Anodic Dissolution Reaction Research Articles

Hydrazinecarbothioamide Derivative as an Effective Inhibitor for Corrosion Control: Electrochemical, Surface and Theoretical Studies

Aluminium has played a significant role in the advancement of metal matrix composites (MMC) and has drawn the attention of researchers since Al composites find extensive application in aerospace, military and automobile industries. This paper describes the corrosion property of 6061 Al-15 vol%. SiC(p) composites in hydrochloric acid medium. This composite with high strength-to-weight ratio and other alluring properties undergoes corrosion in acid media and a study has been made in 0.5 M hydrochloric acid using (2Z)-2-(2-hydroxy-3methoxybenzylidene) hydrazinecarbothioamide (HCT) as an inhibitor. Results of the electrochemical studies and surface morphology are presented. With the increase in HCT concentration, inhibition efficiency increased. But efficiency decreased with an increase in temperature. The maximum efficiency was found to be 56.8% for the addition of 10 × 10–5 M HCT concentration at 303 K. The inhibitor was found to behave as a mixed inhibitor affecting both anodic metal dissolution reaction and cathodic hydrogen evolution to the same extent. The HCT molecules were found to physisorb over the Al-composite surface and adsorption followed Langmuir’s adsorption isotherm. Adsorption of HCT was confirmed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Computational studies using density functional theory (DFT) supported experimental findings. Density functional theory calculations gave a clear insight into the mechanistic aspects of corrosion inhibition.Graphic

First-Principles Investigation on Work Function of Martensitic Carbon Steels: Effect of Interstitial Carbon on Anodic Dissolution Resistance

The effect of interstitial carbon on the work function and the dissolution resistance of martensitic carbon steels was investigated. Ultraviolet photoelectron spectroscopy measurements of 0.001%C, 0.44%C, and 0.88%C specimens showed that the work function of steels increased with the amount of interstitial carbon. In addition, first-principles calculations indicated that the presence of interstitial carbon clearly increased the work function on both the (110) and (100) orientation surfaces. The immersion tests and potentiodynamic polarization measurements of the specimens were conducted in 50 mM C 8 H 5 KO 4 at pH 4.0, and it was clarified that the anodic dissolution reaction was suppressed as the amount of interstitial carbon increased. The improvement in work function appeared to be related to the superior anodic dissolution resistance.

Influence of dislocation on sour corrosion of carbon steel in a low H2S sour environment

AbstractThe influence of dislocation on corrosion of low alloy steel in a low H2S sour corrosion environment was investigated experimentally (immersion corrosion test and polarization measurement) and theoretically (ESM‐RISM simulation). The results showed that dislocation increases corrosion weight loss by promoting the anodic dissolution reaction. The Fe atom solubilities of two kinds of Fe slab models simulating conditions with/without lattice defects were evaluated, and the high Fe solubility of the model with lattice defects was clarified. Based on these experimental and theoretical findings, the mechanism by which dislocation influences anodic dissolution was discussed.

Novel cost-effective aqueous Amorphophallus paeoniifolius leaves extract as a green corrosion inhibitor for mild steel corrosion in hydrochloric acid medium: A detailed experimental and surface characterization studies

Corrosion resistance property of eco-friendly Amorphophallus paeoniifolius leaves (APL) extract on mild steel surface in 1 M hydrochloric acid solution was studied by chemical, electrochemical and surface characterization methods. The functional groups and compositions of pure APL extract and corrosion product were investigated by FT-IR and UV–visible spectroscopy. Experimental methods proved the extent of metal surface deterioration in acidic medium was diminished as the APL extract concentrations increased. Corrosion inhibition mechanism is suggested to be a mixed type based on results obtained by polarization measurements. The data obtained by electrochemical impedance spectroscopic method indicates the development of protective film around the metal surface. Surface morphological studies such as FESEM, contact angle measurements and AFM studies performed on mild steel surfaces further confirm the protective ability of the inhibitor towards corrosion. It was well supported by EDAX studies indicating restricted anodic dissolution reaction in the presence of inhibitor. Adsorption isotherms showed a good fit to Langmuir isotherm and the data obtained indicates the spontaneous adsorption with the majority being physisorption. Thermodynamic and activation parameters showed the efficacy of inhibitor in controlling the corrosion and the efficiency of corrosion inhibition was found to be inversely proportional to the solution temperature. Percentage corrosion inhibition efficiency (92.49) obtained by electrochemical impedance spectroscopy on mild steel for 10% v/v concentration of APL extract was in good agreement with other experimental methods.

