Stainless Steel Anode Research Articles

Elimination of phenol by sonoelctrochemical process utilizing graphite, stainless steel, and titanium anodes: optimization by taguchi approach

Phenol is one of the worst-damaging organic pollutants, and it produces a variety of very poisonous organic intermediates, thus it is important to find efficient ways to eliminate it. One of the promising techniques is sonoelectrochemical processing. However, the type of electrodes, removal efficiency, and process cost are the biggest challenges. The main goal of the present study is to investigate the removal of phenol by a sonoelectrochemical process with different anodes, such as graphite, stainless steel, and titanium. The best anode performance was optimized by using the Taguchi approach with an L16 orthogonal array. the degradation of phenol sonoelectrochemically was investigated with three process parameters: current density (CD) (25, 50, 75, and 100 mA/cm2), time (1, 2, 3, 4 h), and phenol concentration (100, and 200 mg/l). Signal-to-noise (S/N) ratio and analysis of variance (ANOVA) were utilized to examine the impact of each factor. The optimal conditions for phenol removal were 100 mA/cm2, 100 mg/l of phenol, and 4 hours of electrolysis. Under optimal operating conditions, the phenol removal efficiency was 80.99%. The CD was the most influential factor on phenol elimination effectiveness, while the phenol concentration had the least impact.

Controlled Compositions in Zn–Ni Coatings by Anode Material Selection for Replacing Cadmium

Cadmium-based coatings have long been used to protect high-strength steel in aerospace, but due to cadmium’s toxic and carcinogenic nature, its use is increasingly restricted. Zinc–nickel coatings, containing 10–14 wt% Ni, offer superior corrosion resistance compared to pure zinc, making them a promising alternative. However, Zn–Ni coatings are prone to cracking, which can compromise their protection. This study investigates how different anode materials influence crack formation and coating properties during electrodeposition. Zinc and nickel anodes produced coatings with consistent thicknesses of 13–15 µm, while 1020 steel and stainless steel resulted in thicker coatings of up to 33 µm. Notably, coatings deposited with nickel anodes demonstrated strong adhesion and consistent interface quality. Zinc anodes achieved a high Ni content of about 13.5 wt%, whereas 1020 steel and stainless steel produced lower Ni content, around 7 wt%. Additionally, zinc and nickel anodes led to fewer defects and minimal porosity, in contrast to the higher porosity observed with 1020 steel and stainless steel anodes. Furthermore, zinc anodes maintained stable voltages (~0.5 V), contributing to more uniform coatings. In terms of corrosion resistance, zinc anodes exhibited a lower corrosion rate of 0.44 mm/year compared to 1.54 mm/year for nickel anodes. This study highlights the importance of anode selection in reducing cracking and optimizing Zn–Ni coatings, presenting them as a safer and more effective alternative to cadmium-based coatings.

Recommended Practices for the Electrochemical Recovery of Cobalt from Lithium Cobalt Oxide: A Case Study of the Choline Chloride:Ethylene Glycol Deep Eutectic Solvent.

We recommend best practices for the recovery of cobalt from LiCoO2 (LCO) lithium-ion battery (LIB) cathodes by (i) leaching using green deep eutectic solvents (DES) and (ii) subsequent electrodeposition, through a case study of the choline chloride (ChCl):ethylene glycol (EG) DES. DES physical properties (conductivity, viscosity, and surface tension) were tailored by varying the composition between mole ratios of 1:2 and 1:5 (ChCl:EG). Examined along with leaching process parameters (temperature, duration), increasing the fraction of hydrogen bond donors (HBDs) decreased DES surface tension and enhanced leaching. Complete Co recovery was achieved using1:5 ChCl:EG DES at 160oC and 48 hours. Leaching temperatures >160oC are discouraged due to DES thermal degradation. The electrodeposition process was optimized for selective Co recovery with high faradaic efficiency. The leaching ability of the DES was antithetical to the stability of electrodeposition cell components and required operational parameter adjustment to minimize degradation. The optimized system (copper cathode and stainless-steel anode) employing 1:5 DES leachate exhibited a faradaic efficiency of ~80 %, specific Co recovery of ~0.8 mg hr-1 cm-1 at 50 oC and evidence of uniform deposition. DES surface tension is a key descriptor of metal recovery, and guidelines are presented to maximize selective Co recovery.

