Chloride Research Articles

Double Electrode Experiments Reveal the Processes Occurring at PEDOT-Coated Neural Electrode Arrays.

Neural electrodes have recently been developed with surface modifications of conductive polymers, in particular poly(3,4-ethylenedioxythiophene) (PEDOT), and extensively studied for their roles in recording and stimulation, aiming to improve their biocompatibility. In this work, the implications for the design of practical neural sensors are clarified, and systematic procedures for their preparation are reported. In particular, this study introduces the use of in vitro double electrode experiments to mimic the responses of neural electrodes with a focus on signal-recording electrodes modified with PEDOT. Specifically, potential steps on one unmodified electrode in an array are used to identify the responses for PEDOT doped with different anions and compared with that of a bare platinum (Pt) electrode. The response is shown to be related to the rearrangement of ions in solution near the detector electrode resulting from the potential step, with a current transient seen at the detector electrode. A rapid response for PEDOT doped with chloride (ca. 0.04 s) ions was observed and attributed to the fast movement of chloride ions in and out of the polymer film. In contrast, PEDOT doped with poly(styrenesulfonate) (PSS) responds much slower (ca. 2.2 s), and the essential immobility of polyanion constrains the direction of current flow.

Water-based corrosion inhibitor for prevention and repair of reinforcement in chloride and carbonated environment

This paper explores the influence of 2-aminopyridine (2AP) as water-based migratory corrosion inhibitor (M-CoI) on the corrosion resistance of reinforcing steel bars embedded in ordinary Portland cement and pozzolanic Portland cement concrete subjected to combined chloride and carbonation ingress. Two applications of 2AP are considered i.e., preventive (applied before exposure to aggressive environment) and repair (applied after corrosion initiates). Corrosion performance was assessed using electrochemical techniques and gravimetric mass loss method. The study also examines the impact of 2AP application on chloride ion concentration and carbonation depth of both concrete systems. The compressive strength of each concrete system was also measured to study the impact of M-CoI application on strength properties. Surface condition of hardened concrete and extracted rebar was evaluated by optical microscopy. Results conclude that 2AP effectively retards reinforcement corrosion when used as preventive measure by forming a homogeneous inhibitive layer on steel. However, when used as a repair technique, localised and uniform corrosion was perceived. An attempt has been made to identify the cause of non-performance of 2AP as repair measure. It was concluded that reached concentration of 1 mM was not sufficient to reduce ongoing corrosion due to the accumulation of corrosion products. The influence of the inhibitor on chloride profile and carbonation depth was found to be insignificant. It is concluded that chloride ions initiate the corrosion mechanism, while carbonation exacerbates it, particularly in blended cement concrete. Nonetheless, inhibitor application can provide similar resistance in both concrete systems.

Accelerated removal of organic pollutants by biochar-based iron carbon granule-activated periodate in chloride-containing water: The role of active chlorine

Ubiquitous in water environments, the chloride ion (Cl−) can impact the decontamination capacity of an oxidation system. However, minimal studies are available on its effects in periodate (PI)-based advanced oxidation processes. In this study, a novel biochar-based iron-carbon (FeBC) granule was synthesized to activate PI and remove organic pollutants from water containing Cl−. The FeBC/PI/Cl− system (FeBC: 0.5 g/L; PI: 0.5 mM; AO7: 20 mg/L; NaCl: 50 mM) exhibited excellent performance on various organic pollutants, with ＞ 85 % of Acid Orange (AO7) removal over a pH range of 3–10. Within 20 min after the tenth run, approximately 80 % of AO7 was removed. Inorganic ions and natural organic matter had a negligible effect on AO7 removal. Characterization results confirmed that the presence of Cl− enhanced Fe corrosion, thereby improving PI activation efficiency for removing AO7. Electron paramagnetic resonance spectroscopy and active species trapping experiments verified that radicals (•OH and O2•−) and nonradical (1O2, Fe(IV), and electron transfer) oxidation processes participated in the FeBC/PI system. Moreover, the presence of Cl− accelerated •OH, O2•−, 1O2, and Fe(IV) formation and generated active chlorine, such as HOCl. The main pathways involved in the generation of multiple reactive species were evaluated. AO7 degradation pathways were proposed, and numerous intermediates exhibited decreased toxicity. These findings provide new insights for the decontamination of organic contaminants in water containing Cl−.