Recent Developments in Mechanistic Modeling of Mild Steel Corrosion in H2s Environments

The corrosion of mild steel in hydrogen sulfide (H2S) environments, as a serious concern in the oil and gas transmission pipelines, has been investigated over the past decades. However, the mechanisms of corrosion of mild steel in H2S environments have been studied in more detail only in recent years. In the present study, a comprehensive mathematical model was developed based on the recent advancement in the mechanistic understanding of corrosion processes in aqueous H2S environments in order to predict the corrosion rate and the polarization response of steel in this system. In this model, the cathodic reaction was developed based on H2S dissociation and its buffering effect. The only cathodic reaction in the system is hydrogen ion reduction. The results confirmed that H2S buffering capacity can thoroughly explain the “double wave” characteristics of the cathodic polarization as well as the increased cathodic limiting current densities of steel in this system. In addition, the anodic iron dissolution reaction was revised by considering the effect of hydrogen sulfide on this reaction. On that account, a reaction pathway with the sulfide intermediates was introduced parallel to the acidic iron dissolution reaction. The developed model was then compared with the available experimental data in the literature, and it was shown that it could reasonably represent the characteristic electrochemical behaviors of H2S corrosion of steel. Furthermore, the predicted corrosion rates are shown to be in good agreement with experimental data over a wide range of experimental conditions.

Influence of Thermomechanical Treatments on Corrosion of Carbon Steel in Synthetic Geopolymer Fly Ash Pore Solution

In this study the effect of thermomechanical treatments in chloride induced pitting corrosion is presented for carbon steel rebars exposed to synthetic fly ash (FA) pore solution. Due to the likely phase transformations that steel reinforcements in concrete experience during the event of a fire, the understanding of the corrosion behavior of such phases is key in predicting the stability of the structure. The motivation for this study arrives from the scarce literature regarding the corrosion behavior of thermomechanically treated steel reinforcements in FA environments and the need for further investigation to understand its mechanism. In order to better understand the effects on the corrosion behavior electrochemical measurements including cyclic potentiodynamic polarization curves (CPP) and electrochemical impedance spectroscopy (EIS) were used. It was found that quenched specimens showed enhanced corrosion kinetics as their icorr values were higher, being of 3.18 × 10−5 and 2.20 × 10−5 A/cm2 for water and oil quenched compared to 2.13 × 10−6 A/cm2 for the as-received. Furthermore, the effective capacitance of the double layer (Ceff,dl) showed the lower stability of the passive film for the quenched specimens, with values of 1.11 × 10−3 µF/cm2 for the as-receive sample that decreased to 8.12 × 10−4 µF/cm2 for the water quenched sample. The anodic charge transfer coefficient in the synthetic FA alkaline pore solution changes from 0.282 to 0.088, for the as-received and water quenched rebars specimens, respectively. These results indicate a lower energy barrier for the anodic dissolution reaction of quenched specimens, indicating that martensite and bainite microstructures promote corrosion process. Enhanced corrosion was found on quenched samples presenting martensite and bainite microstructure as showed by the increased pith depth, with values of 5 μm compared to 1 μm observed in the as-received samples.

Effects of gap on galvanic corrosion behavior of aluminum alloy A5052/carbon steel SS400 couples in NaCl solutions

Galvanic corrosion behavior of Al-Mg alloy A5052/carbon steel SS400 couples with different gaps was investigated in NaCl solutions at various concentrations. The corrosion morphology of the couples differed from each other depending on the gap and NaCl concentration. Steel corrosion was observed as NaCl concentration and/or the gap decreased. When the gap was 10 mm, no corrosion occurred on the SS400 side in all the test solutions, suggesting that anodic dissolution reaction was dominant on the AA5052 side. However, as the gap was decreased, the corrosion of the steel became obvious in the solutions at lower concentrations, although the A5052 also showed localized corrosion. These results indicated that anodic dissolution reaction was generated both on the A5052 and the SS400 under the smaller gap conditions with decreasing the NaCl concentrations. In this study, the effects of gap on the galvanic corrosion behavior were also discussed based on the results of the change in the solution chemistry in addition to galvanic current and potential of the A5052 and SS400 couples.

