDE process was experimentally conducted and theoretically modelled. The H2 and H2SO4 production was accelerated and the current efficiency for both electrodes was improved with a proper increase in current density (50−100 mA/cm2) or temperature (293−318 K), but further increasing current density to 150 mA/cm2 or temperature to 333 K led to a negative trend because of the anode corrosion or declined SO2 solubility. The increasing initial H2SO4 concentration (10−40 wt%) facilitated the cathodic H2 production and current efficiency, while negatively influenced the anodic SO2 conversion. The parasitic reactions occurred at cathode consumed H2 and resulted to the cathodic current efficiency well below 100%. A rigorous mathematical regression model correlating the production rates of H2 and H2SO4 with current density, temperature, and initial H2SO4 concentration was developed, and combined with the analysis of variance, current density was suggested the biggest factor affecting products generation in SDE process. These findings demonstrate a practical avenue for efficient SO2 conversion and H2 production in SDE process of hybrid sulfur cycle.

Exploring the potential of nickel-chloride bath for electroforming of pure nickel and nickel composites

Electroforming is becoming increasingly important as a reliable method for the production and replication of independent parts. Researchers are continually striving to reduce production costs for the fabrication of complex tools with the highest precision and lowest cost, and electroforming is a key technique for achieving this goal. The present research aimed to produce pure nickel foils via electroforming using a simple and inexpensive nickel-chloride bath, which has not been previously utilized for electroforming. The effects of saccharin concentration, nickel-chloride concentration, direct current density, and the use of graphite as an insoluble anode were investigated. The surface morphology of the electroformed products was characterized through scanning electron microscopy (SEM) and their chemical composition was analyzed using energy dispersive x-ray (EDX) and x-ray diffraction (XRD) pattern. The microhardness of the foils was determined using the Vickers hardness test. Results showed that specimens produced using the nickel-chloride bath had a good surface appearance with acceptable brightness and satisfactory microhardness. Ten electroforming tests were conducted to determine the optimal bath components, pH, and direct current density for the fabrication of pure nickel products. It was found that these parameters had a significant influence on the quality of the appearance and surface morphology of the foils. In addition, using a graphite anode was seen to reduce the cathode current efficiency as compared to a soluble nickel anode and was affected by the preferred orientation of nickel crystal plates. It can be concluded that the nickel-chloride bath has excellent potential for the production of pure nickel products using the electroforming method.

Ti/Ti4O7 Anodes for Efficient Electrodeposition of Manganese Metal and Anode Slime Generation Reduction.

Preventing lead-based anodes from causing high-energy consumption, lead pollution, and harmful anode slime emission is a major challenge for the current electrolytic manganese metal industry. In this work, a Ti4O7-coated titanium electrode was used as anode material (Ti/Ti4O7 anode) in manganese electrowinning process for the first time and compared with a lead-based anode (Pb anode). The Ti/Ti4O7 anode was used for galvanostatic electrolysis; the cathodic current efficiency improved by 3.22% and energy consumption decreased by 7.82%. During 8 h of electrolysis, it reduced 90.42% solution anode slime and 72.80% plate anode slime formation. Anode product characterization and electrochemical tests indicated that the Ti/Ti4O7 anode possesses good oxygen evolution activity, and γ-MnO2 has a positive catalytic effect on oxygen evolution reaction (OER), which inhibited anode Mn2+ oxidation reaction and reduced the formation of anode slime. In addition, the low charge-transfer resistance, high diffusion resistance, and dense MnO2 layer of the anode blocked the diffusion path of Mn3+ in the system and inhibited the formation of anode slime. The Ti/Ti4O7 anode exhibits excellent electrochemical performance, which provides a new idea for the selection of novel anodes, energy savings and emission reduction, and the establishment of a new mode of clean production in the electrolytic manganese metal industry.

Study of the process of preparing amorphous Fe–W(La) alloy plating by induced co-deposition

To obtain high-performance Fe–W alloy plating instead of environmentally hazardous chromium plating, the effects of the cathode material, electrolyte pH, temperature, current density, plating time and rotational speed on the cathode current efficiency and alloy plating are investigated in this paper. The results show that the pH and current density of the plating solution greatly influence the morphology and current efficiency of the cathode. The current efficiency of the cathode can reach 63.56%, and the tungsten content can reach 55% at pH = 8, 60 °C, 12 A/dm2, 100 r/min, 75 min, 0.1 mol/l of Fe2+ and 0.2 mol/l of W6+. After XRD analysis, the plating is found to consist of the Fe7W6 amorphous phase. In addition, La is added to the Fe–W alloy under optimal conditions. By analyzing the polarization curve, the potential of the Fe–W(La) alloy is positively shifted by 0.039 V compared with the Fe–W alloy, which has good corrosion resistance.