Research on the Chloride Ion Corrosion Resistance of Cu-Sb-Added Low-Carbon Steel

The corrosion resistance of low-carbon steel and two new low-alloy, corrosion-resistant steels containing Cu-Sb and Cu was studied in a simulated seawater environment. The effects of Cu and Sb on corrosion resistance were analyzed by an electrochemical test and accelerated corrosion test. The results show that Cu and Sb reduce the corrosion current density by increasing the corrosion potential and increasing the polarization resistance. Sb can promote the formation of Cu-containing compounds with a strong corrosion inhibition performance, and it can enhance the overall corrosion resistance of steel. In addition, Sb can also promote the conversion of Fe2+ ions into a corrosion-resistant compound, α-FeOOH, and it also further improves the corrosion resistance of steel.

Photogeneration of Chlorine Radical from a Self-Assembled Fluorous 4CzIPN•Chloride Complex: Application in C-H Bond Functionalization.

The chlorine radical is a strong HAT (Hydrogen Atom Transfer) agent that is very useful for the functionalization of C(sp3)-H bonds. Albeit highly attractive, its generation from the poorly oxidizable chloride ion mediated by an excited photoredox catalyst is a difficult task. We now report that 8Rf8-4CzIPN, an electron-deficient fluorous derivative of the benchmark 4CzIPN photoredox catalyst belonging to the donor-acceptor carbazole-cyanoarene family, is not only a better photooxidant than 4CzIPN, but also becomes an excellent host for the chloride ion. Combining these two properties ultimately makes the self-assembled 8Rf8-4CzIPN•Cl- dual catalyst highly reactive in redox-neutral Giese-type C(sp3)-H bond alkylation reactions promoted by the chlorine radical. Additionally, because of its fluorous character, the efficient separation/recovery of 8Rf8-4CzIPN could be envisioned.

Photogeneration of Chlorine Radical from a Self‐Assembled Fluorous 4CzIPN•Chloride Complex: Application in C−H Bond Functionalization

AbstractThe chlorine radical is a strong HAT (Hydrogen Atom Transfer) agent that is very useful for the functionalization of C(sp3)−H bonds. Albeit highly attractive, its generation from the poorly oxidizable chloride ion mediated by an excited photoredox catalyst is a difficult task. We now report that 8Rf8‐4CzIPN, an electron‐deficient fluorous derivative of the benchmark 4CzIPN photoredox catalyst belonging to the donor‐acceptor carbazole‐cyanoarene family, is not only a better photooxidant than 4CzIPN, but also becomes an excellent host for the chloride ion. Combining these two properties ultimately makes the self‐assembled 8Rf8‐4CzIPN•Cl− dual catalyst highly reactive in redox‐neutral Giese‐type C(sp3)−H bond alkylation reactions promoted by the chlorine radical. Additionally, because of its fluorous character, the efficient separation/recovery of 8Rf8‐4CzIPN could be envisioned.

The role of the STAS domain in SLC26A9 for chloride ion transporter function

The anion exchanger solute carrier family 26 (SLC26)A9, consisting of the transmembrane (TM) domain and the cytoplasmic STAS domain, plays an essential role in regulating chloride transport across cell membranes. Recent studies have indicated that C-terminal helices block the entrance of the putative ion transport pathway. However, the precise functions of the STAS domain and C-terminal helix, as well as the underlying molecular mechanisms governing the transport process, remain poorly understood. In this study, we performed molecular dynamics simulations of three distinct models of human SLC26A9, full-length, STAS domain removal (ΔSTAS), and C-terminus removal (ΔC), to investigate their conformational dynamics and ion-binding properties. Stable binding of ions to the binding sites was exclusively observed in the ΔC model in these simulations. Comparing the full-length and ΔC simulations, the ΔC model displayed enhanced motion of the STAS domain. Furthermore, comparing the ΔSTAS and ΔC simulations, the ΔSTAS simulation failed to exhibit stable ion bindings to the sites despite the absence of the C-terminus blocking the ion transmission pathway in both systems. These results suggest that the removal of the C-terminus not only unblocks the access of ions to the permeation pathway but also triggers STAS domain motion, gating the TM domain to promote ions’ entry into their binding site. Further analysis revealed that the asymmetric motion of the STAS domain leads to the expansion of the ion permeation pathway within the TM domain, resulting in the stiffening of the flexible TM12 helix near the ion-binding site. This structural change in the TM12 helix stabilizes chloride ion binding, which is essential for SLC26A9’s alternate-access mechanism. Overall, our study provides new insights into the molecular mechanisms of SLC26A9 transport and may pave the way for the development of novel treatments for diseases associated with dysregulated ion transport.

