Chloride Research Articles

Corrosion protection performance of stretched graphene-modified cold-sprayed zinc coating for steel rebar

The cold-sprayed zinc technology exhibits unique advantages in the field of metal corrosion prevention due to its environmental friendliness and convenient construction. However, compared to hot-dip galvanizing, there is still a necessity to improve its corrosion resistance. Graphene as a filler material, effectively strengthens the anticorrosive properties of the coating. Nevertheless, the resistance of graphene-modified cold-sprayed zinc coating to chloride ion induced metal corrosion remains unknown. In this study, cold-sprayed zinc coating and graphene-modified zinc coating were employed to steel rebar that was subjected to different levels of tensile stress. The passivation and de-passivation process of the stretched zinc-coated rebar in the simulated concrete pore solution were investigated with electrochemical tests and microscopic analyses. The research findings reveal that compared with ordinary cold-sprayed zinc coating, graphene-modified coating can significantly improve the coating resistance and reduce the corrosion rate of rebar under different levels of tensile stress attributed to the high surface area of graphene. However, due to the discontinuity between zinc powders induced by graphene, a complete passivation film cannot form on the surface of graphene-modified zinc coating, which resulted in a lower resistance against chloride ion induced de-passivation. This study indicates that graphene-modified cold-sprayed zinc-coating is not fit for marine environment.

Anion-pairing effect in Cd(II) coordination with a tetrabenzotetraza-crown macrocyclic ligand

Three new complexes of a tetrabenzotetraza-crown ether macrocyclic ligand (L) with Cd(II) chloride (1), iodide (2), and acetate (3) salts were synthesized and characterized by FT-IR, 1H NMR spectroscopy, elemental microanalysis, and single crystal X-ray diffraction. Complex 1 has the formula [Cd(L)Cl]2 [CdCl4] with two square pyramidal [Cd(L)Cl]+ subunits interconnected through the CdCl42− counter anion. Meanwhile, the reaction with CdI2 produces the discrete complex [Cd(L)I]I (2) with an octahedral geometry about the Cd(II) center. A distorted six-coordinated asymmetric unit was observed for [Cd(L)OAc]2(OAc·H2O)2 (3), wherein two [Cd(L)OAc]+ subunits are held together by a flat (OAc·H2O)2 acetate-water cluster. Hirshfeld Surface calculations were applied to confirm the dominant interactions in 1–3, namely π–π, and X⋯H/H⋯X (X-H, C, O, and halogen) interactions as the main factors for their structural differences. At the same time, the structure of [Cd(L)L′]+ (L′ = Cl, I, and OAc) core remained almost unchanged. The Cd(II) coordination with L in the presence of different Cd(II) salts was followed by 1H NMR spectroscopy. All three Cd(II) salt displays 1:1 stoichiometry, with binding constants in the order CdCl2 < CdI2 < Cd(OAc)2.

Cl--dependent amplification of excitatory synaptic potentials at distal dendrites revealed by voltage imaging.

The processing of synaptic signals in somatodendritic compartments determines neuronal computation. Although the amplification of excitatory signals by local voltage-dependent cation channels has been extensively studied, their spatiotemporal dynamics in elaborate dendritic branches remain obscure owing to technical limitations. Using fluorescent voltage imaging throughout dendritic arborizations in hippocampal pyramidal neurons, we demonstrate a unique chloride ion (Cl-)-dependent remote computation mechanism in the distal branches. Excitatory postsynaptic potentials triggered by local laser photolysis of caged glutamate spread along dendrites, with gradual amplification toward the distal end while attenuation toward the soma. Tour de force subcellular patch-clamp recordings from thin branches complemented by biophysical model simulations revealed that the asymmetric augmentation of excitation relies on tetrodotoxin-resistant sodium ion (Na+) channels and Cl- conductance accompanied by a more hyperpolarized dendritic resting potential. Together, this study reveals the cooperative voltage-dependent actions of cation and anion conductance for dendritic supralinear computation, which can locally decode the spatiotemporal context of synaptic inputs.

