Chloride Research Articles

A Novel Method for Increasing the Concrete Resistance to Chloride Ions Erosion

Concrete structures generally play an important role in the infrastructure construction. The corrosion of reinforcing steels in concrete structures is one of the main causes of the degradation and reduction of their service life, especially when they are exposed to marine environment or de-icing salts. An understanding of the process of chloride transportation in concrete is of great importance for engineers to predict the service life of concrete structures. Therefore, we synthesized corrosion inhibitor for improving the chlorine resistance of concrete.

Effect of Mg Addition on Molten Chloride Salt Corrosion Resistance of 310S Stainless Steel with Aluminum

Effect of Mg Addition on Molten Chloride Salt Corrosion Resistance of 310S Stainless Steel with Aluminum

Chloride permeation resistance of sulphoaluminate cement-based composite characterized by both alternating current section and RCM methods

Sulphoaluminate cement (SAC) was widely used for rapid repair and strengthening of building structures due to its excellent quick hardening and high early strength behavior. This study developed a SAC-based engineering cement composites (ECC) with ultra-high molecular weight polyethylene (UHMWPE) and investigated its mechanical properties. Chloride ion permeability coefficient were evaluated by new alternating-current sectioning and rapid chloride migration (RCM). The mechanism of the SAC-ECC against chloride erosion were quantified using nitrogen isothermal adsorption. The results show that the fracture energy, tensile strength and strain of SAC-ECC samples are higher than that of normal ECC. The polyethylene (PE) fiber could significantly improve the flexural strength and toughness with PE fiber content of 0.75 % by volume. The hydration products generated could react with chloride ion to make it chemically stabilized, leading to reduce the chloride ion diffusion coefficient significantly. Based on microscopic analysis (SEM), the pore structure in SAC-ECC composite improved remarkedly while the volume of harmful pore decreased evidently as well. SAC-ECC developed in this paper could be poetically applied to strengthening and repair of marine concrete structures.

Combined effects of carbonation and salt solution on chloride desorption, pH, and composition of fly ash blended pastes

The most consumed human-made material, concrete, is permeable and chloride-bearing deicers penetrate the concrete, causing deterioration. Chloride ions exist in concrete in two forms: free and bound chlorides. Free chlorides are the primary cause of chloride-induced corrosion because they can move in concrete pores, reaching the rebar surface to initiate corrosion. Bound chlorides are those chloride ions that are adsorbed by the concrete matrix and cannot actively participate in reinforcement corrosion. Although chloride binding is a beneficial process, chloride binding is reversible. In addition, most concrete infrastructures are subject to environmental attacks such as carbonation, causing pH reduction in the concrete pore solution and subsequently resulting in the release of bound chlorides (chloride desorption). The combined effects of carbonation and chloride attack on fly ash containing pastes are not well-studied, particularly concerning their impact on chloride desorption, pH changes, and compositional changes. This investigation aims to address this gap by exposing fly ash-blended cement paste to NaCl salt solution and carbonation. This study quantifies chloride desorption, monitors pH change, and analyze the compositional changes in pastes, including the measurement of Friedel's salt, portlandite, and calcite contents. Samples were first exposed to NaCl solution for 35 days and then 4 weeks of accelerated carbonation, during which their pH and composition at different depths were monitored. XRD and TGA tests were utilized to identify and quantify the main phases. The results show that carbonation reduced the pH from 13 to nearly 11 in OPC pastes and 10 in fly ash pastes. The inclusion of 15 % fly ash led to weakened carbonation resistance compared to OPC. After combined exposure to the salt solution and carbonation, the calcite content, representing carbonation, in fly ash pastes significantly increased by 190.9 % after one week carbonation and 282.1 % after two weeks of accelerated carbonation. Friedel's salt content, indicating bound chloride, dropped by roughly 78 % in OPC paste and 87 % in fly ash paste after one week of carbonation and completely dissolved after two weeks of carbonation. The results emphasize the importance of considering chloride desorption, similar to chloride binding, which has been incorporated into service life models. This negligence can lead to an overestimation of the service life of concrete infrastructures.