Impact of basalt fiber reinforced concrete in protected buildings: a review

This study investigates on the impact of basalt fiber reinforcement concrete in protected building and structures. Basalt fibers, derived from the melting of basalt rock at temperatures ranging from 1,500 to 1700°C, are recognized as sustainable and environmentally friendly fiber materials. Various studies have revealed differing optimal percentages of basalt fibers for enhancing the mechanical and chemical properties of concrete. The objectives of this paper are to investigate the effects of basalt fibre reinforcement on mechanical properties like tensile, compressive, and bending strengths. Additionally, performance indicators like void content, water absorption, chloride ion permeability, alkali and slag resistance, temperature stability, shrinkage characteristics, and abrasion resistance will be evaluated. Basalt fibre is typically utilised to increase the mechanical properties and durability of concrete, which has an impact in the effect on protected buildings and structures. The findings indicate that the most effective percentage range for improving mechanical properties lies between 0.1% and 0.3% of basalt fibers. Notably, concrete reinforced with basalt fibers demonstrates superior mechanical and chemical performance in alkaline environments compared to other fiber types. Moreover, the addition of 0.5% basalt fibers to concrete has been shown to significantly reduce chloride ion penetration, as evidenced by a decrease in RCPT load from 2,500 (C) to 1900 (C), indicative of enhanced chloride resistance. Reinforced concrete containing basalt fibers exhibits remarkable temperature resistance, withstanding temperatures exceeding 800°C due to its high-water absorption capacity. Additionally, basalt fibers exhibit resilience at temperatures up to 200°C. However, it is noted that the introduction of 0.14% basalt fibers leads to a slight increase in water absorption from 4.08 to 4.28. In general, basalt fibres are beneficial to many aspects of concrete; they strengthen resistance to temperature, alkali, acid exposure, and chloride while also improving mechanical qualities such as bending and tensile strength. The development of basalt fibres that extend building lifespans and improve concrete quality for structural engineering applications is making encouraging strides, according to all the results.

A comprehensive understanding of the role of sodium sulfate in calcium looping via in-situ experiments and DFT studies: Performance and mechanism

Adding alkali metal salt promoters to calcium-based materials can influence the cycling performance of CaO-based sorbents. So far, most research on alkali metal salts focus on carbonate and chloride salts, while little attention is paid to sulfates. In this paper, we present an in-depth study of the role of Na2SO4 in calcium looping via in-situ experiments and DFT simulations. The results show that the effective conversion rate of Na2SO4-CaO after one cycle is 0.779 with the energy storage density of 2476.1 kJ/kg, while the effective conversion rate of CaO is 0.562 with the energy storage density of 1786.4 kJ/kg. After 80 cycles, the effective conversion and energy storage density of Na2SO4-CaO are lower than CaO, which is attributed to Na+ reducing the surface energy and accelerating the sintering. Moreover, an optimization strategy based on coordination effect among Na2SO4, CaO and inert oxides is proposed to slow down the sintering problems. Among them, Na2SO4-(CaO + ZnO) has the best adsorption performance and energy storage performance and ZnO is cheap, which can be considered a cost-effective sorbent. This work provides a new approach for developing efficient, simple and cost-effective calcium-based materials by simultaneously achieving fast reaction rates and good cycling stability of CaL.

One-Pot Synthesis of Diverse Anion-Binding Macrocycles

AbstractA one-pot synthetic protocol to access a diverse library of diamide–diester macrocycles from the same starting materials is reported. The molecular symmetry can be readily tuned based on the reaction sequence, while the core structure can be varied using amino acids and aromatic building blocks. The first class of macrocycles with C2 axes in their molecular plane were obtained in 24 h with 40–70% yield, while another class with C2 axes perpendicular to the plane were synthesized in 18 h in 10–30% yield. The phenyl- and serine-derived macrocycles of the first class could bind acetate, chloride, and phosphate ions. These macrocycles can be functionalized with hydrophobic groups and potentially be used as ion transporters.