Solar-driven remediation of antibiotics in synthetic and real reverse osmosis brine: Addressing lattice oxygen demand and electron transfer for improved purification

This study investigated the significance of integrated advanced oxidation process with reverse osmosis (RO) to ensure the purification and elimination of micropollutants, primarily pharmaceuticals prior to the discharge of brine to the environment. To envisage this, TiO2 based solar driven photocatalysis was employed, highlighting the crucial role of oxygen vacancy formation in the lattice of TiO2 for enhancing the purification of antibiotic contaminants from RO brine. The study elucidated how variations in oxygen environments such as oxygen rich yellow TiO2 (Y-TiO2) and oxygen vacancy black TiO2 (B-TiO2) influence photodegradation reaction kinetics taking ofloxacin (OFX) and tetracycline (TC) as model pollutants. The B-TiO2 exhibited 8.5 times higher photodegradation for OFX compared to Y-TiO2, proving significance in tuning of oxygen environment in lattice. The photodegradation efficiency plot showcases B-TiO2′s efficacy, demonstrating 99.8 % and 99.4 % for OFX and TC, respectively. Additionally, the study investigated the photocatalytic degradation mechanism, identifying predominant charge carriers and reactive species involved, while also assessing the durability of photodegradation processes. The impact of pH on the photocatalytic performance of B-TiO2 in degrading antibiotics explored, spanning pH levels from 2.5 to 10.5. An exploration on band alignment formation in B-TiO2 explains the effectiveness of it over Y-TiO2. Lastly, efficacy of B-TiO2 in degrading antibiotics in real RO brine with high level of salinity (60,200 ppm TDS) is demonstrated, which resulted with photodegradation efficiency of 31.25 % for OFX and 67.8 % for TC, proving applicability of integrated system as a sustainable purification approach. Moreover, the blockage of chloride ions quenching demonstrated improvements in photodegradation emphasizing the influence of chloride ions in high saline conditions.

Computing the solubility of argon and xenon in molten sodium chloride and potassium chloride salts

Molten salt reactors (MSRs) offer significant advancements in nuclear reactor safety and efficiency by operating at higher temperatures and lower pressures compared to traditional reactors. A critical aspect of MSR operation involves understanding the solubility of fission byproducts, particularly noble gases, in the molten salts used. This study employs molecular dynamics (MD) simulations to compute Henry’s law constants and enthalpies of solvation for argon and xenon in molten sodium chloride (NaCl) and potassium chloride (KCl). We developed a new pairwise potential for the noble gas and salt interactions based on first principles calculations. We then used this potential to calculate Henry’s law constants of the two gases in the molten salts, which were modeled using both a rigid ion model (RIM) and a polarizable ion model (PIM). The solubility calculations, performed using the Widom insertion method, show qualitative agreement with limited experimental data, highlighting the temperature dependence and greater solubility of both gases in KCl compared to NaCl. Additionally, free volume analysis elucidated the role of available space within the molten salts in governing solubility trends. Our findings suggest that PIM trajectories provide more reliable predictions for noble gas solubility than RIM due to their accurate density representation. These results enhance understanding of gas solubility in MSR environments, and the methods can be readily extended to other systems.

Study on mechanical and chloride salt freezing-thawing resistance of CSW concrete

Concrete slurry waste (CSW) is the product of cleaning, filtering, and sieving concrete waste, which is a solid waste material with porous structure. This article aims to explore the possibility of raising CSW as a new type of cementitious material to prepare high-performance concrete. Mechanical properties and chloride salt freezing-thawing properties of CSW concrete were investigated, and chloride ion diffusion coefficients in CSW concrete were derived according to Fick's second law, in addition to ionic content of CSW concrete simulated using COMSOL simulation software. The results indicated that CSW contains Portlandite, Quartz, Calcite, C2S, and C3S, and has pozzolanic activity. Compared to freezing-thawing in water, freezing-thawing in a 3 % NaCl solution causes greater damage to CSW concrete. However, a mixture of 10 % CSW, 10 % fly ash, and 3 % silica fume (Q10F10S3) improves the mechanical properties and resistance to chloride salt freezing-thawing. Compared with the Q10F0S0, the 28 d compressive strength can be increased by 7.4 %, and chloride ion diffusion coefficients of Q10F10S3 was 10.77 × 10–11 m2/s. The COMSOL simulation software simulation was similar to the experimental values.

