High Cl Research Articles

Chloride-Enhanced Removal of Ammonia Nitrogen and Organic Matter from Landfill Leachate by a Microwave/Peroxymonosulfate System

Landfill leachate contains not only high concentrations of refractory organic matter and ammonia nitrogen, but also high concentrations of chloride ions (Cl−). The modification of reactive species of the peroxymonosulfate (PMS) oxidation system by Cl− and its priority sequence for the removal of NH4+-N and organic matter from landfill leachate remain unclear. This study investigated the removal characteristics of NH4+-N and organic matter in the microwave (MW)/PMS system with high Cl− content. The results show that increasing Cl− concentration significantly improves the production of hypochlorous acid (HOCl) in the MW/PMS system under acidic conditions, and that the thermal and non-thermal effects of MW irradiation have an important influence on the HOCl produced by PMS activation. The maximum cumulative concentration of HOCl was 748.24 μM after a reaction time of 2 min. The formation paths of HOCl are (i) SO4•− formed by the MW/PMS system interacting with Cl− and HO•, and (ii) the nucleophilic addition reaction of PMS and Cl−. Moreover, the high concentration of HOCl produced by the system can not only remove NH4+-N in situ, but also interact with PMS to continuously generate Cl• as an oxidant to participate in the reaction with pollutants (e.g., NH4+-N and organic matter). Common aqueous substances (e.g., CO32−, HCO3−, NO3−, and humic acid) in landfill leachate will compete with NH4+-N for reactive species in the system, and will thereby inhibit its removal to a certain extent. It was found that when NH4+-N and leachate DOM co-exist in landfill leachates, they would compete for reactive species, and that humic acid-like matter was preferentially removed, leading to the retention of fulvic acid-like matter. It is hoped that this study will provide theoretical support for the design and optimization of methods for removing NH4+-N and organic matter from landfill leachate with high chloride ion content.

Geochemical fingerprint and spatial pattern of mine water quality in the Shaanxi-Inner Mongolia Coal Mine Base, Northwest China

The spatial distribution of mine water quality and geochemical controls must be investigated for water safety and ecosystem protection in Shaanxi-Inner Mongolian Coal Mine Base (SICMB). Based on 122 mine water samples collected from 14 mining areas, self-organizing maps (SOM) combining with principal component analysis (PCA) derived that the mine water samples were classified into seven clusters. Clusters 1 and 3 (C1 and C3) samples were dominant by HCO3-Ca and mixed types, which were distributed in the recharge area of the middle SICMB. In this area, the active groundwater circulation contributed to the good water quality. Cluster 2 (C2) samples were characterized by HCO3-Na type, mainly distributed in the discharge area of the middle SICMB. These samples were threatened by heavy fluorine contamination and high residual sodium carbonate (RSC) because of slow groundwater flow in this area. Clusters 4 and 5 (C4 and C5) samples, distributed in the northeast and middle SICMB, were characterized by high Cl− concentration and light fluorine contamination. They were influenced by anthropogenic input through faults or underground mining. In contrast, Clusters 6 and 7 (C6 and C7) samples with high salinity and sulfate were distributed in the southwest SICMB. The deep groundwater circulation enhanced water-rock interaction and contributed to poor water quality. These findings are beneficial to the management of mine water resources in the SICMB and provide an insight to investigate the mine water quality in large spatial scale.

Removal characteristics of ammonia nitrogen and refractory organic matter in waste leachate by Co2+/peroxymonosulfate process at high chloride ion concentration