Simultaneous precipitation removal of fluoride ion and chloride ion from smelting waste acid using renewable remover

Purification and reuse is a potential method of smelting waste acid disposal. High concentrations of fluoride and chloride in waste acid are harmful impurity and must be removed. Previous studies have shown that fluoride removal with rare earth and chloride removal with bismuth have similar cyclic process of "precipitation removal-agent regeneration" and similar reaction conditions. In this paper, a method of simultaneous precipitation removal of F− and Cl− from waste acid using La(OH)3 and Bi2O3 as a mixed remover was proposed, and the mixed remover is regenerated by sodium hydroxide solution for the recycling of the remover. Thermodynamic analysis of La3+-Bi3+-F−-Cl−-H2O system verified the feasibility of simultaneous removal. The experimental results showed that under the optimum reaction conditions, the removal efficiencies of F− and Cl− were 93.67 % and 96.47 %, respectively, and the concentrations of F− and Cl− in the solution after removal were 66.70 mg/L and 71.10 mg/L, respectively. Under the optimum conditions, the regeneration efficiencies of La(OH)3 and Bi2O3 were 96.80 % and 96.95 %, respectively. The proposed process has the advantages of no waste output, short process, and low energy consumption and provides an environmentally friendly method of removing fluoride and chloride from waste acid.

Structural Study of Aqueous Electrolyte Solution by MeV Liquid Electron Scattering.

The impact of ions on water has long been a subject of great interest, as it is closely tied to the hydration structure, dynamics, and properties of electrolyte solutions. Over centuries of investigation, the influence of ions on water's structure remains highly debated. Prevailing techniques, such as neutron and X-ray scattering, primarily focus on the microscopic structure of salt solutions at very high concentrations, mostly above 1 mol/L. In this study, we measured the structure of aqueous potassium iodide (KI) and potassium chloride (KCl) solutions using MeV liquid electron scattering (MeV-LES) across a concentration range of 0.10 to 0.75 mol/L. The obtained results provide detailed insights into the variations in ion-oxygen and oxygen-oxygen correlations as a function of concentration. The observed structural differences between KI and KCl solutions are in line with the structure maker/breaker theory, which suggests that iodide ions exert a more pronounced effect than chloride ions on disrupting the water shell. This work demonstrates the potency of MeV-LES for investigating the atomic structure in liquids, augmenting the modern analytical toolbox.

Enhanced phosphate anion flux through single-ion, reverse-selective mixed-matrix cation exchange membrane

Phosphate recovery from wastewater is vital for both environmental sustainability and resource conservation, offering the dual benefit of reducing phosphate pollution while providing a valuable source of this essential nutrient. We previously reported an approach for synthesizing hydrous manganese oxide (HMO) nanoparticles within a polymeric cation-exchange membrane (CEM) to achieve a phosphate-selective mixed-matrix membrane (PhSMMM); however, the phosphate flux was lower than desired. Herein, we demonstrate a next-generation PhSMMM membrane with enhanced phosphate flux and selectivity. Experimental results confirm the successful incorporation of up to 28 wt% HMO nanoparticles into the polymeric CEM. The new PhSMMM exhibits a phosphate flux of 1.57 mmol∙m–2.hr–1 (an 8.5X enhancement), with selectivity over chloride, nitrate, and sulfate ions of 9, 11, and 104, respectively. This significant enhancement in phosphate flux marks a promising advancement in a sustainable solution for phosphate removal and recovery from wastewater.

The interactome of cystic fibrosis transmembrane conductance regulator and its role in male fertility: A critical review.