Anion‐Modulated Construction of Two Novel Tetra‐ and Hepta‐Nuclear Ni(II) Salamo‐Type Clusters: Comparison of the DFT Calculations and Weak Interaction Analyses

ABSTRACTTwo novel tetra‐ and hepta‐nuclear Ni(II) salamo‐type clusters, [Ni4(L)2(μ2‐Cl)2(μ3‐OH)2(EtOH)2]⋅4CH2Cl2 (1) and [Ni7(L)3(μ3‐OEt)2(μ3‐OH)6(EtOH)2] (2), were constructed by modulating different anions (Cl− and NO3−). X‐ray crystallographic researches revealed that cluster 1 is a tetranuclear cluster consisting of a symmetric binuclear structure in which chloride ions are involved in coordination. Although cluster 2 consists of seven Ni(II) ions, three deprotonated (L)2− parts, two μ3‐ethoxy groups, six μ3‐OH− anions, and two coordinated ethanol molecules, in which it is quite rare for a large number of water molecules to be deprotonated to participate in the bridging of the cluster due to the alkaline environment. TEM electron scanning displayed the distinct shapes. Comparison of DFT calculations revealed that cluster 2 is less chemically reactive and more kinetically stable, which is in accordance with the analytical results of weak interactions, where the stronger weak interaction forces were presented, the more stable the molecule is. Finally, a comparative analysis of UV–Vis, IR, and fluorescence spectra were carried out.

Acute toxicity of sodium chloride-based road salt formulations to juvenile aquatic invertebrates

Globally millions of tons of de-icing agents are applied each year, and about half of these salts enter surface water adjacent to sites of application. While numerous studies have demonstrated the potential impact de-icing agents such as NaCl have on freshwater invertebrates, many of these studies have used laboratory grade NaCl for evaluation, and less is known about the relative toxicity of formulations. The purpose of this study was to compare the 24 and 96 h LC50s of NaCl and two NaCl-based road salt formulations for three aquatic species: juvenile Hyalella azteca, Hexagenia rigida, and Chironomous dilutus. As expected, LC50 values were greater for 24 h exposures than 96 h exposures. However, the relative toxicity of the road salt formulations varied by exposure duration and species. Although the acute LC50 values found in this study were within environmental concentrations of chloride ions reported by existing literature, more research is needed to evaluate chronic or sublethal effects of road salt formulations on a range of freshwater macroinvertebrates.

Synthesis of Carbon Nitride Polymorphs by Sacrificial Template Method: Correlation between Physicochemical Properties and Photocatalytic Performance.

Carbon nitride compounds (CNCs) in the form of graphitic carbon nitride (g-C3N4) and poly(heptazine imide) were synthesized using different metal chloride salts (MClx), i.e., NaCl, KCl and CaCl2, as sacrificial templates and by varying the MClx to melamine molar ratios. A systematic study of their photocatalytic activity for H2 production in relation to the physicochemical, morphological, and optical properties was carried out. Each sample was tested achieving the highest hydrogen evolution rates of about 7660 µmol g-1 h-1, 5380 µmol g-1 h-1 and 3140 µmol g-1 h-1 using CaCl2, KCl, and NaCl, respectively. This work demonstrates how the synthesis of CNCs with different MClx leads to the production of high-performance photocatalysts due to a combination of factors as the formation of vacancies or cyano groups, a shift in the optical threshold and tuning of micro(nano)structure. The results demonstrate that, when CaCl2 is used as a sacrificial template, porous and exfoliated g-C3N4 nanosheets are formed leading to hydrogen productions which outperform most of the previously reported g-C3N4 prepared using a single synthetic step.

Biphasic Production of 5-hydroxymethylfurfural (HMF) in a Recyclable Deep Eutectic Solvent-based System Catalyzed by H4SiW12O40.