Impact of applied potential range on corrosion behavior of stainless steel oxygen evolution electrode under potential cycle loading

We investigated the corrosion behavior of 310S stainless steel anode for alkaline water electrolyzer under various triangle-wave potential cycle loadings by changing the lower (x) and higher (y) vertex potentials to simulate the power fluctuation characteristics of renewable energy sources. The anode was subjected to the loadings of x = 0.5–1.5 and y = 1.8–2.5 V in 7 M KOH solution. The dissolution of Fe and Cr into the electrolyte depended significantly on x. Notably, under conditions of x ≥ 1.35 V, the total dissolution amounts of Fe and Cr after the 20,000 potential cycles decreased to approximately 7 % of the condition where x = 0.5 V. Conversely, y had less influence on the total dissolution amounts. Interestingly, the molar ratios of the eluted Fe and Cr into the electrolyte depended on both x and y, suggesting distinct corrosion behaviors of the stainless steel induced by the potential cycles of x ≤ 1.35 and y = 1.8 V, compared to those at x ≥ 1.35 and y = 2.5 V. These findings suggest the importance of precise potential control of the stainless steel anode in alkaline water electrolysis for preventing potential fluctuation-induced corrosion.

Bioelectrochemical reactor to manage anthropogenic sulfate pollution for freshwater ecosystems: Mathematical modeling and experimental validation

Anthropogenic sulfate loading into otherwise low-sulfate freshwater systems can cause significant ecological consequences as a biogeochemical stressor. To address this challenge, in situ bioremediation technologies have been developed to leverage naturally occurring microorganisms that transform sulfate into sulfide rather than implementing resource-intensive physio-chemical processes. However, bioremediation technologies often require the supply of electron donors to facilitate biological sulfate reduction. Bioelectrochemical systems (BES) can be an alternative approach for supplying molecular hydrogen as an electron donor for sulfate-reducing bacteria through water electrolysis. Although the fundamental mechanisms behind BESs have been studied, limited research has evaluated the design and operational parameters of treatment systems when developing BESs on a scale relevant to environmental systems. This study aimed to develop an application-based mathematical model to evaluate the performance of BESs across a range of reactor configurations and operational modes. The model was based on sulfate transformation by hydrogenotrophic sulfate-reducing bacteria coupled with the recovery of solid iron sulfide species formed by the oxidative dissolution of dissolved ferrous iron from a stainless steel anode. Sulfate removal closely corresponded to the rate of electrolytic hydrogen production and hydraulic residence time but was less sensitive to specific microbial rate constants. The mathematical model results were compared to experimental data from a pilot-scale BES tested with nonacidic mine drainage as a case study. The close agreement between the mathematical model and the pilot-scale BES experiment highlights the efficacy of using a mathematical model as a tool to develop a conceptual design of a scaled-up treatment system.

Insight into the effective electrocatalytic sulfide removal from aqueous solutions using surface oxidized stainless-steel anode and its desulfurization mechanism

The electrochemical oxidation of hydrogen sulfide (H2S) has shown its potential for the real application of H2S emission control in wastewater treatment. In this study, a surface corrosion treatment of stainless steel (SS) was optimized by regulate Ni content in the oxide film on the SS AISI 304 surface for sulfide removal. The X-ray photoelectron spectroscopy and linear sweeping voltammetry results indicated a higher Ni content in the oxide film of surface-oxidized stainless steel (SOSS) attributed to a higher sulfide removal potential. Sulfide removal experiment results showed that SS-150 (with 150 s anodic pretreatment) anodes achieved the highest Ni content of 69% with the best sulfide removal efficiency, i.e., 97% within 48 h, which increased by 20% compared to the untreated SS. This study also demonstrated a strategy for in situ removal of deposited sulfur on the anodes by cathodic treatment at −0.38 V vs. RHE to alleviate the common issue of sulfur passivation. Density functional theory (DFT) calculation revealed that NiOOH was the major active species in SS-150 oxide film for a faster sulfide removal rate. The study developed a SS surface modification process for Ni content regulation that contributed to better sulfide removal efficiency.

