Chloride Concentration Research Articles

Effect of semi-permeable film stabilisation treatment on dry and wet cyclic corrosion behaviour of Q420qENH weathering steel plates and welded joints in deicing salt media

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 Iβ-FeOOH+FeOCl /Iα-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.

Development of Environmental Monitoring Sensor for Steel Corrosion in Concrete based on Micro-Electro-Mechanical Systems (MEMS)

Many bridges located near marine environments usually have high risk to lose their structural performance due to corrosion of reinforcing bars with chloride attack. While a huge amount of budget to maintain may be consumed for the structural maintenance methodologies, an efficient monitoring system for Reinforced Concrete (RC) structures in the corrosive environment is strongly demanded. Thus, structural health monitoring in real situations is significant for bridge asset management. The alternative way for preventing severe damage propagation is proactively monitoring the environmental condition containing chloride ion and its effect on the durability of concrete structures, for which numerous methods have been conventionally suggested such as dry gauze method to capture chlorides in air. In this study, Micro Energy Harvester (MEH) based on Micro-Electro-Mechanical Systems (MEMS) is technically applied to develop a sensor to identify the corrosion environment with chlorides in the exposure condition. MEMS is a rapidly evolving device, which enables to monitor the changes in natural frequency and amplitude at nodal locations of the targeting structure due to vibration-based electrostatic power generation induced by the corrosive environment. The purpose of this research is to develop a system for detecting the high corrosion-prone areas and finding the suitable metal sheet material for various chloride ion conditions, using the metal sheet as a cantilever structure for the MEMS device. 4 types of metal, aluminium, copper, iron and zinc are considered for the parametric experiments. Several scenarios are considered including chloride ion concentration, temperatures, and wet and dry conditions to compare the dominant frequency changes of each metal sheet and determine their sensitivity to corrosion environment. From the preliminary results, iron and zinc have a significant drop in frequency with the elapsed exposure period, which indicates that they are highly sensitive to the external chloride ion environment. These results offer an innovative and proactive approach to structural health monitoring for further developed applications. It enables prompt maintenance and early detection of potential issues for corrosion of steel bars in concrete, ensuring the longevity and safety of RC bridge structures.

Preparation and characterization of cementitious materials from dedioxinized and dechlorinated municipal solid waste incineration fly ash and blast furnace slag

To address the resource utilization issue of MSWI fly ash, a method has been proposed to prepare cementitious materials using harmlessly processed MSWI fly ash (HPFA). After washing and thermal treatment, The physicochemical properties of HPFA were characterized using QXRD, ICP, XRF, and GC-MS. Cementitious materials were prepared using HPFA, gypsum and blast furnace slag (BFS) as raw materials, Through XRD, TG, FTIR, TEM, and SEM-EDS methods, the hydration and hardening characteristics were investigated, and the leaching of heavy metals from solidified materials in simulated surface water and landfill environments was evaluated using ICP-MS. The results indicate that the harmless treatment can effectively reduce the chloride content and dioxins in MSWI FA but still contains heavy metals. The addition of HPFA (10%-50%) can enhance the compressive strength of cementitious materials, accelerate the exothermic process of cement hydration, and increase the total heat release of hydration, implying an improvement in the degree of hydration of the system.HPFA could effectively promote the hydration of gypsum and BFS, resulting in the higher formation of ettringite and C-(A)-S-H（C/S=1，Al/Si=0.3）.The formation of C(Mg/Fe)-(A)-S-H suggests that the Fe-Mg solid solution phase in HPFA may have participated in the hydration reaction. The increased stability of highly cross-linked (Q4) silicate tetrahedral structure with time implies that the material may have good durability. The leaching amount of heavy metals met the standards of Class I surface water in GB3838–2002 and GB5085.3–2007 which implies that the material has environmental safety. This study innovatively provides a preparation path for harmless MSWI fly ash and cementitious material ratios, reveals the hydration mechanism of HPFA in cementitious materials, evaluates the solidification ability of heavy metals, and provides important ideas for the resource utilization of MSWI fly ash.

Promotive Effects of Chloride and Sulfate on the Near-Complete Destruction of Perfluorocarboxylates (PFCAs) in Brine via Hydrogen-tuned 185-nm UV Photolysis: Mechanisms and Kinetics.

