High Concentration Of Chloride Ions Research Articles

High-sensitivity and energy-efficient chloride ion sensors based on flexible printed carbon nanotube thin-film transistors for wearable electronics

The advent of flexible single-walled carbon nanotube thin-film transistors (SWCNT-TFTs) has transformed electronics, providing significant benefits like low operating voltage, reduced power consumption, cost-effectiveness, and improved signal amplification. This study focuses on leveraging these attributes to develop a novel flexible high-sensitivity and energy-efficient chloride ion sensors based on printed flexible SWCNT-TFTs utilizing polymers-sorted semiconducting SWCNTs (sc-SWCNTs) as the active layers and ion liquids-poly(4-vinylphenol as dielectric layers along with the evaporated deposition of aluminum electrodes and printed silver electrodes as the gate and source-drain electrodes, respectively. The sensors exhibit several operational advantages, including low voltage requirements (≤1 V), rapid response speed (5.32 s), significant signal amplification (Up to 702.6%), low power consumption (0.31 μJ at 1 mmol chloride ion), good repeatability, high sensitivity for both low and high concentrations of chloride ion (up to 100 mmol/L) and excellent mechanical flexibility (No obvious changes after bending for 10,000 times with a 5 mm radius). The detection mechanism of chloride ions was analyzed using X-ray Photoelectron Spectroscopy (XPS). It was found that chloride ions react with silver nanoparticles (AgNPs) to form silver chloride (AgCl) on printed electrodes, impeding carrier transport and reducing the currents in SWCNT TFTs. Importantly, our sensors' compatibility with smart devices allows for real-time monitoring of chloride ion levels in human sweat, offering significant potential for daily health monitoring.

Mechanism of local hydrogen entry into Fe sheets induced by atmospheric corrosion: Significance of potential, pH, and rust layer thickness

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.

Separation of Chloride and Sulfate Ions from Desulfurization Wastewater Using Monovalent Anions Selective Electrodialysis.

The high concentration of chloride ions in desulphurization wastewater is the primary limiting factor for its reusability. Monovalent anion selective electrodialysis (S-ED) enables the selective removal of chloride ions, thereby facilitating the reuse of desulfurization wastewater. In this study, different concentrations of NaCl and Na2SO4 were used to simulate different softened desulfurization wastewater. The effects of current density and NaCl and Na2SO4 concentration on ion flux, permselectivity (PSO42-Cl-) and specific energy consumption were studied. The results show that Selemion ASA membrane exhibits excellent permselectivity for Cl- and SO42-, with a significantly lower flux observed for SO42- compared to Cl-. Current density exerts a significant influence on ion flux; as the current density increases, the flux of SO42- also increases but at a lower rate than that of Cl-, resulting in an increase in permselectivity. When the current density reaches 25 mA/cm2, the permselectivity reaches a maximum of 50.4. The increase in NaCl concentration leads to a decrease in the SO42- flux; however, the permselectivity is reduced due to the elevated Cl-/SO42- ratio. The SO42- flux increases with the increase in Na2SO4 concentration, while the permselectivity increases with the decrease in Cl-/SO42- ratio.

Electrochemical migration behavior between Cu and Ag under a thin electrolyte layer containing chloride

