Chloride Ions In Solution Research Articles

Effect of oxygen content in CuO x nanofilms on chloride ion detection for ion sensor applications

Sensors for detecting chloride ions have been required for routine monitoring of industry and human health. This study proposes a concept of an ion sensor based on CuO x nanofilms with different oxygen contents. The CuO x -based sensors exhibited an increase in DC current for those with low oxygen content and a decrease for those with high oxygen content following exposure to a chloride ion solution. AC impedance analysis suggested differential reactions of chloride ions in the bulk and surface regions of CuO x , dependent on the oxygen content. For the CuO x -based sensors with a ratio of 0.78 oxygen to copper atoms at chloride ion concentrations of 10−1000 ppm, the sensitivity in the bulk region calculated from AC impedance was 61−2926, which was higher than the sensitivity of 1.3−2.6 calculated from DC impedance. Finally, CuO x -based sensors demonstrated identifiability for chloride ions compared to sodium and calcium ions.

Investigation of hydrolysis properties of MgH2 in different anionic/cationic salt solutions

MgH2 is a promising metal hydride for high-density hydrogen storage, offering advantages such as operational safety, high hydrogen yield, and cost-effectiveness in hydrolysis-based hydrogen generation. However, challenges persist in this field, including reaction interruption caused by the formation of passivating layers and sluggish kinetics. In this study, MgH2 hydrolysis experiments were conducted, utilizing various solutions including 1 M AlCl3, Al2(SO4)3, Al(NO3)3, NiCl2, NiSO4, Ni(NO3)2, FeCl3, Fe2(SO4)3, and Fe(NO3)3 at different temperatures. The resulting hydrolysis products were analyzed using X-ray diffraction and scanning electron microscopy to examine their phases and morphology. Through comprehensive analysis of the hydrolysis mechanism and kinetics, chloride ion solutions were identified as highly efficient, demonstrating excellent rates and yields. Notably, AlCl3, NiCl2, and FeCl3 outperformed other solutions, exhibiting kinetic performance with hydrolysis activation energies of 17.3 ± 1.7, 24.2 ± 1.3, and 14.7 ± 1.7 kJ/mol, respectively. Furthermore, we extended our investigation to compare the hydrolysis effects of different cations, incorporating MnCl2, CoCl2, and CuCl2. Mechanistic analysis pinpointed Al3+ and Fe3+ as catalysts with exceptional hydrolysis performance and remarkable kinetic properties. The aforementioned remarkable MgH2 hydrolysis properties are of significant interest for investigating the corresponding Mg-based alloy hydrides, which are worthwhile to consider.

Reactive molecular dynamics study on carbon steel corrosion induced by chloride: Effects of applied potential and temperature

The corrosion and oxidation mechanisms of steel in chloride-contaminated environment were studied through the utilization of reactive molecular dynamics simulations with self-developed force fields under various applied electric fields and temperatures. The impact of variations in the external electric field on the thickness of the oxide layer and the dissolution of iron during the corrosion reaction process was scrutinized. The results reveal that under an electric field strength of 10 MV/cm, marginal corrosion was observed within the iron matrix during the simulation period. The surface lattice of the iron matrix retained a relatively intact and regular arrangement. However, under alternative external electric field conditions, as the strength of the external electric field increased, the corrosion behavior of iron in chloride ion solutions became increasingly severe, leading to deeper oxidation levels. Additionally, localized pitting on the iron matrix surface gradually evolved into larger corroded spots. Simulation results within the temperature range studied (278 K, 298 K, 318 K) suggest that temperature elevation amplifies the thermodynamic energy of chemical reactions on the iron surface, consequently leading to a reduction in the bond strength of Fe-O and increase in the corrosion extent.