Hydrogen-tuned 185 nm vacuum ultraviolet (VUV/H2) photolysis is an emerging technology to destroy per- and polyfluoroalkyl substance (PFAS) in brine. This study discovered the promotive effects of two major brine anions, i.e., chloride and sulfate in VUV/H2 photolysis on the hydrated electron (eaq-) generation and perfluorocarboxylates (PFCAs) destruction and established a kinetics model to elucidate the promotive effects on the steady-state concentration of eaq- ([eaq-]ss). Results showed that VUV/H2 achieved near-complete defluorination of perfluorooctanoic acid (PFOA) in the presence of up to 1000 mM chloride or sulfate at pH 12. The defluorination rate constant (kdeF) of PFOA peaked with a chloride concentration at 100 mM and with a sulfate concentration at 500 mM. The promotive effects of chloride and sulfate were attributed to an enhanced generation of eaq- via their direct VUV photolysis and conversion of additionally generated hydroxyl radical to eaq- by H2, which was supported by a linear correlation between the predicted [eaq-]ss and experimentally observed kdeF. The kdeF value increased from pH 9 to 12, which was attributed to the speciation of the H·/eaq- pair. Furthermore, the VUV system achieved >95% defluorination and ≥99% parent compound degradation of a concentrated PFCAs mixture in a synthetic brine, without generating any toxic perchlorate or chlorate.

Fluid and electrolyte balance following consumption of skimmed milk and a plant-based soya beverage at rest in euhydrated males.

Cow's milk is one of the most hydrating beverages, but many individuals choose not to consume dairy in their diet due to intolerance, allergy, or dietary preference. Milk is commonly replaced with plant-based beverages, including soya which has the most comparable protein content, but little is known about their hydration potential. This study compared fluid and electrolyte balance responses between a soya beverage and skimmed cow's milk. Ten healthy males [age 27 (6) y; body mass index 24.6 (2.3) kg/m2] completed two randomised counterbalanced trials, involving consuming 1000mL water from approximately isocaloric amounts of skimmed cow's milk (MILK) or a sweetened soya beverage (SOYA), in four aliquots over 30min in a euhydrated fasted state. Volume, specific gravity, and electrolyte (sodium, potassium, chloride) concentrations were determined in total-void urine samples collected pre-/post-beverage ingestion, and hourly for 180min thereafter. Hunger, thirst, nausea and stomach fullness were rated proximal to urine samples. Total urine mass (MILK, 986 ± 254g; SOYA, 950 ± 248g; P = 0.435) and urine specific gravity (P = 0.156) did not differ between trials. Potassium balance was greater in SOYA 0-180min post-beverage (P ≤ 0.013), whilst chloride balance was greater in MILK 0-120min post-beverage (P ≤ 0.036). Sodium balance (P = 0.258), total electrolyte balance (P = 0.258), and subjective measures (P ≥ 0.139) were not different between trials. Replacing cow's milk with a soya beverage did not negatively impact fluid balance in healthy young males, making it a viable option for those who choose not to consume dairy in their diet.

The Mechanical Properties and Chlorine Resistance of Concrete Based on the Effects of Pouring Interval Time

In practical engineering construction, differences in time intervals during concrete pouring arise due to issues in concrete quality control and construction procedures, thereby affecting the mechanical and durability properties of concrete. This study conducted compressive strength tests, splitting tensile strength tests, and natural immersion tests to investigate the influence of time intervals in layered pouring on the mechanical strength and chloride ion concentration distribution of staged pouring concrete. Additionally, the study elucidated the mechanism by which pouring interval time affects the mechanical properties and resistance to chloride ion erosion of staged pouring concrete at the microstructure level. The results indicate that compared to ordinary concrete specimens, the splitting tensile strength of staged pouring concrete demonstrates a continuous decrease with increasing pouring interval time. The most significant splitting tensile strength decrease occurred at a 24 h interval. The compressive strength of staged pouring concrete initially decreases and then increases with increasing pouring interval time. At a pouring interval time of 12 h, the compressive strength of staged pouring concrete decreased the most. Results from the natural immersion tests demonstrate that chloride ion concentrations at the bonding interface and on both sides of staged pouring concrete increase continuously with the extension of pouring interval time. The chloride ion concentration at the bonding interface is consistently higher than that on both sides, and the difference between them decreases with increasing diffusion depth. The chloride ion concentration difference ΔC was proposed to evaluate the influence of bonding interface performance on chloride ion concentration, which decreases to varying degrees with increasing depth. The findings of this study can provide guidance for the research on the mechanical properties and durability of staged pouring concrete in practical engineering construction, as well as for engineering protective measures.