Landfill leachate contains high concentrations of refractory organic matter (ROM), ammonia nitrogen (NH4+), and chlorine ion (Cl–). With efficient ROM removal being the focus of advanced oxidation processes, there is an urgent need to clarify the role of high Cl– concentration on reactive species and preferential reactivity towards coexistent ROM and NH4+. This study investigated the removal characteristics of ROM and NH4+ using a Co2+/peroxymonosulfate (Co2+/PMS) process with high Cl– concentration. The results showed that the system produced large amount of hypochlorous acid (HOCl), with a maximum accumulated HOCl concentration reaching 2.78 mM at Co2+, PMS, and Cl– concentrations of 105 μM, 10 mM, and 17 mM, respectively. The differences in Cl–-to-PMS molar ratios altered HOCl formation pathway, and both Co3+ and SO4•− played important roles in HOCl generation. Although the initial concentrations of PMS, Co2+, and Cl– were proportional to the cumulative HOCl concentration, increasing pH significantly inhibited HOCl formation. The coexisting anions commonly found in waste leachate (i.e., CO32−, HCO3−, and NO3−) promoted HOCl production to some extent, but both NH4+ and dissolved organic matter (humic acid and amino acid complex) severely depleted the formed HOCl. Analysis of the removal characteristics of NH4+ and ROM in co-occurrence in actual waste leachate at high Cl– concentrations revealed that NH4+ and ROM competed for HOCl, and preferential removal of humic-like substances led to retention of fulvic-like substances. These results provide theoretical support for the design and optimization of methods for NH4+ and ROM removal from waste leachate containing high Cl– content.

Construction of microbial electrodialysis cells equipped with internal proton migration pathways: Enhancement of wastewater treatment, desalination, and hydrogen production

Microbial electrodialysis cells (MEDCs) offer simultaneous wastewater treatment, water desalination, and hydrogen production. In a conventional design of MEDCs, the overall performance is retarded by the accumulation of protons on the anode due to the integration of an anion exchange membrane (AEM). The accumulation of protons reduces the anolyte pH to become acidic, affecting the microbial viability and thus limiting the charge carrier needed for the cathodic reaction. This study has modified the conventional MEDC with an internal proton migration pathway, known as the internal proton migration pathway-MEDC (IP-MEDC). Simulation tests under abiotic conditions demonstrated that the pH changes in the anolyte and catholyte of IP-MEDC were smaller than the pH changes in the anolyte and catholyte without the proton pathways. Under biotic conditions, the performance of the IP-MEDC agreed well with the simulation test, showing a significantly higher chemical oxygen demand (COD) removal rate, desalination rate, and hydrogen production than without the migration pathway. This result is supported by the lowest charge transfer resistance shown by EIS analysis and the abundance of microbes on the bioanode through field emission scanning electron microscopy (FESEM) observation. However, hydrogen production was diminished in the second-fed batch cycle, presumably due to the active diffusion of high Cl¯ concentrations from desalination to the anode chamber, which was detrimental to microbial growth. Enlarging the anode volume by threefold improved the COD removal rate and hydrogen production rate by 1.7- and 3.4-fold, respectively, owing to the dilution effect of Cl¯ in the anode. This implied that the dilution effect satisfies both the microbial viability and conductivity. This study also suggests that the anolyte and catholyte replacement frequencies can be reduced, typically at a prolonged hydraulic retention time, thus minimizing the operating cost (e.g., solution pumping). The use of a high concentration of NaCl (35 g L−1) in the desalination chamber and catholyte provides a condition that is close to practicality.

Effects of processing technology on the electrochemical behavior and Zn deposition process of Al-Mn-Ca alloy cathodes in high Cl− ions ZnSO4 solutions

Effects of processing technology on the electrochemical behavior and Zn deposition process of Al-Mn-Ca alloy cathodes in high Cl− ions ZnSO4 solutions

Geochemical Characterization of Groundwater in the Confined and Unconfined Aquifers of the Northern Italy

Having an accurate and easily accessible geochemical database is crucial for a correct groundwater management. Here, for the first time in Italy, chemico-physical data of groundwater collected by different Environmental Protection Agencies during the 2018 were integrated into a single database to assess the geochemical status of a wide and complex aquifer system. Data were assembled, reformatted, corrected, homogenized, and then grouped according to the aquifer type (phreatic, semi-confined, and confined) and the sampling seasons. A total of 3671 validated samples were classified into hydrochemical facies; inorganic N compounds and trace elements were also evaluated. The water were classified mainly as Ca-HCO3 and Ca-Mg-HCO3 (90%); locally, Na-HCO3, Mg-HCO3, Ca-SO4, Na-Cl, and Ca-Cl types were detected. In the phreatic aquifers, NO3 contamination and high concentrations of Na+, K+, and NH4+ were found and linked to anthropogenic sources, such as agricultural and livestock activities. Along the Adriatic coast, Na-Cl water confirmed saltwater intrusion phenomena. Landward, evaporitic rocks dissolution, and the upconing of relict marine water explained high EC, Na+, K+, Cl−, and SO42− concentrations. The dissolution of Fe-Mn oxide-hydroxides coupled with organic carbon oxidation under reducing environment justified high NH4+, Fe, Mn, and As recorded in the semi-confined and confined aquifers.

