Influence Of Chloride Ions Research Articles

Effect of Chloride Ions on the Electrochemical Performance of Magnesium Metal‐Organic‐Frameworks‐Based Semi‐Solid Electrolytes

AbstractThe majority of research on magnesium (Mg) electrolytes has focused on enhancing reversible Mg deposition, often employing chloride‐containing electrolytes. However, there is a notable gap in the literature regarding the influence of chloride ions in semi‐solid Mg electrolytes. In this study, we systematically explore the impact of chloride ions on Mg deposition/dissolution on a copper (Cu) anode using a semi‐solid electrolyte composed of Mg‐based mixed metal‐organic frameworks, MgCl2 and Mg[TFSI]2. We separate the Mg deposition/dissolution process from changes in the anode's surface morphology In this respect, the morphological and compositional transformations in the electrolyte and electrode following galvanostatic cycling are meticulously investigated. Initial potential cycling reveals the feasibility of Mg deposition/dissolution on Cu electrodes, albeit with reduced reversibility in subsequent cycles. Extending the upper potential limit to 4.0 V vs. Mg/Mg2+ enhances Mg dissolution, attributed to chloride ions facilitating Cu surface dissolution. Our findings provide insights into optimizing semi‐solid electrolytes for advanced Magnesium battery technologies.

Influence of chloride ions on corrosion behaviour of zinc-alloy in the simulated body fluid solution

ABSTRACT The bio-corrosion behaviours of the Zn alloy in the simulated body fluid (SBF) at different chloride ion concentrations were investigated. The Potentiodynamic Polarisation Curve (PDP) and Electrochemical Impedance Spectroscopy (EIS) results indicate that the corrosion rate of Zn alloy decreases with higher chloride ion concentrations. The decrease in corrosion rate is due to the formation of a protective layer of ZnCl2 nanofibres and agglomerates. The surface morphology and analytical studies of the Zn alloy were carried out by scanning electron microscopy (SEM), EDX, atomic force microscopy (AFM), and X-ray diffractometry. The SEM, EDX, and X-ray diffraction studies indicate the formation of nanofibres and agglomerates of ZnCl2. The AFM measurements show the increase in surface roughness due to the in situ formation of nanofibres and agglomerates on the alloy surface. Therefore, these results are useful to tailor the design of Zn alloy-based biomedical materials being implanted for the living body.

Enhanced recovery of phosphorus from hypophosphite-laden wastewater via field-induced electro-Fenton coupled with anodic oxidation

Electrochemical recovered ferric phosphate (FePO4) precipitates from hypophosphite-laden wastewater were shown to be an efficient method for phosphorus (P) recovery. However, the influence of chloride ions (Cl−) coexisting commonly in wastewater is not known for this treatment. Herein, a field-induced electro-Fenton coupled with anodic oxidation electrochemical system consisting of a Ti-RuO2 anode, an Fe inductive electrode and an activated carbon fiber (ACF) cathode, namely Ti-RuO2/Fe/ACF(NaCl) system, was established to recover phosphorus (P) as FePO4 from hypophosphite-laden wastewater in the presence of Cl−. This system enabled a hypophosphite (H2PO2−, 1.0 mM) removal ratio of ~100% and all P was recovered within 30 min at 5.0 V under the initial solution pH of 3.0. The Faradaic efficiency and energy consumption of P recovery achieved the maximum value (~94%) and the lowest value (~16 kW h kg−1 P), respectively. Reactive oxygen species including 1O2, FeIVO2+, •O2− and •OH contribute to convert H2PO2− to PO43−, which immediately formed FePO4 with the generated Fe3+ at the optimized conditions. Therein, the contribution of non-radical 1O2 was very considerable. This system exhibited good stability. The efficiency and cost for treatment of actual hypophosphite-laden wastewater were addressed to check its applicability for P recovery.

Electrochemical investigations of the multicopper oxidase from Aquifex aeolicus under direct electron transfer with carbon electrodes

The study of redox proteins confined over an electrode surface is a powerful approach enabling precise modulation of the driving force for interfacial electron transfer through the control of the electrode potential. In this work, we present the investigation of a protein variant of the multicopper oxidase from Aquifex aeolicus obtained by directed evolution. Motivated by the enhanced performance of the protein variant for the oxidation of organic compounds in solution, the enzyme is studied under direct electron transfer with the electrode. A marked dependence of the redox potential with the pH of the electrolyte solution is observed, which is further confirmed by studies under non-turnover conditions. Further investigations show the need for an initial reductive activation to attain maximum bioelectrocatalytic activity for O2 reduction, in agreement with similar observations made for other multicopper oxidases (MCOs). Moreover, the influence of chloride ions on the bioelectrocatalytic reaction is described. The O2-reduction activity is barely affected at KCl concentrations as high as 100 mM. However, a shift in the O2-reduction potential towards more negative values is observed at low pH, explaining the apparent loss in activity for the oxidation of organic substrates in the presence of KCl. The obtained results contribute to a more detailed understanding of the electrochemical properties of metallo-oxidases and other MCOs.