Identification of deep Czech Republic–Austria transboundary aquifer discharge and associated river chloride loading

The deep transboundary aquifer of regional scale along the Czech Republic–Austria border in Central Europe serves as a thermal-mineral water resource for balneotherapy and plays an important role in the region’s development. The aquifer is composed mostly of Jurassic carbonates at depths from 160 to − 3000 masl. Despite more than two decades of exploitation, no complex analysis of groundwater flow directions and groundwater fluxes ever took place. Now, cross-border cooperation enabled the research team to gather crucial information on the Jurassic aquifer. For a better understanding of the groundwater flow system, a numerical model was developed. To simulate the effect of variable density and viscosity occurring in such a deep aquifer, the SEAWAT numerical model was used. The simulation shows that there is an inflow of low mineralised groundwater from the crystalline outcrops in the northwest and inflow of saline groundwater from southeast. Aquifer discharge was identified along the zone partly corresponding to the course of the Dyje River. To check the model’s accuracy, the river water was sampled together with streamflow measurements. Detected sections of increasing chloride concentration indicate zones of the Jurassic aquifer discharge into the Dyje River. The discharge rate of 85 L/s derived from streamflow and chloride concentrations matches the value computed by the model. The relatively high discharge of the Jurassic aquifer contributes significantly to the high chloride loading observed in the Dyje River.

Electrochemical Polishing Method for Titanium Alloys with a Microgroove Structure

TI–6AL–4V alloys are widely used in various fields owing to their excellent corrosion resistance, high-temperature resistance, and low-temperature toughness. Herein, a microgroove fixture was used to simulate the microgrooves in a titanium alloy with different aspect ratios to study the influence of the electrolyte flow rate on the polishing effect. The optimization of the electrochemical polishing parameters was conducted using experiments and simulations. The effects of process parameters, such as the concentration of sodium chloride (NaCl) and zinc chloride (ZnCl2), polishing time, and processing voltage, on the quality of the post-polished surface were studied. Experiments were conducted on microgrooves with different aspect ratios under the optimized polishing process parameters. Changes in the surface elements of the microgrooves after polishing were detected. The experimental results indicated that the optimal electrochemical polishing solution flow rate, NaCl concentration, ZnCl2 concentration, polishing time, and processing voltage were 0.2 m/s, 4.0 wt.%, 0.4 wt.%, 8 min, and 90 V, respectively. After 8 min of electrochemical polishing, a TiO2 passivation film was formed on the surface of the microgroove. The surface roughness of the notch and bottom of the microgroove decreased from 250 nm to below 40 nm, with a minimum of 24.5 nm.

Effect of high-temperature molten salt corrosion on the mechanical properties of stainless steel

The corrosivity of molten salt can be detrimental to the safe operation and longevity of concentrated solar thermal power generation equipment. Additionally, the presence of impurity Cl− can increase corrosion on metal materials, leading to mechanical property degradation. To assess the extent of this effect, the corrosion behaviour of three types of stainless steel (304, 316L, and 347H) in molten salt at high temperatures was studied using the loss-in-weight method and tensile tests. According to the findings, the Rdepths of 304, 316L, and 347H stainless steels are 0.0018 mm/a, 0.0016 mm/a, and 0.0019 mm/a, respectively, resulting in a decrease in elongation of 12.2%, 7.0%, and 3.7% after 720 h of corrosion at 600°C. Furthermore, at a higher temperature of 680°C, the Rdepths of all stainless steels increased, and the elongation decreased by 25.4%, 18.9%, and 13.5%, respectively. Similar corrosion behaviour was observed in 347H stainless steel with increased chloride ion concentration. However, the yield strength and tensile strength of stainless steel did not exhibit significant changes under different experimental conditions. The corrosion mechanism of metal alloys in molten salt is mainly due to the selective corrosion of Cr and its dissolution into molten salt in the form of ions.

