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[Display omitted] Theoretical assessment of Cl-excessive, mixed-halide grain boundaries in hybrid perovskite thin films demonstrates that ordered 3D/2D interfaces along perovskite (100) crystallographic planes are the most energetically favored among other possible cases. [ABSTRACT FROM AUTHOR]

Chloride ions are responsible for triggering severe corrosion in the marine environment. Hence, there is a need to deploy corrosion resistant materials such as hexagonal boron nitride (h-BN) sheet to protect mechanical components operating under such harsh conditions. In this work, a first-principles approach was employed to investigate the effect of fluorine modification on the thermodynamic and kinetic behaviors of oxygen on different kinds of vacancy-defective hexagonal boron nitride (h -BN) in a Cl-containing marine environment. Geometrical and electronic structures were systematically analyzed along with adsorption and diffusion behaviors. The existence of a low energy barrier implies that there is a relatively attenuated ability to inhibit O diffusion for double vacancy V BN - h -BN sheet compared to single vacancy V B - h -BN and V N - h -BN sheets. Interestingly, the fluorine functionalization for three defective h -BN sheet is found to cause an increased energy barrier of O diffusion. The F @ Cl @ V N - h -BN sheet possesses the highest diffusion energy barrier, indicating a superior anti-oxidation property in the marine environment. This study provides some fundamental guidelines for realizing high-performance h -BN sheets for protecting equipment and components used in marine applications. [ABSTRACT FROM AUTHOR]

For corrosive chloride solution, an excellent corrosion-resistant coating is required. In this view, introducing graphene oxide-modified Al 2 O 3 , TiO 2 , and MnO 2 in a nickel matrix is a novel strategy for achieving this goal. Electrodeposition is used for manufacturing these nanocomposite coatings. The microstructure, electrochemical corrosion resistance, composition, and contact angle are then thoroughly investigated. Electrochemical results revealed that Ni-GO-TiO 2 nanocomposite coating has a low corrosion current density of 10.86 μA/cm2 and a high charge transfer resistance of 2328 Ω cm2. Furthermore, the Ni-GO-TiO 2 nanocomposite coating outlasts pure nickel films. The mechanism of GO-TiO 2 -promoted nickel corrosion resistance turns out to be that GO-TiO 2 may impede the growth of nickel crystals and make them finer. Furthermore, this coating improves smoothness and reduces pores and cracks, resulting in less damage by chloride ions. Based on these findings, incorporating GO-TiO 2 into nickel coatings may provide insights into preventing corrosion of steel pipelines exposed to chloride ions. [Display omitted] • Nickel coating was reinforced with graphene oxide doped Al 2 O 3 , TiO 2 , and MnO 2. • Composition, crystal size, morphology, and hydrophobicity were compared. • Electrochemical and immersion tests were performed on all coatings. • Ni-GO-TiO 2 exhibited superior barrier performance due to improved properties. [ABSTRACT FROM AUTHOR]

Chloride is the most important anion in ore-forming hydrothermal fluids, and chlorine isotopes are therefore potentially sensitive tracers of the origin and evolution of ore-forming fluids. However, they remain a relatively under-utilized tool in ore deposit geochemistry due to the lack of knowledge of chlorine isotope fractionation during ore-forming processes. Using first-principles density functional theory, this study estimates chlorine isotope fractionation factors for various ore-forming processes. All metal-Cl complexes in hydrothermal fluids are enriched in 37Cl compared to chloride ions, but the change in δ37Cl of the fluid trapped in ore minerals is small after the destabilization of metal-chloride complexes during ore mineral deposition. In the precipitation of evaporite minerals from brine, the sequence of enrichment of the heavy Cl isotope (37Cl) is halite > carnallite > aqueous chloride > kainite > sylvite > bischofite. The results of this study agree with the experimental observations that progressive precipitation of halite from brine lowers the δ37Cl value of the residual fluid until the formation of K-Mg chlorides. In low-temperature deposits, δ37Cl values for fluid inclusions and minerals reflect those of the hydrothermal fluid provenance and the mixing of this fluids with saltwater or basinal brines. In high-temperature magmatic-hydrothermal ore deposits that undergo liquid–vapour phase separation, chlorine isotopes fractionate among phases of silicate melt, vapour and chloride-rich liquid. The considerable range in δ37Cl in fluid inclusions may also reflect fluid mixing and hydrothermal alteration. At ambient temperature, the δ37Cl values may reflect evaporative processes and, in the case of chemical weathering of metallic mineral deposits, may record the supergene enrichment of the metals. This study highlights the use of chlorine isotopes as a new tool for interpreting ore-forming processes. [ABSTRACT FROM AUTHOR]

The efficient treatment of refractory organics in reverse osmosis concentrate (ROC) is a critical issue for achieving emission reduction or even zero emission in the petrochemical industry. A simple and efficient electrocatalytic process was proposed for treating actual petrochemical ROC using a highly active self-assembling Ti/SnO 2 -Sb anode. The Ti/SnO 2 -Sb anode was prepared by using citric acid (CA) and ethylene glycol (EG) as precursors, with a mole ratio of Sn:Sb of 5:1 and a metal salts to CA to EG mole ratio of 1:3:16. The resulting electrode surface had a complete mesh pit structure after calcination at 550 ºC. Several key factors were found to affect the degradation of dissolved organic carbon (DOC), including current density, chloride ion concentration, Fe (II) concentration, and acidity. The presence of chloride ions on the anode surface significantly improved the conversion efficiency of hydroxyl radicals, which played a crucial role in the oxidation of the organics. Additionally, near the cathode, oxidative radicals such as H 2 O 2 and O 2 -∙ were generated, while hydroxyl radicals were produced with the addition of Fe (II) and H+. Under a current density of 20 mA·cm−2, the Ti/SnO 2 -Sb anode achieved a COD removal rate of 94.5% and a DOC removal rate of 43.4%. [Display omitted] [ABSTRACT FROM AUTHOR]

Collagen IV is an essential structural protein in all metazoans. It provides a scaffold for the assembly of basement membranes, a specialized form of extracellular matrix, which anchors and signals cells and provides microscale tensile strength. Defective scaffolds cause basement membrane destabilization and tissue dysfunction. Scaffolds are composed of α-chains that coassemble into triplehelical protomers of distinct chain compositions, which in turn oligomerize into supramolecular scaffolds. Chloride ions mediate the oligomerization via NC1 trimeric domains, forming an NC1 hexamer at the protomer-protomer interface. The chloride concentration-" chloride pressure"-on the outside of cells is a primordial innovation that drives the assembly and dynamic stabilization of collagen IV scaffolds. However, a Cl-independent mechanism is operative in Ctenophora, Ecdysozoa, and Rotifera, which suggests evolutionary adaptations to environmental or tissue conditions. An understanding of these exceptions, such as the example of Drosophila, could shed light onthe fundamentals of how NC1 trimers direct the oligomerization of protomers into scaffolds. Here, we investigated the NC1 assembly of Drosophila. We solved the crystal structure of the NC1 hexamer, determined the chain composition of protomers, and found that Drosophila adapted an evolutionarily unique mechanism of scaffold assembly that requires divalent cations. By studying the Drosophila case we highlighted the mechanistic role of chloride pressure for maintaining functionality of the NC1 domain in humans. Moreover, we discovered that the NC1 trimers encode information for homing protomers to distant tissue locations, providing clues for the development of protein replacement therapy for collagen IV genetic diseases. [ABSTRACT FROM AUTHOR]

• Salt stress reduced growth and physiological attributes of celosia argentea. • Application of Moringa zinc oxide nanoparticles (MZnO-NPs) improved growth attributes and floral characteristics. • Salt stress mitigation was credited to reduced uptake of chloride ions and increase in quantum yield of photosystem II. Soil salinization is a significant environmental risk that affects the production of commercial crops. Celosia argentea is an important medicinal and decorative plant. Keeping in mind the economic importance and salt sensitivity of C. argentea , this study was designed to improve the salinity tolerance of C. argentea. Salt stress reduced growth of C. argentea plants grown in salt stress conditions. The quantum yield of Photosystem II (Phi2) decreased by 15%, 20%, and 30% at 100, 200, and 400 mmol L−1 of Cl− salt, respectively as compared to non-saline conditions. In the present study, we used foliar applications of different concentrations (500, 250, and 100 mg L−1) of green synthesized, Moringa Zinc Oxide nanoparticles (MZnO-NPs) to induce tolerance against Cl-salt in C. argentea. Increasing concentration of Cl-salt considerably reduced growth attributes (shoot and root length, fresh weight and dry weight, leaf area) and floral characteristics (density, length, and diameter) C. argentea, while the little effect on the tissue water content of the plant. Cl-salt declined the soluble component of sugars (60%) and proline (10%), but no effect was found in soluble proteins. Accumulation of toxic ion (Cl) and nutrient (K and NO 3) deficiency was more in the shoot than root tissue of plants exposed to Cl−salt. Cl-salt reduces the carotenoid content and Quantum yield of Photosystem II while enhancing photosynthetic pigments (Chl and b) and PhiNPQ. The foliar applications of MZnO-NPs substantially enhanced the biomass, root length, and flower height of C. argentea under Cl-salt but no positive effect was found in improving water content. All NPs increased the soluble sugar and protein of salinity-treated plant but soluble proline was unaffected. The exogenous treatment of MZnO-NP reduces the Cl uptake while enhancing the nutrient (K, Mg, and NO 3) content in the plant. Moreover, NPs increased photosynthetic pigments, carotenoid content, and Quantum yield of Photosystem II while reducing PhiNPQ. It concluded that MZnO-NPs have the potential to improve the growth and floral property of C. argentea when cultivated with saline resources. [ABSTRACT FROM AUTHOR]