PurposeThe purpose of this paper is to investigate the effects of chloride ion concentration and applied bias voltage on the electrochemical migration (ECM) behavior between Cu and Ag under an NaCl thin electrolyte layer (TEL).Design/methodology/approachA self-made experimental setup for the ECM behavior between Cu and Ag was designed. An HD video measurement microscopy was used to observe the typical dendrite/corrosion morphology and pH distribution. Short-circuit time (SCT), short-circuit current density and the influence of the galvanic effect between Cu and Ag on their ECM behavior were studied by electrochemical tests. The surface morphology and composition of dendrite were characterized by FESEM/EDS.FindingsThe SCT increased with increasing NaCl concentration but decreased with increasing applied bias voltage, and the SCT between Cu and Ag was less than that between Cu and Cu because their galvanic effect accelerated the dissolution and migration of Cu. When NaCl concentration was less than or equal to 6 mmol/L, cedar-like dendrite was formed, whereas no dendrite formed and only precipitation occurred at high chloride ion concentration (100 mmol/L). The composition of the dendrite between Cu and Ag was copper.Research limitations/implicationsThe significance of this study is to clarify the ECM failure mechanism of printed circuit board (PCB) with an immersion silver surface finish (PCB-ImAg).Practical implicationsThis study provides a basic theoretical basis for the selection of protective measures and metal coatings for PCB.Social implicationsThe social implication of this study is to predict the service life of PCB.Originality/valueThe ECM behavior of dissimilar metals under a TEL was investigated, the influence of the galvanic effect between them on their ECM was discussed, and the SCT increased with increasing NaCl concentration.

Oxalate anions-intercalated NiFe layered double hydroxide as a highly active and stable electrocatalyst for alkaline seawater oxidation

Seawater electrolysis is gaining recognition as a promising method for hydrogen production. However, severe anode corrosion caused by the high concentration of chloride ions (Cl–) poses a challenge for the long-term oxygen evolution reaction. Herein, an anti-corrosion strategy of oxalate anions intercalation in NiFe layered double hydroxide on nickel foam (NiFe-C2O42– LDH/NF) is proposed. The intercalation of these highly negatively charged C2O42– serves to establish electrostatic repulsion and impede Cl– adsorption. In alkaline seawater, NiFe-C2O42– LDH/NF requires an overpotential of 337 mV to gain the large current density of 1000 mA cm−2 and operates continuously for 500 h. The intercalation of C2O42– is demonstrated to significantly boost the activity and stability of NiFe LDH-based materials during alkaline seawater oxidation.

Two Novel Metformin Carboxylate Salts and the Accidental Discovery of Two 1,3,5-Triazine Antihyperglycemic Agent.

Metformin (MET), commonly marketed as a hydrochloride salt (MET-HCl) for better pharmacokinetic profile over the free base, would release a high concentration of chloride ions and cause adverse gastrointestinal effects. The preparation of chloride-free MET salts could potentially circumvent this issue. In this study, seven carboxylic acids (formic acid, acetic acid, malonic acid, succinic acid, fumaric acid, cinnamic acid, and acetylsalicylic acid) were used for preparing MET carboxylate salts. When compared with MET-HCl, all MET salts/salt hydrates show lower dissolution rates in pH 6.8 phosphate buffer. However, the cinnamic acid and acetylsalicylic acid show significantly higher dissolution rates in the forms of MET salt/salt hydrate. In the permeability test, the permeability of the MET in all of the salts was not improved. However, the permeability of cinnamic acid in the MET cinnamate is reduced, and the permeability of acetylsalicylic acid in the MET acetylsalicylate is increased. Meanwhile, at a higher crystallization temperature, the acetone solvent and a hydrolyzed product of acetylsalicylic acid react with MET respectively, leading to two unexpected 1,3,5-triazine derivatives. The results of in vitro bioactivity assays indicate that one of the triazine molecules promote glucose consumption more effectively than MET-HCl, and had relatively weak lactate production ability at low concentration. This glucose metabolism regulating compound may serve as a novel lead antihyperglycemic agent for further optimization.

Hybrid Polymer Salogels for Reversible Entrapment of Salt-Hydrate-Based Thermal Energy Storage Materials.