CORROSION RATE OF REINFORCED CONCRETE WITH COMBINED DETERIORATION BY CHLORIDE ATTACK AND ASR

Chloride ions destroy the passive film of steel bars in concrete and induce corrosion. Moreover, the alkali-silica reaction (ASR) produces map cracks in concrete through the formation and expansion of a hygroscopic gel around aggregates. Some existing structures simultaneously experience these two types of deteriorations. In this study, the corrosion rate of steel embedded in mortar with this combined deterioration was evaluated. That is, the presence or absence of reactive aggregates and chloride ions was set as experimental parameters, and specimens with single or combined deterioration of chloride attack and ASR were produced. Cracks and rebar corrosion rates were measured and the influences of chloride ions and ASR on rebar corrosion were discussed based on the polarization curves and resistivity. As conclusions, compared with chloride attack alone, concrete with combined deterioration had more oxygen supply through ASR cracks and a faster corrosion rate. Furthermore, the presence of chloride ions facilitated the formation of electric circuits. In contrast, ASR cracks hindered the formation of an electric circuit. Therefore, the mortar resistivity was the lowest in the case of chloride attack alone, the highest in the case of ASR alone, and intermediate in the case of combined deterioration.

Predictions and Evolution Characteristics of Failure Modes of Degenerate RC Piers

During the service process, piers are often in harsh chloride ion erosion environments. The failure mode evolution of reinforced concrete (RC) piers may occur under the action of continuous corrosion. Accurately identifying the failure mode types and evolution characteristics of corroded RC bridge piers is a prerequisite for the lifetime seismic performance evaluations of bridges. First, based on Fisher’s theory and 174 RC pier columns as the analysis samples, a two-stage discrimination formula for the pier failure modes was established and compared with the existing theoretical discrimination methods. Then, based on Fisher’s discriminant grouping, and combined with Bayes’ formula and chloride erosion theory, a failure mode discrimination method for corrosion-damaged bridge piers that considers probability was developed. Finally, taking a medium-span concrete bridge as an example, the failure modes of the corroded pier in different service periods were predicted, and the influences of the various parameters on the failure mode evolution process of the corroded pier were studied. The results show that the accuracy of the proposed discriminant model was significantly improved compared with those of previous theoretical studies. The development of the failure mode features depends on how the distinct RC pier material qualities degrade under the influence of chloride ions. The degradation of the stirrups and concrete accelerates the nonductile failure of RC bridge piers, while the degradation of the longitudinal reinforcements delays it.

Investigation on the chloride ion erosion mechanism of cement mortar in coastal areas: From experiments to molecular dynamics simulation

• The influences of chloride ions on the phsysical and mechanical properties of cement mortar were analyzed. • The mechanism of bound and free chloride ions on the cement mortars properties were investigated in long-term erosion. • The effect of chloride ions in pores on C S H adsorption was investigated by molecular dynamics simulation. Chloride salts in groundwater are a serious threat to the durability of underground reinforced concrete structures in coastal areas. In order to effectively improve the durability performance of underground structural concrete in coastal areas, physical and mechanical properties such as compressive strength, water absorption rate and chloride ion permeability of cement mortar were studied. The influence laws of mineral additives such as fly ash, ground granulated blast-furnace slag and chloride ions on the relevant properties of cement mortar were analyzed. The effect of chloride ions on these physical and mechanical properties was investigated. The main hydration product categories of cement mortar were derived using microscopic analysis (XRD). The internal microstructure and the surface morphology of cement mortar were obtained by scanning electron microscopy (SEM). The effect of chloride ions in pores on C S H adsorption was studied by using molecular dynamics simulations. The results showed that chloride ion erosion increased the compressive strength of cement mortars doped with FA and GGBS at 28, 100, and 180 days by 2.76 %, 14.32 %, and 7.83 %, respectively. Chloride ion erosion moderately increased the compressive strength of cement mortar doped with FA and GGBS at all curing period. After chloride ion erosion, the electric fluxes of the four groups of specimens at 180 days decreased by 30.37 %, 31.64 %, 23.22 % and 17.41 %, respectively. After the addition of mineral additive, the bound chloride ions changed the influence law of water absorption rate of cement mortar, and reduced the electric flux of cement mortar. The molecular dynamics simulations revealed that the chloride ions in the pores weakened the physical adsorption of external chloride ions by C S H, resulting in the easier passage of external chloride ions through the pores. Microscopic analysis showed that the Friedel's salt generated by chloride ions attacking the cement-based materials filled communicating pores, which may be one of the reasons for the reduced electric flux of the cement mortar.