Phosphonic Chloride Assisted Fabrication of Highly Emissive Mixed Halide Perovskite Films in Ambient Air for Blue Light-Emitting Diodes.

Blue perovskite light-emitting diodes (LEDs) have emerged as promising candidates for full-color display and lighting applications. However, the fabrication of blue-emitting perovskite films typically requires an inert environment, leading to increased complexity and cost in the manufacturing process, which is undesirable for applications of perovskite LEDs. Herein, we report a strategy to fabricate bright blue-emitting perovskite films in ambient air by incorporating phosphonic chlorides in a perovskite precursor solution. We used two different phosphonic chlorides, diphenylphosphonic chloride (DPPC) and phenylphosphonic dichloride (PPDC), and comparatively studied their effects on the properties of perovskite films and the blue LEDs. It is found that PPDC possesses a stronger chlorination ability due to higher hydrolysis reactivity; meanwhile, it has a stronger interaction with the perovskite compared to DPPC, resulting in an improved film quality and enhanced blue emission with a photoluminescence quantum yield of 45%, which represents the record value for the air-processed blue perovskite films. Blue perovskite LEDs are fabricated, and the emission wavelengths are effectively tuned by controlling the concentration of phosphonic chlorides. Benefiting from the optimized perovskite films with reduced nonradiative recombination and promoted charge injection and transport, the PPDC-derived blue perovskite LEDs exhibit improved performance with an external quantum efficiency of 3.3% and 1.2% for the 490 and 480 nm emission wavelength, respectively.

Updating Durability Models for Concrete Structures in Chlorine Environment Based on Detection Information

The assessment of concrete structure durability in chlorine environments is significantly impacted by the uncertainty inherent in existing durability models. It introduces an integrated approach for updating these models based on the detection information of existing structures. This approach narrows the gap between theoretical predictions and observed structural durability. Specifically, we refined the probability model of critical chloride content by analyzing steel bar corrosion sample proportions using Bayesian theory for greater accuracy. The enhanced model enables more reliable life expectancy prediction, forming a solid foundation for maintaining and strengthening existing structures. This method was demonstrated through a case study of a reinforced concrete industrial building with a service life of 12 years.

Chloride transport through the interface in repaired marine concrete systems in a cracked state

AbstractIn repaired marine concrete structures, generally, an interface exists between old and new concrete, however, the influence of this interface on durability has yet not been well understood. In this study 18 reinforced concrete beams with new‐to‐old concrete interfaces (N–O interfaces) were designed to investigate chloride transport through a cracked interface. The effects of crack widths at the interface, concrete strain, and the chloride exposure time were considered, respectively. Results showed that the N–O interfaces having crack widths between 0 and 0.13 mm posed no significant impact on the chloride transport in the depth direction of the N–O interfaces, however when the crack width exceeded 0.13 mm, the chloride concentration gradually increased as the crack width increased. Chloride transport through the horizontal direction of the N–O interface was different between new and old concrete matrix when the crack width reached 0.18–0.20 mm. The surface layer with a range of 5–10 mm depth of concrete was sensitive to the variation of concrete strain, and the evolution of chloride concentration with concrete strain presented a logarithm relationship. Within the exposure period between 60 and 90 days, the increasing rate of chloride concentration was higher than that between 30 and 60 days. The study can provide some recommendations for repair of concrete elements exposed to a chloride‐laden exposure environment.

#2725 Chronic kidney disease is a risk factor for hyperchloremic metabolic acidosis after plasma exchange

