Adsorption Of Chloride Ions Research Articles

Chloride Ion Adsorption Enables Ampere-Level CO2 Electroreduction over Silver Hollow Fiber.

Electrochemical conversion of CO2 into valuable feedstocks is a promising strategy for carbon neutrality. However, it remains a challenge to possess a large current density, a high faradaic efficiency and excellent stability for practical applications of CO2 utilization. Herein, we report a facile tactic that enables exceedingly efficient CO2 electroreduction to CO by virtue of low-coordination chloride ion (Cl- ) adsorption on a silver hollow fiber (Ag HF) electrode. A CO faradaic efficiency of 92.3 % at a current density of one ampere per square centimeter (1 A cm-2 ) in 3.0 M KCl with a sustained performance observed during a 150-hour test was achieved, which is better than state-of-the-art electrocatalysts. The electrochemical results and density functional theory (DFT) calculations suggested a low-coordination Cl- adsorption on surface of Ag HF, which not only suppressed the competitive hydrogen evolution reaction (HER), but also facilitated the CO2 reduction kinetics.

Chloride Ion Adsorption Enables Ampere‐Level CO 2 Electroreduction over Silver Hollow Fiber

Electrochemical conversion of CO2 into valuable feedstocks is a promising strategy for carbon neutrality. However, it remains a challenge to possess a large current density, a high faradaic efficiency and excellent stability for practical applications of CO2 utilization. Herein, we report a facile tactic that enables exceedingly efficient CO2 electroreduction to CO by virtue of low-coordination chloride ion (Cl−) adsorption on a silver hollow fiber (Ag HF) electrode. A CO faradaic efficiency of 92.3 % at a current density of one ampere per square centimeter (1 A cm−2) in 3.0 M KCl with a sustained performance observed during a 150-hour test was achieved, which is better than state-of-the-art electrocatalysts. The electrochemical results and density functional theory (DFT) calculations suggested a low-coordination Cl− adsorption on surface of Ag HF, which not only suppressed the competitive hydrogen evolution reaction (HER), but also facilitated the CO2 reduction kinetics.

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

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

Breaking of Odd Chirality in Magnetoelectrodeposition

Electrodeposition under magnetic fields (magnetoelectrodeposition; MED) can induce surface chirality on copper films. The chiral signs of MED films should depend on the magnetic field polarity; namely, the reversal of the magnetic field causes the opposite chiral sign. This represents odd chirality for the magnetic field polarity. However, odd chirality was broken in several MED conditions. This paper makes a survey of breaking of odd chirality in the MED conditions such as low magnetic fields, specific adsorption of chloride ions, micro-electrode, and cell rotation. These results indicate that the ordered fluctuation of magnetohydrodynamic micro-vortices induces the breaking of odd chirality and that the random fluctuation results in the disappearance of surface chirality.

Investigation of the process of desalination of the concentrate of reverse osmosis plants by energy waste

PURPOSE. To investigate the cleaning process of the reverse osmosis water filtration system (ROWFS) concentrate with energy waste, to obtain and determine its quality indicators, to study the mechanism of sulfate and chloride ions adsorption by sorption material on the basis of energy waste, to consider the process of sulfate and chloride ion adsorption by this sorption material under static and dynamic conditions.METHODS. The method of variable weights was used to determine the adsorption capacity of the sorption material. Methods of titrimetric and photocolorimetric analysis were used during determining of water quality indicators.RESULTS. In this paper the technology of desalination of the ROP concentrate by the adsorption method was studied. Under static conditions the adsorption isotherm has been constructed. On the basis of ground sludge the granular sorption material has been developed. The possibility of using ionexchange filters with granular loading has been considered, the adsorption curve under dynamic conditions has been constructed.CONCLUSION. The sorption based on energy waste - carbonate sludge material for the purification of ROWFS concentrate has been developed. Adsorption isotherms of sulfate and chloride ions were constructed on the basis of experimental data. For investigation the purification of the ROWFS concentrate under dynamic conditions the granular sorption material was obtained. The adsorption technology of ROWFS concentrate purification from sulfate and chloride ions by energy waste is presented.

Study on a Hydrogel for Adsorption of Chloride Ions in Cementitious Materials.