One of the challenges preventing wide use of inorganic salt hydrate phase change materials (PCMs) is their low viscosity above their melting point, leading to leakage, phase segregation, and separation from heat exchanger surfaces in thermal management applications. The development of a broad strategy for using polymers that provide tunable, temperature-reversible shape stabilization of a variety of salt hydrates by using the lowest possible polymer concentrations is hindered by differences in solubility and gelation behavior of polymers with change in the type of ion. This work addressed the challenge of creating robust, temperature-responsive shape-stabilizing polymer gels (i.e., salogels) using a low cost PCM, calcium chloride hexahydrate (CaCl2·6H2O, CCH). Due to the extremely high (9 M) concentration of chloride ions and the tendency to salting-out polymer chains, the previous strategy of using single-polymer salogels was not successful. Thus, this work introduced a strategy of using two polymers, poly(vinyl alcohol) and ultrahigh molecular weight polyacrylamide (PVA and PAAm, respectively), along with borax as a cross-linker to achieve temperature-reversible, shape-stable salogels. This system resulted in robust salogels whose gel-to-sol transition temperature (Tgel) was tunable within an application-relevant range of gelation temperature (30-80 °C). This behavior was enabled by a synergistic combination of dynamic covalent cross-links between PVA units and entanglements of PAAm chains which were combined into a single hybrid network. The hybrid salogels had <5 wt % polymer content, maintaining ∼95% of the heat of fusion of the pure PCM. Importantly, the noncovalent nature of gelation supported thermo-reversibility of gelation, shape stability, and retention of thermal properties over 50 melting/crystallization cycles.

Ultrahigh dark and light-improved chloride removal performance of magnetite bismuth oxide thin flakes with low crystallinity

The high concentration of chloride (Cl-) ions in wastewater poses environmental risks. The bismuth oxide (Bi2O3)-based Cl- removal method has gained significant attention due to its high selectivity towards Cl- ions. However, it still faces challenges related to strong acid condition and excessive dosage. Herein, the mixed-ferrites (M-Fe3O4) nanoparticles with broadband absorption property were combined with Bi2O3 to form to the magnetite Bi2O3 (FBO) composites. Due to the space separation of M-Fe3O4 nanoparticles in the thin Bi2O3 flakes, FBO had a loose structure, and its sample after 100 °C treatment (FBO-100) possessed weak crystallinity and the largest specific surface area, which enabled it to possess the highest Cl- removal efficiency of 98.4% at pH = 1 in the dark. Under UV-Vis-NIR irradiation, the Cl- removal efficiencies of FBO-100 at pH = 2, 3, and 5 increased from 71.4%, 56.3%, and 54.5% to 84.6%, 65.5%, and 58.0%, respectively. During the light-irradiated Cl- removal process, the heterostructures of Bi2O3/M-Fe3O4, Bi2O3/BiOCl/M-Fe3O4, and BiOCl/M-Fe3O4 were successively built, and the oxidative photocorrosion of Bi2O3 caused by holes played the predominant role in improving the Cl- removal efficiency, compared with the •OH, Cl•, and O2•− radicals. FBO-100 had stable cyclic Cl- removal performance and high safety, which is expected to be of a good application prospect for Cl- removal.

Association of hypertension in pregnancy with serum electrolyte disorders in late pregnancy among Cameroonian women