Understanding the corrosion and structural potential of 95Al-RHA-PSA composite for advance application

Material reinforcement has become popular in improving properties, such as corrosion, mechanical and wear behaviour. Aluminium-base composite has found usefulness in the technology of automobiles, aerospace, and marine and designs of a wide range of components. The use of reinforcement materials increases the efficiency of composites products and reduces overall expenses. Aluminium alloy composite provides low-cost advantages over many other matrix composites. The use of agro-based waste material as reinforcement alternatives is becoming very important because of its close to nothing cost and availability to produce nanoparticles. This study aim to use agro based processed rice hulls (RHA) and periwinkle shells (PSA) to improve aluminium properties in an attempt to gain prominence in today's automotive advancements. SEM imaging was conducted at a magnification of 15,000 at 20 kV to evaluate structural properties, while X-ray Diffractometer (XRD) images were utilized to observe the crystallography peaks and phases of the developed alloys. Rockwell hardness testing, in accordance with ASTM E18 standards, involved subjecting the samples to a 30 kg/f load for 30 s using a hardened steel ball for indentation. Corrosion properties were assessed via linear polarization resistance and open circuit potential measurements. From the results, there is a higher corrosion resistance from 95Al-RHA-PSA composite samples compared to the control (aluminium alloy) samples. The lower values of jcorr and higher values of Pr of the 95Al-RHA-PSA composite samples also indicated that the RHA and PSA content of the composite minimized the penetration of chloride ions into the active sites of the composite samples. The 95Al-2RHA-3PSA composite sample exhibited the lowest Cr of 1.4172 mm/year, lowest jcorr of 1.220E-04 A/cm2 and highest Pr of 70.02 Ω, which indicated the 95Al-2RHA-3PSA composite sample provided the most significant passivation, leading higher corrosion resistance. The XRD of the control sample has several crystallographic phases, with AlNi3Al2SiO8 exhibiting the most elevated peak intensity at about 550 a.u (2θ = 39°). In comparison, the peak intensity of the other crystals is less than 200 a.u. However, the 95Al-RHA-PSA composite samples exhibited crystallites of higher peak intensities and better morphological strengthening characteristics. The findings suggest promising prospects for the development of sustainable and long-lasting aluminium alloy for automotive use.

The fate and biostimulant potential of metal lactates in silt loam soil

AbstractConventional farming practices have negatively impacted micronutrient fertility and overall soil health. Metal lactates are an organic micronutrient amendment that provide both a labile carbon substrate as well as mineral nutrition for plant and microbial growth. To determine the ability of metal lactates to provide readily available micronutrients, Zn, Cu, Mn, Ni, and Co in lactate and chloride salt form were amended to soils and incubated for 28 days. Operationally defined speciation was determined using sequential extraction on samples incubated for 1, 5, or 28 days. The results show a comparable distribution of metals in chloride and lactate form; however, differences were detected in water‐soluble and exchangeable Ni and Zn at each timepoint. For example, in the water exchangeable fraction, there was 2.6%–2.9% less Ni and 0.2%–0.3% less Zn in the metal lactate‐treated soil compared to soil treated with metal chlorides. Furthermore, carbonate‐bound Ni averaged 4.1% and 4% less in metal lactate‐treated soils as compared to metal chloride‐treated soils on days 1 and 5, and Cu decreased 2.9%–3.3% during the treatment period for the lactate‐bound form. Additionally, microbial phospholipid fatty acid (PLFA) was performed and found a stimulatory effect of metal lactates on bacterial biomass with an increase of 12%–18% relative to the metal chloride treatment. Results from this study support the use of metal lactates as a sustainable alternative to conventional fertilizers by providing bioavailable micronutrients for plant nutrition in addition to a labile carbon source to support the growth of microbial populations.

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.