Abstract Background and Aims Observational studies have demonstrated that metabolic acidosis due to hyperchloremia is an often encountered metabolic disorder following plasma exchange (PE) with an albumin-saline solution. Because of the reduced capacity for acid and chloride excretion, we hypothesized that patients with chronic kidney disease have the highest risk for hyperchloremic metabolic acidosis, in particular when multiple PE sessions are performed in a limited period. Method We prospectively collected data from all patients who received PE at Amsterdam UMC, between February 2023, and January 2024. We collected data on demographics, exchanged plasma volume, replacement fluids, and collected blood for analysis of sodium, chloride and bicarbonate before and after plasma exchange. We selected patients who received ≥5 plasma exchanges in an intensive cycle (≥4.2 sessions/week). We excluded patients who received Omniplasma, intravenous sodium bicarbonate or dialysis during the PE period. We assessed the effect of PE and kidney function on plasma bicarbonate and chloride concentration throughout the PE period with repeated measures mixed ANOVA, corrected for baseline plasma bicarbonate concentration, volume of exchanged plasma and PE intensity. Results Data from 26 patients, corresponding to 130 plasma exchanges, were included in the analysis. The mean age was 56 ± 14 years and 46% was female. Mean eGFR was 45 ± 14 ml/min/1.73 m2. Patients with an eGFR ≤59 ml/min/1.73 m2 (n = 17) had a significantly lower baseline plasma bicarbonate concentration (19.0 ± 2.8 versus 24.0 ± 1.9 mmol/L; p < 0.001) and used oral bicarbonate supplements (29% versus 0%; p = 0.02) more often than patients with an eGFR ≥60 ml/min/1.73 m2 (n = 9). Despite the lower baseline plasma bicarbonate and more frequent use of oral bicarbonate supplements, the plasma bicarbonate levels decreased the most in subjects with an eGFR ≤59 ml/min/1.73 m2 (mean difference −4.2; 95% CI −7.1 to −1.3; p = 0.006; Fig. 1A) during a cycle of 5 PE sessions. Baseline plasma chloride concentration was similar in both groups (103 ± 7 vs 103 ± 4 mmol/L) and increased the most in patients with an eGFR ≤59 ml/min/1.73 m2 (mean difference −1.4; 95% CI −2.2 to 5.0; p = 0.426; Fig. 1B). Conclusion Repeated plasma exchange with albumin-saline as a replacement fluid is associated with a significant decrease in plasma bicarbonate concentration in patients with impaired kidney function. Future studies should determine whether this hyperchloremic metabolic acidosis has impact on the patients’ symptoms or long-term outcome.

#1694 The Cl-/HCO3-ratio as a predictor of decompensated metabolic acidosis in CKD stages G4 and G5

Abstract Background and Aims Metabolic acidosis (MA) is a common disorder in patients with chronic kidney disease (CKD) and is associated with both a normal anion gap (AGMA) and a high anion gap (HAGMA). AGMA is typically detected early in the course of CKD, whereas HAGMA appears later in the course of CKD due to the accumulation of non-chloride anions such as phosphate, sulphate, and an array of organic acids. The anion gap (AG) is usually calculated as the difference between serum concentration of cations and anions using the formula AG=Na+-(Cl−+HCO3−). The most important anions in serum are chlorides (Cl−) and bicarbonates (HCO3−). The more advanced the CKD, the higher the AG. As eGFR decreases, a reciprocal decrease in HCO3− and an increase in chloride concentration is observed to correct the AG. The aim of this study is to determine whether the Cl−/HCO3− ratio can be used to predict decompensated metabolic acidosis with pH decline in CKD stages G4 and G5. Method A total of 115 patients (median age 63 ± 17 years), with CKD stage G4 or G5 were enrolled in this cross-sectional study. Demographic and comorbidity data was obtained from medical records, and the Charlson Comorbid Index (CCI) was calculated. A two-year clinical follow-up was conducted to assess the clinical status of each patient. The number of patients, the time dialysis was started, and deaths were all recorded. All patients were qualified for arteriovenous fistula creation in predialysis period. The arterial (A) and venous (V) blood samples were taken during surgery, directly after vessel dissection, and evaluated in a point of care testing analyzer (POCT). The ratio of arterial Cl− and HCO3− concentration were calculated. According to mean arterial pH (pH-A) the group was divided into Group A pH-A<7.33 and Group B pH-A≥7.33 (Table 1). Results In Group A was significantly lower pH-A, pH-V, HCO3−-A, HCO3−-V, pCO2-A, pCO2-V, and significantly higher both arterial and venous Cl− and the Cl−/HCO3− ratios compared to Group B. No such differences were observed in the case of AG. Cl−/HCO3−-A ratio negatively correlated with pH (r = −0.77, p < 0.01) (Fig. 1A). The discriminative power of Cl−/HCO3−-A ratio for predicting pH-A≤7.33 was 0.917 (95% confidence interval [CI] = 0.87–0.97; p < 0.01) which provided 87% sensitivity and 84% specificity (Fig. 1B). The best cut-off was 6.22 (mmol/l)/(mmol/l). Conclusion The Cl−/HCO3− ratio lower than 6.22 (mmol/l)/(mmol/l) may be used as predictor of decompensated metabolic acidosis.