Photocatalyzed CO2 reduction to CO by supramolecular photocatalysts made of Ru(II) photosensitizers and Re(I) catalytic subunits containing preformed CO2TEOA adducts

Two new supramolecular photocatalysts containing Ru(II) polypyridine units as light-harvesting photosensitizers and Re(I) polypyridine subunits as catalytic centers have been prepared. The new species, RuRe2A and Ru2ReA, contain catalytic Re(I) subunits coordinated by the preformed CO2TEOA adduct (known to be the effective catalytic subunits; TEOA is triethanolamine) and exhibit quite efficient and selective photoreduction of CO2 to CO, with outstanding TONs of 2368 and 2695 and a selectivity of 99.9% and 98.9%, respectively. Such photocatalytic properties are significantly improved with respect to those of previously studied RuRe2 and Ru2Re parent compounds, containing chloride ligands instead of the CO2TEOA adduct. Comparison between photocatalytic performance of the new species and their parent compounds allows to investigate the effect of the CO2TEOA insertion process as well as the eventual effect of the presence of chloride ions in solution on the photocatalytic processes. The improved photocatalytic properties of RuRe2A and Ru2ReA compared with their parent species are attributed to a combined effect of different distribution of the one-electron reduced form of the supramolecular photocatalysts on the Ru-subunit(s) (leading to decreased CO formation due to a poisoning ligand loss process) and on the Re-subunit(s) and to the presence of chloride ions in solution for RuRe2 and Ru2Re, which could interfere with the CO2TEOA adduct formation, a needed requisite for CO forming catalysis. These results strongly indicate the utility of preparing supramolecular photocatalysts containing preformed adducts.

Study on the Effect of Bentonite on the Resistance to Corrosion of Plastic Concrete

Objective: To study the effect of bentonite on the corrosion resistance of concrete. Methods: Using the direct immersion method, the chloride ion solution and sulphate ion solution were prepared to simulate the corrosive water environment, and the test blocks were placed in the corrosive solution for corrosion. The cube compressive strength of plastic concrete with different bentonite admixtures was tested under standard curing conditions, after immersion in chloride ion solution and after immersion insulfate ion solution immersion curing. The relationship between the amount of bentonite admixture and the strength of the test block after dissolution in ambient water was analyzed in comparison with the reference group. The microstructure of the internally doped bentonite was studied using SEM (scanning electron microscopy) , and its corrosion mechanism was discussed. Results: As the proportion of bentonite in the cementitious material increases, the cube compressive strength of plastic concrete gradually decreases. In the range of 0~30%, the corrosion degree of chloride ion solution on the concrete strength first decreases and then increases. When the content of bentonite is 20%, the corrosion effect is the smallest; the effect of corrosion of sulfate ion solution on concrete strength continues to decrease, and is minimized at 30%. Conclusion: A certain amount of bentonite can effectively reduce the strength loss of plastic concrete after corrosion.

Initiation of Sulfide Stress Cracking Using Potentiostatic Liquid-Phase Ion Gun

A liquid-phase ion gun (LPIG) was used to create a local H2S enriched environment near Cr-containing steel surface in Na2S solutions in attempt to induce sulfide stress cracking on the specimen surface. In a 1.5 mM Na2S solution, anodic polarization of LPIG Pt microelectrode at a potential of 1.90 V vs SHE resulted in that local solution was successfully acidified to below pH 4, a pseudo-sour environment. When Cr-containing steels were potentiostatically polarized under this pseudo-sour environment by LPIG, sulfides were formed on the specimen surface depending on Cr-concentration, specimen potential, and chloride ion in solution. When LPIG was operated on Cr-containing steels subjected to tensile stress using a four-point bending tester, cracks were formed on the steel surface.

Study on effect of chloride and temperature on corrosion behavior of CoCrFeMnNi high entropy alloy

The effect of chloride ion concentration and solution temperature on the corrosion behavior of CoCrFeMnNi high entropy alloy (HEA) was studied by electrochemical measurements, atomic force microscope (AFM) and immersion test. The result shows that increasing [Cl-]/[OH-] ratio or solution temperature enhances the electrochemical reaction ability, weakens the protection of passive film, and generates more severe pitting corrosion. The negative impact of temperature on the corrosion behavior of the HEA is more obvious than that of chloride concentration. A synergistic effect is produced between solution temperature and chloride ion concentration, which significantly destructs the denseness of passive film, and greatly decreases the anti-corrosion properties of the HEA. The pits occurred on the HEA could be ascribed to the selective dissolution of Fe, Co and Ni elements.