Copper and cobalt from industrial operations build up in the environment, posing a substantial health risk. This study examined how ethylenediaminetetraacetic acid (EDTA), citrate, and chloride ions affected the fluidized bed homogeneous granulation process' (FBHGP) ability to recover both individual and combination of copper and cobalt ions from simulated waste streams. A 99% copper removal and 95% granulation efficiency were attained in copper-based solutions. The soluble copper still present in the solution caused a 4% variation in the removal and granulation efficiencies. There were 99% removal and 99% granulation efficiencies in cobalt-based solutions. When EDTA was present in a copper-based solution, 95% removal and 86% granulation were reached, and for cobalt-based solutions, 95% and 91% were the removal and granulation efficiency, respectively. The presence of citrate in the copper-based solution obtained the removal of 83% and granulation efficiency of 54% at 0.1 MR of citrate to copper. No copper phosphate precipitate was formed when the MR was greater than 0.1. There were 96% removal and 92% granulation efficiency when citrate was present in cobalt-based solutions. The presence of chloride ions in copper solution achieved a 99% removal and 91% granulation efficiency, while in cobalt solutions, 99% removal and 98% granulation efficiency were attained. Solutions with combined copper and cobalt with chloride ions achieved 99% removal and 95% granulation efficiency for copper and 99% removal and 95% granulation efficiency for cobalt. The granule sizes decreased as the MR of the complexing agents to metal, and the concentration of chloride ions increased. The peaks on the XRD pattern exactly matched the peaks of cobalt phosphate hydrate (Co 3 (PO 4) 2 ·8 H 2 O). FBHGP has effectively recovered copper and cobalt from the waste streams of simulated metals. [ABSTRACT FROM AUTHOR]

[Display omitted] The mechanism of the carbon dioxide and alkene oxide reaction catalyzed by the pentagonal-bipyramidal CrIII complex, dichloro[2,6-diacetylpyridine bis(benzoylhydrazone)(1−)] chromium, includes the steps of sequential binding of the epoxide molecule, chloride ion and CO 2 with the catalytic particle and subsequent cyclization, accompanied by dissociation of Cl−. The solvent effect is important for the formation of the cyclic carbonate product. [ABSTRACT FROM AUTHOR]

Massive discharge of ammonia nitrogen wastewater not only causes eutrophication of the water body but also has a toxic effect on humans and living things. How to deal with ammonia nitrogen wastewater is a crucial topic for researchers. Here, a novel catalyst of Pt@Ti–Si where platinum was supported on a composite oxide of titanium oxide (TiO 2) and silicon oxide (SiO 2) via a one-pot method was successfully synthesized for catalytic wet air oxidation (CWAO) of ammonia with a high concentration (more than 2000 ppm). Due to the improved specific surface area of SiO 2 and the excellent acid-base resistance of TiO 2 , the prepared composite oxide-supported platinum catalyst has excellent catalytic performance and good stability for CWAO with a high concentration of ammonia. At 200 °C and the O 2 pressure of 2 MPa for 2 h, the 1%Pt@Ti10–Si1 catalyst has a 96.32% conversion of 2470 ppm ammonia and 97.15% selectivity to N 2 and has good catalytic performance even after five cycles. Under the same reaction conditions, when the chloride concentration in the system is 3000–10000 ppm, the CWAO reaction can be inhibited at an early stage and promote conversion and selectivity at a later stage. The results show that the catalyst has good tolerance to chloride ions, and the treated ammonia nitrogen wastewater can be used for subsequent biochemical processes. Therefore, the developed novel catalyst in this study is effective for the CWAO of highly concentrated ammonia and has potential industrial application value. [Display omitted] [ABSTRACT FROM AUTHOR]

Membrane fouling reduces the performance of membrane processes. In this work, a coupling between anodic oxidation and electrodialysis was designed and studied to prevent and control fouling of the AMX anion exchange membrane during the electrodialysis process. Analysis of the AMX membrane surface by SEM, EDS and ATR-FTIR revealed that the presence of sodium dodecyl benzene sulphonate in the solution led to membrane fouling. The fouling resulted in an increase in the membrane electrical resistance and a decrease in the chloride ion transfer flux through the membrane. It was shown that the combination of anodic oxidation with electrodialysis not only greatly reduces the fouling of the AMX membrane but also removes a persistent organic pollutant present in the effluent to be treated. Furthermore, the study of the effect of certain operating parameters on the membrane fouling and the mineralization of the solution has shown that the increase in the current density of the anodic oxidation leads to a decrease in the membrane electrical resistance and an improvement in the efficiency of mineralization. On the other hand, the application of a current density of 40 mA cm−2, natural pH and Na 2 SO 4 as electrolyte supporting during 120 min of eletrodialysis led to an increase in the electrical resistance of the membrane of only 1.23 times and a strong mineralization of the solution (96 %). [Display omitted] • Ions exchange membranes fouling leads to increased membrane electrical resistance. • Organic membrane fouling affects the transfer of mineral ions. • AO-ED coupling mitiges organic fouling of anions exchange membranes. • AO-ED coupling decreases the COD of the solution in contact with the membrane. • Mineralization efficiency depends on the pH, the current density and the nature of the supporting electrolyte. [ABSTRACT FROM AUTHOR]

• CWAO achieved high TOC removal in high-salinity high-organic wastewater. • A salt-tolerant catalyst LaFe0.85Ru0.15O3-δ was developed in CWAO process. • TOC removal of LaFe0.85Ru0.15O3-δ is 45.51% better than the commercial catalyst. • LaFe0.85Ru0.15O3-δ has novel Cl− resistance no matter the concentration of Cl−. • Fe site can adsorb Cl− to protect Ru site and oxygen species to exert catalytic activity. Catalytic wet air oxidation (CWAO) coupled desalination technology provides a possibility for the effective and economic degradation of high salinity and high organic wastewater. Chloride widely occurs in natural and wastewaters, and its high content jeopardizes the efficacy of Advanced oxidation process (AOPs). Thus, a novel chlorine ion resistant catalyst B-site Ru doped LaFe 1- x Ru x O 3-δ in CWAO treatment of chlorine ion wastewater was examined. Especially, LaFe 0.85 Ru 0.15 O 3-δ was 45.5% better than that of the 6%RuO 2 @TiO 2 (commercial carrier) on total organic carbon (TOC) removal. Also, doped catalysts LaFe 1- x Ru x O 3-δ showed better activity than supported catalysts RuO 2 @LaFeO 3 and RuO 2 @TiO 2 with the same Ru content. Moreover, LaFe 0.85 Ru 0.15 O 3-δ has novel chlorine ion resistance no matter the concentration of Cl− and no Ru dissolves after the reaction. X-ray diffraction (XRD) refinement, X-ray photoelectron spectroscopy (XPS), transmission electron microscope (TEM), and X-ray absorption fine structure (XAFS) measurements verified the structure of LaFe 0.85 Ru 0.15 O 3-δ. Kinetic data and density functional theory (DFT) proved that Fe is the site of acetic acid oxidation and adsorption of chloride ions. The existence of Fe in LaFe 0.85 Ru 0.15 O 3-δ could adsorb chlorine ion (catalytic activity inhibitor), which can protect the Ru site and other active oxygen species to exert catalytic activity. This work is essential for the development of chloride-resistant catalyst in CWAO. [Display omitted] [ABSTRACT FROM AUTHOR]

Infrastructures treated with de-icing salts and those which are in direct contact with sea water are subjected to degradation by chloride ingress. Concrete composed of reactive sources of silica and used near such regions can suffer from both, alkali silica reaction (ASR) and chloride ingress subsequently. This research aims at empirically investigating the residual mechanical properties of plain and steel fiber reinforced concrete damaged by alkali silica reaction (ASR) and subsequent chloride ion ingress. Accelerated degradation tests on three concrete mixes such as plain concrete (PC,control), steel fiber reinforced concrete (SFRC) and high strength fiber reinforced concrete (HSFRC) were done. Specimens were initially damaged by ASR, and then submerged in chloride solution at temperature ranges of 5 oC, 25 oC and 40 oC. 1 mol/L NaOH solution and 3% NaCl solution were used for a period of 20 and 40 weeks. Steel fibers were found to be effective in reducing surface crack widths at 5 oC and 25 oC. Accelerated mortar bar test showed that steel fibers were able to reduce expansion by 31.5% and 65.3% using single and double hooked fibers. By examining the residual compressive and flexure strengths, it was found that exposure to chloride environment aided in hydration reaction which counter-balanced the damage due to ASR. Fiber-matrix bonding developed over time inducing friction which led to higher ductility and less damage in flexure strength in steel fiber reinforced concrete prisms. [ABSTRACT FROM AUTHOR]

The glucose fuel cells (GFCs) leverage the implant surface as an electrode, representing an optimal approach for miniaturizing implantable power sources. A conductive hydrogel electrode membrane is crafted through in situ reduction and electrochemical co-deposition techniques by employing bacterial cellulose as a scaffold. This process enables the seamless integration of the GFC directly onto the implant surface. The integrated GFC exhibits an impressive open-circuit voltage peak of 0.894 V and a peak power density of 94.7 μW cm−2. Additionally, the fuel cell demonstrates resistance to chloride ion toxicity under simulated interstitial fluid conditions. Although performance within horse serum is moderate, the methodology presents a viable strategy for developing GFCs on implant surfaces. • Cell's cathode and anode utilize bacterial cellulose and platinum nanoparticles. • Bacterial cellulose templating and electrochemical co-deposition are utilized. • The GFC exhibits a Voc of 0.894 V, along with a power density of 94.7 μW cm−2. • The anode membrane resists chloride ion poisoning, enhancing cell stability. [ABSTRACT FROM AUTHOR]