Removal of sulfate and chloride ions from reverse osmosis concentrate using a two-stage ultra-high lime with aluminum process

Reverse osmosis (RO) concentrate generated from RO desalination is necessary to be managed due to its discharge toxicity and mineral scaling. In this work, the removal of SO42− and Cl− from RO concentrate and further improvement of water quality were systematically investigated using the two-stage ultra-high lime with aluminum (UHLA) process and carbonation post-process, respectively. Firstly, batch results of the one-stage UHLA process proved the competitive inhibition effect of coexisting SO42− on Cl− removal. Thus, a two-stage UHLA process was designed to preferentially precipitate SO42− as ettringite (Ca6Al2(SO4)3(OH)12) in stage I and then dislodge partial Cl− as Friedel's salt (Ca4Al2Cl2(OH)12) in stage II. Results showed that almost all of SO42− and 77.8 % of Cl− could be removed at the optimal conditions. And the XRD and SEM analysis results showed formation of ettringite and Friedel's salt with good crystal morphology in stage I and stage II, respectively. This technology was further applied in the real RO concentrate treatment and achieved almost complete SO42− removal and high Cl− removal of 70.5 %, which confirmed the feasibility and effectiveness of the two-stage UHLA process. Finally, the carbonation post-process was applied to precipitate remaining Ca2+ as well as lower the pH and conductivity, so as to improve the treated water quality. This two-stage UHLA process is promising to be applied to saline wastewater containing high concentrations of SO42− and Cl−.

Corrosion behavior of Q235 steel by synergistic action of high concentration Cl− and complex scale in mixed salt flooding

The corrosion mechanism of Q235 steel by the synergistic effect of high concentration Cl− and complex scale in the preparation process of a mixed salt oil displacement method was investigated using measurements of weight loss, electrochemical impedance spectroscopy, linear polarization curve and open circuit potential. Scanning electron microscope and energy dispersive spectroscopy results indicated that the amount of Na2CO3 in the preparation process had an influence on the composition of the complex scale. This study investigated the corrosion process on Q235 steel using solutions with three different CO32−/Cl− molar ratios R: 0.11, 0.27, and 0.37. At a low concentration of CO32−, serious pitting corrosion occurred and the composition of corrosion product was diverse. When the R was 0.27, a discontinuous passive film was formed on the metal surface, and crevice corrosion took place between the adsorbed Si scale and substrate. With a further increased in CO32− concentration, the steel surface was covered with a passive film that was mainly composed of FeCO3 and Fe2O3. The initial growth process of calcium carbonate was restricted. At the R = 0.37 solution, corrosion was successfully inhibited, making this a good candidate for use in the oil recovery process.

Asymmetric CoN3 P1 Trifunctional Catalyst with Tailored Electronic Structures Enabling Boosted Activities and Corrosion Resistance in an Uninterrupted Seawater Splitting System.

Employing seawater splitting systems to generate hydrogen can be economically advantageous but still remains challenging, particularly for designing efficient and high Cl- -corrosion resistant trifunctional catalysts toward the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). Herein, single CoNC catalysts with well-defined symmetric CoN4 sites are selected as atomic platforms for electronic structure tailoring. Density function theory reveals that P-doping into CoNC can lead to the formation of asymmetric CoN3 P1 sites with symmetry-breaking electronic structures, enabling the affinity of strong oxygen-containing intermediates, moderate H adsorption, and weak Cl- adsorption. Thus, ORR/OER/HER activities and stability are optimized simultaneously with high Cl- -corrosion resistance. The asymmetric CoN3 P1 structure based catalyst with boosted ORR/OER/HER performance endows seawater-based Zn-air batteries (S-ZABs) with superior long-term stability over 750 h and allows seawater splitting to operate continuously for 1000 h. A self-driven seawater splitting powered by S-ZABs gives ultrahigh H2 production rates of 497μmol h-1 . This work is the first to advance the scientific understanding of the competitive adsorption mechanism between Cl- and reaction intermediates from the perspective of electronic structure, paving the way for synthesis of efficient trifunctional catalysts with high Cl- -corrosion resistance.