Study on the adsorption mechanism of chloride ion in aqueous solution on Mg/Al-CLDH modified by high temperature calcination

The co-deposition method prepared the Mg/Al double hydroxyl composite metal hydroxide with interlayer anion CO32−. Mg/Al-CLDH was obtained by calcination at high temperatures, and its potential to adsorb chloride ions in an aqueous solution was studied. The adsorption effect was the best when the roasting temperature was 550 ℃. The optimal adsorption temperature in the sodium chloride solution of 300 mg/L was 65 ℃ and reached equilibrium after a 180 min reaction. The unit adsorption mass can get 172 mg/L in the sodium chloride solution with a 2000 mg/L concentration. According to the adsorption equilibrium isotherm and adsorption equilibrium kinetic analysis, the maximum unit adsorption capacity of Mg/Al-CLDH can reach 182.88 mg/g, and the adsorption mode is mainly monolayer adsorption and chemical adsorption. The adsorption of chloride ions primarily depends on the interlayer ion exchange and filling. High-temperature calcination makes part of CO32− in the original structure separate from the interlayer in the form of CO2. Part of the chloride ions in the solution enter the interlayer to fill the vacancy. On the other hand, chloride ions can be fixed by ion exchange with the remaining CO32−.

Formation of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) in the electrochemical oxidation of polluted waters with pharmaceuticals used against COVID-19

The COVID-19 pandemic has produced a huge impact on our lives, increasing the consumption of certain pharmaceuticals, and with this, contributing to the intensification of their presence in wastewater and in the environment. This situation demands the implementation of efficient remediation technologies, among them, electrochemical oxidation (ELOX) is one the most applied. This work studies the application of ELOX with the aim of eliminate pharmaceuticals used in the fight against COVID-19, assessing its degradation rate, as well as the risk of formation of toxic trace by-products, such as unintentional POPs like polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). To this end, model solutions containing 10 mg L-1 of dexamethasone (DEX), paracetamol (PAR), amoxicillin (AMX), and sertraline (STR) with two different electrolytes (NaCl and Na2SO4) have been evaluated. However, electrochemical systems that contain chloride ions in solution together with PCDD/Fs precursor molecules may lead to the formation of these highly toxic by-products. So, PCDD/Fs were quantified under conditions of complete degradation of the drugs. Furthermore, the presence of PCDD/Fs precursors such as chlorophenols was determined, as well as the role of Cl-, Cl• and SO4•− radicals in the formation of the by-products and PCDD/Fs. The maximum measured concentration of PCDD/Fs was around 2700 pg L-1 for the amoxicillin case in NaCl medium. The obtained results emphasise the importance of not underestimating the potential formation of these highly toxic trace by-products, in addition to the correct selection of oxidation processes and operation variables, in order to avoid final higher toxicity in the medium.

Prospective of the LDI MS to characterization the corrosion products of silver-copper alloys on an example of the Ag-Cu-X (X- Zn, Pd, In) system

This work presents the perspective of applying the laser desorption/ionization mass spectrometry (LDI MS) for characterization the anode film of the Ag60Cu26Zn14, Ag58.5Cu31.5Pd10, and Ag63Cu27In10 alloys (at high concentrations of chloride ions in solutions). The reference LDI mass spectra of anode films of pure Ag and Cu have been used for the identification of product corrosion. Knowing the clusters detected in the reference spectra lead to the facilitating identification of the LDI mass spectrum of the sample and reduces the analysis time. The LDI MS analysis of these alloys revealed that the predominant corrosion product are AgCl (from AgnCln+1−/+, n = 1–3), and CuCl (from “superhalogen” CumCln− clusters, m = 1–2, n = 2–6); it also revealed Cu2(OH)3Cl (from Cu2(OH)(H2O)2+) and Cu2O (from Cu(H2O)+, Cu2O doped with chlorine). These results are in accordance with the X-ray diffraction and Raman analysis. The LDI MS spectra of alloys contain the additional peaks formed due to the mutual influences of different metals in the alloys (AgCuCl3− (AgCl-CuCl2−), AgCu2Cl4− (AgCl-CuCl-CuCl2−), and Ag2CuCl4− (AgCl-AgCl-CuCl−), which is consistent with the identified corrosion products. It should be noted that the LDI MS suggest the presence of CuCl2, which can be interpreted as the corrosion products retained in the porous films of alloys, and not detected by the other methods due to a small amount. The future theoretical and experimental studies of metal clusters, significant for metallurgy, can contribute that the LDI MS is becoming a powerful analytical tool for characterization the metal surfaces.