Multiple electrolyte disorders, including sodium, potassium and calcium disorders, have been associated with hypertension in pregnancy. Most of these studies failed to evaluate the combined effect of low and high sodium, potassium, calcium and chloride ion concentrations on hypertension in pregnancy. This study evaluates the combined effect of these ion categories (low, normal, high) on hypertension in pregnancy. Biochemical ion assays and blood pressure measurements were carried out on 1074 apparently healthy pregnant women in late third trimester. Serum potassium, sodium, chloride, and ionised calcium were measured by ion-selective electrode potentiometry, while total plasma calcium was measured by absorption spectrophotometry. Hypertension in pregnancy was defined as systolic blood pressure ≥ 140 mmHg and/or diastolic blood pressure ≥ 90 mmHg. The prevalence of hyponatraemia, hypokalaemia, hypochloraemia, ionised hypocalcaemia and total hypocalcaemia in late pregnancy was 1.30 [0.78–2.18]%, 3.55 [2.60–4.84]%, 1.96 [1.28–2.97]%, 1.49 [0.92–2.21]% and 43.58 [40.64–46.56]%, respectively. Hypernatraemia, hyperkalaemia, hyperchloraemia, ionised hypercalcaemia and total hypercalcaemia were found in 1.49 [0.92–2.41]%, 2.34 [1.59–3.43]%, 4.38 [3.31–5.77]%, 39.94 [37.06–42.90]%, 2.79 [1.96–3.96]% of the participants, respectively. The prevalence of hypertension in pregnancy was 7.17 [5.77–8.87]%. When ion categories were considered in multiple logistic regression, only ionised and total calcium had significant associations with hypertension in pregnancy. Women with ionised hypercalcaemia had lower odds of hypertension in pregnancy (AOR = 0.50 [0.29–0.87], p-value = 0.015), and women with total hypocalcaemia had higher odds of hypertension in pregnancy (AOR = 1.99 [1.21–3.29], p-value = 0.007), compared to women with ionised and total normocalcaemia, respectively. Increasing kalaemia was associated significantly with higher odds of hypertension in pregnancy; however, kalaemia below and above the normal concentrations had no significant association with hypertension. Nonetheless, participants with kalaemia ≤ 3.98 mmol/L, had lower odds of hypertension in pregnancy compared with those with higher kalaemia (OR = 0.40 [0.24–0.66], p-value = 0.0003). Calcium disorders remain the most frequent electrolyte disorders in pregnancy. When normal cut-offs are considered for calcium and other ions, only ionised and total calcium influence the occurrence of hypertension in pregnancy. Kalaemia seems to affect hypertension in pregnancy but primarily within its normal concentrations. Serum electrolyte follow-up is indispensable for a proper pregnancy follow-up.

The role of reactive chlorine and nitrogen species in micropollutant degradation in UV/monochloramine

Monochloramine (NH2Cl) is applied upstream of reverse osmosis (RO) membranes for biofouling control. Residual NH2Cl can undergo UV photolysis downstream, generating reactive species for an AOP to occur. At the bench-scale, NH2Cl is typically generated from combining sodium hypochlorite and ammonium chloride or sulfate. This study investigated the degradation of four compounds of interest – acetaminophen, caffeine, sucralose and 1,4-dioxane – in UV/NH2Cl at the bench scale to study their reactivity with reactive chlorine species (RCS) and reactive nitrogen species (RNS). With methanol acting as a scavenger of •OH radicals, the performance of UV/NH2Cl was compared to UV/H2O2 and UV/HOCl. In UV/H2O2, dioxane was severely inhibited at 1–2 mg/L H2O2 and comparable at 5 mg/L to UV/NH2Cl. When ammonium sulfate ((NH4)2SO4) was used as the ammonia source over ammonium chloride (NH4Cl), the overall degradation of micropollutants was higher and caffeine was exclusively degraded. At 1–2 mg/L NH2Cl, dioxane degraded by 16.2–17.8% and 2.92–5.29% from (NH4)2SO4 and NH4Cl respectively while caffeine degraded by 7.45–9.61% with NH2Cl ((NH4)2SO4), but not degrade with NH2Cl (NH4Cl). The higher concentration of chloride ions from NH4Cl significantly influenced the speciation of generated radicals and impacted micropollutant degradation. This suggests that the reactivity of more selective RCS (Cl2•−, •ClO, ClOH•−) and RNS (•NH2, •NO, •NO2, etc.) varies with micropollutants of interest. The presence of higher chloride concentration from the ammonia source inhibited the generation of •OH radicals with •OH consumed by RNS to form NO3− (μg/L levels), showing the impact of the choice of ammonia source and the water matrix on UV/NH2Cl performance.