Nickel layers properties produced by electroplating were influenced by spinning permanent magnet

A spinning magnet is an alternative engineering approach to produce the Ni layer. In the present research, the Ni layer was plated on Cu alloy substrates influenced by a spinning magnet. Various rotating speeds (0, 500, and 800 rpm) were used to influence the Ni layer’s properties were formed. A digital scale was used to measure the deposition rate and cathodic current efficiency. XRD, SEM-EDS, potentiostat, and hardness tests were performed to determine the properties of the Ni layers. A rotating magnetic field can reduce the deposition rate and cathodic current efficiency by reducing the ionic movement from the anode to the cathode. The XRD and SEM results revealed a distinct crystallite size and surface morphology. Exhibiting a spinning could result in a decrease in oxygen in the Ni layer and a slight change in the corrosion rates. Different hardness is also seen in the various sample due to crystallite size.

Effect of low magnetic field during nickel electroplating on morphology, structure, and hardness

Nickel (Ni) layers are commonly utilized in various applications, such as automotive components. By using a magnetic field during the electroplating process, it is possible to achieve better properties. Ni electroplating was conducted in 0.5 M nickel sulphate in this research. Various low intensities of the magnetic field (0.08 T and 0.14 T) were applied during the electroplating process. In the past, it has been demonstrated that an increase in low magnetic field could result in a decrease in crystallite size and a rise in hardness. Samples were weighed with a digital scale to determine the deposition rate and current efficiencies. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and hardness tester were performed to investigate Ni layers properties. The magnetic field influences the deposition rate, cathodic current efficiency, surface morphology, structure, and hardness properties. The increase in the magnetic field caused a wider grain and smaller crystallite sizes. The crystallite sizes of the NiS - 0, NiS - 8, and NiS - 14 samples are 33.536 nm, 33.083 nm, and 28.540 nm, respectively. The hardness of the NiS - 0, NiS - 8, and NiS - 14 samples are 212.33 HV, 255.01 HV, and 267.214 HV, respectively. Higher hardness could be reached by reducing the size of crystallites. The influence of the magnetic field could enhance hardness during the electroplating process.

Eco-friendly and efficient strategy for lead recovery from spent lead paste by bagged cathode solid-phase electroreduction

Spent lead paste is a registered hazardous solid waste containing high-grade lead. Disposal of spent lead paste with high efficiency and the low energy consumption is of great importance in the view of environment and resource recycling. Herein, a novel, eco-friendly and cost-effective process for direct electroreduction of spent lead paste with bagged cathode to produce metallic lead in Na2SO4 electrolyte is proposed. Thermodynamic analysis proves that direct solid-phase electroreduction of spent lead paste in Na2SO4 electrolyte is feasible. The bagged cathode improves the lead recovery ratio and current efficiency. The mechanism of the solid-phase electroreduction is discussed, and the optimum electroreduction conditions are established, under which a cathode current efficiency of 98.5%, desulfurization rate of 99.6%, lead recovery ratio of 97.3%, and energy consumption of 587.2 kWh per ton paste are achieved. The electrolyte can be facilely regenerated and recycled by neutralization with lime. A closed-loop, economical and high-efficiency process for manufacturing metallic lead from spent lead paste has thus been proposed, which can be potentially used for practice.

Energy-saving recovery of lead from waste lead paste via in-situ hydrometallurgical reduction and electrochemical mechanism

The reasonable prudent disposal of secondary lead resources including waste lead-acid batteries has become a growing concern to prevent the adverse impacts. Herein, a facile zero-emission hydrometallurgical reduction approach is proposed for the recovery of spent lead paste (SLP) possessing energy-saving and high current efficiency merits. The effect of activated carbon (AC) additives on lead recovery efficiency, desulfurization efficiency, cathode current efficiency, and energy consumption was investigated during the hydrometallurgical reduction of SLP. The introduction of AC promotes the current efficiency and shortens the electrolysis time, which contribute to the diminution of the whole energy consumption. Especially, the specific energy consumption of hydrometallurgical reduction drops to 483.5 kWh t–1 with 2.0% AC from the initial 596.6 kWh t–1. Notably, the nucleation mechanism of lead on the SLP cathodes all follows three-dimensional instantaneous growth with the diffusion control. Moreover, the SLP plates after hydrometallurgical reduction could be directly employed as the negative electrodes of lead-carbon batteries, avoiding the formation stage. The electrochemical hydrometallurgical reduction with carbon additives presents a promising strategy for enabling zero emissions, low energy consumption operation of SLP recovery and reutilization.