Effect of NaCl Solution and Simulated Concrete Pore Solution Environment on the Efficiency of Steel Bar Energized Corrosion.

As the main problem of the durability deterioration of concrete structures, the corrosion of steel bars is usually made by the method of electrified corrosion with a short cycle and low cost. However, there is a big difference between the actual corrosion depth and the theoretical corrosion depth after the reinforcement is electrified. In this paper, through the accelerated corrosion test of steel bars, the change law and influence factors of corrosion efficiency of steel bars in concrete simulated pore solution and NaCl solution are studied. The test results show that the corrosion efficiency of reinforcement in the NaCl solution is higher than that in the concrete simulated pore solution, and the corrosion efficiency in the NaCl solution changes in two stages with the corrosion degree of reinforcement. The corrosion efficiency of concrete in the simulated pore solution decreases with the increase of corrosion degree of reinforcement, which is more significant than that in the NaCl solution. Under the same conditions, the corrosion efficiency is higher in the chloride ion solution with high concentration, and the influence of chloride ion concentration change in the simulated pore solution of concrete on the corrosion efficiency is more significant. The corrosion efficiency of reinforcement under low current density is higher than that under high current density.

Effect of chloride ion content on pitting corrosion of dispersion-strengthened-high-strength steel

Chloride ion is an important corrosion factor in marine environment. Chloride ion has a small radius and strong permeability, which can destroy the oxide film on the surface of marine structural steel. The uneven adsorption of chloride ion on the metal surface will cause pitting corrosion. The effect of chloride ion content on pitting corrosion of the as-cast and heat-treated Dispersion-Strengthened-High-Strength (DSHS) steel was studied by electrochemical test, composition analysis and surface analysis. The results showed that high content of chloride ion reduced the content of dissolved oxygen in the solution, and the corrosion rate of DSHS steel was the slowest in 5.0 wt.% NaCl solution. In high content chloride ion solution, the formation of α-FeOOH was inhibited and the protection of corrosion products was weakened. Pitting corrosion of DSHS steel before and after heat treatment was the most serious in 2.0 wt.% NaCl solution. After heat treatment, grain size of DSHS steel decreased, and more dense and stable protective corrosion products were produced. Therefore, the induction and development of pitting corrosion of heat-treated DSHS steel were inhibited.

Picomolar glutathione detection based on the dual-signal self-calibration electrochemical sensor of ferrocene-functionalized copper metal-organic framework via solid-state electrochemistry of cuprous chloride

Chemical biosensing techniques are essential for food analysis and disease diagnosis. Nanomaterials with redox activity show great potential in electrochemical analysis, acting as signal labels or signal amplification unit, which can reflect the targets concentration in foods and biological samples. Here, an ultra-sensitive dual-signal intrinsic self-calibration electrochemical platform for GSH was firstly fabricated based on the novel electroactive nanomaterial of ferrocene-functionalized copper metal–organic framework (Fc-Cu-MOF). Due to the solid-state electrochemical property of cuprous chloride (CuCl), a sharp characteristic peak with an increased signal appears with the coexistence of chloride ions in solution. The stronger specific affinity between Cu+ and GSH than that of Cu+ and Cl- triggers a “crowding effect” that causes the current signal of CuCl decrease greatly. Meanwhile, the peak current of ferrocene keeps unchanged as an internal reference. Based on the ratio of the peak current variation (ΔICu/ΔIFc) as the signal output, Fc-Cu-MOF modified electrode showed wider linear range in 0.1 nM −1 μM for GSH with the detection limit as low as 0.025 nM. And the sensor was successfully applied in the determination of GSH with excellent recoveries in various real samples such as food and serum samples, providing good prospect in application of bioanalysis and food screening.