Sustainion is an anion exchange water electrolyzer membrane that has exhibited a scalable performance. In this work, we present a molecular model for the Sustainion membrane incorporating functionalization of the polymer in order to better mimic experimental conditions. Here in, we present a comprehensive exploration of its structural and transport properties like density, diffusivity and conductivity at various operating hydration levels using molecular dynamics simulations. The density exhibits a non-monotonic trend while the diffusivity showcases a non-linear behaviour with hydration. Furthermore, diffusion exhibits an Arrhenius-like dependence on temperature with the activation energies exhibiting a non-monotonic relationship akin to the density. It is concluded that the afore-mentioned properties of the Sustainion membrane are due to the counteracting influence of the enhancement in coordination number, and a reduction in the potentials of mean force of the different atomic pairs in the system. The effect of added salt on Sustainion properties is also determined and collated with experiments. Based on comparison with experiment, we deduce that vehicular diffusion is the predominant mechanism in the diffusion of the chloride ion, while it contributes approximately 15% to the diffusivity of the hydroxide ion. [Display omitted] • MD simulations used to determine the performance characteristics of Sustainion • Enhancement of CN leads to increase of density and reduction of diffusivity • Reduction of PMF reduces density but leads to an enhancement of diffusivity • Results compared with exp. data and observed to match for the Cl − ion • Effect of charge distribution on various properties discerned [ABSTRACT FROM AUTHOR]

In this paper, the influence of semi-permeable film stabilisation on the corrosion trend, corrosion type and corrosion mechanism of bridge weathering steel in a deicing salt medium was investigated by dry and wet alternating accelerated corrosion test. The results indicate that the semi-permeable film stabilisation treatment reduces the inflection point of corrosion rate reduction of weathering steel plates and welded specimens in the deicing salt medium, reduces the value of n, which represents the trend of full-scale corrosion, and improves their resistance to full-scale corrosion. After 30 days of corrosion, the peak intensity ratios of I β-FeOOH+FeOCl /I α-FeOOH for untreated plates and welded specimens were 1.092 and 1.132 times higher than that of the semi-permeable film stabilisation treatment specimens, respectively. With a reduction of defects and an increase in densification in the rust layer, and a significant reduction in the concentration of chloride ions at the interface between the rust layer and the substrate. During the whole corrosion process, the self-corrosion potential of the rust layer after the stabilisation treatment of the semi-permeable film was increased by 1.08–1.12 times, the impedance was increased by 1.13–1.32 times, and the electrochemical stability was significantly improved. The semi-permeable film in the pre-corrosion period effectively blocked the penetration of chloride ions, reducing the concentration of corrosion medium in the rust layer, reduced the generation of unstable phases of β-FeOOH and FeOCl. At the same time, the stabiliser treatment improves the Cu, Cr and Ni elements in the rust layer, promoted the formation of the stable phase α-FeOOH in the rust layer and the refinement of the rust grains, thus significantly improving the corrosion resistance of the weathering steel in the deicing salt medium. [ABSTRACT FROM AUTHOR]

• The CuO/RuO 2 electrode was prepared by the two-step thermal decomposition method for the first time. • Compared with the ordinary RuO 2 electrode, the selectivity of CER of CuO/RuO 2 electrode is remarkably improved. • During the preparation of AEW, the HClO content of AEW2 (prepared by CuO/RuO 2) is 2.5 times that of AEW1 (prepared by RuO 2). • In the sterilization experiments on E. coli and B. subtilis , the germicidal efficacy of AEW2 is obviously superior to that of AEW1. Electrochemical chlorine evolution reaction (CER) is one of the most important practical applications of electrochemical reaction, which can be used for electrochemical disinfection. The electrochemical disinfectant of acidic electrolyzed water (AEW) is obtained by electrolyzing extremely dilute chlorine-containing solution in ion-exchange membrane electrolyzer. In the anode area, HClO is produced by CER, which has a strong bactericidal effect. Due to the low concentration of chloride ion, it is necessary to improve the CER selectivity of the electrode in order to improve the efficiency of chlorine electrolysis. In this paper, CuO/RuO 2 electrode was prepared by the two-step thermal decomposition method, and the surface morphology and electronic structure of RuO 2 electrode were modified. Compared with the ordinary RuO 2 electrode, the CER activity of CuO/RuO 2 electrode is improved. For the oxygen evolution reaction (OER), the activity of CuO/RuO 2 electrode is significantly lower than that of RuO 2 electrode. The CER mechanism of CuO/RuO 2 electrode is the second electron transfer, and the OER mechanism is the formation and transformation of OH ads. The potential difference between CER and OER of CuO/RuO 2 -3 electrode is 105 mV, which is 52 mV higher than that of RuO 2 electrode, so the selectivity of CER of CuO/RuO 2 electrode is remarkably improved. During the preparation of AEW, the HClO of AEW2 (prepared by CuO/RuO 2 -3 electrode) is 0.72 mmol/L, which is 2.5 times that of AEW1 (prepared by RuO 2 electrode). In the sterilization experiments on E. coli and B. subtilis , the germicidal efficacy of AEW2 (3.71 and 2.99 log 10 CFU/mL) is obviously superior to that of AEW1 (0.76 and 0.61 log 10 CFU/mL). [ABSTRACT FROM AUTHOR]

[Display omitted] • Sludge porous carbon created rough surface and exposed flake structure for mayenite. • The removal efficiencies of Cl− and SO 4 2− reached 68 % and 77 %, respectively. • A high Cl− adsorption capacity of 97 mg/g was achieved from FGD wastewater. • Mayenite has a negative Cl embedding energy and is favorable for the embedding of Cl. • The Cl− removal product possessed high degradation efficiency of carbonyl sulfide. The high concentration of chloride ions (Cl−) in flue gas desulfurization (FGD) wastewater not only corrodes equipment but also reduces the quality of desulfurization gypsum. The mayenite (Ca 12 Al 14 O 33) has a notable capacity for adsorbing Cl−, but its efficacy is hindered by its inherently low specific surface area and long reaction time. To improve the effectiveness of mayenite in Cl− removal, the porous carbon derived from sewage sludge (SSC) was employed to modify the mayenite-based Ca/Al oxides (CAO). The resultant SSC/CAO composites featured a predominant mayenite phase with rough surface and exposed flake structure, leading to an increase in surface area from 2 m2/g for CAO to 54 m2/g for SSC/CAO-1 (mass ratio of sewage sludge: CAO = 1: 1). Within 2 h of reaction, SSC/CAO-1 achieved a Cl− removal efficiency of 68 % and a high Cl− adsorption capacity of 97 mg/g. The Cl− removal mechanism is related to the presence of a higher percentage of AlO 4 5-, more oxygen vacancies, and larger surface area in SSC/CAO-1 compared to that in CAO, which facilitated the dissolution and reconstruction of the [Ca − Al − O] framework, resulting in the formation of Ca 2 Al(OH) 6 Cl·2H 2 O with high crystallinity. The negative Cl embedding energy indicates that Ca 12 Al 14 O 33 is favorable for the embedding of Cl, and its transformation into Ca 2 Al(OH) 6 Cl·2H 2 O occurs spontaneously. The final product after Cl− removal consisted of efficient components to obtain high catalytic hydrolysis efficiency of carbonyl sulfide, which holds great importance to address the issue of handling the Cl– removal product during backend treatment. [ABSTRACT FROM AUTHOR]

The durability of concrete is significantly affected by the chloride solidification property of the binder. This study investigated the chloride-binding capacity and penetration process of metallurgical slag (MS)-based binder and mortar. It also analysed the influence of the ratio of steel slag (SS) to granulated blast furnace slag (GBFS). The results showed that the C–S–H gels and Friedel's salt (Fs) bound more chloride ions in high- and low-concentration NaCl solutions, respectively. In a 0.1 mol/L NaCl solution, Fs captured 0.01–0.04 mmol/g Cl–. However, in a 5 mol/L NaCl solution, the chloride bound by the C–S–H gels was 0.07–0.20 mmol/g. In addition, the increase of the SS to GBFS ratio (SGR) promoted the generation of Fs through the activity promoting of GBFS and reduced the Cl content captured by the C–S–H gels by improving calcium ions and their unstable connections with silicate chain oxygen. The increasing SGR decreased the percentage of pores smaller than 10 nm, reaching a minimum of 22.6 % at R3. However, the chloride resistance of R3 also exhibited the highest C s of 1.01 % and the lowest D a of 8.54 × 10–12 m2/s among MS-based mortars due to a 0.10 % decrease in porosity. Furthermore, the chloride-binding capacity and resistance performance of MS-based binders were all better than those of ordinary Portland cement. • The MS binder of 1:9 SGR had highest compressive strength and bound chloride content. • At a 0.1 mol/L NaCl solution, Fs captured 0.01–0.04 mmol/g Cl–. • At a 5 mol/L NaCl solution, C–S–H gels bound 0.07–0.20 mmol/g Cl–. • The SGR increasing caused the decrease of <10 nm pores percentage and mortar porosity. [ABSTRACT FROM AUTHOR]

The durability of recycled concrete is susceptible to degradation from both chloride salt attack and carbonation when exposed in service environment. The depth of carbonation in recycled concrete subject to chloride salt attack was studied here. This investigation assessed the effects of mineral admixture, replacement rate of recycled coarse aggregate, and quality of recycled coarse aggregate on the carbonation depth. The carbonation depth Recycled concrete was studied through accelerated simulated carbonation in the laboratory for 7d, 14d and 28d. Based on the results, the correlation analysis was conducted to investigate the relationship between depth of carbonation, mineral admixture, recycled coarse aggregate replacement rate, recycled coarse aggregate quality and the presence of chloride ions. The objective of this study was mainly to investigate the effect of internal chloride ions on the depth of carbonation of recycled concrete subjected to chloride salt attack. The study referred to previous academic research on carbonation in recycled concrete that had not been affected by chloride salts, and conducted a comparative analysis to identify the carbonation depth pattern in recycled concrete influenced by chloride salt exposure. The study discovered a negative correlation between the replacement rate of mineral admixture and recycled coarse aggregate and the carbonation resistance of concrete. Moreover, enhancing the quality of recycled coarse aggregate positively impacted the carbonation resistance of concrete. An improved model was developed that considers the effect of internal chloride salts on the carbonation depth of recycled concrete, in reference to the empirical prediction model presently available. The model demonstrated a high level of agreement with experimental outcomes, displaying an error range of between −4.32% and 8.27%. It enables an in-depth comprehension of the carbonation behavior of recycled aggregate concrete in an environment exposed to chloride salt attack. Based on the model, the service life of recycled concrete structures can be more accurately forecasted, which can provide a theoretical direction for enhancing the durability of engineering structure. • This study aims to investigate the impact of chloride salts on carbonation in recycled aggregate concrete. • The influence of recycled aggregate on carbonation of recycled aggregate concrete has been studied. • The carbonation depth of recycled concrete is reduced due to the presence of chloride ions. • An empirical prediction carbonation model of recycled aggregate concrete with embedded chloride ions has been developed. [ABSTRACT FROM AUTHOR]