Increased Readiness for Water Splitting: NiO-Induced Weakening of Bonds in Water Molecules as Possible Cause of Ultra-Low Oxygen Evolution Potential.

The development of non-precious metal-based electrodes that actively and stably support the oxygen evolution reaction (OER) in water electrolysis systems remains a challenge, especially at low pH levels. The recently published study has conclusively shown that the addition of haematite to H2SO4 is a highly effective method of significantly reducing oxygen evolution overpotential and extending anode life. The far superior result is achieved by concentrating oxygen evolution centres on the oxide particles rather than on the electrode. However, unsatisfactory Faradaic efficiencies of the OER and hydrogen evolution reaction (HER) parts as well as the required high haematite load impede applicability and upscaling of this process. Here it is shown that the same performance is achieved with three times less metal oxide powder if NiO/H2SO4 suspensions are used along with stainless steel anodes. The reason for the enormous improvement in OER performance by adding NiO to the electrolyte is the weakening of the intramolecular O─H bond in the water molecules, which is under the direct influence of the nickel oxide suspended in the electrolyte. The manipulation of bonds in water molecules to increase the tendency of the water to split is a ground-breaking development, as shown in this first example.

Electrochemical oxidation of methyl blue dye by stainless steel tubes bundle anode

Methyl blue dye was successfully electrochemically oxidised in a flow-through batch circulation process using a stainless-steel tube bundle anode. The experimental design and process optimisation were conducted according to the response surface Methodology with Rotatable Central Composite Design method. The controlled variables in this study were the solution flow rate, applied current, electrolyte concentration, and time. A quadratic mathematical model expressing the removal percentage as a function of the operating variables and their interactions was constructed from the experimental data. The accuracy of the model was confirmed using residual plots and an R2 value of 0.8526. Solution flow rate was found to promote the removal percentage up to 1.5 l/min, the applied current promoted the removal efficiency significantly up to 400 mA, the electrolyte concentration had a positive effect up to 2 M, and the removal efficiency increases generally with time, reaching the equilibrium removal percentage at 67.121 min. The optimum conditions for the target with the highest removal percentage of 91.333% were found to be 1.5 l/min solution flow rate, 400 mA applied current, 2 M electrolyte solution, and 67.121 min.

Spray coating of carbon nanoparticles as an effective and scalable method to enhance the performance of stainless steel anode in microbial electrochemical systems

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Bioenergy Production from Tannery Waste via a Single-Chamber Microbial Fuel Cell with Fly Ash Cathodic Electrodes

Microbial Fuel Cells (MFCs) are attracting attention for their application in simultaneous energy production and waste treatment, as innovative biochemical reactors. They usually operate under adiabatic conditions, utilizing microorganisms to treat wastewater compositions using mainly carbon-based electrodes as anodes and cathodes. During the past years, various anodic and cathodic electrodes with plenty of variations were used in MFC configurations. On the anode side metal-based electrodes are used while on the cathode, ceramic electrodes are currently introduced. In this study, a stainless steel anode is used in a single chamber MFC. Ceramic cathodic electrodes are used, coated with Fly Ash (FA). The mixed transition oxides of FA are tested as potential cathodic catalysts in the operation of the MFC. The FA powder was deposited by two methods: an ultrasound-assisted method and a conventional brush coating. Tannery liquid waste is used as the waste/substrate to be treated in the single-chamber MFC. The configuration with ultrasound-assisted Fly-Ash produced cathodic electrodes, led to the highest power output in batch operation modes and a high degree of simultaneous COD decrease of the tannery waste reaching the values of 0.44 mW/gcat and 85.6% COD removal respectively.