Decrease in electrolyte after vitrectomy surgery may affect the results of forensic investigations using vitreous humor

PurposeVitreous humor (VH) is used for postmortem biochemical studies because it is well protected in an uncontaminated state even after death. The goal of this research was to investigate electrolyte concentrations in the VH from human eyes with and without a history of vitrectomy surgery.MethodsWe analyzed the sodium (Na), potassium (K), chloride (Cl) and magnesium (Mg) concentrations from 34 VH samples from 34 patients. Eleven samples were from eyes with a history of vitrectomy, and the remaining 23 eyes had no history of vitrectomy. The correlations of Na, K, Cl and Mg concentrations with patient age, interval between first and second vitrectomy, and lens status (history of cataract surgery) were also evaluated.ResultsThe Na, K, Cl and Mg concentrations in VH from vitrectomized eyes were 134.1 ± 7.9 mmol/L, 3.7 ± 0.2 mmol/L, 99.7 ± 6.7 mmol/L and 0.59 ± 0.09 mmol/L, respectively; all were significantly lower than the corresponding concentrations in VH from control eyes (lower by 5.0%, 11.0%, 11.7%, and 22.6%, respectively). Na, K, Cl and Mg concentrations in VH from vitrectomized eyes did not show significant correlations with patient ages or the interval between their first and second vitrectomies. There were no significant differences in Na, K, Cl and Mg concentrations in VH between phakic eyes and intraocular lens-implanted eyes.ConclusionsWith the increasing number of vitrectomies being performed, it is necessary to consider the history of vitrectomy when using a subject’s VH in forensic examination.

Surface snow bromide and nitrate at Eureka, Canada, in early spring and implications for polar boundary layer chemistry

Abstract. This study explores the role of snowpack in polar boundary layer chemistry, especially as a direct source of reactive bromine (BrOx = BrO + Br) and nitrogen (NOx = NO + NO2) in the Arctic springtime. Surface snow samples were collected daily from a Canadian high Arctic location at Eureka, Nunavut (80° N, 86° W) from the end of February to the end of March in 2018 and 2019. The snow was sampled at several sites representing distinct environments: sea ice, inland close to sea level, and a hilltop ∼ 600 m above sea level (a.s.l.). At the inland sites, surface snow salinity has a double-peak distribution with the first and lowest peak at 0.001–0.002 practical salinity unit (psu), which corresponds to the precipitation effect, and the second peak at 0.01–0.04 psu, which is likely related to the salt accumulation effect (due to loss of water vapour by sublimation). Snow salinity on sea ice has a triple-peak distribution; its first and second peaks overlap with the inland peaks, and the third peak at 0.2–0.4 psu is likely due to the sea water effect (a result of upward migration of brine). At all sites, snow sodium and chloride concentrations increase by almost 10-fold from the top 0.2 to ∼ 1.5 cm. Surface snow bromide at sea level is significantly enriched, indicating a net sink of atmospheric bromine. Moreover, surface snow bromide at sea level has an increasing trend over the measurement period, with mean slopes of 0.024 µM d−1 in the 0–0.2 cm layer and 0.016 µM d−1 in the 0.2–0.5 cm layer. Surface snow nitrate at sea level also shows a significant increasing trend, with mean slopes of 0.27, 0.20, and 0.07 µM d−1 in the top 0.2, 0.2–0.5, and 0.5–1.5 cm layers, respectively. Using these trends, an integrated net deposition flux of bromide of (1.01 ± 0.48) × 107 molec.cm-2s-1 and an integrated net deposition flux of nitrate of (2.6 ± 0.37) × 108 molec.cm-2s-1 were derived. In addition, the surface snow nitrate and bromide at inland sites were found to be significantly correlated (R = 0.48–0.76) with the [NO3-]/[Br-] ratio of 4–7 indicating a possible acceleration effect of reactive bromine in atmospheric NOx-to-nitrate conversion. This is the first time such an effect has been seen in snow chemistry data obtained with a sampling frequency as short as 1 d. BrO partial column (0–4 km) data measured by MAX-DOAS show a decreasing trend in early spring, which generally agrees with the derived surface snow bromide deposition flux indicating that bromine in Eureka atmosphere and surface snow did not reach a photochemical equilibrium state. Through mass balance analysis, we conclude that the average release flux of reactive bromine from snow over the campaign period must be smaller than the derived bromide deposition flux of ∼ 1 × 107 molec.cm-2s-1. Note that the net mean fluxes observed do not completely rule out larger bidirectional fluxes over shorter timescales.