The cystic fibrosis transmembrane conductance regulator (CFTR) is a cyclic adenosine monophosphate (cAMP)-regulated chloride and bicarbonate ion channel found in many human cells. Its unique biochemical characteristics and role as a member of the adenosine triphosphate (ATP)-binding cassette transporters superfamily are pivotal for the transport of several substrates across cellular membranes. CFTR is known to interact, physically and functionally, with several other cellular proteins. Hence, its properties are essential for moving various substances across cell membranes and ensuring correct cell functioning. Genetic mutations or environmental factors may disrupt CFTR's function resulting in different possible phenotypes due to gene variations that affect not only CFTR's function, localization, and processing within cells, but also those of its interactors. This has been reported as an underlying cause of various diseases, including cystic fibrosis. The severe clinical implications of cystic fibrosis have driven intense research into the role of CFTR in lung function but its significance to fertility, particularly in men, has been comparatively understudied. However, ongoing and more recent research into CFTR and its interacting proteins in the testis or specific testicular cells is beginning to shed light on this field. Herein, we provide a comprehensive and up-to-date overview of the CFTR, its interactome, and its crucial role in male reproduction, highlighting recent discoveries and advancements in understanding the molecular mechanisms involved. The comprehension of these complex interactions may pave the way for potential therapeutic approaches to improve fertility of men suffering from alterations in the function of CFTR.

Evaluation of Biosurfactants to Preflush for Offshore Wells.

With the improvement of environmental protection requirements in offshore oil and gas exploration, there is a great demand to find environmentally friendly surfactants for cementing preflush fluids. In the present paper, the application potential of three biosurfactants of rhamnolipid, lipopeptide, and sophorolipid in the preflush fluid was evaluated through a series of experiments. The experiments studied the interfacial tension (IFT) of the biosurfactants, resistance to temperature, salt resistance (sodium chloride and sea salt), and the influences of the studied biosurfactants on the rheological compatibility and capabilities to convert the wettability of the formation from oil-wet to water-wet, mud cake removal efficiency, and to improve the interfacial bonding properties of the preflush fluid. The results showed that rhamnolipid, lipopeptide, and sophorolipid exhibited excellent surface activities in high-temperature and sodium chloride (NaCl) environments. When exposed to sea salt, lipopeptides lost their function due to agglomeration, while rhamnolipids and sophorolipids maintained structural stabilities and high surface activities. When rhamnolipid was mixed with sophorolipid in a ratio of 2:1 at the same concentration, the combined biosurfactant had the best surface activity among the studied surfactants. The combined biosurfactant not only had good rheological compatibility with the drilling fluid and cement slurry but also showed excellent properties in the removal of mud cake. In addition, the effect of the removal of the mud cake was verified by the gas channeling experiment. The experimental results show that the presence of mud cake can reduce the bonding strength. When rhamnolipid was mixed with sophorolipid in a ratio of 2:1 at the same concentration, the removal efficiency of mud cake was the highest, and the interfacial bonding property of the cement sheath can be improved.

Diphosphonic ionic liquids as anion-exchangers for palladium(II) and platinum(IV): Synthesis, complexation and selective extraction from hydrochloric solutions

The demand for platinum group metals (PGMs) continues to grow. To reduce the negative environmental impact, it is necessary to switch to secondary sources of PGMs and to improve the separation and purification processes of these metals. In this work, new phosphonium-based ionic liquids (diphosphonium salts) were synthesized as extractants for the selective recovery of palladium(II) and platinum(IV) from hydrochloric acid solutions. Substances synthesized contain a doubly-charged cation, which significantly affects the selectivity of extraction compared to singly charged phosphonium extractants. It was found that diphosphonium salts have a high extraction efficiency of metallic ions that form stable doubly-charged chloride anionic complexes. Thus, solutions of synthesized ionic liquids in 3-nitrobenzotrifluoride can selectively extract palladium(II) and platinum(IV) in the presence of all d‐metal ions studied, which are contained in PGMs secondary sources. The extraction efficiency under optimal conditions is 99.6 % and 98.5 % for palladium(II) and platinum(IV), respectively. The extraction mechanism has been investigated by X-ray diffraction, DFT calculations and 31P, 111Cd NMR spectroscopy. Extraction proceeds through the anion-exchange mechanism, however, in the case of the studied compounds, the significant role of bromide as a counterion of ligands was shown. It was found that bromide is likely included in the extracted ion pair, displacing chloride ions from anionic metal complexes during extraction.