Synthesis of Green Brucite [NixMg1−x(OH)2] by Incorporation of Nickel Ions in the Periclase Phase (MgO) Applied as Pigments

Magnesium oxide is typically white and can be colorized with transition metal insertion by doping. We present the preparation of a green-colored hydroxide by the exchange of Mg2+ on the crystalline lattice with Ni2+ in MgO, using three nickel salts. MgOst was prepared by the colloidal starch suspension method, using cassava starch. The oxides and hydroxides, before and after, were characterized by X-ray diffraction (XRD), and show that a phase change occurs: a transition from periclase (MgO) to brucite (Mg(OH)2) due to the incorporation of nickel ions from different salts (acetate, chloride, and nitrate), resulting in the solid solution [NixMg1−x(OH)2]. The FTIR spectrum corroborates the crystallographic structure identified through XRD patterns, confirming the formation of a crystal structure resembling brucite. The new samples present a green color, indicative of the incorporation of the Ni2+ ions. The antimicrobial activity of products resulting from the doping of magnesium oxide with nickel and the precursor MgOst was assessed through the minimum inhibitory concentration (MIC) test. The evaluation included three bacterial strains: Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922), Salmonella gallinarum (ATCC 9184), and a yeast strain, Candida albicans (ATCC 10231). The obtained results were promising; the tested samples exhibited antimicrobial activity, with a MIC ranging from 0.312 to 0.625 μg.μL−1. The nickel compound, derived from the precursor chloride salt, demonstrated superior MIC activity. Notably, all tested samples displayed bactericidal activity against the S. aureus strain and exhibited a broad spectrum of inhibition, encompassing both Gram-positive and Gram-negative strains. Only the nickel compounds derived from precursors with acetate and nitrate anions demonstrated antimicrobial activity against C. albicans, exhibiting a fungistatic behavior. Based on the conducted studies, [NixMg1−x(OH)2] has emerged as a promising antimicrobial agent, suitable for applications requiring the delay or inhibition of bacterial growth.

Research on NaCl-KCl High-Temperature Thermal Storage Composite Phase Change Material Based on Modified Blast Furnace Slag

The high-temperature composite phase change materials (HCPCMs) were prepared from solid waste blast furnace slag (BFS) and NaCl-KCl binary eutectic salt to achieve efficient and cost-effective utilization. To ensure good chemical compatibility with chlorine salt, modifier fly ash (FA) was incorporated and subjected to high-temperature treatment for the processing of industrial solid waste BFS, which possesses a complex chemical composition. The HCPCMs were synthesized through a three-step process involving static melting, solid waste modification, and mixing–cold pressing–sintering. Then, the influence of the modification method and the amount of SiC thermal conductivity reinforced material on chemical compatibility and thermodynamic performance was explored. The results demonstrate that the predominant phase of the modified solid waste is Ca2Al2SiO7, which exhibits excellent chemical compatibility with chlorine salt. HCPCMs containing less than 50 wt.% chloride content exhibit good morphological stability without any cracks, with a melting temperature of 661.76 °C and an enthalpy value of 108.73 J/g. Even after undergoing 60 thermal cycles, they maintain good chemical compatibility, with leakage rates for melting and solidification enthalpies being only 6.3% and 0.23%, respectively. The equilibrium was achieved when 40 wt.% of chloride salt was encapsulated upon the addition of 10% of SiC, and the incorporation of SiC resulted in an enhancement of thermal conductivity for HCPCMs to 2.959 W/(m·K) at room temperature and 2.400 W/(m·K) at 200 °C, with an average increase of about 2 times. The cost of the prepared HCPCMs experienced a significant reduction of 81.3%, demonstrating favorable economic performance and promising prospects for application. The research findings presented in this article can offer significant insights into the efficient utilization of solid waste.

Preliminary investigation and life cycle assessment of artificial reefs with recycled brick-concrete aggregates

An economical and environment-friendly artificial reef concrete using fully recycled brick-concrete aggregate as raw material was proposed. This study investigates the mechanical properties, drying shrinkage, chloride ion penetration, and biological adaptability of the reef. A comparative analysis is conducted on the environmental impacts (EI), carbon emission impact and cost efficiency of artificial reefs, considering natural aggregate concrete and recycled brick-concrete aggregate concrete at the material level. The results indicate that the use of recycled brick-concrete aggregates can achieve service performance equivalent to that of natural aggregates. Field investigations involving samples immersed in seawater for six months reveal the positive trapping effects of recycled materials on aquatic organisms. The Life Cycle Assessment (LCA) results reveal that achieving a 100 % replacement rate of recycled brick concrete aggregate (RBCA) creates a positive feedback loop for carbon emissions when appropriately incorporating industrial waste materials like fly ash and silica fume. In comparison to ordinary concrete, the utilization of recycled materials can significantly reduce construction costs, up to 63.7 %, thereby presenting notable economic advantages.