Multimodal assessment of the curing of agglomerated ores in the presence of chloride ions

Agglomeration and subsequent curing are widely used as pre-treatment for ore prior to heap leaching as it both improve the permeability of the heap and brings leaching solution into close contact with the ore, initializing the leaching reactions. Despite its widespread use there have been limited studies into the processes occurring within the agglomerates over the curing process. In this study both destructive and non-destructive imaging techniques are used to assess both the physical and chemical changes occurring within the agglomerates as they cure.The SEM/EDX is one of the most popular imaging techniques for mineral samples. It can only be carried out once for a given sample due to its destructive preparation method but provides detailed mineralogical information. A complementary tool is X-ray Microtomography (XMT), which is non-destructive and can be used to image the same object multiple times over the course of the experiment. Its main limitation, though, is that the acquired images are of X-ray attenuation values and need to be independently assigned to different mineral classifications based on, for instance, the corresponding SEM images. Combining the ability of SEM/EDX measurements to identify different mineral phases with the 3D time resolved XMT measurements can thus produce superior results to those achievable using either of the modalities on their own.In this study, we propose a methodology for quantifying the formation and depletion of mineral components of agglomerates. These methodologies will be demonstrated in ores agglomerated using a combination of sulphuric acid and ferric sulphate as well as in samples in which sodium chloride is added to the agglomeration recipe. The curing process was tracked beyond the typical time scales used industrially, highlighting that the presence of chloride ions makes a substantial difference to the chemical and structural evolution of the sample. Over this curing process most of the observed leaching occurs during the first 20 days in the presence of NaCl, while there is virtually no metal dissolution for the standard samples without NaCl. During curing the solution does not leave the agglomerates other than via evaporation. Thus, reprecipitation of metal containing mineral species was observed, especially near the agglomerate surfaces. In the presence of NaCl precipitated Cu-S-O-Cl complexes were observed suggesting that the chloride ions in solution are playing a key role in the leaching process. After 65 days of curing, the samples were water washed in order to remove soluble species, extracting 50% of the original sulphides from the agglomerates containing sodium chloride, but only 20% from the other agglomerates.

Phototransformation of tetrabromobisphenol A in saline water under simulated sunlight irradiation

The widespread use of halogenated flame retardants in recent years has led to the accumulation of TBBPA in water, which may cause potential harm to living organisms. The phototransformation of the flame retardant TBBPA in alkaline saline water under simulated sunlight irradiation was investigated. The effects of abiotic factors such as the initial concentration of TBBPA, chloride ion concentration, solution pH, inorganic anions and cations, dissolved organic matter (DOM) were studied. The results showed that the phototransformation rate of TBBPA accelerated with the decrease of the initial concentration of TBBPA, the increase of chloride ion concentration and solution pH. The scavenging experiments showed that •OH, 1O2, O2•- and 3TBBPA* all participated in the phototransformation of TBBPA. The presence of NO3−, CO32−, SO42−, Mg2+, Ca2+, Fe3+ and fulvic acid (FA) all inhibited the phototransformation of TBBPA in the present study. The phototransformation products of TBBPA were detected by liquid chromatography-mass spectrometry (LC-MS), and the phototransformation pathways were proposed. This is the first report on the photo-induced generation of halogen exchange products from TBBPA in saline solutions, which will contribute to a better understanding of the environmental behavior and risks of BFRs in water.

Recovery of palladium (II) from aqueous solution through photocatalytic deposition in presence of ZnO under UV/Visible-light radiation

A shortage of market supplies is nowadays recorded for precious metals such as palladium, due to a wide range of applications in which they are used. The development of efficient and inexpensive recovery methodologies of precious metals from waste materials is thus necessary and urgent. In the present study a zinc oxide based photocatalytic system under UV/Visible-light radiation was chosen for palladium (II) deposition from solutions containing it. The effect of ethanol as sacrificial agent was investigated at varying catalyst load, irradiation conditions (UV+visible/visible/dark), metal starting concentration as well as the presence of cupric and chloride ions in solution. Moreover, ZnO dissolution at pH under 6.0 was proposed for the recovery of pure metallic palladium. A network of reactions and a kinetic model were proposed.

Effect of SLM process parameters on hardness and microstructure of stainless steel 316 material

Selective laser melting (SLM) is an additive manufacturing process in which layers of metallic powder are selectively melted and fused by a high-powered laser to form near-fully dense 3D components. The SS316L is an austenitic chromium-nickel stainless steel containing a deliberate amount of molybdenum which increases general corrosion resistance and especially improves its pitting resistance to chloride ion solutions. The importance of process parameter such as layer thickness and orientation of specimen on the hardness and microstructure are being explored. Hence, it is essential to carry out research in that direction. The aim of the study is to understand the effect of layer thickness and angle orientation on hardness of the material as it is one of the desirable properties for SS316 material. The excellent hardness (218.835 BHN) was attained at the angle orientation of 90° and layer thickness of 40 µm according to ANOVA analysis.