Chloride ions in the seaside environment can corrode the steel reinforcement in concrete, which greatly endangers the safety of seaside structures. As an excellent adsorption material, hydrogel is widely used in the field of water treatment but is rarely used in cementitious materials. In this study, a polyacrylamide–chitosan hydrogel (PAMC) was prepared with N,N-methylenebisacrylamide as the cross-linking agent and acrylamide as the monomer. The prepared PAMC gel could effectively adsorb chloride ions in simulated seawater and simulated sea sand environments, and the maximum adsorption capacity of chloride ions by PAMC-1 (prepared from 2.5 g acrylamide and 1% content of N,N-methylenebisacrylamide relative to acrylamide) gels in simulated seawater was 55.53 mg/g. The adsorption behavior of the PAMC gels in solution fit the Langmuir isotherm model. The composition and morphology of the PAMC gel were characterized, and the responsiveness of the PAMC gel to the environment was studied. The results showed that the PAMC gels adsorbed better in alkaline environments and thus could be used in alkaline cement-based environments. The mortar sample containing the PAMC-1 gel had higher resistance to chloride ion penetration, and the chloride ion content at 7.5–10mm from the surface of the sample cured for 28 days was reduced by 41.4% compared to the samples without the gel.

Large-Scale Synthesis of Spinel Nix Mn3-x O4 Solid Solution Immobilized with Iridium Single Atoms for Efficient Alkaline Seawater Electrolysis.

Seawater electrolysis not only affords a promising approach to produce clean hydrogen fuel but also alleviates the bottleneck of freshwater feeds. Here, a novel strategy for large‐scale preparing spinel NixMn3‐xO4 solid solution immobilized with iridium single‐atoms (Ir‐SAs) is developed by the sol–gel method. Benefitting from the surface‐exposed Ir‐SAs, Ir1/Ni1.6Mn1.4O4 reveals boosted oxygen evolution reaction (OER) performance, achieving overpotentials of 330 and 350 mV at current densities of 100 and 200 mA cm–2 in alkaline seawater. Moreover, only a cell voltage of 1.50 V is required to reach 500 mA cm–2 with assembled Ir1/Ni1.6Mn1.4O4‖Pt/C electrode pair under the industrial operating condition. The experimental characterizations and theoretical calculations highlight the effect of Ir‐SAs on improving the intrinsic OER activity and facilitating surface charge transfer kinetics, and evidence the energetically stabilized *OOH and the destabilized chloride ion adsorption in Ir1/Ni1.6Mn1.4O4. This work demonstrates an effective method to produce efficient alkaline seawater electrocatalyst massively.

How Temperature Rise Can Induce Phase Separation in Aqueous Biphasic Solutions

Ionic-liquid-based acidic aqueous biphasic solutions (AcABSs) recently offered a breakthrough in the field of metal recycling. The particular mixture of tributyltetradecylphosphonium chloride ([P4,4,4,14]Cl), acid, and water presents the unusual characteristic of a lower solution critical temperature (LCST), leading to phase separation upon a temperature rise of typically a few tens of degrees. We address here the microscopic mechanisms driving the phase separation. Using small-angle neutron scattering, we characterized the spherical micelle formation in a binary ionic liquid/water solution and the micelle aggregation upon the addition of acid due to the screening of electrostatic repulsion. The increase in both the acid concentration and the temperature eventually leads to micelle flocculation and phase separation. This last step is achieved through chloride ion adsorption at the surface of the micelle. This exothermic adsorption compensates for the entropic cost, leading to a counterintuitive behavior, and may be generalized to a number of molecular systems with an LCST.

Synthesis and characterization of layered double hydroxides hybrid microcapsules for anticorrosion via self-healing and chloride ion adsorption

Self-healing and corrosion resistance microcapsule (S/CMC) was fabricated by solvent evaporation method with tung oil (TO) as core, layered double hydroxides (LDH) as corrosion inhibitor and ethyl cellulose (EC) as wall. The average particle size of microcapsule increased with the increase of LDH content when LDH was less than 20 wt%. LDH component was present in the wall of S/CMC by surface loading, the chlorine adsorption performance of microcapsule in neutral environment was superior to that in alkaline environment. LDH was hybridized in EC to form stable wall structure. The LDH embedded in hybrid wall captured chloride ion by surface adsorption and ion exchange to improve the corrosion resistance of steel bar. This study provides a solution for the compatibility of anti-corrosion and self-healing technology, and provides a new perspective for the anti-corrosion application of microcapsule.