Influence of external tensile stress on corrosion and trench formation of low alloy steel in a low H2S content sour corrosion environment

AbstractThe influence of external tensile stress on corrosion and trench formation of low alloy steel in a low H2S content sour corrosion environment was investigated. These experiments were conducted with steel for pipelines, and electrochemical methods were used. The results showed that external stress increases the amount of corrosion weight loss and trench depth by promoting the anodic dissolution reaction, and stress concentration was proven to be one of the driving forces for trench formation due to localized corrosion. Based on the experimental findings, the mechanism of trenching was discussed from the viewpoint of promotion of the anodic dissolution reaction by dislocations.

Template-free, microscale dimple patterning of pure titanium surface through anodic dissolution using non-aqueous ethylene glycol-TiCl4 electrolytes

We report a single-step anodic dissolution route for the template-free patterning of pure titanium (Ti) surfaces into a microscale, dimpled topography using non-aqueous ethylene glycol-TiCl4 electrolytes. Anodic dissolution of Ti metal (i.e. 0.04 M Ti4+) into a 40 EG:1 TiCl4 electrolyte was found to induce a predominant change in the anodic dissolution reaction of Ti metal, converting its surface morphology from a slightly-pitted, bright finish into a dimple-patterned surface. The dimple pattern, ca. 4.5 μm in size and 1 μm in cusp height, was found self-organised with no apparent relation to underlying metal grain structure and independent of the applied potential within the anodic current plateau. The origin of the dimple pattern is surmised to arise from a dynamic self-organisation of the anode film, resulting in a Turing structure.

New corrosion inhibitor for 13Cr stainless steel in 20% HCl solution

Purpose A novel compound was synthesized by cyclohexylamine, acetophenone and cinnamaldehyde through Mannich reaction in laboratory to use as corrosion inhibitor for steel in acidification process. Design/methodology/approach The corrosion and inhibition of 13Cr stainless steel in conventional acidification solution were investigated by electrochemical measurements and soaking experiments. The corrosion appearance was observed with scanning electron microscope on the whole surface of 13Cr stainless steel in 20% HCl solution, and the protection film was confirmed on the surface in presence with inhibitor. Findings Results manifested that the inhibitor C23H27NO can effectively inhibit the corrosion reaction by forming an adsorption layer function as a barrier. Polarization curves indicated that the mixed inhibitor can reduce anodic dissolution and cathodic hydrogen evolution reactions simultaneously. The results of impedance measurements indicated that this inhibitor cannot change the corrosion mechanism of 13Cr stainless steel in 20% HCl solution. The results of the study can provide a theoretical basis for the application of 13Cr stainless steel in conventional acidification solutions during oil well acidification construction process. Originality/value A novel compound was synthesized by cyclohexylamine, acetophenone and cinnamaldehyde through Mannich reaction in laboratory to use as corrosion inhibitor for steel in acidification process. The corrosion and anti-corrosion mechanism of 13Cr steel in acid solution was proposed.

Preparation, characterization, and evaluation of corrosion inhibition efficiency of sodium lauryl sulfate modified chitosan for mild steel in the acid pickling process

The polar head and a hydrophobic long alkyl chain end of surfactants show effective adsorption on the metal surfaces and metal/solution interfaces. The present study deals with the investigation of corrosion inhibition efficiency of chitosan modified with an anionic surfactant, namely sodium lauryl sulfate. The modified chitosan was characterized using spectral techniques such as ATR- FTIR and NMR, thermal analytical methods that include TGA and DSC. The surface charge and particle size distribution were analyzed using Zeta potential analyzer. The corrosion inhibition efficiency of the water-soluble modified chitosan was evaluated using gravimetric and electrochemical methods. A maximum corrosion inhibition efficiency of 96.44% for 6 h of immersion period at 303 K was obtained. The adsorption process obeyed Langmuir isotherm. The adsorption mechanism involved both physisorption and chemisorption. Tafel and impedance studies showed results in agreement with the gravimetric method. Tafel plot indicates the inhibitor controlled both cathodic hydrogen evolution and anodic metal dissolution reactions. AC impedance study supports the increase in surface coverage of the metal surface by the inhibitor, forming a protective film. Further evidence comes from the surface characterization of the inhibited metal surface by contact angle measurement, SEM, EDAX spectra, and atomic force microscopic studies. DFT and Monte Carlo simulation studies showed a proper alignment with the experiment results.