Degradation of tetracycline antibiotics by Fe2+-catalyzed percarbonate oxidation

Antibiotics improve the quality of human life but their intrusion into water matrices comes with adverse effects on natural bacterial communities that may result in the proliferation of antibiotic resistant bacteria and antibiotic resistance genes. Hence, antibiotic-laden wastewaters require adequate treatment prior to their release to the natural environment. Herein, we investigate the degradation of tetracycline (TC) antibiotics in aqueous solutions by ferrous ion-catalyzed oxidation in the presence of sodium percarbonate (SPC). Control experiments without Fe 2+ but with SPC, and vice versa resulted in negligible TC removal. The effects of reactant dosing and solution pH on the extent and rate of TC removal were examined. Hydroxyl radicals were the dominant reactive oxygen species (ROS) identified from indirect ROS scavenging experiments and confirmed by electron paramagnetic resonance analysis. Treatment of actual wastewaters was simulated by adding chloride, nitrite, nitrate and ammonium ions to the water matrix at varying concentrations and their effects on TC removal were examined. Negligible impact on TC degradation was noted for N-species while chloride ion accelerated degradation kinetics and reached complete tetracycline abatement in 10 min. Residual chemical analysis showed continued Fe 2+ consumption and H 2 O 2 production even with complete tetracycline elimination. Experimental results showed complete abatement of 0.2 mM TC with k 1 of 9.3 × 10 −2 min −1 and over 40% TOC removal in 45 min of treatment under optimized conditions of 0.5 mM of Fe 2+ , 0.75 mM SPC, at pH 3.0. The study showed the effectiveness of percarbonate oxidation as a tertiary treatment technology and the results can be used in designing treatment systems for wastewaters containing antibiotics and other pharmaceuticals. • Percarbonate oxidation completely removed tetracycline from water. • Reaction kinetics followed the pseudo-first order model. • Chloride ions in solution accelerated tetracycline degradation. • Hydroxyl radicals were the dominant reactive oxygen species.

Study on the Electrochemical Corrosion Behavior of 304 Stainless Steel in Chloride Ion Solutions

Study on the Electrochemical Corrosion Behavior of 304 Stainless Steel in Chloride Ion Solutions

Effect of the chloride environmental exposure on the flexural performance of strengthened RC beams with self-anchored prestressed CFRP plates

Carbon fibre-reinforced polymer (CFRP) plates are widely used to strengthen reinforced-concrete (RC) structures. At present, most studies focused on the short-term performance of strengthened RC beams with a prestressed CFRP plate, and very limited information is available on their durability, which is of importance in certain cases, such as high-piled wharfs and bridges in marine environments. This study investigates the effects of chloride environment exposure on the flexural performance of strengthened RC beams with self-anchored prestressed CFRP plates. In total, seven RC beams, four of which were strengthened by a self-anchored prestressed CFRP plate, were fabricated and tested under three-point bending. The testing parameters included 25% and 40% prestress level of the ultimate tensile strength of the CFRP plate, 5% and 10% tensile steel rebar corrosion ratio of mass loss and 10% and 20% anchor corrosion ratio in the chloride environment. The evolution of time-dependent prestress losses in the strengthened beam was determined, and the flexural behaviour of the strengthened beams was analysed. A theoretical model is proposed to predict the flexural strength of prestressed CFRP strengthened RC beams in a chloride environment. The experimental results indicated that the coupling of the corrosion expansion of the metal anchor and rebar in the chloride environment had a large negative effect on the flexural performance of the beams strengthened by the self-anchored prestressed CFRP plates. After exposure to the chloride ion solution, the failure mode of the RC beams strengthened by the prestressed CFRP changed from concrete crushing in the compression section to anchor pullout. The proposed model, which considered the effect of a chloride environment to predict the flexural strength of the strengthened beams, agreed well with the test results.