The reaction with in situ extraction to yield 5-hydroxymethylfurfural (HMF) from Fru was investigated using a biphasic system based on a self-consuming deep eutectic solvent (DES) as reaction phase. The significance of choline chloride (ChCl), a cost-effective and safe quaternary ammonium salt, was evident in enhancing 5-HMF yield through fructose dehydration and concurrently suppressing side reactions. The DES system demonstrated fast reactions with high selecivities and recyclability across five cycles. The observed decline in H4SiW12O40 activity, primarily due to proton leaching, was successfully restored with the addition of HCl. Furthermore, ChCl exhibited ease of recrystallization in the presence of acetonitrile. This research proposes an environmentally friendly approach for 5-HMF production through a reusable-biphasic process. The presented reaction system suppresses completely the formation of levulinic and formic acid leading to HMF yields of up to 84% of selectivities of up to 88% after 30 minutes at 80 °C. The system was recycled over 16 runs and after an initial slight loss of activity the system in the run 0-5, run 6-15 has shown a constant HMF output as in the first recycling run.

Microstructure evolution of cement-based materials under Cl−-SO42- coupling erosion in simulated ocean tidal area

To disclose the corrosion principle of cement-based materials used in ocean tidal surrounding, the effects of chloride ion (Cl−) and sulfate (SO42−) coupling erosion on the microstructure of cement-based materials were mainly investigated. In the presence of Cl− solution at a concentration of 0.6 mol/L, the phase composition, pore structure distribution, and microscopic morphology of the hardened slurry of composite cementitious material containing 30 % fly ash (FA), or 30 % ground granulated blast furnace slag (GGBS), or mixed with 15 % FA and 15 % GGBS with varying concentrations of SO42− were investigated, respectively. The impact of SO42− concentration and mineral admixtures on the chemical binding Cl− and microstructure was examined from the microscopic level. The results showed that adding GGBS or FA can resist Cl− and SO42− erosion; however, GGBS is more effective at chemically solidifying Cl− than that of FA. The erosion of Cl− and SO42− influence each other and contain each other. Furthermore, Friedel salt (FS) transforms into Ettringite (AFt) after the introduction of SO42−, which releases bonded Cl− into the pore solution thereby increasing free Cl− content. In higher concentration (0.8 mol/L) of Na2SO4 solutions, the cement-based material is subjected to the superimposed destruction of physical crystallization and chemical erosion of the salt solution.

Study on the automatic control method for evaporation treatment of wet flue gas desulfurization wastewater in power plants

ABSTRACT DRFNN is used to predict the evaporation state of wastewater, and incremental PID algorithm is combined to adjust the control quantity. By real-time monitoring the state and parameter changes of wastewater evaporation treatment process, online adjusting and optimizing the parameters of DRFNN and incremental PID, the automatic control of desulfurization wastewater evaporation treatment is completed. The experimental results show that this method can achieve more accurate and reliable automatic control, short control time, strong ability to deal with emergencies, and can converge to stability in a short time. This method can effectively reduce the number of early alarms and failures of the system and save maintenance costs. The IAE values of chloride ion (Cl) and mercury (Hg) in this method are 0.3558 and 0.3872, respectively, which proves that the difference between the actual output and the expected output of this method is very small, which proves that the system in this paper has high accuracy.

Evaluation of adsorption isotherms and kinetics of anionic pollutant in water using biochar derived from locally available agro-waste

The uses of agricultural byproduct solid wastes to develop low cost sorbents are advantageous and promising for the removal of water contaminants. It serves the purposes of both environmental remediation and appropriate management of agricultural waste generated during agricultural processing. In this study, locally available apricot seed shell and Salix Alba leaves were utilized as agro-waste for the preparation of adsorbents. The biochar was prepared at 300-370oC via pyrolysis and 80 mesh particle sizes were modified by 1N HCl. The unmodified and acid modified local Salix Alba leaves and Apricot seed shell biochar were used to study the adsorption of chloride ion in water, which can damages appliances of industries and also poses health issues at elevated concentration. Adsorption kinetics and equilibrium studies were conducted at pH 7. The adsorption efficiency of modified biochar was much higher than the unmodified biochar due to induce surface positive charge. The Langmuir maximum adsorption of modified Salix Alba leaves sorbent was found to 22.98 mg/g, while modified Apricot seed shell biochar was found 25.83 mg/g. The experimental data were simulated and applied to fit Langmuir, Freundlich isotherm, pseudo 1st and 2nd order kinetics models and found a better compliance with Freundlich isotherm model and pseudo 2nd order kinetics model.