Improving cathode cleaning and current efficiency by regulating loose scale deposition in scale inhibitor-containing water

For electrochemical water softening in practical water containing scale inhibitor, unsatisfactory cathodic cleaning and low hardness removal effect greatly limit its wide large-scale application. An effective improvement is not only dependent on the performance of external mechanical cleaning, but also closely related to the scale structure itself. In this work, the deposition of loose scale layer in the presence of scale inhibitor and its promotion on current efficiency and cathode cleaning efficiency were investigated from interfacial electrochemical perspective. Results reveal that such scale formation is attributed to the relatively high enrichment degree of scaling ions at cathode-water interface. At a high current density or low flow velocity, a relatively high interfacial pH is obtained and the thickness of this alkaline interface is larger than that at lower current density or higher flow velocity. This leads to the increase of CO32− generated by the reaction of HCO3− with more OH−. Besides, due to the weak chelation ability of the scale inhibitor at the alkaline interface, more Ca2+ are released and interact with cathodically formed CO32–. Corresponding scaling driving force is higher than that at lower current density or higher flow velocity. This leads to the deposition of loose scale layer with less stable morphology and a higher specific surface area. This as-deposited scale layer not only acting as seeds accelerates the crystallization and enhances the current efficiency, but also acting as an fragile pre-deposition layer facilitates the cleaning of cathode and produces the highest cleaning efficiency over 95%. This is beneficial for the stable operation of hardness removal device.

An environmentally friendly and high current efficiency acid mist inhibitor for zinc electrowinning

Acid mist inhibitor is an effective additive for suppressing the generation of acid mist during electrowinning process. However, the traditional acid mist inhibitor has a low current efficiency, leading to high energy consumption. Thus, novel acid mist inhibitors are crucial for the development of the electrowinning industry. In this paper, three new acid mist inhibitors (Famigo® FS-101, Famigo® FS-301, and Famigo® FS-401) are used in zinc electrowinning process, while the mechanism of action in suppressing the generation of acid mist is characterized by the volume of bubble attached on the cathode surface and surface tension. The impacts of the concentration of the acid mist inhibitors on the bath voltage, current efficiency, power consumption, and electrochemical properties, as well as the enhancement mechanism on the current efficiency, are studied. The obtained results demonstrate that an adequate concentration of Famigo®FS-101, Famigo®FS-301, and Famigo®FS-401 allows to increase the cathode current efficiency and decrease the energy consumption, from 3219 kWh t−1 in zinc electrolyzer to 2948 kWh t−1, 3090 kWh t−1, and 2884 kWh t−1 using a concentration of 5 mg l−1 of Famigo®FS-101, Famigo®FS-301, and Famigo®FS-401, respectively. The proposed inhibitors have high acid mist inhibition efficiency and current efficiency in the zinc electrowinning process. Furthermore, if engineered, they may contribute to the development of the electroposition industry.

Energy-Efficient and Green Extraction of Bismuth Metal in Methanesulfonic Acid-Based Membrane Electrochemical Systems

As the mainstream hydrometallurgical medium of bismuth sulfide concentrate, chloride/hydrochloric acid suffers from high volatility, strong corrosiveness, and inferior deposit quality. In this paper, methanesulfonic acid (MSA) with low volatility and high stability was adopted as the bismuth hydrometallurgical system, and the membrane electrochemical deposition method was proposed to extract bismuth metal from a bismuth-containing solution. The effects of additives, such as calcium lignosulfonate (CL), tetrabutylammonium chloride, β-naphthol, and lugalvan NES, on the morphology of bismuth deposits and electric energy consumption (EEC) were investigated in detail. The addition of CL as an additive could produce dense and flat bismuth deposits while the EEC is reduced simultaneously. Cyclic voltammetry and chronoamperometry analysis reveal the electrochemical behavior of bismuth deposition in the CL-assisted MSA medium, and the nucleation and growth of bismuth grains follow a 3D ″nucleation/growth″ mechanism. Under a cathode current density of 180 A/m2, a flat metallic bismuth deposit (purity > 99.96%) is produced in the presence of 0.5 g/L CL. The cathodic current efficiency (CCE) and EEC of membrane electrodeposition are 98.25% and 705 kWh/t Bi, respectively. Compared with chloride/hydrochloric acid, the bismuth membrane electrodeposition process in the CL-assisted MSA system has the advantages of being energy-saving, green, and safe, and it has a good application prospect in the field of bismuth hydrometallurgy.