Assessment of the water and mass balance in the landfill body by modelling using the example of the Dubna city landfill

To predict the migration of pollutants in groundwater from the landfill site, it is necessary to know the infiltration rate and the concentration of pollutants in the moisture entering the groundwater level below the landfill. It is shown that the HELP program for calculating moisture transport in the unsaturated zone can be used to estimate the infiltration rate by the example of the municipal solid waste in Dubna, To estimate chloride ion concentration in the leachate entering the groundwater level, the VS2DT program for calculating the transport of pollutants with moisture in the unsaturated zone can be used. It is shown how uncertainty and insufficiency of information about the landfill site affects the estimation of these parameters, in what cases it is possible to use information about a similar dump, how test calculations help to verify hypotheses of formation of groundwater pollution under the landfill. The ranges of infiltration rate and chloride ion concentrations in moisture entering the groundwater level under the landfill body obtained as a result of calculations of the water and mass balance of the landfill in Dubna were further used to calculate the chloride ion transport in groundwater.

The Investigation of Phase Transformation Process of Nano-Citrogypsum via Recycling Saline Solution

Because citric acid may be used to preserve food, the citric acid business has grown to play a significant role in the food and beverage sector. Environmental problems with gypsum waste, or citrogypsym, resulted from the manufacture of citric acid. Calcium sulfate dihydrate (DH), with low material physical characteristics, is the primary component of gypsum. As a result, the goal of this research is to examine the phase transformation process of citrogypsum using the hydrothermal process, which is a method of recrystallizing an example solution in an appropriate setting. To do this, a recycling calcium chloride solution was used, and it was heated to 95°C for five hours under atmospheric pressure to form alpha calcium sulfate hemihydrate (α-HH). The present of -OH at 1600 cm-1 wave numbers in the FT-IR spectra of α-HH, indicates that CaSO4 has 0.5 water molecules in its crystal. Moreover, the DSC thermograms of α-HH reveal endothermic peaks at 151.2°C and 183.14°C, respectively, which correspond to the loss of 0.5 water molecules in CaSO4. The TGA thermogram of α-HH also shows a crystal water content of 4.5 wt%. Furthermore, SEM images validate the hexagonal structure of α-HH morphology. In addition, because chloride ions have an impact on corrosive materials, the saline solution can be recycled at least four times to save money and the environment.

Research on quantitative design methods for the durability of reinforced concrete structures in a hot ocean environment

This paper establishes a quantitative design method for the durability of concrete structures in cross-sea bridges through investigation, rapid chloride migration coefficient method (RCM) and theoretical calculation, considering the impact of temperature on chloride ion diffusion rates in a hot marine salt erosion environment. Combined with the RCM test and bridge service data, a quantitative design method for bridge concrete durability is proposed. Test results show that the growth rate of the chloride ion diffusion coefficient of concrete is approximately 1.028 for every 1 °C increase. For every 5 °C increase, the growth rate of the chloride diffusion coefficient of concrete is about 1.15, and the cover depth of the concrete structure should be multiplied by a coefficient of 1.07. Therefore, the concrete cover depth should be appropriately increased, considering the influence of ambient temperature. Furthermore, fly ash, slag, and stone powder can increase the concrete’s resistance to chloride corrosion. When the influence of temperature on the chloride ion diffusion coefficient is considered, the durability design of the concrete structure of the sea-crossing bridge is conducted, which is beneficial for ensuring their service life.

The complexities of salt taste reception: insights into the role of TMC4 in chloride taste detection.

Although salt is an essential substance vital to life, excessive salt intake could cause various health issues. Therefore, new technologies and strategies should be developed to reduce salt intake without compromising taste. However, the underlying physiological mechanisms of salt taste reception is complex and not completely understood. Sodium chloride is a typical salty substance. It is widely believed that only sodium is important for the generation of salty taste. On the other hand, from a psychophysical perspective, the importance of chloride in salty taste has been indicated. Thus, understanding the mechanisms of both sodium- and chloride-tastes generation is necessary to completely comprehended the fundamentals of salt taste reception. However, the mechanism for detecting chloride taste has remained unclear for many years. Recently, we have identified transmembrane channel-like 4 (TMC4) as the first molecule that mediates the reception of chloride taste. TMC4 functions as a voltage-dependent chloride channel and plays an important role in the reception of the chloride taste by detecting chloride ions. In this mini-review, we first introduce the known reception mechanism of salty taste, and then discuss the roles of TMC4 in the salt taste reception. The finding of TMC4 may serve as a basis for developing new technologies and formulating strategies to reduce salt intake without compromising taste.