Use of catalytic wet air oxidation (CWAO) for pretreatment of high-salinity high-organic wastewater

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 LaFe1-xRuxO3-δ in CWAO treatment of chlorine ion wastewater was examined. Especially, LaFe0.85Ru0.15O3-δ was 45.5% better than that of the 6%RuO2@TiO2 (commercial carrier) on total organic carbon (TOC) removal. Also, doped catalysts LaFe1-xRuxO3-δ showed better activity than supported catalysts RuO2@LaFeO3 and RuO2@TiO2 with the same Ru content. Moreover, LaFe0.85Ru0.15O3-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 LaFe0.85Ru0.15O3-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 LaFe0.85Ru0.15O3-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]

A comparative study of the structure and corrosion resistance of ZnAl hydrotalcite conversion layers at different Al3+/Zn2+ ratios on electrogalvanized steel

The dissimilarities of the composition, crystal structure, and corrosion resistance of ZnAl hydrotalcite (ZnAl-HT) conversion films grown “in situ” on electrogalvanized (EG) steel substrate were investigated for different Al3+/Zn2+ ratios at pH 12. The corrosion behavior of all conversion films in 0.1 M NaCl was compared through electrochemical techniques. The composition, morphology, structure, and thickness of conversion films with different Al3+/Zn2+ ratios were characterized by Fourier-transform infrared spectroscopy (FT-IR), scanning electronic microscopy (SEM), and electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS), and X-ray diffraction (XRD). The polarization curves indicated that the ZnAl-HT films provided anodic inhibition for EG steel and the inhibition efficiency of the ZnAl-HT conversion films increases sharply with decreasing the Al3+/Zn2+ ratios from 5/1 to 5/3, while, for the 5/4 and 5/5 ratios, the corrosion resistance of ZnAl-HT conversion films showed a downward trend after two immersion hours. However, the corrosion behavior of HT conversion films with the Al3+/Zn2+ ratios from 5/3 to 5/5 remained stable for a longer immersion time. The protection performance of the ZnAl-HT films can be attributed to the barrier effects, ion-exchange competitive adsorption of chloride ions, and protective deposition of ZnO on the EG steel surface.

Chloride ions adsorption behavior on CaMnFe-LDHs and solidification performance of chloride ions on cement slurry blocks containing CaMnFe-LDHs

Chloride ions adsorption behavior on CaMnFe-LDHs and solidification performance of chloride ions on cement slurry blocks containing CaMnFe-LDHs

Influence of morphology on photoanodic behaviour of WO3 films in chloride and sulphate electrolytes

Photoelectrochemical (PEC) synthesis is gaining an increasing interest amongst the advanced oxidation processes, which can convert solar energy to chemical energy in the form of value-added oxidants suitable for water treatment and disinfection. To ensure the efficient generation of desired product, careful engineering of semiconductor/electrolyte interface is required. In this study the effect of surface morphology on the competition between the photoanodic oxidation of water molecules and anions occurring on the surface of tungsten (VI) oxide electrodes in sulphate and chloride electrolytes is analysed. Four WO3 coatings composed of plate-like particles, similar in shape but of different sizes, were prepared using chemical solution deposition technique and methanol, ethanol, isopropanol or butanol as reductants. Crystalline structure, morphology, surface chemical composition and optical properties of the coatings were characterised applying X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and photoluminescence spectroscopy techniques. The photoelectrochemical performance of WO3 layers was studied using the methods of electrochemical impedance spectroscopy, cyclic voltammetry and chronoamperometry. Possible photoanodic processes are analysed on the basis of the proposed potential-assisted photochemical approach, which takes into consideration high oxidizing power of photogenerated holes in WO3 and formation of radicals as intermediates. Significant role of specific adsorption of chloride ions as well as intermediate products of their oxidation (Cl·, Cl2˙−) in lowering the photocurrent onset potential, trapping the photogenerated charge carriers as well as protecting WO3 surface from accumulation of hydroxo species is revealed. Influence of morphology on the competition between certain photoanodic reactions occurring at the semiconductor/electrolyte interface in the PEC systems investigated is explained considering the effects of steric hindrance as well as electrostatic interactions between adsorbing/reacting species at rough electrified interfaces.