The effect of crack tip environment on crack growth behaviour of a low alloy steel at cathodic potentials in artificial seawater

The environment at crack tip and its effect on the crack growth behaviour of low alloy steel- E690 steel were studied at cathodic potentials in artificial seawater. The results showed that the micro environment at crack tip and crack growth behaviour were related to the electrochemical reactions at crack tip, which were affected by the stress state and applied potentials. The crack tip environment was acidified under cyclic loading, resulting from the crack tip anodic dissolution reaction and corresponding hydrolysis reaction. Because of the hydrogen evolution and the inhibited anodic dissolution inside the crack, the crack tip pH increases as the cathodic potential decreases. The effect of cathodic potentials on the electrochemical reactions caused the variation of the hydrogen content, which influenced the crack growth rate because the crack growth behaviour was controlled by hydrogen embrittlement mechanism. This resulted in a fact that with the negative decrease of potential, the crack growth rate first decreased and then increased, with the minimum rate at −0.75 V. And the crack growth path exhibited transgranular fracture.

Investigation of the Corrosion Behavior of Mild Steel/H2SO4 Systems

The corrosion behavior and mechanism of mild steel/H 2 SO 4 systems were examined using hydrogen gas evolution, HE, and weight loss, ML as chemical measurements, and electrochemical impedance spectroscopy, EIS, and potentiodynamic polarization, PDP as electrochemical measurements at 30 o C. From the chemical results, the corrosion rate of mild steel increased as well as increasing acid concentration, with a reaction constant of 0.70 and 0.60 for HE and WL, respectively. Different features including general and pitting corrosion can be shown on the mild steel surface after dipping in different concentrations of H 2 SO 4 , and the latter became more distinct at higher acid concentrations. EIS results showed that the R p value decreases while the C dl value increases along with increasing acid concentration. PDP results clearly revealed that the dissolution of mild steel undergoes anodic control. The chemical and electrochemical method suggested that the dissolution mechanism of mild steel is the same at different H 2 SO 4 concentrations. Based on the results and observations, the mechanism of mild steel corrosion in H 2 SO 4 can be explained based on the role of anions, the main corrosive agent in aqueous solutions, which partake directly in anodic dissolution and cathodic reaction during corrosion.

Microbiologically influenced corrosion of 304 stainless steel by nitrate reducing Bacillus cereus in simulated Beijing soil solution

In this work, microbiologically influenced corrosion (MIC) of 304 stainless steel (SS) caused by Bacillus cereus was investigated by electrochemical measurements and surface analyses in simulated Beijing soil solution under aerobic condition. The nitrate-reducing bacterium (NRB), B. cereus, was isolated from Beijing soil and identified using 16S rDNA. Confocal laser scanning microscopy (CLSM) images showed that the largest pit depths on 304 SS with and without B. cereus after 14 days of incubation were 7.17 and 4.59 μm, respectively, indicating that pitting corrosion was accelerated by B. cereus. X-ray photoelectron spectroscopy (XPS) and energy dispersive spectrometry (EDS) results revealed that B. cereus and its metabolic products were detrimental to the integrity of the passive film on 304 SS. The electrochemical results showed that B. cereus significantly reduced the corrosion resistance of 304 SS and accelerated the anodic dissolution reaction, thereby speeding up the corrosion process.

Effect of stored energy on corrosion fatigue properties of ultrafine grained Fe-20%Cr steel by equal channel angular pressing

Corrosion fatigue properties of ultrafine grained (UFG) Fe-20%Cr steel by equal channel angular pressing was investigated in term of grain refinement and stored energy. The corrosion fatigue life of the ECAP processed and the post-ECAP annealed sample was analysed. Under annealing temperature of 773 K, due to the recrystallization stage, there was a little difference in microstructure from the four passes ECAP. After the annealing process, the strength of the samples pressed four passes decreases, while the elongation showed more ductile. Two mechanisms for crack propagation have been well recognized for stainless steel. One is slipping step dissolution mode. In this model, the slip step formed by active dislocation at a crack tip is anodic dissolution reaction, so that crack tip advance to further distance. The other is stress adsorption mechanism. The corrosion fatigue cracks initiation and cracks propagation process of iron-chromium alloy can be characterized by corrosion pits and intergranular fracture, respectively. The corrosion fatigue behaviour of non-equilibrium and equilibrium grain boundary of iron-chromium alloy was occupied by crack initiation.