Stainless Steel Anode for Alkaline Water Electrolysis: Recent Progress in Active and Durable Surface Catalyst Layer Generation

Stainless Steel Anode for Alkaline Water Electrolysis: Recent Progress in Active and Durable Surface Catalyst Layer Generation

RESPONSE SURFACE METHODOLOGY APPLIED TO ELECTRO-FENTON PROCESS FOR DEGRADATION OF RED BEMACID AS TEXTILE DYE MODEL

The textile industry produces persistent organic pollutants (POPs) that pose significant risks to ecosystems because of their toxic and hazardous nature. Consequently, there is an urgent requirement for the development of effective techniques to treat the effluents and remove these compounds. This work studied the viability of the Electro-Fenton (EF) process as a potential alternative for treating textile wastewater contaminated with POPs. A batch electrochemical reactor, equipped with a platinum grid cathode and stainless-steel sacrificial anode, was utilized to eliminate Red Bemacid (RB) dye. The study investigated the impact of four key operational parameters: (i) stirring speed (rpm), (ii) oxygen flow rate (L/min), (iii) supporting electrolyte concentration [Na2SO4] (mg/L), and (iv) current intensity (A), as well as their interactions on RB removal. To perform this, Central Composite Experimental Design (CCD) and Response Surface Methodology (RSM) were employed. Under optimized EF conditions for RB removal (stirring speed = 205.09 rpm, oxygen flow rate = 0.20 L/min, current intensity = 0.306 A, and supporting electrolyte concentration = 0.09 M), the EF process demonstrated exceptional removal efficiency, achieving approximately 94.51% removal of RB. The obtained results showed that the kinetic data of RB removal were in good agreement with the Behnajady-Modirshahla-Ghanbery (BMG) model. The CCD analysis revealed that the main effect of the current intensity had a significant impact on RB removal, as well as the interaction of all paired variables.

Ru-Cu Nanoheterostructures for Efficient Hydrogen Evolution Reaction in Alkaline Water Electrolyzers.

Combining multiple species working in tandem for different hydrogen evolution reaction (HER) steps is an effective strategy to design HER electrocatalysts. Here, we engineered a hierarchical electrode for the HER composed of amorphous-TiO2/Cu nanorods (NRs) decorated with cost-effective Ru-Cu nanoheterostructures (Ru mass loading = 52 μg/cm2). Such an electrode exhibits a stable, over 250 h, low overpotential of 74 mV at -200 mA/cm2 for the HER in 1 M NaOH. The high activity of the electrode is attributed, by structural analysis, operando X-ray absorption spectroscopy, and first-principles simulations, to synergistic functionalities: (1) mechanically robust, vertically aligned Cu NRs with high electrical conductivity and porosity provide fast charge and gas transfer channels; (2) the Ru electronic structure, regulated by the size of Cu clusters at the surface, facilitates the water dissociation (Volmer step); (3) the Cu clusters grown atop Ru exhibit a close-to-zero Gibbs free energy of the hydrogen adsorption, promoting fast Heyrovsky/Tafel steps. An alkaline electrolyzer (AEL) coupling the proposed cathode and a stainless-steel anode can stably operate in both continuous (1 A/cm2 for over 200 h) and intermittent modes (accelerated stress tests). A techno-economic analysis predicts the minimal overall hydrogen production cost of US$2.12/kg in a 1 MW AEL plant of 30 year lifetime based on our AEL single cell, hitting the worldwide targets (US$2-2.5/kgH2).

Development of a New Type of Electrochemical Reactor for Low Temperature Lime and Cement Production