To enhance the compactness of concrete in coastal areas and impede the ingress of chloride solutions into the structures, Cementitious capillary crystalline waterproofing material (CCCW) was internal incorporated into concrete. This study employed one-dimensional chloride immersion diffusion tests and wet-dry cycle tests to emulate the deterioration of concrete under natural conditions due to chloride ions. The optimal dosage of CCCW was determined by conducting chemical titration to measure the chloride ion concentration at various depths within the specimens. Subsequently, the influence of incorporating CCCW on the compressive strength of concrete under chloride conditions was assessed. Finally, employing experimental methods such as MIP, SEM and EDS, the pores within cementitious materials and the formation of internal crystals was examined at a microscopic level. Research indicates that in chloride salt environments, the penetration of salt solutions can trigger the formation of spider silk biomimetic shape crystalline structures within the internal pores of CCCW. thereby enhancing the compactness of concrete to achieve a self-healing effect while preventing the intrusion of chloride salt solutions. [Display omitted] • Utilized a kind of CCCW Material to enhance the compactness of the cementitious matrix. • Microscopic experiments are performed to evaluate crystals from different perspective, providing comprehensive analysis and evaluation. • The effect of adding CCCW materials on the compressive strength and chlorine salt resistance of concrete was studied. [ABSTRACT FROM AUTHOR]

This study details the sonication-assisted synthesis and characterization of a cathodically deposited novel nickel-graphene oxide -zinc oxide (Ni-GO-ZnO) composite coating achieved through electrodeposition and its comparison with anodically deposited GO. This coating was comprehensively characterized using Fourier-transform infrared (FTIR), X-ray diffraction (XRD), Raman spectroscopy, Field emission scanning electron microscopy (FE-SEM) coupled with Energy-dispersive X-ray spectroscopy (EDAX). Subsequently, its corrosion resistance for MS1010 mild steel in 3.5 wt % (NaCl) was evaluated via weight loss, contact angle, electrochemical impedance spectroscopy (EIS), Potentiodynamic polarization, and surface analysis techniques. These observations suggest that graphene oxide-zinc oxide (GO-ZnO) adsorbs nickel onto the MS surface effectively and reduces defects, which helps in blocking active corrosion sites. Tafel plots and EIS revealed that the Ni-GO-ZnO coating exhibited the lowest current density (39.95 µAcm²) and the highest charge transfer resistance (1211 Ωcm²). This was further validated by long-term immersion testing, where the Ni-GO-ZnO coating exhibited significantly less weight loss (1.33 mils/Y) compared to the deposited GO coating (2.2 mils/Y). The mechanism of formation of deposited GO and Ni-GO-ZnO coating on the metallic surface is proposed. The enhanced corrosion resistance of the Ni-GO-ZnO coating is attributed to its ability to 1) form a more compact metallic layer and 2) Minimize the active surface area vulnerable to corrosion attack. 3) Diminishes the presence of holes and cracks for corrosive ion ingress.4) Functionally impedes the ingress of chloride ions, primarily liable for steel degradation. The synergistic effect of the GO-ZnO constituents within the nickel matrix significantly enhances the long-term durability and integrity of the protective layer, a phenomenon hitherto unexplored. The empirical outcomes advocate for the advanced application of GO-ZnO-nickel coatings in safeguarding infrastructural materials against corrosive degradation. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A number of copperII) chloride complexes with caffeine (1, 1a, 1b, 1c, 2) were prepared, their composition and structure being determined by the synthetic method and the solvent type; the synthetic scheme of the compounds interrelations is developed. • Recrystallization from organic solvents results in formation of a linear polymeric- or cyclic oligomeric structures (compounds 1a , 1b , 1c). • Four-nuclear copper(II) bromide complex with acetamide (3) has been prepared and studied. Four bromide ions in it are non-equivalent to the other four and this fact may result in modification of the exchange integral between bonded copper ions. • DFT calculation for copper(II) halide compounds with the considered ligands were performed for a number of possible reactions. • Theoretical calculations demonstrate that thermodynamic stability of the complexes rises with the growth of a number of copper atoms and chloride bridges, but increasing water content has an opposite effect. The present article is devoted to the consideration of the interconversions of copper(II) chloride complexes with caffeine (caf) ([CuII 2 (μ 2 -Cl) 2 (caf) 2 (H 2 O) 2 ] (1), [CuII 3 (μ-Cl) 6 (caf)(H 2 O)] n (1a), [Cu 4 (μ 2 -Cl) 6 (μ 4 -O)(caf) 4 ] (1b) , 2[CuII(caf)Cl 2 ].0.25 THF (1c) , [CuII(caf) 2 Cl 2 ] (2)) , depending on the synthesis conditions, and to studies on the four-nuclear copper(II) bromide complex with acetamide (AcAm) ([Cu 4 (μ 2 -Br) 6 (μ 4 -O)(AcAm) 4 ] (3)). The results obtained have been confirmed by different methods (powder XRD, single crystal XRD analysis, IR-, ESI-MS-, EPR-spectroscopy, and magnetic properties studies). Two bromide ions in (3) are non-equivalent to the other four and this fact may result in the modification of the exchange integral between bonded copper ions. Single crystal XRD data have been compared with the results of DFT calculations. It has been found that the thermodynamic stability of the complexes grows with an increase in the number of copper atoms and bridging chloride ions and a decrease in the number of water molecules in the formula unit of the compound. The calculation results for complexes with acetamide are in a good correlation with those of caffeine and experimental data. [ABSTRACT FROM AUTHOR]

[Display omitted] • The first development of AgNO 3 -DCFS-STARCH colorimetric sensor for Cl− detection. • Self-volume-calibrating strategy to eliminate volume errors in colorimetry. • Application of deep learning algorithms for rapid determination of Cl− concentrations. • Visualization of CNN decision mechanism by class activation mapping algorithm. Chloride ions (Cl−) are widely present in nature, and accurate measurement of Cl− is of great significance for health management and water quality monitoring. Based on the principle of argentometry, where Ag+ react with Cl− in silver measurement to produce insoluble AgCl, we developed a colorimetric sensor composed of AgNO 3 , 2′,7′-dichlorofluorescein (DCFS) and starch, which is defined as ADS sensor. Cl− react with Ag+ in the ADS sensor to form positively charged AgCl colloids, which can adsorb negatively charged DCFS dyes and cause a color change in DCFS, thus providing sensing information about Cl− concentrations. To eliminate the error caused by the unfixed sample volume, a novel self-volume-calibrating strategy based on the unique shape of the sample holder was proposed. We further utilized deep learning (DL) algorithms to analyze data from 3,900 colorimetric images, enabling rapid determination of 1 × 10−5 to 7 × 10−2 mol/L Cl− with unfixed sample volumes. The Class Activation Mapping (CAM) algorithm was also used to visualize the decision-making mechanism of Convolutional Neural Network (CNN), verifying that the colorimetric regions and volume change regions of the sensor is the primary decision-making information for CNN. Compared with traditional method, this approach has the advantages of low cost, wide detection range, simple operation and rapid response. We envision that this method for Cl− detection can be used as an alternative and promising tool for the detection of a wider variety of analytes. [ABSTRACT FROM AUTHOR]

Steel structures often experience significant durability degradation over time due to extreme environments. To better understand the impact of chloride environments on the mechanical properties of steel compression members, accelerated corrosion tests were conducted on H-shaped steel short columns with applied current. Monotonic tensile tests were also performed on steel specimens, and axial compression tests were carried out on H-shaped steel short columns with varying degrees of corrosion. The results revealed that the corrosion rate increased with higher current intensity and longer electrification duration while changing with different chloride ion concentrations. As the corrosion rate increased, the steel material exhibited a linear decrease in yield strength, ultimate strength, and elastic modulus. Consequently, the mechanical properties of the H-shaped steel columns, such as stiffness, ductility coefficient, and load-bearing capacity, were adversely affected. Based on these findings, a predictive formula was proposed to estimate the ultimate load-bearing capacity of H-shaped steel columns with different degrees of corrosion in chloride salt environments. The experimental results were further validated through numerical simulations, and parameter analysis indicated a negative correlation between flange width-to-thickness ratio, web height-to-thickness ratio, and ultimate load-bearing capacity of H-shaped steel columns. Finally, a random corrosion pit generation algorithm is proposed, effectively simulating the actual corrosion pit distribution and calculating the ultimate bearing capacity of columns. • The deterioration model for mechanical properties with corrosion ratio and various parameters in accelerated corrosion tests, demonstrating a linear relationship. • Secondary development of Abaqus software using Python language to randomly generate corrosion pits on the surface of the model, making the numerical simulation results more accurate. • A random corrosion pit generation algorithm is proposed to simulate the actual corrosion pit distribution and obtain the ultimate bearing capacity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Studying the impact of iron addition on the corrosion resistance of the copper matrix, founding the corrosion resistance of Cu-Fe alloys would increase with the increase of Fe content in a trend of rising and then decreasing. • The primary iron phase of the copper-iron alloy in the cold drawn tensile state is gradually distributed with the increase of the iron content, which is beneficial to the formation of a dense oxide film surface of the copper-iron alloy in the chloride ion environment. • After salt spray corrosion, the surface corrosion products of the alloy are mainly based on the oxides of Cu, and with the increase of Fe content, the surface corrosion products of the alloy are mainly based on the chlorides and hydroxides of Fe. To assess the corrosion resistance of Cu-Fe deformation in situ alloys in a chloride ion environment, Cu-Fe alloys with varying Fe contents (5 wt%, 10 wt%, and 14 wt%) were prepared using vacuum induction melting, and the impact of Fe content on the corrosion resistance was examined. The corrosion morphology and corrosion products were analyzed, and the corrosion rate, corrosion period, dynamic potential polarization curves, electrochemical parameters, and electrochemical impedance spectra with different Fe contents were determined. However, the corrosion resistance of Cu-Fe alloys initially increased with an increase in Fe content before decreasing, with Cu-10 wt% Fe alloys (95% reduction rate) exhibiting the best corrosion resistance. As the Fe content increased, the amount of primary Fe phase gradually increased and became more densely distributed. This led to an increase in the dense oxide film on the surface, thereby enhancing the corrosion resistance of the material. Moreover, with a further increase in Fe, the primary Fe phase exhibited coarsening and non-uniform distribution. This resulted in the oxide film becoming looser, leading to a decreased corrosion resistance of the alloy. [ABSTRACT FROM AUTHOR]