Analysis on the Influence of Chloride Ion on Sludge Activated System

Analysis on the Influence of Chloride Ion on Sludge Activated System

Influence of chloride ions on strength and microstructure of geopolymer concrete containing fly ash, and blend of fly ash-GGBS

Chloride attack is an important aspect in long-term mechanical and durability performance of geopolymer concrete (GPC) in marine environment. Keeping this in view, in this study, the effect of chloride ions on compressive strength at different ages were investigated, as well as the microstructural changes in terms of molar ratio and morphology of GPC mixes. Two types of GPC mixes were prepared; the first one using 100% fly ash (FAGPC), developed under elevated curing temperature at 80 °C for 48 h, and the other one using a blend of 85% fly ash and 15% ground granulated blast furnace slag (GGBS) (FASGPC), developed under ambient condition. To investigate the effect of chloride ions, sodium chloride (NaCl) was added at 0%, 1.5%, and 3.5% by mass of geopolymer solids during the preparation of GPC mixes. From the test results, it is observed that the FASGPC exhibited lower strength as compared to FAGPC at the early age (7 days) due to lower extent of geopolymerization reaction under ambient condition. However, at later age (360 days), FASGPC showed higher strength as compared to FAGPC. The chloride added GPC mixes exhibited lower strength as compared to control GPC mixes. Furthermore, the FAGPC mixes with added chloride exhibited a higher decrease in strength when compared to FASGPC mixes at both ages. The percentage increase in strength with increase in age (i.e., from 7 to 360 days) was in the range of 106.5% to 110.5%, and 45% to 70.4% for FASGPC, and FAGPC mixes respectively, at all chloride concentrations. The obtained FESEM images indicated the formation of geopolymer gels in the GPC mixes. Furthermore, the variations in strength of GPC mixes with GGBS content and age are in line with the variations in atomic Al/Si and Ca/Si ratios obtained from the EDS analysis.

Quantitative study of the kinetics of hydrogen evolution reaction on aluminum surface and the influence of chloride ion

The behaviors and kinetics of hydrogen evolution reaction (HER) on pure aluminum with passive film in the presence and absence of chloride ion are quantitatively investigated by using the tip generation/substrate collection mode of scanning electrochemical microscopy (SECM) with dual Al/Pt ultramicroelectrode (UME) as tip electrode and Pt UME as substrate electrode. The standard rate constants k0 and transfer coefficients αH of HER in ClO4−- and Cl−-containing solution are 6.9 × 10−7 cm/s and 0.22, 7.1 × 10−6 cm/s and 0.19, respectively. Results show that the kinetic of HER is slow and the destruction of Cl− on passive film can significantly promote the HER on Al surface. Moreover, these αH far less than commonly used 0.5 in corrosion research, can explain the great difference between theoretical Tafel slopes and experimental results. Besides, the existence of current plateau in Al electrode explains the large difference in corrosion potential during parallel testing.

Corrosion surveillance program for tank, fuel cladding and supporting structure of 30 MW Indonesian RSG GAS research reactor

Abstract The objective of this research is to understand the condition of the structural material of the 30 MW RSG-GAS research reactor as input for the aging management program. Furthermore, this should enable a prediction of the remaining life of the components. In the current experiment, corrosion surveillance was carried out at Interim Storage for Spent Fuel (ISSF), that has similar water quality as in reactor pool by using a corrosion probe which is made of aluminum alloy and stainless steel. The probe set is designed to understand the effect of water quality in the ISSF pond. The corrosion processes observed were pitting, crevice and galvanic corrosion. Two sets of corrosion probes were immersed into the ISSF pool in 2007, hanging by steel wire, 1-meter height from the bottom surface. One probe set consists of horizontal and vertical positions. The soaking time was 7 years. The observations made were water chemical content, corrosion rate and visual analysis, macro and micro. For macro visual observations an optical microscope was used, for micro-observations SEM-EDX. From the results of macro-observations, information on the presence of galvanic corrosion, crevice and pitting was obtained. SEM-EDX provides information on the influence of chloride ions on corrosion products. This experience will be very useful in dealing with the aging process of Indonesia’s nuclear power plants in the future.