Influence of chloride ions on corrosion behaviour of zinc-alloy in the simulated body fluid solution

ABSTRACT The bio-corrosion behaviours of the Zn alloy in the simulated body fluid (SBF) at different chloride ion concentrations were investigated. The Potentiodynamic Polarisation Curve (PDP) and Electrochemical Impedance Spectroscopy (EIS) results indicate that the corrosion rate of Zn alloy decreases with higher chloride ion concentrations. The decrease in corrosion rate is due to the formation of a protective layer of ZnCl2 nanofibres and agglomerates. The surface morphology and analytical studies of the Zn alloy were carried out by scanning electron microscopy (SEM), EDX, atomic force microscopy (AFM), and X-ray diffractometry. The SEM, EDX, and X-ray diffraction studies indicate the formation of nanofibres and agglomerates of ZnCl2. The AFM measurements show the increase in surface roughness due to the in situ formation of nanofibres and agglomerates on the alloy surface. Therefore, these results are useful to tailor the design of Zn alloy-based biomedical materials being implanted for the living body.

Dibromo- and Dichlorotriphenylphosphino N-Acyclic Carbene Complexes of Platinum(II)—Synthesis and Cytotoxicity

Some new dichloro- and dibromotriphenylphosphino isonitrile and N-acyclic (NAC) carbene complexes of platinum(II) were synthesized, starting from suitable dinuclear precursors. The reaction of cyclohexylisonitrile with trans-[Pt(μ-X)X(PPh3)]2, followed by the addition of N,N-diethylamine afforded the corresponding N-acyclic carbene (NAC)derivatives cis-[PtX2(PPh3)(NAC)] in 61–64% isolated yield. The cis geometry was attributed based on the comparison with known structures. The stability of the complexes in pure DMSO, DMSO/H2O, and DMSO/NaClaq mixtures was evaluated. While pure DMSO, as well as DMSO/H2O, did not affect the nature of either dichloro- or dibromo-compounds, dibromo derivatives were not stable in the presence of chloride ions. Since a high concentration of chloride ions is essential to perform in vitro cell assays, only dichlorocomplexes were tested as cytotoxic agents against HepG2 and human tumor cells. Among the tested complexes, NAC derivatives showed a moderate effect on MSTO-211H.

Ni3S2/Co9S8 directly grown on nickel foam as an environmentally friendly electrocatalyst for seawater splitting

Seawater is one of the most abundant sources of hydrogen on Earth, so its decomposition for producing hydrogen has a significant advantage. However, because of the presence of high concentration of chloride ion (Cl−) in seawater, it has corrosive effect on the catalyst. Therefore, the exploration and construction of highly robust anticorrosive OER electrocatalyst were studied. Furthermore, this work describes Co9S8@Ni3S2/NF as a catalyst, which provides a current density of 100 mA cm−2 with a required overpotential of only 154 mV, with emphasis on their remarkable OER selectivity. The experimental analysis demonstrate that the promotion of Co9S8@Ni3S2/NF catalyst activity can be attributed to the construction of heterogeneous interface, the rapid transfer of charge and the exposure of more reaction centers. Density functional theory analysis demonstrates that the Co9S8 material presents greater water adsorption energy, indicating that water preferentially adsorbs on its surface. The introduction of the Ni3S2 electrode greatly promotes the synergistic effect of the Co9S8@Ni3S2/NF electrode. It is the synergistic catalysis of these two electrodes that enhances the catalytic activity and selectivity of the materials. The work furnishes a novel idea for the exploration of efficient, environmentally friendly and highly selective electrodes for seawater splitting.

Corrosion Behavior of AA70 Reinforced Zea mays Husk Particle in NaCl/H2SO4 Concentrations