The cement industry is responsible for more than 8% of the global CO2 emissions, making it one of the largest contributors to global warming. Two-thirds of these emissions are coming from unavoidable process gases caused by the calcination reaction of limestone (CaCO3). The remaining emissions are mainly coming from the combustion of fossil fuels. Due to the high temperature requirement (≈1500°C), direct electrification is difficult to consider. For these two reasons, the cement industry is therefore known as a challenging sector to decarbonize.A new electrochemical pathway for cement production has gained prominence in the scientific literature in recent years [1]. This technology has the potential to electrify the cement and lime production while producing at the same time valuable gases (O2, CO2, H2). It is based on a new type of hybrid electrolyser capable of working with solid, liquid and gaseous phases. Thanks to the acidity generated by water oxidation at the anode, the solid limestone feed, precursor of cement, is being dissolved. This dissolution produces pure CO2 which is mixed with pure O2 generated by electrolysis and which is easily captured for later use. The calcium ions are then migrating towards the cathode under the effect of the electric field. The OH- hydroxyl ions, produced at the cathode by water reduction, meet the calcium ions to form the final solid product, hydrated lime (Ca(OH)2). This lime can be used as such or converted into cement by additional steps.In this research, a laboratory-scale setup has been developed to study the feasibility of such a process. Different geometries have been tested and the main operational parameters affecting the different steps of the process have been investigated. Our results show first of all the formation and stabilization of a pH gradient within the electrolyser, which allows at the same time for the complete dissolution of CaCO3 in the acidic anodic environment while producing a white precipitate of Ca(OH)2 at the cathode. The setup also presents ideal faradaic efficiencies when using an IrO2 coated titanium anode and a nickel cathode in a 1M NaClO4 electrolyte. Alternative electrode materials, including a 316L stainless steel anode and an Inconel 718 cathode, have been considered as well. Finally, it was shown that the energetic efficiency can be further improved by pushing the kinetics of the dissolution and precipitation reactions through increasing the mobility of calcium ions, using Ca-based electrolytes, like Ca(ClO4)2. Based on our results, all the elementary concepts behind the hybrid electrolyser have been established, and a first blueprint of a continuous industrial process will be proposed.[1] - L. D. Ellis, et al. (2019). Toward electrochemical synthesis of cement—An electrolyzer-based process for decarbonating CaCO3 while producing useful gas streams. PNAS , 117, 12584-12591. Figure 1

Apparent and true mineralization during combined electro‐oxidation and electro‐coagulation on stainless steel anode

AbstractPresent study is a novel attempt to experimentally verify that electrochemical treatment of organic pollutants on stainless steel (SS) anode is a combination of electro‐oxidation (EO) and electro‐coagulation (EC) with quantitative estimation of individual contributions of the two mechanisms. Target organic pollutants, metformin HCl (MET‐HCl) and lamotrigine (LAM), were electrochemically treated with SS anode for this purpose. Experiments were designed using central composite rotatable design (CCRD) to assess the effect of current density (CD) and supporting electrolyte concentration (SEC) as independent process parameters. Under all conditions, the process was experimentally verified to be a combination of EO and EC. For MET‐HCl, true mineralization (TM) as a result of EO contribution varied between 50.13% and 66.64%. EO contribution and resulting TM for LAM ranged from 37.5% to 61.83%. EC contributed 30.6%–31.84% towards MET‐HCl remediation causing the TOC to be transferred from the liquid to the sludge produced (SP). EC contribution was 23.68%–35.89% for LAM remediation. Thus, apparent mineralization (AM), the sum of EO and EC contributions, ranged from 80.63% to 97.79% for MET‐HCl and 61.18% to 96.82% for LAM.Process parameters were statistically optimized using response surface methodology (RSM) to simultaneously maximize TM and AM with minimal energy consumption and maximal current efficiency. The optimized conditions were 0.83 mA/cm2 CD and 86.66 ppm SEC for MET‐HCl. The corresponding values were 1.31 mA/cm2 CD and 79.51 ppm SEC for LAM.

Three-dimensional macroporous structure and surface carbon-coating modification of stainless-steel anode boost bioelectrocatalytic performance

Bioelectrochemical systems (BESs) is a promising and sustainable technology for wastewater treatment, and the practical application of BESs generally requires scalable three-dimensional (3D) electrodes. In this study, we present a stainless-steel crochet mesh electrode (P-SS) with 3D macroporous structure, and modified by carbon coating through pyrolyzing residual lubricating oil in the mesh production process. The effect of 3D macroporous structure and surface carbon-coating modification on the improvement of electrode bioelectrocatalytic performance was investigated during the study. When the electrode was used as the anode in BESs reactors, a superior bioeletrocatalytic current was generated, reaching a maximum projected current density of 9.95 mA·cm−2 and achieving a highest geometric current density of 1.89 mA·cm−2 ever recorded. We found the 3D macroporous structure and surface carbon-coating modification enabled the electrode well mass transfer, excellent biocompatibility and fluent electron transport, finally boosted the superior bioeletrocatalytic performance. We also verified the electrode has a remarkable stackability as suggested by the bioelectrocatalytic current increasing linearly with the increase of electrode thickness. In addition, the acceptable capital cost (＜6500 $·m−3), adequate mechanical strength and feasible industrial process of this novel electrode all indicate its great prospects for the scaling-up of BESs.