Influence of deicing salt on the surface properties of concrete specimens after 20 years

The low temperature of ice and snow all year round in Sweden leads to the common use of deicing salt to melt the roads, but the splash of the deicing salt on the reinforced concrete (RC) on both sides of the roads brings about the deterioration of the durability of RC components. The chloride ions diffusion coefficient is an important parameter to evaluate the durability of RC. By adopting the rapid chloride migration method (RCM) and replacing chloride ions with iodide ions, the samples of concrete blocks exposed on the side of the highway for 20 years were taken. This is directly beneficial to study the influence of the type, content, and water-cement ratio of mineral additions on the diffusion and distribution of iodide ions in concrete and analyze the surface environmental effect depth of concrete. The influence of chloride ions on the pore structure and microscopic morphology of concrete also were studied by scanning electron microscope-energy dispersive spectrum and X-ray diffractometer. The results show that as the water-cement ratio increases, the surface environmental effect depth of concrete and the diffusion area of iodide ions gradually increase. Silica fume and ground granulated blast furnace slag (GGBF slag) have an impediment to the diffusion of iodide ions, especially with the high volume of the GGBF slag (about 50%), the diffusion of iodide ions is very low. In general, this research is helpful to provide some empirical ideas and suggestions for the manufacturing and durability design of concrete structures in marine environments or deicing salt road environments.

Influence of Chloride Ions on Electrochemical Corrosion Behavior of Dual-Phase Steel over Conventional Rebar in Pore Solution

Reinforced steel bars (rebar) are extensively used in construction, and the main challenge is in minimizing corrosion due to oxide or passive layer breakdown. In contrast, dual-phase (DP) steel has good corrosion resistance. This study investigated the effect of Cl− ions on the electrochemical corrosion behavior of DP rebar and conventional rebar. Corrosion behavior studies and electrochemical measurements were conducted on DP rebar and conventional rebar in simulated concrete pore solution with different concentrations of Cl− ions. Microstructure analysis, surface morphology analysis, and corroded surface characterization were performed using optical microscopy, field emission scanning electron microscopy, and Raman spectroscopy, respectively. Potentiodynamic polarization and electrochemical impedance spectroscopy measurements revealed that DP rebar has good passivity, leading to better corrosion resistance and greater strength compared to ordinary rebar. In addition, DP rebar showed better passivity behavior compared to conventional rebar in alkaline solution. Therefore, the presence of a dual phase (ferrite and martensite) in reinforced concrete structured steel induces good corrosion resistance.

Influence of High Chloride Concentration on pH Control in Hydroxide Precipitation of Heavy Metals

Removal of zinc and cadmium from highly saline solutions by hydroxide precipitation is discussed. Experimental solubilities of zinc and cadmium in highly saline solutions were compared to modeled results obtained using Pitzer’s approach. An amphoteric character of zinc and cadmium and an influence of chloride ion on the concentration of dissolved metals were investigated. In order to avoid errors linked to pH measurements in concentrated aqueous solutions, the method of calibration of glass pH electrodes was developed and evaluated. The method uses easily prepared buffers whose pHs were determined with the Pitzer ion-interaction approach. The presented investigations address two issues of high significance in industrial wastewater treatment, namely: precise pH measurements and rigorous modeling of highly saline wastewaters. The results can be implemented in the treatment of hydrometallurgical wastewaters such as zinc refinery wastewater. Additionally, an implementation of the presented investigations is not limited to wastewater treatment but can easily be extended to other high-chloride metallurgical processes wherein the pH measurements in highly saline streams are required.Graphical

Influence of chloride ion on zinc electrodeposition from choline chloride based deep eutectic solvent

When deep eutectic solvent (DES) is used to recycle Zn from zinc-containing dusts, chlorine present in these dusts will enter into the resulting solution and inevitably affects subsequent electrodeposition of zinc. This paper investigated the effect of added chloride ions on the electrodeposition behavior of zinc from choline chloride-urea-ethylene glycol (ChCl-urea-EG) DES-containing zinc oxide. Compared with the blank ChCl-urea-EG DES, the addition of chloride ion is found to increase the current efficiency, reduce the energy consumption, and improve the compactness of Zn deposits. In addition, cyclic voltammetry results and kinetic parameters lead to the conclusion that the added chloride ions have an inhibiting effect on Zn(II) ion migration, but have a promoting effect on reduction reaction of Zn(II) ion. The results of X-ray diffraction analysis reveal that the addition of chloride ions affects the crystallographic orientation by enhancing the growth of (101), (102), and (103) planes.