Removal of dichloromethane from gas streams by droplet triggered gas discharge

The removal of dichloromethane (DCM) from gas streams by a novel gas discharge reactor triggered by solution droplets was experimentally investigated. The influences of operation parameters such as input energy, gas flow rate, oxygen concentration, droplet dropping frequency, and the solution composition of droplets on the effectiveness of reactor operation and DCM removal efficiency were examined. Experimental results showed that DCM in the gas stream can be effectively degraded, and the removal of DCM decreased with the increase of the initial DCM concentration in the gas stream. With the increase of droplet dropping frequency, the removal of DCM experiences a process from increase to decrease, and the optimal droplet dropping frequency is around 0.5–1 drop·s−1. It was also found that the oxygen concentration in the range of 5–10 % in the gas stream is better for DCM decomposition, and the use of alkaline solution as droplets can effectively improve the removal of DCM. The final gas phase products of DCM degradation were mainly CO2 and O3 with the presence of O2 in the gas stream, and the liquid phase products were chloride (Cl-) and hypochlorite (ClO-) ions.

Effect of Enteromorpha-diatom adhesion on mortar performance

With the development of the marine economy, seawater is becoming more eutrophic. The risk of green tides from Enteromorpha is rising, which adversely affects the service of coastal infrastructure structures. To better evaluate the influence of algae on the long-term service performance of the structural concretes in coastal infrastructure, this study investigates the law of Enteromorpha-diatom attachment and growth on the mortar surface and its influence on the microstructure and durability of mortar. The results show that: 1) at 15 days, diatoms appeared on the surface of the mortar and biofilm appeared，the time period of adhesion and germination of Enteromorpha spores on the mortar surface was between 60 and 75 days. 2) Within 60 days, the spores released by the Enteromorpha preferentially germinate on the edges and in the pores of the mortar specimen, which can create micro-cracks on the mortar surface. Calcium carbonate may be involved in the metabolism of algae. 3) The pore size of the mortar surface gradually increases in the presence of bio-organic acids, which can accelerate the decrease of pH on mortar surfaces and reduce the resistance of mortar against chloride ions. This study confirms that green tide outbreaks may reduce the durability of cementitious materials, and provides a practical guide in the timing of protecting coastal infrastructure structures during the period of green tide outbreaks.

Unraveling Lattice Dislocation‐Driven Energy Band Convergence Mechanism to Enhance Electrocatalytic Hydrogen Production in Alkaline Seawater

AbstractHydrogen evolution reaction (HER) from seawater electrolysis still faces challenges of low reactivity and chloride ions poison at the active sites, leading to reduced efficiency and stability of electrocatalysts. This study presents edge dislocation strategy aimed at inducing lattice strain in ferric oxide through Mo doping, consequently regulating the catalyst's band structure. Through in situ characterizations and DFT analysis, it is confirmed that lattice strain effectively modulates the band structure, intensifies the hybridization between Mo(d)‐Fe(d)‐O(p) orbitals, thereby accelerating the charge transfer rate of HER. Furthermore, band structure modulated by lattice strain enhances water adsorption capacity, reduces the adsorption energy of Cl−, and optimizes the hydrogen adsorption‐free energy (ΔGH*) for HER. Benefiting from above, the optimized 2%‐Mo‐Fe2O3 catalyst demonstrates HER activity and stability in alkaline seawater electrolysis comparable to that of commercial Pt/C. Additionally, the assembled electrolytic cell utilizing an anion exchange membrane (AEM) maintains long‐term stability for >100 h at 500 mA cm−2, showcasing a sustained catalytic effect.