A Series of Polyhydric Esters As Novel Candidates for Battery Solvents in Lithium Metal Cells: Electrochemical Investigations and Influences of Moisture and Alcohol Residues in Contact with Lithium Metal

In recent years, the lithium metal anode has aroused great interest, not at least through the development of the lithium//sulfur and the lithium//air battery technologies, in all-solid-state batteries. However, the application of lithium metal anodes is limited by safety issues and several failure mechanisms, including, dendrite growth and direct chemical reactions with electrolyte components like battery solvents, which leads to fast capacity losses. In this context, a new series of polyhydric propyl-based esters were investigated, namely n-propyl acetate, isopropyl acetate (monohydric esters), trimethylene diacetate, 1,2-propylene glycol diacetate (dihydric esters) and triacetin (trihydric ester) as attractive and environmental friendly candidates for electrolyte solvents in lithium metal battery applications.The above mentioned organic esters were examined in respect to their reactivity in contact with lithium metal, influenced by water or alcohol impurities. The resulting reaction products were analyzed and determined via 1H-NMR spectroscopy. Additional experiments were performed and the resulting products compared to anticipated reaction products which were prepared separately, to evidence possible reaction mechanisms like the occurrence of a CLAISEN-condensation. Furthermore, the here mentioned propyl-based esters and the reaction products were analyzed by cyclic voltammetry against copper, platinum and aluminum as working electrode to evaluate the anodic and cathodic stability, as well as possible anodic dissolution reactions in the presence of LiTFSI as conducting salt. In both cases, the reactivity in contact with lithium metal and the anodic dissolution of aluminum, a reactivity could be observed whereupon the trihydric esters were least reactive followed by the dihydric and monohydric esters. In absence of water and alcohols all investigated esters show no detectable reaction with lithium metal. ACKNOWLEDGMENT The authors want to acknowledge the German Federal Ministry for Economic Affairs and Energy (BMWi) for funding within the project FesKaBat (03ET6092E). The authors also acknowledge the analytical group of Sascha Nowak (MEET Battery Research Center, University of Münster) for all performed TXRF measurements.

Electrochemical corrosion mechanisms of nickel-aluminium bronze with different nickel contents using the rotating disc electrode

The open circuit potential, cathodic and anodic polarisation characteristics of nickel-aluminium bronze (NAB) with different nickel contents in 3.5 wt.% NaCl solution were investigated under well-defined hydrodynamic conditions. The results showed that irreversible cathodic oxygen reduction reaction was under kinetic control, whereas the reversible anodic copper dissolution reaction was under mixed transport-kinetic control. The increase in Ni content decreased the total amounts of α phase and β' phase in the microstructures of NAB alloys, resulting in the decrease in both cathodic kinetic current and anodic current, and thus improved the corrosion resistance of NAB alloys under flowing conditions.

Effect of Ni and Cu Addition on Corrosion Behaviors of Pre-Oxidized Ultra-Strong Steel for Automotive Applications

The incomplete elimination of oxide scale formed during the normalizing process can result in severe degradation of the surface and mechanical properties of ultra-strong steels. This study revealed that the formation of oxide scale was highly dependent upon the alloying elements Ni and Cu. Ni-bearing steel showed a much higher oxidation rate, resulting in much thicker scale than Cu-bearing steel. Uneven scale/steel interfaces and oxide penetration along the grain boundary of the steel were clearly observed in the Ni-bearing steel. The difference in the solid solubility limit of Ni and Cu to austenite could lead to the enrichment of Ni and precipitation of Cu at scale/steel interfaces in the two types of steels, respectively. This resulted in the different structure and properties of the oxide scales, which influenced the subsequent corrosion behavior in chloride containing conditions. Linear polarization resistance measurements showed that the addition of Ni and Cu to the steel had a beneficial influence on the corrosion resistance, by suppressing the anodic dissolution and cathodic reduction reactions of Ni and Cu-bearing steels, respectively. This study provided a proposed mechanism for the difference in corrosion behaviors between the two types of steel. Key words: nickel, copper, steel, oxidation scale, corrosion

Effect of Gap Size on Galvanic Corrosion between AA5052 Aluminum-Magnesium Alloy and SS400 Carbon Steel in Aqueous NaCl Solutions