Synthesis and application of aminosiloxane‐modified cationic waterborne polyurethane as fixing agent for nylon fabric

AbstractIn order to make up for the lack of washing fastness and chlorinated water fastness of nylon dyed with acid dyes, an aminosiloxane modified cationic waterborne polyurethane (KWPU) with the ability to reversibly adsorb chloride ions was synthesized. N‐methyldiethanolamine and ethylenediamine was used as chain extender. N‐aminoethyl‐γ‐aminopropyltrimethoxysilane was used to block the remaining isocyanate groups and provide secondary amine groups for reversible adsorption of chloride ions. The structure of KWPU was characterized by Fourier transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), 1H NMR, and differential scanning calorimetry (DSC). Particle size and zeta potential were tested to evaluate the emulsion stability. The research results showed that when the N‐methyl diethanolamine content was 14%, the water absorption rate of KWPU film was 82.1%, and when the KH‐792 content was 6%, the water absorption rate of KWPU was 34.8%. The addition of siloxane can significantly improve the thermal resistance of the KWPU film. The color fastness of the dyed nylon fabric treated with KWPU emulsion was significantly improved, the rubbing fastness was improved by 0.5 or 1 grade, the washing fastness was improved by 1 grade, and the fastness to chlorinated water was improved by 1.5 or 2 grade.

Intergranular SCC mechanism of ultrasonic nanocrystalline surface modified AISI 304 SS in H2SO4 solution containing chloride

In this work, the stress corrosion cracking (SCC) susceptibility of AISI 304 stainless steel processed using ultrasonic nanocrystalline surface modification (UNSM) treatment, was studied in 1 M H2SO4 containing 5 wt.% NaCl by means of combined slow strain rate test with electrochemical methods. The mechanical properties are improved by the UNSM, however the time to failure decreases due to the higher anodic dissolution kinetics of the UNSM sample, which remain in the order of mA/cm2 compared to µA/cm2 of the as-received (AR) sample. Adsorption of chloride ions has been identified by the presence of an inductive loop in the Nyquist plot, indicating a more reactive surface of the UNSM sample, which promotes dealloying of the metal. The development of several transgranular SCC (TG‒SCC) areas in the UNSM sample, compared to the AR, plus the nucleation of intergranular SCC (IG‒SCC) in the UNSM region is studied by scanning electron microscopy (SEM), X-ray micro-computed tomography (micro-CT), and electron back scattered diffraction (EBSD).

Research progress of metal organic frameworks and their derivatives for adsorption of anions in water: A review

Anion pollution in water has become a problem that cannot be ignored. The anion concentration should be controlled below the national emission standard to meet the demand for clean water. Among the methods for removing excess anions in water, the adsorption method has a unique removal performance, and the core of the adsorption method is the adsorbent. In recent years, the emerging metal-organic frameworks (MOFs) have the advantages of adjustable porosity, high specific surface area, diverse functions, and easy modification. They are very competitive in the field of adsorption of liquid anions. This article focuses on the adsorption of fluoride, arsenate, chromate, radioactive anions (ReO4−, TcO4−, SeO42−/SeO32−), phosphate ion, chloride ion, and other anions by MOFs and their derivatives. The preparation methods of MOFs are introduced in turn, the application of different types of metal-based MOFs to adsorb various anions were discussed in categories with their crystal structure and functional groups. The influence on the adsorption of anions is analyzed, including the more common and special adsorption mechanisms, adsorption kinetics and thermodynamics, and regeneration performance are briefly described. Finally, the current situation of MOFs adsorption of anions is summarized, and the outlook for future development is summarized to provide my own opinions for the practical application of MOFs.