Study on the influence of early frost attack on the performance of cement mortar

The loss of strength and durability caused by early frost attack is the macro performance of internal microstructure deterioration. Understanding the influence mechanism of early frost attack at the micro level is necessary to avoid or minimize the early frost attack to macro performance. In this study, the influence of early frost attack on the strength, water sorptivity, chloride permeability, and microstructure of cement mortar was investigated. The fresh mortars were pre-cured for 10, 12, 14, and 16 h and then frozen at −10 °C for 7 days to simulate an early frost attack. After freezing, the standard curing (20 °C) was carried out until the testing. It is found that after standard curing of 28 days, the strength of early-frozen mortar can reach more than 95 % of the 28-day strength of unfrozen mortar. Interestingly, the sorptivity coefficient and total charge passed of early-frozen mortar are much higher than the level of unfrozen mortar, and the loss of resistance to water penetration and chloride ion penetration exceeds 20 %, indicating that early frost attack causes more severe damage to the durability than to the strength of mortar. Mercury intrusion porosimetry (MIP) results show that early frost attack can increase the pore volume of >50 nm and coarsen the pores within 10–50 nm. Correspondingly, key pore parameters (critical pore diameter, threshold pore diameter, and tortuosity) that affect the durability of mortar are also negatively affected. Energy dispersive spectroscopy (EDS) analysis also shows that after suffering early frost attack, the interfacial transition zone (ITZ) thickness of mortar is increased from 4 to 10 μm to 8–13 μm, and the probability of high Ca/Si ratios (4–10) in the ITZ is also increased. Finally, it is concluded that the coupling effect of pore structure coarsening and ITZ degradation leads to more severe durability loss.

Effects of Ti and Y on resistance to corrosion in Fe–Cr-X Alloys

The effect of Ti and Y on the corrosion behavior of the FeCr alloy was investigated in a 3.5% NaCl solution. Ti was found to inhibit the formation of the σ phase, significantly reducing the presence of pitting in the material. In addition, Ti acted indirectly on the oxide layer, increasing the concentrations of Cr and Fe, consequently generating a probable enrichment of Cr2O3 and FeOOH, which enabled the formation of a more stable passive film resistant to attack by chloride ions. On the other hand, Y caused the precipitation of a phase identified as Fe17Y2, which was accompanied by an elongated σ phase, both located at the grain boundaries, besides the formation of Cr23C6 and Y2O3. Its addition resulted in an improvement in the corrosion resistance of the FeCr alloy by reducing the precipitation of the σ phase. However, its effect was much less important than that of Ti, since the results showed that the FeCrY alloy was still highly susceptible to localized forms of corrosion.

Simultaneous desalination and removal of organic pollutants in a novel bifunctional FCDI system: The enhancement by in-situ reutilization of chloride ions

A new system of flow electrode capacitive deionization coupled with in situ electro-oxidation (FCDI-EO) was constructed to achieve the degradation of organic pollutants while maintaining high desalination efficiency. The effects of different parameters of potential difference, electrolyte, and pH on the chloride removal performance of FCDI-EO and the removal performance of rhodamine B (RhB) were investigated. Under the optimal conditions of potential difference = 4 V, [Cl−] = 500 mg/L, and pH = 4, the removal of chloride ions, RhB and total organic carbon (TOC) was as high as 88.74 %, 99.02 %, and 87.82 %, respectively. The quenching experiments showed that hydroxyl radicals (OH) and reactive chlorine species (RCS) were involved in the FCDI-EO system. The liquid chromatography-mass spectrometry (LC-MS) analysis suggested the possible mineralization pathway of RhB. Furthermore, toxicity assessment analysis showed that the toxicity of the degradation intermediates of RhB decreased during the treatment. Overall, this study provides a promising process that reducing the generation of high-concentration saline water in desalination and in situ utilizing the Cl− gathered from the feed water. The findings of this study could provide useful guidance for the development of flow electrode capacitive deionization technology and organic pollutant control.