Ultrasonic-electrodeposition construction of high hydrophobic Ce-PDMS-PbO2/SS electrode for p-nitrophenol degradation: Catalytic, kinetics and mechanism

In this work, a novel hydrophobic microsphere Ce-PDMS-PbO2 structure on stainless steel (SS) was prepared via ultrasonic-electrodeposition as an efficient anodic electrocatalyst for p-nitrophenol (PNP) degradation. Compared to PbO2/SS, such Ce-PDMS-PbO2/SS electrode exhibits obviously lower activation energy (19.20 kJ mol−1) and charge transfer resistance (3.268 Ω cm−2), tolerable stability, higher exchange current density (1.171 ×10−5 A cm−2) and electrochemical active area (202.0 cm2). The as-synthesized Ce-PDMS-PbO2/SS anode achieved drastically enhanced PNP removal efficiency of 96.9% in 120 min, and the degradation reaction-order was calculated to be 0.9123 conformed to the quasi-first-order reaction kinetics. The GC-MS results reveal the possible PNP degradation pathway under the action of both anodic and cathodic reactions. Furthermore, the DFT calculation results show that Ce doping can decrease the activation energy barrier of ·OH and promote the ·OH generation. Overall, this work offers a new strategy and comprehension to construct a high-efficiency electrode for PNP pollutants degradation.

Performance of activated stainless steel and nickel-based anodes in alkaline water electrolyser

Performance of activated stainless steel and nickel-based anodes in alkaline water electrolyser

Modification of Child-Langmuir Law for Electrodes of Different Materials and Shapes Using Nitrogen Gas

A dc glow discharge plasma between the planar electrode and planar, conical, and hemispherical electrodes was studied. The electrode materials made of aluminum, graphite, and stainless steel (SS) were used. The experimental results showed a deviation in the traditional Child-Langmuir (CL) law as a result of the use of different shapes and materials of anodes and cathodes. The new parameters of the modified CL law as a function in the surface areas of electrodes, their work function materials, and their contributions to the electrical discharge. The lowest discharge characteristics were for the aluminum planar electrode (anode or cathode) with the aluminum and graphite hemispherical one. The planar aluminum cathode with the conical SS anode gave the highest discharge characteristics. The planar aluminum anode with conical SS cathode had the lowest Paschen curve values. In Paschen curves, the highest values were discovered to be for the planar cathode in a comparison with different cathodes. The hemispherical aluminum anode had the highest Paschen values compared with different anodes. Moreover, the contribution ratio of the anode to the cathode in the discharge for the aluminum planar diode was equal to the ratio between their surface areas and the ratio between their work function materials. In contrast, this contribution ratio for the other discharge cases was equal to the multiplication of the surface areas ratio of the anode to cathode and the ratio of their materials’ work functions. The modified CL law and its coefficient were generalized for the electrodes of different shapes, materials, and used gases.

Novel application of electrochemical chloride extraction fixing polymer-modified conductive repair mortar as anode

Electrochemical chloride extraction (ECE) technique provides an effective technique to remove the chloride ions from concrete and realize reinforcements performance recovery. In this study, a novel type of polymer-modified conductive repair mortar (PCRM) was developed as the anode of ECE system, while the impacts of electrochemical parameters, anode types and reinforcements layout on the chlorides extraction efficiency were investigated, in addition, an innovative method is also proposed to further enhance the ECE efficiency. The results highlight that PCRM can be successfully fabricated with proper initial/final setting time, which presents the similar extraction efficiency compared with PC-based repair mortar and stainless-steel mesh anode. Furthermore, reinforcement cages provide target concrete with lower extraction efficiency inside the cage, and the efficiency can be remarkably increased by pulse current. Most importantly, the chloride extraction efficiency of PCRM anode is increased from 45.1% to 59.6% (electrochemical parameters), 53.7% (reinforcements layout), 60.2% (pulse current), respectively.