Influence of Chloride Ions on Corrosion Behavior of Steel Bars in a Simulated Concrete Pore Solution

Influence of Chloride Ions on Corrosion Behavior of Steel Bars in a Simulated Concrete Pore Solution

Electrochemical Removal of Humic Acids from Water Using Aluminum Anode: Influence of Chloride Ion and Current Parameters

The removal by electrochemical treatment in batch of humic acids (HA) extracted from leonardite has been analyzed using aluminum electrodes at 25°C and neutral pH, under galvanostatic conditions. HA removal, inferred from UV-Vis spectra and total organic carbon determination, occurred within few minutes of treatment under the experimental conditions tested, and no electrode passivation was observed. The removal rate increased with NaCl concentration and electric current density. Our data indicate that energy consumption per unit weight of HA removed can be significantly reduced by operating at low current density under galvanostatic conditions and/or high salt concentration, thus confirming electrochemical treatment as a powerful technology for wastewater treatment.

The Effect of Chlorine Ion on Metal Corrosion Behavior under the Scratch Defect of Coating

The influence of chloride ion on the corrosion of metal under coating with scratch defects was researched by wire beam electrode (WBE) technology and electrochemical impedance spectroscopy (EIS) technology. The results showed that the current of metal surface could be characterized by the WBE technology. In the case of scratches on the coating, the location of the damage always showed an anodic current, and the cathodic reaction took place adjacent to the damaged location. The cathode area surrounded the defect and migrated to the far end over time. With the increase of Cl- concentration, the corrosion reaction speeded up, the rate of cathode migration also increased, and the speed of coating stripping did as well. Combined with electrochemical impedance spectroscopy, uniform laws were obtained.

Korozija i zaštita betona u pogonu za proizvodnju katodnog bakra

The most complex type of corrosion in the plants of Copper Smelter and Refineries in Bor is present in the plant of Electrolytic Copper Refinery, where the solution of copper (II) sulfate causes the corrosion of concrete and concrete reinforcement as well as the applied steel materials. The processes of corrosion and destruction of concrete surfaces are particularly pronounced. Corrosion of concrete reinforcement is recognized as the main cause of degradation the concrete structure in many cases, both under the influence of sulfates and the influence of chloride ions. Regarding to this, the protection system also requires a knowledge on corrosion problems, both steel and concrete surfaces. The protection system applied in the Copper Electrolysis Plants consists of laying the acid-resistant plates in the epoxy mass, on a previously primed concrete base. This protection system provides minimum 10 years of a protection durability. This work will present the problems of corrosion of concrete structures that occur daily in the plants of Copper Electrolytic Refinery in Bor, the method they are solved and the method of applying the protection systems.

Interpretation on the influence of chloride ion on early hydration evolution for cementitious materials by a non-contact monitoring method

The investigation of the hydration behavior of cementitious material with sea water has drawn a great attention for several decades since the dissolved Cl− ions in sea water may significantly affect the micro scale reactions. And the evolution of micro scale reaction of fresh cementitious material will determine the later performance of the hydration products and structures. In the past, thermal analysis and image amplification equipment were normally used to reveal the changes of microstructure of cementitious materials indirectly and a directly respectively. The major drawback of these methods is that temperature is a kind of coarse experimental parameter susceptible to environmental impact so that is not able to sensitively detect tiny variation of microstructure. Also, image amplification equipment, i.e. SEM, TEM and optical microscopes could only capture instantaneous images which are insufficient to describe the continuous processes. Therefore, in this study, an attempt was made to take advantage of a non-contact monitoring method which is good at both continuously detecting the hydration process of cementitious materials and investigating the microscale chemical and physical variations of liquid phase at the micro scale, i.e., the conductive material. It is found that the replacement of regular mixing water with seawater will evidently change the early stage hydration behavior of cementitious materials. And the seawater is found to take part in the microstructural development of cementitious materials, which can change the hydration rate and hydration degree of the cement-based material structure and its electrical conductivity after deceleration of hardening.