Recently, aluminum alloys (AAs) have been utilized to automobile body parts in order to reduce the weight of the body and improve fuel consumption efficiency. Although some aluminum alloys such as 5000 and 6000 series have relatively good corrosion resistance in atmospheric environments, galvanic corrosion between aluminum alloys and other electroconductive materials is one of the critical issues on automotive application of the aluminum alloys. So far, we have investigated galvanic corrosion between AA5052 aluminum-magnesium alloy and SS400 carbon steel in aqueous NaCl solutions and reported that the galvanic corrosion behavior changes depending on the concentration of NaCl solutions [1]. In this study, effect of gap size between aluminum alloys and steel on galvanic corrosion behavior was investigated in aqueous NaCl solutions. A galvanic couple used in this study was almost the same as that reported before, which was made of AA5052 Al-Mg alloy (Mg: 2.65, Si: 0. 08, Fe: 0.27, Cu: 0.01, Cr: 0.17, Zn: 0.01, Al: bal. (mass%)) and carbon steel (JIS SS400). The plate of both materials was 10-mm width and 15-mm length and 5-mm thickness. After lead wires were connected to each plate, both plates were embedded together in an epoxy resin. In this study, both plates were placed separately along the surface with gap sizes from 500 um to 10 mm so that a coplaner galvanic couple was prepared. The surface of the galvanic couple was ground with SiC papers up to JIS 2000 grit and rinsed in EtOH. Galvanic corrosion experiments were done for 72 h in aqueous NaCl solutions of various concentrations ranging from 5 mM to 2 M. Galvanic current and corrosion potential of the couple were measured during the immersion in the solutions. It was found from the results of corrosion potential, galvanic current, and surface observation that galvanic corrosion behavior changes depending on the gap size between AA5052 and SS400 in the NaCl solutions. When the gap size was 10 mm, no corrosion occurred on the SS400 side in all of the test solutions, suggesting that anodic dissolution reaction was dominant on the AA5052 side. However, when the gap size was decreased, the corrosion of the steel occurred in the solutions at lower concentrations, although the aluminum alloy also showed localized corrosion. These results indicated that anodic dissolution reaction was generated on both materials in the smaller gap-size condition with decreasing the NaCl concentrations. In this study, the change in the galvanic corrosion behavior with the gap size was also discussed from the results of change in the solution chemistry and polarization behavior of the materials. 1. K. Ota, E. Tada, A. Ooi, A. Nishikata, ECS meeting abstracts, MA2018-02, 574, 2018.

Features affecting the cupric chloride leaching of gold

The current study investigated gold dissolution in cupric chloride solution, which is one of the most promising alternatives to replace cyanide, although not yet in operation on industrial scale. In this paper, the gold dissolution reaction rate and mechanism were studied by varying the process variables of temperature (28–95 °C), cupric concentration (0.02–1.0 M), chloride concentration (1–5 M), rotational speed (100–2500 RPM), and pH (0.5–2.0). The parameters affecting either the anodic or cathodic reaction, or both, were identified for the first time to the best of the authors’ knowledge in this wide range and with these parameter intervals. Tafel and linear polarization methods as well as cyclic voltammetry were used for pure gold with both rotating disk and stationary gold electrodes. An increase in the gold dissolution rate was observed with an increase in temperature, chloride concentration, and rotational speed. Additionally, an increase in cupric concentration ([Cu2+] = 0.02–0.75 M) promoted the gold dissolution rate, whereas the gold dissolution rate decreased with [Cu2+] from 0.75 to 1.0 M. The conditions for maximizing the gold dissolution rate in cupric chloride solution were concluded to be T > 55 °C, [Cu2+] = 0.5–0.75 M, [Cl−] = 5 M, and pH = 1.0 and the highest gold dissolution rate (2.9 · 10−4 mol m−2 s−1) was achieved at 95 °C with [Cu2+] = 0.5 M, [Cl−] = 5 M, pH = 1.0, and ωcyc = 2500 RPM. The pH was shown not to affect the gold dissolution rate at all, but only to affect the solubility of the oxidant. It was suggested that gold dissolved as aurous species in the conditions of this study, although the increase in chloride concentration promoted the dissolution of gold as both, auric and aurous, species.The reaction mechanism was interpreted using mixed potential theory. An increase in temperature was shown to promote only the cathodic reduction of cupric ion to cuprous at lower temperatures (28–55 °C); however, both the anodic gold dissolution reaction and cathodic cupric reduction reaction were enhanced at higher temperatures (65–95 °C). The cathodic reaction was also enhanced with an increase in cupric concentration (0.02–0.5 M), whereas the anodic reaction was promoted when the cupric concentration was increased from 0.5 to 0.75 M. When the cupric concentration was increased from 0.75 to 1.0 M, the cathodic reaction rate decreased. However, the reason for the decrease in the cathodic reaction rate was not clear. An increase in chloride concentration enhanced the cathodic reaction in the investigated range (1–5 M), whereas an increase in rotational speed (i.e., improved mass transfer) increased the anodic gold dissolution rate, specifically at low rotational speeds.