Knowing the chloride ingress rate is crucial in predicting the service life of reinforced concrete in chlorine environment. While empirical diffusion model is available, fundamental knowledge of Cl− diffusion in calcium silicate hydrate (C-S-H) is largely lacking as it is experimentally challenging to prepare a bulk pure C-S-H. In this study, synthesized C-S-H powder was compacted to form pellets of controlled pore structure and Ca/Si. Effective diffusion coefficients of Cl− in these C-S-H matrixes were measured using steady-state natural diffusion and electric-migration tests, as a function of Ca/Si and porosity. Increased pore tortuosity significantly reduced diffusivity even when porosity remains nearly unchanged. The influence of pore-solution pH to Cl− diffusion is distinct between natural-diffusion and electric-migration. Our data provides the first direct measure of Cl− diffusion coefficient in pure C-S-H matrix, and new insights into the surface effect for diffusion in extremely small pores. [ABSTRACT FROM AUTHOR]

An Oscillating Water Column (OWC) power plant is typically a partially immersed concrete structure that generates energy by moving waves, forcing air to flow back and forth through the turbine to produce a consistent amount of energy. Due to the repeated air pressure application, chloride penetration can be accelerated in the OWC structure. However, long-term studies on chloride penetration monitoring are lacking. Therefore, the water-soluble chloride content of concrete subjected to repeated air pressures was measured after 108 months of the OWC structure. The results were analyzed, along with measurements taken 31 months after OWC completion. Concrete powder samples were collected from three areas: the bypass room, which was subjected to repeated air pressure; the tidal zone, which was subjected to alternate dry/wet conditions of seawater; and the splash zone in the offshore atmosphere. The collected samples were then titrated. Fick's 2nd law was used to derive diffusion coefficients. The experimental results indicated that the concrete in the bypass room had the highest water-soluble chloride content. Compared with the results obtained 31 months after completion, the water-soluble chloride content and diffusion coefficient decreased over time. This is attributed to the relatively small effect of air pressure and the clogging of pores owing to the accumulation of chloride ions on the surface. Comparing the measurements in 2017 and 2023, the splash zone exhibits the highest increase over time. This is attributed to the lower initial chloride penetration, which makes diffusion easier owing to the higher concentration differences compared to other locations. In the future, ensuring the reliability of the chloride penetration behavior in concrete subjected to repeated air pressures through periodic monitoring of the chloride content will be crucial. Additionally, research is needed to establish the crystallization and pore-clogging phenomena in concrete subjected to repeated air pressures through microstructural and chemical analyses. • The chloride content of concrete in ocean wave power plants was measured. • The effects of marine environment and repeated pressure have been analyzed. • The long-term behavior of the actual structure was analyzed. • The chloride content increased on the surface of the concrete in repeated pressure. • As the depth of concrete increases, the effect of repeated pressure decreases. [ABSTRACT FROM AUTHOR]

Recycled aggregate concrete (RAC), which is used in Northwest China, is inevitably subjected to various aggressive environments. However, the aggressive ions of chloride, sulfate, and magnesium and the original ions of calcium and hydroxide in RAC under the combined action of magnesium-sulfate-chloride attack and dry–wet (D&W) cycles have received little attention in previous studies. Therefore, in this study, the content of aggressive and original ions in exposed RAC was quantified, and the influence of the replacement ratio of supplementary cementitious materials (SCMs) on diffusion was investigated. Results showed that the contents of chloride, sulfate, and magnesium in exposed RAC increased with an increase in the replacement ratio of silica fume (SF) and metakaolin (MK). In contrast, the contents decreased with the increase in the replacement ratio of granulated blast furnace slag (GBFS). At the same exposure time and depth, the content of RAC with ternary cementitious materials from the highest to the lowest was in the order of cement–fly ash –SF, cement–fly ash–MK, and cement–fly ash–GBFS. Visual appearance, relative compressive strength, and the diffusion coefficient exhibited a similar change law. An exponential relationship was observed between the diffusion and time delay coefficients and the replacement ratio of SCMs, and the content of aggressive ions on the exposed surface decreased linearly with increasing exposure time. Diffusion models of aggressive ions were established to consider the multiple effects. Aggressive ion–original ion interaction influenced the mineral phases' composition in the corrosive zone and led to a difference in the diffusion process and depth. • Quantifying the content of aggressive and original ions in RAC exposed to MgSO4-Na2SO4-NaCl and D&W cycles. • Investigating the effects of the SCMs replacement ratio on the diffusion of RAC with ternary cementitious materials. • Establishing the models of diffusion coefficient on chloride, sulfate, and magnesium of the exposed RAC. • Discuss the diffusion mechanism under the reciprocal effect between the aggressive and original ions. [ABSTRACT FROM AUTHOR]

In the study of the durability of concrete structures, the chloride ion diffusion coefficient (D t) is a key parameter that directly affects the prediction of concrete's service life. This study aims to explore the relationship between the chloride ion diffusion coefficient in concrete and the "curing age (t ref)" and "exposure time (t)." By conducting long-term curing and seawater exposure experiments on three different mixes of high-performance concrete samples, we collected experimental data with a curing age of 3 years and a seawater exposure time of 4.5 years. Through in-depth analysis of these data, we found that there is a significant power function relationship between the chloride ion diffusion coefficient and exposure time, while the relationship with curing age is not significant. This finding suggests that in the derivation of the concrete chloride ion diffusion theory model, the time range of the definite integral of D t should be from 0 to t, rather than from t ref to t ref +t. Furthermore, we have validated the concrete life prediction model using actual data from the Swedish Marine Exposure Station, further confirming the accuracy and reliability of our research results. This study provides a more scientific and accurate theoretical basis for the durability assessment and service life prediction of concrete structures. • ClinConc and ChaDuraLife V1.0 differ in considering "curing age (t ref)" in chloride diffusion theory. • Concrete chloride ion diffusion coefficient relates to "exposure time (t)" via a power function. • In the chloride ion diffusion model, D t 's integral time range is 0∼t, not t ref ∼t ref +t. • ChaDuraLife V1.0 outperforms ClinConc in predicting concrete chloride ion diffusion. [ABSTRACT FROM AUTHOR]

• Adsorption kinetic and regeneration of polyacrylic and polystyrene resins are compared. • Low salt dosage cannot regenerate PFAS; high dosage causes salting out effect. • H 2 O 2 is effective in mitigating ClO 3 − and ClO 4 −, enhancing PFOA destruction/defluorination. • Methanol improved regeneration recovery but hindered PFAS electrochemical oxidation. • 1 % Na 2 SO 4 is a favorable brine/electrolyte for the integrated IX/EC process. This study proposes an integrated approach that combines ion-exchange (IX) and electrochemical technologies to tackle problems associated with PFAS contamination. Our investigation centers on evaluating the recovery and efficiency of IX/electrochemical systems in the presence of five different salts, spanning dosages from 0.1 % to 8 %. The outcomes reveal a slight superiority for NaCl within the regeneration system, with sulfate and bicarbonate also showing comparable efficacy. Notably, the introduction of chloride ion (Cl−) into the electrochemical system results in substantial generation of undesirable chlorate (ClO 3 −) and perchlorate (ClO 4 −) by-products, accounting for ∼18 % and ∼81 % of the consumed Cl−, respectively. Several agents, including H 2 O 2 , KI, and Na 2 S 2 O 3 , exhibited effective mitigation of ClO 3 − and ClO 4 − formation. However, only H 2 O 2 demonstrated a favorable influence on the degradation and defluorination of PFOA. The addition of 0.8 M H 2 O 2 resulted in the near-complete removal of ClO 3 − and ClO 4 −, accompanied by 1.3 and 2.2-fold enhancements in the degradation and defluorination of PFOA, respectively. Furthermore, a comparative analysis of different salts in the electrochemical system reveals that Cl− and OH− ions exhibit slower performance, possibly due to competitive interactions with PFOA on the anode's reactive sites. In contrast, sulfate and bicarbonate salts consistently demonstrate robust decomposition efficiencies. Despite the notable enhancement in IX regeneration efficacy facilitated by the presence of methanol, particularly for PFAS-specific resins, this enhancement comes at the cost of reduced electrochemical decomposition of all PFAS. The average decay rate ratio of all PFAS in the presence of 50 % methanol, compared to its absence, falls within the range of 0.11–0.39. In conclusion, the use of 1 % Na 2 SO 4 salt stands out as a favorable option for the integrated IX/electrochemical process. This choice not only eliminates the need to introduce an additional chemical (e.g., H 2 O 2) into the wastewater stream, but also ensures both satisfactory regeneration recovery and efficiency in the decomposition process through electrochemical treatment. [Display omitted] [ABSTRACT FROM AUTHOR]