Ferric nitrate-induced phase transformation of Bi2O3 with ion exchange property for enhanced chloride removal from high-salinity wastewater

The bismuth oxide (Bi2O3)-based method for removing chloride (Cl−) ions has garnered considerable interest because of its superior selectivity and efficiency in removing Cl−. However, the slow release of Bi3+ poses a challenge to the effectiveness of Bi2O3. In this study, a novel chloride removal agent composed mainly of Fe3+-doped Bi5O7NO3 (BF-x) was synthesized through the phase transformation of Bi2O3 by ferric nitrate. By optimizing the Fe/Bi mass ratio to 3 %: 1 (BF-3), a remarkable Cl− removal efficiency of 86.4 % was achieved, representing a substantial improvement compared to the 31.2 % removal efficiency observed for pure Bi2O3. The investigation of the mechanism and formation energy calculation revealed the inherent instability of Bi5O7NO3 in comparison to that of Bi2O3, which facilitated the release of Bi3+ and enabled the direct formation of BiOCl precipitate through ion exchange of NO3– with Cl−. The synergistic effect of chemical precipitation and ion exchange contributes to the excellent Cl− removal performance of BF-3. The final Cl− removal product, comprised of BiOCl and FeOOH, exhibited significant photocatalytic efficacy in the decomposition of organic contaminants. This study proposes a novel strategy for designing and preparing high-efficiency Cl− removal agents.

Unravelling the effect of molecular interactions on macroscale properties in Sustainion anion exchange membrane (AEM) under hydrated conditions using MD simulations

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.

Evaluating boron removal from aqueous solutions using membrane capacitive deionization (MCDI): Efficacy and limitations

In the present study, the feasibility of employing activated carbon-based membrane capacitive deionization (MCDI) for boron removal was systematically evaluated under various conditions, including different applied voltages, pH levels, initial boron concentrations, and boron-to-chloride molar ratios. When the pH of the solution exceeds 9, borate ions with a negative charge become the predominant species, facilitating easier removal during the charging period of both capacitive deionization (CDI) and MCDI. As demonstrated, MCDI can achieve a relatively higher mean deionization capacity of 2.84±0.19 mg/g at 1.2 V and pH 11, associated with a corresponding high charge efficiency of 99% and low energy consumption of 0.04 kWh/m3. More specifically, the results revealed a significant improvement in boron removal performance with the incorporation of ion exchange membranes into CDI. Additionally, MCDI exhibited considerably higher selectivity of boron over chloride ions compared to CDI, attributed to the charge promotion effect. However, the selectivity coefficient of boron over chloride was still need to be improved, identified as the primary constraint of MCDI. With the same ionic charge, chloride with smaller hydrated radius compared to boron was preferentially electrosorbed, thereby suppressing the electrosorption of borate ions. These findings suggest potential future directions for the treatment of boron in practical applications such as seawater desalination and wastewater reclamation in the semiconductor industry.

Environmental impacts and performance assessment of recycled fine aggregate concrete.

Natural disasters and human demolition create vast amounts of construction and demolition waste (CDW), with a substantial portion being concrete waste. Managing this concrete waste is a daunting challenge for developing countries with limited resources, aiming to mitigate its harmful environmental effects. Therefore, the proposed approach involves using recycled fine aggregates (RFA) instead of fresh fine aggregates (FFA) in concrete, which aligns closely with achieving sustainable environmental objectives. Extensive laboratory tests were conducted to assess the effects of adding RFA to concrete. The influence of 0 to 100% RFA replacement and different curing times was investigated on compressive strength, tensile strength, resistance against chloride ion penetration and chemicals exposure, and quality of aggregates. So, around 30%, 35%, 20%, and 79% reductions in compression strength, tensile strength, modulus of elasticity, and workability were estimated when 100% RFA was used in recycled aggregate concrete (RAC). However, according to results analyses, the performance of RAC is reliable up to 50% of RFA in proposed conditions and mix design. In addition, major environmental impacts such as global warming potential, aquatic eutrophication, and aquatic acidification were reduced by 47%, 40%, and 18%, respectively, for concrete having 50% RFA than concrete having 100% FFA.