Long-term releasing and migration characteristics of chloride ions in chloride-based asphalt mixtures

Chloride-based pavement lowers freezing point of pavement surface and delays ice formation by releasing chloride ions. However, the long-term effectiveness of chloride filler has not been well-understood. This study combined the experimental and simulation methods to investigate the long-term releasing characteristics of chloride ions inside chloride-based mixtures. In this study, two types of chloride-based asphalt mixtures (AC-13 and OGFC-13) were prepared with Mafilon (MFL) and immersed in deionized water. The electrical conductivity tests were conducted on leaching water to evaluate the long-term releasing characteristic of chloride ions. The migration simulation was carried out on MFL AC-13 subjected to wet-dry cycles to explore the migration characteristics of chloride ions inside MFL AC-13 mixture. Results show that chloride ions experiences a rapid release within 30d in water, followed by a gradual and sustained release. Half of the chloride ions in mixture containing 70 % MFL will released into water after immersion for 278d at 20°C or 74d at 60°C, respectively. The long-term release of chloride ions can be significantly improved by increasing the MFL dosage in asphalt mixtures. Chloride ions in mixture surface preferentially released into leaching water, resulting in a higher concentration of residual chloride in core of the mixture. During the drying phase, the chloride ions concentration throughout the asphalt mixture tends to become uniform as drying time increases. The findings achieved in this study would benefit and promote the better use of MFL in anti-icing pavement.

Crack/Cl− - triggered design and tensile self-healing mechanism of epoxy coatings on offshore steel bars

The double-walled microcapsules triggered under the crack/Cl− condition were prepared by using isocyanate and 1,6-diaminohexane respectively as the internal and external core material, and polyurea as the wall material. During the synthesis process, lead sulfate was added to the wall material to trap chloride ions. The morphology and dispersion of the microcapsules embedded in the epoxy composite were characterized, using the scanning electron microscope (SEM) and super depth of field microscope. Self-healing coatings containing 0.0 wt%, 3.0 wt%, 5.0 wt%, and 8.0 wt% of composite double-walled microcapsules were subjected to tensile tests. The digital speckle correlation method (DSCM) and pull-out test were applied to analyze the mechanical properties and crack-triggering principle of the coating. The toughening effect and self-healing behavior of the epoxy resin with varying dosages of microcapsules were studied. The self-healing efficiency and mechanism of the composite coating were obtained during the process of stretching, crack expansion, and micro-capsule triggering.

Regioselective ligand substitution in square-planar Pt(II) complexes bearing N^C and C^C chelating ligands with pyrazole derivatives

The regioselectivity of the ligand substitution reaction of square-planar Pt(II) complexes with chelating ligands pyridyl-NHC (Py-NHC), phenyl-NHC (Ph-NHC), and phenyl-pyridine (ppy, Ph-Py) was studied. The reaction of the dichlorido Pt(II) complex bearing these chelating ligands in the presence of pyrazole (pz) ligands afforded mono-pyrazole adducts [PtCl(ChL)(pz)]n+ (n = 0 and 1; ChL=chelating ligand (Py-NHC, Ph-NHC, Ph-py)). The structures of the PtCl(pz) complexes with the Py-NHC, Ph-NHC, and Ph-Py chelating ligands were confirmed by X-ray crystallographic analysis. The regioselectivity of the ligand substitution reaction between the pyrazole moieties and chloride ions can be controlled by the strength of the trans effect of the chelating ligands. Based on the structures of the products, a clear trend of Py < NHC < Ph was observed in the trans effect of the chelating ligands. This finding provides a rational synthetic procedure for asymmetric Pt(II) complexes with chelating ligands in a stepwise manner.