Developing novel chloride-trapping inhibitors is of great significance for enhancing the durability of marine concrete structures. In this study, a novel LDHs-VB3- inhibitor was synthesized through the ion exchange method. Then, the corrosion inhibition mechanism of LDHs-VB3- inhibitor for rebar in the whole process of release - capture - adsorption - retardation was studied using experiments and density functional theory (DFT) simulations. The chloride ion exchange test demonstrates that the LDHs-VB3- inhibitor has a chloride trapping capacity of 35.5 mg/g in the saturated Ca(OH) 2 solution containing 0.14 M NaCl, implying that it could capture Cl- in concrete pore solution. According to the electrochemical tests, the critical chloride concentration of rebar in the simulated concrete solution containing LDHs-VB3- falls within a range of 0.22 M–0.28 M, which is much higher than that in the solution without LDHs-VB3- (0.10 M–0.14 M). DFT simulations indicate that LDHs-VB3- exhibits more positive binding energy and uneven binding forces in contrast to LDHs-Cl-. Consequently, VB3- could be easily replaced by Cl- and then released into the pore solution of concrete. Moreover, the released VB3- could adsorb on the α-Fe 2 O 3 surface in a concrete environment via the interaction of surface Fe atoms with N and O atoms of VB3-. The preadsorbed VB3- could diminish the interaction of Cl- with the α-Fe 2 O 3 surface by reducing electron transfer, thereby mitigating the risk of passive film breakdown and retarding the chloride-induced corrosion of rebars. [Display omitted] • A novel layered double hydroxides (LDHs) inhibitor of LDHs-VB3- was synthesized. • The anti-corrosion mechanism of LDHs-VB3- was studied by experiments and DFT. • The release–capture–adsorption–retardation behavior of LDHs-VB3- was revealed. • The presence of VB3- reduces the electron transfer between α-Fe 2 O 3 surface and Cl−. [ABSTRACT FROM AUTHOR]

Local hydrogen entry under a NaCl droplet on Fe sheets was analysed by employing a hydrogenochromic sensor and electrochemical hydrogen permeation tests. Large crystallographic pits barely promoted hydrogen entry, because crystallographic pitting proceeded at potentials higher than the potential of the hydrogen evolution reaction. Hydrogen entry was accelerated because of acidification under an island-like rust layer. The rust layer became thick in its outer regions, mainly owing to severe corrosion and alkalisation around the rust-formed area. Hydrogen entry was prominent under the thick rust layer after disappearance of the droplet, owing to the high concentrations of chloride ions and protons. • Crystallographic pitting proceeded at potentials higher than the potential of the HER. • Acidification mainly contributed to accelerating hydrogen entry on the corroded area. • Hydrogen entry under the thick rust layer was greater than under the thin rust layer. [ABSTRACT FROM AUTHOR]

[Display omitted] • 15 %Ag 2 CO 3 /TiO 2 /SiC (ATS-15) photodegraded 95.87 % tetracycline (TC) in 30 min. • ATS-15 maintains high TC degradation rates among pH 3 to 9 and in natural water. • The generated AgCl combines with ATS-15 to enhance photoactivity. • Dual Z-scheme charge transfer and SiC surface oxidation enhance catalytic activity. The increasing issue of antibiotic contamination in water has sparked significant interest in seeking effective solutions. In this research, a dual Z-scheme ternary photocatalyst Ag 2 CO 3 /TiO 2 /SiC (ATS) was synthesized by a mechanochemical-coprecipitation method. The experimental results demonstrated that the 15 %Ag 2 CO 3 /TiO 2 /SiC (ATS-15) reached a remarkable tetracycline (TC) degradation efficiency of 95.87 % (k = 0.1063 min−1) after a 30 min exposure to visible light, which was 46.22 and 13.63 times more effective than SiC (k = 0.0023 min−1) and TiO 2 /SiC (k = 0.0078 min−1), respectively. The synergistic effect of ATS ternary structure to promote Si electron transfer and SiC surface oxidation. The photocatalytic performance of ATS-15 was greatly enhanced due to the synergistic effect of Cl− and CO 3 •−, achieving 95 % of TC degradation within 5 min. In the ATS-15 system, Cl− converts a portion of Ag 2 CO 3 into AgCl and establishes a quaternary electron transfer scheme with ATS-15, thereby enhancing the performance of the photocatalyst. ATS-15 photocatalyst can maintain TC degradation rate above 90 % among pH 3 to 9. The ATS-15 system also exhibits excellent adaptability to various water environment, achieving 94.01 % TC degradation rate in natural river water, with only a 1 % reduction. A novel treatment scheme for antibiotic pollution in a complex water environment was proposed by ATS-15 photocatalyst with high pH stability and water applicability. [ABSTRACT FROM AUTHOR]

[Display omitted] • DFT calculations and experiments are combined to tunne cation types of LDHs. • CaAl-LDH has highest Cl- adsorption capacity, aligned with lowest binding energy. • CaAl-NO 3 -LDH transforms into Friedel's salt after reacted with Cl- • ZnAl-LDH retains the most Cl- after addition of SO 4 2- with crystallinity improved. • Divalent cations dominate LDHs' interlayer spacing and binding energy in some cases. Layered double hydroxides (LDHs) are new concrete additives that improve Cl- sorption capacity by varying their chemical composition. In this work, first-principles calculations were used to design the chemical compositions of LDHs with various cations. Accordingly, four cation types of LDHs (CaAl, MgAl, MgFe and ZnAl) were selected to be synthesized, their Cl- sorption kinetics were further measured. The objective was to establish a high-throughput screening approach to identifying the most promising cations for enhancing the sorption capacity of LDHs towards Cl-. Results revealed that the absolute value of Cl- binding energy increased as the interplanar spacing of different LDHs decreased from first-principles calculations. Particularly, CaAl exhibited the highest adsorption capacity for Cl- (3.25 mmol/g) from experiments, validating the simulation results that it has the highest absolute value of Cl- binding energy. MgFe-Cl-LDH has the smallest absolute value of Cl- binding energy with the lowest adsorption capacity for Cl- as well as the crystallinity. Moreover, multiple factors influencing the Cl- sorption ability of LDHs, such as chemical composition, crystallinity, microstructures and their synergistic effects, are discussed thoroughly based on the experimental results. This study established a connection between the simulation and experimental approaches in understanding the mechanism of Cl- adsorption. [ABSTRACT FROM AUTHOR]

The rapid development of marine concrete structures and the sharp shortage of freshwater resources contribute to the wide investigation of seawater-mixed ultra-high-performance concrete (SWUHPC). However, few studies have investigated the chloride ions (Cl-) binding mechanism of SWUHPC. Herein, the chloride binding experiments and molecular dynamics (MD) simulation were carried out to reveal the physically and chemically bound Cl- mechanisms of SWUHPC. The results of the experiments clearly demonstrate that the addition of silica fume (SF) led to a significant decrease in the capacity of Cl- binding. Conversely, the incorporation of metakaolin (MK) resulted in a marked increase in the content of chemically bound Cl-. Furthermore, it is revealed through MD simulations that the amount of physically bound Cl- heavily depends on the Ca/Si ratio of C-S-H. A higher Ca/Si ratio results in a stronger electrostatic effect of the C-S-H surface on Cl-, which increases the physical binding of Cl- via Ca-Cl bonds. In addition, it is found that Al[6] and Ca in the interlayer region of C-A-S-H formed the main structure layer (Ca 4 Al 2 (OH) 12 2+) of Friedel's salt, and then chemically adsorbed Cl- in the pore solution. These findings provide novel nanoscale insights regarding the physically and chemically bound Cl- mechanisms of SWUHPC. • SF reduced the Cl- binding while MK improved the chemically bound Cl- of SWUHPC. • The higher the Ca/Si, the more Ca-Cl bonds are formed to physically adsorb Cl-. • Al [6] and Ca of C-A-S-H formed the main structure layer of Friedel's salt. [ABSTRACT FROM AUTHOR]

Developing corrosion-resistant oxygen evolution electrocatalysts that can sustain seawater electrolysis is crucial but challenging for hydrogen production. Herein, we develop a bimetallic oxyhydroxide electrocatalyst with self-derived selenate space charge layer (SeO 4 2− SCL) by in-situ electrochemically reconstructing cobalt-doped nickel diselenide (Co-NiSe 2) pre-catalyst, enabling long-term stability for seawater electrolysis. In-situ experiments and theoretical results reveal the promoting effect of cobalt-doping on the reconstruction of NiSe 2 and generation of dynamically stable oxygen vacancy sites. Importantly, the SeO 4 2− SCL derived from the reconstruction process shows a dynamic anti-corrosion behavior, thus protecting metal species from dissolution and meanwhile without blocking the diffusion and adsorption of reactive species. Consequently, a two-electrode cell assembled by this Co-NiSe 2 pre-catalyst as an anode, reaches an industrial current density (500 mA cm−2) at a cell voltage of 1.70 V, and that works stably for over 1500 h in alkaline seawater, which is of significance for promoting the practicality of low-cost catalysts. We develop a bimetallic oxyhydroxide electrocatalyst with a self-derived selenate space charge layer by in-situ electrochemically reconstructing a doping-engineered diselenide pre-catalyst, which can prevent chloride ions from approaching the dynamically generated active sites, thus achieving an ultralong operating stability (1500 h) at an industrial current density (500 mA cm−2) in real alkaline seawater splitting. [Display omitted] • A Co-doped NiOOH electrocatalyst with a space charge layer was in-situ formed. • The space charge layer shows an anti-corrosion behavior for seawater electrolysis. • The electrocatalyst works stably for over 1500 h at an industrial current density. [ABSTRACT FROM AUTHOR]