The effects of Zea mays husk particle and heat treatment on the corrosion behavior of AA70 matrix composite in 1.5 wt.% NaCl/0.0125 M H2SO4 concentrations were studied using an electrochemical technique and optical microscopy. Results showed that the samples had similar anodic-cathodic polarization behavior after heat treatment, with no passivation. However, the heat-treated AA70 matrix composites were more corrosion-resistant than the untreated AA70 matrix composite material in 1.5 wt.% NaCl/0.0125 M H2SO4 concentrations. The composite with 15 wt.% Zea mays husk and a particle size of 300 μm reinforced AA70 matrix revealed the least corrosive tendency and is the most thermodynamically stable in chloride and sulphate ions conditions. Therefore, the corrosion behavior of heat-treated AA70 matrix composites was better compared to that of AA70 material in 1.5 wt.% NaCl/0.0125 M H2SO4 solution. Furthermore, the presence of a high concentration of aggressive chloride ions increases the corrosion susceptibility, and the Zea mays husk particle breaks down the stable oxide film, resulting in increased chloride ion adsorption. The optical microscopy examination suggested the presence of localized corrosion on the material surface.

Methods for removing chloride ions to manufacture zinc from arc melting dust

In this work, we review literature sources to identify an industrial-scale technology for manufacturing cathode zinc from technogenic chlorine-containing raw materials of a complex chemical composition, in particular, from arc melting dust. The conducted review of Russian and foreign publications was used to search for a method of purifying process solutions with a high concentration of chloride ions produced by hydrometallurgical processing of technogenic arc melting dusts. It was found that the existing purification methods are associated with substantial limitations, including strict requirements for the acidity of the treated solution, low efficiency of treatment, secondary contamination of the medium by released chloride ions, and the high cost of reagents or equipment. Approaches to reducing the chlorine content in the initial dust and dechlorination of process solutions based on principles of sedimentation, ion exchange, sorption, and oxidation are described. In addition, we analyzed information published on chlorine removal from process effluents and solutions of various nature. Industrially-implemented and recently-reported laboratory methods of solution dechlorination were compared in terms of their feasibility, economic efficiency, and extent of chloride ion removal. It was concluded that the disadvantages of existing methods for processing technogenic chlorine-containing raw materials of arc melting can be eliminated by developing large, stable, and cheap hydride technologies based on principles of extraction, ion exchange, and sedimentation.

Regulating the Water Molecular in the Solvation Structure for Stable Zinc Metal Batteries

AbstractRechargeable aqueous zinc batteries are promising energy storage devices because of their low cost, high safety, and high energy density. However, their performance is plagued by the unsatisfied cyclability due to the dendrite growth and hydrogen evolution reaction (HER) at the Zn anode. Herein, it is demonstrated that the concentrated hybrid aqueous/non‐aqueous ZnCl2 electrolytes constitute a peculiar chemical environment for not only the Zn‐ions but also water molecules. The high concentration of chloride ions substitutes the H2O molecular in the solvation structure of Zn2+, while the acetonitrile further interacts with H2O to decrease its activity. The hybrid electrolytes both inhibit the dendrite formation and HER, enabling an ultrahigh average Coulombic efficiency of 99.9% in the Zn||Cu half‐cell and a highly reversible Zn plating/stripping with a low overpotential of 21 mV. Using this hybrid electrolyte, the Zn||polytriphenylamine (PTPAn) full cell deliveres a high discharge capacity of 110 mAh g−1, a high power density of 9200 W kg−1 at 100 °C and maintains 85% of the capacity for over 6000 cycles at 10 °C. This study provides a deep understanding between the solvation structure and columbic efficiency of Zn anode, thus inspiring the development for stable Zn batteries.

Use of ionic liquids for extraction separation and concentration of iodide ions in brine samples.

Iodine in natural salt waters such as iodine-rich underground brine generally exists as iodide ions, and to extract iodide ions, it is necessary to oxidize them to nonpolar iodine molecules. In this study, we report that iodide ions in natural brine containing high concentrations of chloride ions can be quantitatively extracted without oxidation by extraction using ionic liquids. Extraction with the ionic liquids trihexyltetradecylphosphonium chloride and trioctyl ammonium chloride was found to be able to enrich trace amounts of iodide in brine samples up to 40- and 100-fold, respectively. The selectivity coefficients for I- over Cl- determined in this study clearly show that the ionic liquids have much higher I-/Cl- selectivity than typical strongly basic anion exchangers. Extraction with trihexyltetradecylphosphonium chloride was applicable as a preconcentration method for iodine determination by XRF analysis. Iodide ions extracted with trioctyl ammonium chloride were quantitatively stripped with an aqueous alkaline solution. These results indicate that ionic liquid extraction is useful for the separation and concentration of iodide from brines.