Impacts of chloride ions on the electrochemical decomplexation and degradation of Cr(III)-EDTA: Reaction mechanisms of HO• and RCS

The removal of Cr(III)-organic complexes, encompassing both decomplexation and ligand degradation, presents significant challenges in industrial wastewater treatment. As one of the most common anions in wastewater, Cl− significantly improves the efficiency of electrochemically removing Cr(III)-organic complexes through generated reactive chlorine species (RCS). In the electrochemical chlorine (EC/Cl2) process, extensive experimentation revealed that ClO• plays a dominant role in the degradation of Cr(III)-EDTA, surpassing the effects of free chlorine, direct electrooxidation, HO•, and other RCS. Density functional theory calculations indicated that RCS, primarily Cl• and ClO•, preferentially oxidize the ligand in Cr(III)-EDTA via H-abstraction, whereas HO• trends to attack the Cr atom through electron transfer. The influential factors on the degradation efficiency of Cr(III)-EDTA, Cr(VI) yield, and total organic carbon removal in EC/Cl2 were also assessed, including Cl− concentration, current density, and pH. Real industrial wastewater was employed as a reaction matrix to evaluate the application of the EC/Cl2 process for treating Cr(III)-EDTA, accompanied by energy efficiency calculations. Additionally, a two-chamber reactor was established to simultaneously oxidize Cr(III)-EDTA at the anode and reduce Cr(VI) at the cathode. This study provided insight into developing RCS-dominated AOPs to effectively decomplex and decompose organic Cr(III)-complexes in Cl−-containing industrial wastewater.

Effect of Chloride Salt Bath on Electrochemical Behavior and Morphology of 304L and 316L Stainless steels

Effect of Chloride Salt Bath on Electrochemical Behavior and Morphology of 304L and 316L Stainless steels

Microstructural evolution and micromechanical properties of asphalt due to chloride salt erosion: Insights from atomic force microscopy

To explore the impact of chloride salt erosion on the microstructure and micromechanical properties of asphalt, this study utilizes the atomic force microscopy (AFM) to examine the evolution of micromorphology, surface roughness, adhesion, and Young’s modulus of asphalt in dry conditions, under various chloride salt concentrations, and after different erosion times. The results indicate significant changes in the microtopography of the asphalt surface due to chloride salt erosion, characterized by the reorganization of nanoscale protrusions and white spots. This results in a decrease in their quantity and total area, while the average area increased, demonstrating a trend of phase dispersion and aggregation. Erosion increased the surface roughness of the asphalt and significantly altered its mechanical properties. Specifically, with an increase in chloride salt concentration, the average roughness (Ra) of asphalt, after one day of erosion relative to its dry state, increased by 7.99 %, 33.06 %, and 52.55 %, respectively. As the erosion time was extended, at a 2.5 % chloride salt concentration, the growth rate of Ra reached 33.06 %, 54.68 %, and 67.22 %, respectively. A declining trend in nano adhesion was observed, indicating internal structural damage and reduced durability, while Young’s modulus significantly increased, suggesting a densification of the asphalt matrix and enhanced rigidity.

Binding and unbinding of flexible surfactant bilayers

We have probed the influence of salt and temperature on the spatial periodicity (d) of the fluid lamellar (Lα) phase formed by two ionic amphiphiles, whose bilayer bending rigidity moduli are widely different. In the case of rigid 1,2-dimyristoyl-3-trimethylammonium-propane (chloride salt) (DMTAP) bilayers, d is found to decrease with increasing salt concentration (Cs) in the solution, in qualitative agreement with the DLVO theory. d depends only very weakly on temperature in this system. On the other hand, in the Lα phase formed by highly flexible didodecyldimethylammonium chloride (DDAC) bilayers, d is not set by the minimum of the DLVO potential over a wide range of Cs, due to inter-bilayer repulsion arising from thermal undulations of the bilayers. An abrupt transformation of this undulation stabilized swollen Lα phase into a collapsed Lα phase, where d is comparable to the bilayer thickness, is observed above a threshold value of Cs. At higher Cs an unbinding transition of the bilayers is observed on heating, where the collapsed Lα phase transforms into a dispersion of spatially uncorrelated bilayers. Our observations are consistent with this transition being first-order.