Electrochemical behavior of 2205 duplex stainless steel in simulated solution containing high concentration Cl− and saturated CO2 at different temperatures

2205 duplex stainless steel (DSS) has good corrosion resistance due to its typical duplex organization, but the increasingly harsh CO2-containing oil and gas environment leads to different degrees of corrosion, especially pitting corrosion, which seriously threatens the safety and reliability of oil and gas development. In this paper, the effect of temperature on the corrosion behavior of 2205 DSS in a simulated solution containing 100 g/L Cl− and saturated CO2 was investigated with immersion tests and electrochemical tests and combined with characterization techniques such as laser confocal microscopy and X-ray photoelectron spectroscopy. The results show that the average critical pitting temperature of 2205 DSS was 66.9 °C. When the temperature was higher than 66.9 °C, the pitting breakdown potential, passivation interval, and self-corrosion potential decreased, while the dimensional passivation current density increased, and the pitting sensitivity was enhanced. With a further increase in temperature, the capacitive arc radius of 2205 DSS decreased, the film resistance and charge transfer resistance gradually decreased, the carrier density of the donor and acceptor in the product film layer with n + p bipolar characteristics also increased and the inner layer of the film with Cr oxide content decreased, while the outer layer with Fe oxide content increased, the dissolution of the film layer increased, the stability decreased, and the number and pore size of pits increased.

Removal of harmful components from MSWI fly ash as a pretreatment approach to enhance waste recycling

Municipal solid waste incineration (MSWI) fly ash contains many harmful components that may limit its potential for recycling. An effective pretreatment is therefore required before any recycling can be implemented. In this study, the effects of four pretreatment methods (water washing, CO2-aided washing, CO32–-aided washing, and CO2 and CO32–-aided washing) on the extraction behavior of chloride, sulfate, and heavy metals were evaluated. Water washing was found to be effective for the extraction of all easily and moderately soluble Cl-bearing salts, achieving Cl extraction ratios of 88%, 90%, and 96% for ash from Chongqing (CQ), Qingdao (QD), and Tianjin (TJ), respectively. Injection of CO2 during washing facilitated decomposition of the hardly soluble Cl-bearing salts, increasing the Cl extraction efficiency by 6% for CQ ash and 9% for QD ash. However, for the TJ ash that contained few insoluble Cl-bearing minerals, CO2 injection decreased the Cl extraction rate. The addition of CO32– had a negative influence on Cl extraction for all ashes, but it slightly promoted sulfate extraction. Despite the high Cl removal rate, only 23–37% of the sulfate and 0.1–12% of heavy metals were removed. Overall, water-based pretreatment, especially CO2-aided washing, significantly altered the physical, chemical, and mineralogical characteristics of the fly ash, making it more suitable for recycling. Consequently, the blending ratio of the fly ash for cement clinker manufacture increased from 0.2 to 0.3% in the raw ash to 3.5–5.5% in the treated ash, enabling the extensive use of ash materials.

Indicator mineral analyses of stream-sediment samples using automated mineralogy and mineral chemistry: Applicability to exploration in covered terranes in eastern Alaska, USA