Electrolysis of seawater is a promising approach to address freshwater scarcity and indirectly mitigate the energy crisis. In this context, the oxygen evolution reaction (OER) plays a crucial role as one of the half−reactions in water electrolysis. However, the development of cost−effective non−precious metal catalysts for OER remains a challenging issue. In this study, we present a facile method for synthesizing Prussian blue sulfides supported on nickel foam (NF) at ambient temperature. The resulting S−FeNi@NF catalyst demonstrates remarkable electrocatalytic performance with an overpotential of only 330 mV at a current density of 100 mA cm⁻² in simulated seawater. Notably, the catalyst exhibits excellent corrosion resistance and electrochemical stability, maintaining its effectiveness for over 120 h following vulcanization. Furthermore, we assessed the catalysts for their resistance to chloride ion corrosion in natural seawater and observed no significant signs of etching for more than 30 days. This outstanding stability of the S−FeNi@NF material can be attributed to its dual protective mechanisms against chloride ions, which encompass both corrosion resistance and the repulsion of chloride ions during electrochemical processes. Our findings offer a fresh perspective on catalyst design, particularly in the context of shielding against chloride−induced degradation in direct seawater electrolysis. • The negatively charged surface of the vulcanised catalyst effectively resists chloride etching. • No visible structural damage after 30 days of immersion in natural seawater. • In situ growth of PBA materials on NF effectively enhances conductivity and facilitates the four-electron transfer process. • The self-supporting electrocatalysts derived from PBA exhibit dual resistance to the effects of chloride ions. [ABSTRACT FROM AUTHOR]

In this paper, a new approach of bidirectional electro-migration rehabilitation (BIEM) using pulse currents was proposed. The effect of the duty cycle and frequency of the square wave pulse current on the BIEM was investigated. The results showed that the desalination efficiency was improved by 10 % with the decrease of duty ratio and frequency. Furthermore, With the increase of duty ratio and frequency, the hydrogen permeation of steel bars decreased by 28.5 %. More uniform desalination efficiency was obtained by using pulse current. The half-cell potential of the rebars was also measured and it was higher for the samples using pulse currents than for those using direct currents, indicating a lower risk of corrosion after pulse current treatment. The pH value of the concrete also increased during the BIEM process. • The amount of hydrogen permeation in the rebars of concrete repaired by pulse current is reduced. • Increasing frequency and decreasing duty cycle of pulse current make the desalination efficiency distributed more evenly. • Decreasing frequency and duty cycle of pulse current will increase the efficiency of chloride ions removal. [ABSTRACT FROM AUTHOR]

Inspired by the easy chemical binding of chloride ions with aluminum, dredged sludge (DS) has the potential to be used in cement to reduce the adverse effects of seawater mixing and accelerate its hardening. Herein, a detailed investigation into the fresh properties, hydration behavior and chloride binding of seawater-mixed sintered sludge cement (SSSC) paste is carried out utilizing methods such as Vicat apparatus, jumping table test, isothermal calorimetry, the bellows technique, SEM, MIP, DTG, ion chromatography and thermodynamic simulation. The research reveals that calcination at 800 ℃ promotes the thermodynamic decomposition of Clinochlore, Calcite and Muscovite in DS, with amorphous phase content ranging from 9.3% to 47.2% and mainly composed of activated alumina. Compared to fresh water mixing, the initial and final setting times of SSSC paste shortens by up to 12.1% and 10.9%, respectively. Meanwhile, the addition of sintered sludge ash (SSA) results in an accelerated onset of autogenous shrinkage in the cement paste, with the degree and pace of shrinkage rising of up to 29.7% and 110.9%, respectively. Amorphous alumina released by SSA facilitates the re-dissolution of aluminate clinker and expedites the formation of AFm phases when mixed with seawater, especially Friedel's salt. Comparatively, seawater mixing results in lower Portlandite content, heightened autogenous shrinkage, and increased cumulative heat release, suggesting a pronounced improvement in the pozzolanic activity of SSA. Moreover, the concentration of leached chloride ions shows a gradual decrease with the rising addition of SSA, which is attributable to the chemical binding of Friedel's salt and physical adsorption due to increased pore tortuosity. [Display omitted] ● The calcination at 800 °C increases the amorphous phase in DS from 9.3% to 47.2%, with Al 2 O 3 as the main component. ● The redissolution of aluminate clinker and the accelerated formation of AFm caused by seawater are retained in SSSC paste. ● The larger reaction rate constants in SSSC paste explain the increase in autogenous shrinkage and hydration heat. ● The increase in Friedel's salt and pore tortuosity reduces the chloride ion leaching concentration of SSSC paste. [ABSTRACT FROM AUTHOR]

Porous surfaces are a common modified surface used to enhance boiling heat transfer. In this paper, a method for preparing gradient porous surfaces is presented, that is, magnetic stirring is added to the electrolyte and the cathode surface to be deposited is placed vertically downward. Within the Cl ion concentration range of 30–140 mg/L, increasing the Cl ion concentration results in lager pore sizes. When the Cl concentration was greater than 120 mg/L, the average pore size of the surface gradually increased from the center to the edge, and the number of pores gradually decreased from the center to the edge. All surfaces showed superhydrophilicity. The critical heat flux of Sample#3 is 158.72 W/cm2, which is 67% higher than the smooth surface. The wall superheat of Sample#3 was only 15 °C in the critical state. This porous surface has plenty of nucleation sites. These nucleation sites are gradually activated when the heat flux increases. At low heat fluxes, heat transfer on these porous surfaces presents a disadvantage because the nucleation sites are not fully activated. At high heat fluxes, these porous surfaces show a decrease in wall temperature. Consequently, the porous surface prepared in this paper has good boiling heat transfer at high heat flux. [Display omitted] • An inverted deposition method was designed to prepare gradient porous surfaces. • The gradient porous surface is superhydrophilic and provides a large number of nucleation sites. • An appropriate increase in Cl-ion concentration increases the pore size and pore wall thickness. [ABSTRACT FROM AUTHOR]

• Chloride diffusion was investigated by a combination of experiments and simulations. • Sodium D-gluconate concentration affected the potential of wire beam electrodes. • A new non-destructive method obtained localized chloride concentrations in concrete. The effects of various concentrations of sodium D-gluconate (SD) on chloride ion diffusion in concrete were investigated using both the wire beam electrode (WBE) technique and the finite element method. WBEs were encapsulated within concrete and immersed in a 3.75 mol/L NaCl solution which contained either 0.0461 mol/L or 0.0152 mol/L SD. Observations indicated that the passive film on the part of WBEs was destroyed by chloride ions on the 14th day, with the surface potential falling below −0.47 V SCE. Furthermore, the number of active corrosion electrodes was less at 0.0461 mol/L SD than at 0.0152 mol/L SD. Simulated chloride ion concentrations on WBEs were in agreement with the experimentally obtained values, demonstrating the viability of WBEs as non-destructive tools for assessing chloride ion concentrations in concrete. [ABSTRACT FROM AUTHOR]

• The effect of anions is determined by their affinity to Al3+, concentration and pH. • Chloride ions had no significant effect on coagulation. • Sulphate decreases Al floc size, with higher SO 4 − concentration giving a greater reduction. • Low phosphate dosage promotes floc growth, while excessive dose inhibits coagulation. • Anions affect primary particle size/crystallinity by participating in hydrolysis. Coagulation efficiency is heavily contingent upon a profound comprehension of the underlying mechanisms, facilitated by the evolution of coagulation theory. However, the role of anions, prevalent components in raw and wastewaters, has been relatively overlooked in this context. To address this gap, this study has investigated the impact of three common anions (i.e., chloride, sulfate, and phosphate) on Al-based coagulation. The results have shown that the influence of anions on coagulation depends predominantly on their ability to compete with hydroxyl groups throughout the entire coagulation process, encompassing hydrolysis, aggregation, and the growth of large flocs. Moreover, this competition is subject to the dual influence of both anion concentration and hydroxyl concentration (i.e., pH). The results have revealed the intricate interplay between anions and coagulants, their impact on floc structure, and their importance in optimizing coagulation efficiency and ensuring the production of high-quality water. [Display omitted] [ABSTRACT FROM AUTHOR]

Eriocheir sinensis megalopa has a special life history of migrating from seawater to freshwater. In order to investigate how the megalopa adapt themselves to the freshwater environment, we designed an experiment to reduce the salinity of water from 30 ppt to 0 at rates of 30 ppt, 15 ppt, 10 ppt, and 5 ppt per 24 h to evaluate the effects of different degrees of hyposaline stress on the osmotic regulation ability and antioxidant system of the megalopa. Experimental results related to osmotic pressure regulation show that the gill tissue of megalopa in the treatment group of 30 ppt/24 h rapid reduction of salinity was damaged, while in the treatment group of 5 ppt/24 h it was intact. At the same time, the experiment also found that in each treatment group with different salinity reduction rates, compared with the control salinity, the NKA activity of megalopa increased significantly after the salinity was reduced to 20 ppt (p < 0.05). In addition, two genes involved in chloride ion transmembrane absorption have different expression patterns in the treatment groups with different salinity reduction rates. Among them, Clcn2 was significantly highly expressed only in the rapid salinity reduction intervals of 30 ppt/24 h and 15 ppt/24 h (p < 0.05). Slc26a6 was significantly highly expressed only in the slow salinity reduction intervals of 10 ppt/24 h and 5 ppt/24 h (p < 0.05). On the other hand, the results of antioxidant and apoptosis related experiments showed that in all treatment groups with different rates of salinity reduction, the activities of T-AOC, GSH-PX, and CAT basically increased significantly after salinity reduction compared to the control salinity. Moreover, the activities of T-AOC and CAT were significantly higher in the 10 ppt/24 h and 5 ppt/24 h treatment groups than in the 30 ppt/24 h and 15 ppt/24 h treatment groups. Finally, the experimental results related to apoptosis showed that the expression trends of Capase3 and Bax-2 were basically the same in the treatment groups with different salinity reduction rates, and their expressions were significantly higher in the 10 ppt/24 h and 5 ppt/24 h treatment groups than in the 30 ppt/24 h and 15 ppt/24 h treatment groups. In summary, the present study found that megalopa had strong hyposaline tolerance and were able to regulate osmolality at different rates of salinity reduction, but the antioxidant capacity differed significantly between treatment groups, with rapid salinity reduction leading to oxidative damage in the anterior gills and reduced antioxidant enzyme activity and apoptosis levels. [Display omitted] • When the environmental salinity decreases rapidly, tissue damage occurs in the anterior gills of E. sinensis megalopa • When the salinity is lower than 20 ppt, E. sinensis megalopa begin to actively absorb inorganic ions • When the environmental salinity slowly decreases, the antioxidant capacity and apoptosis levels of E. sinensis megalopa are higher. [ABSTRACT FROM AUTHOR]