Study of anti-chlorine corrosion of anion exchange resin based superhydrophobic cement mortar in chloride salt environment

Anti-corrosion of reinforced concrete structures in the chloride salt environment is an important issue. Especially the corrosion damage of reinforced concrete by chloride ions seriously affects the safety of concrete structures and quality of the material’s appearance. In this paper, the chlorine corrosion resistance of superhydrophobic anion exchange resin cement mortar in a chloride environment was investigated. The chlorine corrosion resistance of different samples was compared by electrochemical experiments and chloride distribution test. The results show that the as-fabricated mortar has better corrosion resistance to chloride salt attack than the reference sample at a 98.60% increase in corrosion resistance rate. AgNO3 color development experiment and free chloride ion concentration measurements show that the as-fabricated mortar can not only adsorb chloride ions inside the mortar, but also effectively inhibit the penetration of external chloride ions. This internally and externally coordinated anti-corrosion cement mortar is expected to extend the service life of reinforced concrete in chloride salt environments.

Effect of concentration and ionic strength on the lower critical solution temperature of poly(N-isopropylacrylamide) investigated by small-angle X-ray scattering

ABSTRACT Thermoresponsive polymers, with special emphasis on poly(N-isopropylacrylamide) (PNIPAAM) have been the focus of several investigations due to its potential applications in many fields of physical and polymer chemistry. PNIPAAM has a “lower critical solution temperature” at 32°C. The LCST can be finely tuned by copolymerization with hydrophobic or hydrophilic comonomers, and with a change of physical chemical parameters, such as ionic strength of the solution. We investigated the effect of polymer concentration on the LCST in two different solution environment, in pure water and in 50 mM NaCl solution with small-angle X-ray scattering (SAXS) of relatively low molecular mass polymers. We showed that the radius of gyration of the pNIPAAM chains increases with the addition of NaCl to the system due to the low level of specific adsorption of chloride ions on the polymer, whilst increasing the temperature causes a shrinkage of the polymer chains. Furthermore, by increasing the temperature the attractive interaction between the individual polymer chains is enhanced which turns into aggregation at the LCST.

Effect of curing regimes on chloride binding capacity of geopolymer

Chloride attack on reinforced concrete is considered the most important aspect in concrete durability investigation. This study is carried out to investigate effect of curing condition on the chloride binding capacity of fly ash geopolymer pastes containing a range of cast in chloride contents (NaCL), varying from 1%, 2% and 4% by mass of binder. The applied curing regimes were normal, oven, steam and microwave. The impact of induced chlorides on the compressive strength and on the chloride binding capacity of fly ash geopolymers under different curing conditions is determined. A detailed microstructure and phase composition analysis were conducted through SEM and XRD tests. It was observed that applying thermal curing conditions could increase the chloride binding capacity to the formed geopolyric hydration product. High curing temperatures promote the precursor dissolution reactions and will increase the overall generation of polymerization reaction products, while under normal curing a lot of fly ash grains did not fully react. Therefore, thermal curing is important in the activation of geopolymerization process that increase aluminosilicate gel and result in dense and less porous geopolymer matrix and yields in high compressive strength. This results in the physical adsorption and chemical binding of chloride ions on the gel surface, and hence reducing the rate of chloride ingress. It was concluded that the ingress of chlorides can be particularly controlled better through binding the free chloride ions under steam and microwave curing in the fly ash geopolymer concrete.

Chloride binding by calcined layered double hydroxides and alumina-rich cementitious materials in mortar mixed with seawater and sea sand

Seawater and sea sand can alleviate the shortage of resources and reduce the transportation distance of raw materials at the construction of offshore islands, whereas the high content of chloride ions in concrete mixed with seawater and sea sand induces reinforcement corrosion, which is the biggest obstacle to its wide application. This study aims to explore the way to reduce the free chloride ions content and improve the chloride binding capacity of mortar mixed with seawater and sea sand by calcined layered double hydroxide (CLDH) and alumina-rich cementitious materials (metakaolin (MK), fly ash (FA), and calcium aluminate cement (CAC)). The results show that both CLDH, MK, FA, and CAC can effectively improve the chloride binding capacity of mortar by 65%, 65%, 35%, and 200%, when the optimal dosages are 7.5%, 30%, 30%, and 100%, respectively. Moreover, molecular dynamics simulation shows that the radius correlation function (RDF) value of Cl-Ca ionic pairs is cut down at the condition that has CLDH, which reveals that the adsorption of chloride ions by CLDH occurs in the mortar is confirmed.