Fructus cannabis protein extract powder as a green and high effective corrosion inhibitor for Q235 carbon steel in 1 M HCl solution

The Fructus cannabis protein extract powder (FP), was firstly used as a green and high effective corrosion inhibitor through a simple water-extraction method. The composition and surface property of FP were characterized by FTIR, LC/MS, UV, XPS, water contact angle and AFM force-curve measurements. Results indicate that FP contains multiply functional groups, such as NH, CO, CN, CO, etc. The adsorption of FP on the carbon steel surface makes it higher hydrophobicity and adhesion force. The corrosion inhibition performance of FP was researched by electrochemical impedance, polarization curve and differential capacitance curve. Moreover, the inhibitive stability of FP, and the effects of temperature and chloride ion on its inhibition property were also investigated. The above results indicate that the FP exhibits excellent corrosion inhibition efficiency (~98 %), and possesses certain long-term inhibitive stability with inhibition efficiency higher than 90 % after 240 h immersion in 1 M HCl solution. The high temperature brings about the FP desorption on the carbon steel surface, while high concentration of chloride ion facilitates the FP adsorption. The adsorption mechanism of FP follows the Langmuir isotherm adsorption. This work will provide an insight for protein as a green corrosion inhibitor.

Removal of high concentration of chloride ions by electrocoagulation using aluminium electrode.

Wastewater containing a high concentration of chloride ions (Cl- ions) generated in industrial production will corrode equipment and pipelines and cause environmental problems. At present, systematic research on Cl- removal by electrocoagulation is scarce. To study the Cl- removal mechanism, process parameters (current density and plate spacing), and the influence of coexisting ions on the removal of Cl- in electrocoagulation, we use aluminum (Al) as the sacrificial anode, combined with physical characterization and density functional theory (DFT) to study Cl- removal by electrocoagulation. The result showed that the use of electrocoagulation technology to remove Cl- can reduce the concentration of Cl- in an aqueous solution below 250ppm, meeting the Cl- emission standard. The mechanism of Cl- removal is mainly co-precipitation and electrostatic adsorption by forming chlorine-containing metal hydroxyl complexes. The current density and plate spacing affect the Cl- removal effect and operation cost. As a coexisting cation, magnesium ion (Mg2+) promotes the removal of Cl-, while calcium ion (Ca2+) inhibits it. Fluoride ion (F-), sulfate (SO42-), and nitrate (NO3-) as coexisting anions affect the removal of Cl- ions through competitive reaction. This work provides a theoretical basis for the industrialization of Cl- removal by electrocoagulation.

Corrosion Effects on the Seismic Vulnerability Index of Reinforced Concrete Scholar Buildings

The Veracruz - Boca del Río metropolitan area in Mexico presents high temperatures and even high chloride ion concentrations, causing an aggressive environment with significant corrosion rates. Therefore, in reinforced concrete buildings in said area, their service life and integrity can compromise. Rapid Screening Methods (RSM) are used to determine their Seismic Vulnerability Index (SVI). The Benedetti-Petrini RSM can be used to determine the SVI of the corroded structures, adapting how the state of conservation is evaluated and weighted. To that end, the corrosion level and the crack width were correlated to estimate how their state of conservation can be deteriorated, reducing the service life. To test its usefulness, nine faculties, whose ages are close to 50 years, were analyzed, and the SVI of the original and modified methods were compared. Additionally, as expected, the buildings close to the coastline, and the faces exposed to wind direction, were the most damaged. The results indicate that the modified SVI provides rational decisions and improves the action management for each structure.