Different salt types have different effects on the liquid water content of saline soil, resulting in differences in the physico-mechanical properties and water/salt migration process of saline soil. In order to investigate the phase transition process and the change of the liquid water content in composite saline soil, saline soils with the same total salt content and different ratios of sodium chloride and sodium sulfate were taken as the objects. The results indicated that two phase transitions occur in the saline soil with single salt type, while three phase transitions can be found in the composite saline soil with two salt types. Mirabilite crystallization contributes to the 1st phase transition, mirabilite and ice precipitate together in the 2nd phase transition process, and mirabilite, ice, and hydrohalite precipitate simultaneously in the 3rd phase transition process. The liquid water is reduced in the phase transition process during cooling, and the pore characteristic has been changed significantly. The change of the liquid water content reflects the processes of salt crystallization and ice formation in saline soil, then the amounts of ice and hydrated salt were calculated at different temperatures, and the mechanism of inhibiting the deformation of sulfate saline soil was examined by adding sodium chloride. The results have reference value for those seeking understanding of the deformation in natural composite saline soil, and these findings can provide theoretical basis for the phase transition mechanism of saline soil in cold regions. • Three phase transition process exist in composite saline soil with two salt types. • Ice and salt crystallization decrease the liquid water content of saline soil. • Chloride ion mitigates the saline soil deformation by reducing the freezing point. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bimetallic phosphides were directly grown on Cu(OH) 2 nanotubes by electrodeposition method. • Cu(OH) 2 nanotubes were used as a conductive interface and structure guide. • The synergistic effect of the core and shell improved the characteristics of the fabricated sensor. • CuCoP@Cu(OH) 2 was used as a non-enzymatic glucose sensor with high electrocatalytic activity. • The designed sensor was investigated for glucose measurement in physiological and beverage samples. The direct growth of transition metal phosphides with a highly accessible surfaces and copper electroactive centers can be considered as an efficient method to modify the electrode surface and use them as an electrochemical sensor. Herein, a direct, efficient, low-cost and rapid method is used for growing core–shell nanostructures of CuCoP nanosheets on Cu(OH) 2 nanotubes (pre-deposited on glassy carbon electrode). The Cu(OH) 2 nanotubes act as a conductive intermediate and directing agent to obtain CuCoP@Cu(OH) 2 core–shell structure. The growth of CuCoP on Cu(OH) 2 nanotubes provides structural stability and large surface area as well as increases the availability of the catalytic sites for diffusion of analyte species and electrolyte ions into the electrode surface, leading to excellent electrocatalytic performance towards glucose electro-oxidation. The amperometric studies of glucose for electrode modified with CuCoP@Cu(OH) 2 showed two linear ranges of 0.001 mM to 0.105 mM and 0.105 mM to 2.530 mM with very high sensitivities of 8351 and 3932 μA/mM.cm2, respectively. Also, the fabricated sensing platform exhibited excellent selectivity and resistance to chloride ion poisoning, good reproducibility and repeatability, as well as low detection limit of 2.3 μM. In addition, the modified electrode showed a very quick reaction time of 2 s. Finally, to assess the usability of the designed non-enzymatic sensor in practical applications, the as-prepared nanocomposite was examined for measuring the glucose content in biological samples such as human blood serum, saliva, and beverage samples. The outcomes showed that the designed platform can be used as a reliable and efficient sensor for accurate detection and measurement of glucose in real samples. [ABSTRACT FROM AUTHOR]

In industrial applications, components made by Nickel-aluminum bronze (NAB) alloys are commonly encountered by fretting corrosion. This study aims to investigate the effect of seawater salinity on fretting corrosion behavior of the material. Research indicates that due to the synergistic effect of wear and corrosion, both the friction force and wear volume reach the peak value under the salinity of 3.5%. The reduction in wear observed when the salinity increases from 3.5% to 7.5% can be attributed to the hydrolysis of water-soluble CuCl 2 to produce Cu 2 O, which reduces the corrosion degree and provides a lubrication effect. Furthermore, the combination of chloride ions and aluminum leads to the formation of an AlCl 3 passivation layer, which serves to protect the alloy surface. [ABSTRACT FROM AUTHOR]

This paper explored the penetration of chloride into concrete damaged by high-cycle compressive fatigue loading. Two environmental conditions including immersion and wetting-drying cycles were prepared for experimentally investigating the transport performance of chloride in fatigue-damaged concrete. Additionally, a prediction model was developed with the damage index of residual strain. Test results revealed that both apparent diffusion coefficients and contents of chloride at each depth increased in fatigue-damaged concrete, indicating that the fatigue damage significantly degraded the resistance of concrete to chloride penetration. Furthermore, for fatigue damaged concretes with extremely different fatigue cycles and load levels but the same residual strain, the chloride ion content profiles were highly overlapped, which demonstrated the reasonability of selecting residual strains as fatigue damage indexes. The applicability of the transport model was firstly validated with the measured chloride contents and then the chloride transport behavior in gradient fatigue-damaged concrete was investigated numerically using the validated model. The numerical results indicated that the chloride transport was more sensitive to the residual strain at the exposed edge than to the residual curvature and the effect of the later can be neglected. • Fatigue loading definitely accelerate the penetration of chloride ions into concrete. • Transport model of chloride was developed in terms of the residual strain. • The rates of chloride transports were more sensitive to the residual strain at the exposed edge. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) as a novel and green nanomaterial exhibit a promising application in enhancing the chloride binding capacity of cement to extend the service life of reinforced concrete (RC) structures. However, their size influence on the enhancement of chloride binding is still a research gap, enormously hindering the further employment of CDs toward cement system. Herein, their size-induced effect on chloride binding actions of cement is comprehensively unveiled using CDs with various sizes for the first time. Specifically, three kinds of CDs with different sizes are controllably prepared through simply altering the calcinating time of citric acid. And the relationship between sizes of CDs and chloride binding capacity of cement is confirmed through the equilibrium tests. More importantly, the mechanism for the effect of CDs sizes on chloride binding is reasonably proposed according to the alteration analyses of phase compositions. The consequences demonstrate that the chloride binding capacity in cement modified by CDs with average sizes of 1.73, 5.79, and 12.37 nm increases by 41%, 20%, and 14% respectively, compared with that of the blank group after 28-d immersion in 3 mol/L NaCl solution. This testifies that the chloride binding capacity of CDs-incorporated cement is negatively correlative with CDs sizes. The related mechanism is that CDs with smaller sizes can provide more nucleation sites to promote cement hydration, further advancing the production of C–S–H gels and monosulfate (Ms), thus more markedly enhancing the physical adsorption and chemical binding of chloride ions in cement pastes. This work would guide the preparation of CDs with more suitable sizes to improve the chloride binding ability of cement, thus anticipated to extend the service life of RC structures in coastal environment, ultimately reducing the CO 2 emission from cement industry. [Display omitted] • CDs with different sizes are controllably synthesized only changing the calcinating time of citric acid. • Size-induced influence of CDs on chloride binding performance of cement is firstly unveiled. • Effect mechanism of CDs sizes on chloride binding behavior of cement is revealed. [ABSTRACT FROM AUTHOR]

Considering the widespread application of carbon fibre-reinforced polymer (CFRP) as a protective material for reinforced concrete (RC) structures, this study focuses on the ability of CFRP laminates with different numbers of layers bonded to the concrete surface to reduce the ingress of chloride ions. Variations in the free chloride concentration distribution in concrete before and after CFRP bonding were explored systematically. Nonlinear fitting was applied to the experimental data to establish a calculation model for the diffusion of free chloride ions in concrete with CFRP bonded to the surface, which was subsequently validated. Based on the proposed model, the reduction in the surface chloride concentration of concrete after bonding different numbers of CFRP layers was quantified as the reduction value. Moreover, recommendations for the durable design of RC structures bonded with CFRP in wet-dry cyclic environments are provided. The results indicate that the surface chloride concentration in concrete increases continuously with increasing wet-dry cycles, eventually reaching a steady state. Compared with the concrete specimens without CFRP bonding, the bonding of one, two, or three layers of CFRP led to reductions in the stable surface chloride concentration of concrete by 70.8%, 82.6%, and 84.9%, respectively. And no obvious convection zone was observed in the concrete after CFRP bonding. The validation results of the proposed calculation model demonstrated its high accuracy, making it suitable for durable design and service life prediction. • Experimental tests address the impacts of concrete bonded CFRP with different layers under dry-wet cycles on chloride ions resistance performance. • A chloride ion diffusion concentration model of concrete bonded with CFRP was established. • The anti-chloride ion penetration effect of bonding 1, 2, and 3 layers of CFRP was quantified. [ABSTRACT FROM AUTHOR]