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.

Assessment of dumpsites leachate, geotechnical properties of the soil, and their impacts on surface and groundwater quality of Sunyani, Ghana

Leachate from sanitary landfill and dumpsites have potential to cause soil and groundwater contamination, and disrupt ecosystems. However, there is little information about dumpsite leachates and geotechnical properties and their impacts on surface and groundwater in Bono region, Ghana. This study assessed dumpsites leachate, geotechnical properties of the soil, and their impacts on surface and groundwater quality in Sunyani. Six triplicate leachates, eleven triplicate groundwater and three triplicate surface water samples were taken at (up-stream, mid-stream and down-stream) urban dumpsite, and eight triplicate groundwater samples taken around peri-urban dumpsite. Water samples were stored (<4°C) in polyethylene bottle for laboratory analysis. Physicochemical properties of leachate and water samples were analyzed using standard methods. Heavy metals (Cd, Hg, Pb, Zn, Cr, Fe, Cu, and Ni) were determined using atomic absorption spectroscopy. Water quality index (WQI) and leachate pollution loads (LPL) were investigated, while plasticity index (Ip) and liquid index (Il) were determined using Atterberg limit test. The results showed that all leachate samples were heavily polluted with mean concentrations of chlorides ranged between (2830±220 and 63810±340), biochemical oxygen demand (358±36 to 820±80), ammonium ions (82.8±2.2 to 267.6±62), and cadmium (0.49±0.02 to 5.32±1.0); with their leachate pollution index (LPI) and LPL exceeding their leachate disposal standards (LDS>100). WQI ranged from 6.51 to 289, indicating excellent to heavily polluted groundwater sources. Surface water was heavily polluted with WQI between 0.84 and 776.75, with majority having WQI>100. The heavily polluted samples were located 75-155 m away from urban dumpsite. Moderate significant negative association was established between (WQI-P and WQI-H) and distance with multiple R2=0.4709, p=0.0191 and R2= 0.4482, p=0.02425 respectively. Statistically, strong significant negative association between (WQI-P & WQI-H) and Ip (p < 0.05). This implies that when plasticity index and distance from groundwater sources to dumpsite increased, WQI values decreased, and groundwater quality improved.

Characterization and Performance Evaluation of Digital Light Processing 3D Printed Functional Anion Exchange Membranes in Electrodialysis

With the rapid development of 3D printing technologies, more attention has been focused on using 3D printing for the fabrication of membranes. This study investigated the application of digital light processing (DLP) 3D printing combined with quaternization processes to develop dense anion exchange membranes (AEMs) for electrodialysis (ED) separation of Cl− and SO42− ions. It was discovered that at optimal curing times of 40 min, the membrane pore density was significantly enhanced and the surface roughness was reduced, and this resulted in an elevation of desalination rates (97.5–98.7%) and concentration rates (165.8–174.1%) of the ED process. Furthermore, increasing the number of printed layers improved the membranes’ overall polymerization and performance, with double-layer printing showing superior ion flux. This study also highlights the impact of the polyethylene glycol diacrylate (PEGDA) molecular weight on membrane efficacy, where PEGDA-700 outperformed PEGDA-400 in ion transport capabilities and desalination efficiency. Additionally, higher 4-vinylbenzyl chloride (VBC) content improved the quaternary ammonium group concentration and membrane conductivity, and hence elevated the ED performance. Under optimized conditions, DLP 3D printed membranes demonstrated exceptional selectivity of 24.0 for Cl−/SO42− and a selective purity of 81.4%. With a current density of 400 A/m2, the current efficiency and energy consumption were in the range of 82.4% to 99.7%, and 17.2 to 25.4 kW‧h‧kg−1, respectively, showcasing the potential of advanced manufacturing techniques in creating efficient and functional ion exchange membranes.

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.