In the past two decades, significant research efforts have been devoted to porphyry copper indicator mineral (PCIM) identification and mineral chemistry to assist exploration. Such studies are important in the Yukon-Tanana upland region of eastern Alaska because well-established geochemical exploration techniques, such as the geochemistry of stream-sediment samples, are less effective in the search for mineral resources owing to cover materials that subdue geochemical signatures. The unglaciated Yukon-Tanana upland region is well-endowed with mineral resources, including porphyry Cu-Mo-Au deposits at Taurus, Bluff, Dennison, and Oreo. Using automated scanning electron microscope (SEM) techniques, numerous PCIMs have been identified in rocks and stream-sediment samples that would likely not have been observed using visual binocular microscope methods. Sulfide minerals such as chalcopyrite, chalcocite, covellite, bornite, molybdenite, and pyrrhotite were identified in rock samples, and more than half of the stream-sediment samples from drainages containing known porphyry mineral occurrences contain chalcopyrite with or without bornite. Many drainages without known occurrences also contain these minerals, which suggests potential for additional occurrences. Svanbergite, an aluminum phosphate sulfate (APS) mineral [SrAl3(PO4)(SO4)(OH)6], was identified in some of the altered or mineralized rock samples from Taurus, and in stream drainages containing porphyry occurrences and may represent the best indicator mineral for Taurus-like porphyry deposits. Apatite chemistry has great potential as a tool for assessing the presence of porphyry mineralization. Grains from rock and stream-sediment samples that contain high Cl (>∼0.4 wt%), Fe (>0.4 wt%), and Mn (>2000 ppm) clearly distinguish apatite from other sources (metamorphic, unmineralized igneous rocks). This study is one of the first to document new streamlined indicator mineral sample collection and processing methods and to combine automated SEM techniques and chemistry of minerals derived from both bedrock and surficial (stream) sediments as they apply to porphyry exploration.

Impact of natural conditions and anthropogenic activities on groundwater quality in Puntang volcanic area, West Java, Indonesia.

The Puntang area in the southern mountains of West Java has potential water resources that are used to fulfill the community's raw water. The rapid development of the region and tourism will affect the quality of groundwater. This research was conducted on the slopes of Mount Puntang with the aim of analyzing natural and anthropogenic conditions on groundwater quality. Measurements and groundwater samples are taken from 5 springs, 10 dug wells and 8 drilling wells. The research method begins with a literature study followed by data collection in the field and laboratory analysis. Data analysis used statistical analysis and hydrogeochemical spatial analysis. Hydrogeochemical analysis using Piper diagrams. Based on the analysis results, it is known that the groundwater facies are CaCl, CaMgCl CaHCO3, and NaHCO3. The CaCl facies, enrichment of Cl- is caused by contamination of volcanic domain. The CaMgCl facies has enrichment of Mg2+ cations in the process of groundwater and rock water interactions. The high Cl- value in the proximal area is influenced by volcanic domain, while the Cl- value in the medial and distal areas may be influenced by anthropogenic. The CaHCO3 facies is influenced by local meteoric water, with a high structural control that shows water flowing through the fracture. The NaHCO3 facies is a wellbore in the intermediate groundwater flow and anthropogenic influences have occurred. The hydrochemical evolution that occurs is that Ca2+ becomes Mg2+ and then turns into Na+. The CaMgHCO3 facies dominates the proximal to distal area. The presence of HCO3 - indicates that groundwater mixing has occurred and is influenced by the decomposition of organic matter. Indications of groundwater mixing can be seen in groundwater with NaKHCO3 facies in the distal area. The medial and distal areas are densely populated areas which also affect groundwater. Geological and environmental conditions around the water resources are one of the supporting data to determine polluting sources.

Corrosion Performance of Additively Manufactured Stainless Steel by Binder Jetting

The influence of microstructural defects on the corrosion resistance of AISI 316L additively manufactured with Metal Binder Jetting in high Cl- environments were studied herein. A comprehensive metallographic examination was conducted to identify microstructural defects followed by a corrosion study with electrochemical techniques with the aim of finding correlations between impurities in the microstructure and preferential nucleation sites. Despite, the high number of inclusions in the microstructure of the studied samples, none of the conducted corrosion tests showed a clear indication that they resulted in a decreased corrosion resistance as compared to areas with few inclusions. However, a significant higher pitting potential was observed on the as-printed samples compared to samples grinded with 600 grit SiC paper which will be discussed further.

Response of Common Ice Plant (Mesembryanthemum crystallinum L.) to Sodium Chloride Concentration in Hydroponic Nutrient Solution

Common ice plant (Mesembryanthemum crystallinum L.) is a novel edible succulent plant with savory flavor. It has epidermal bladder cells (EBCs) that store water and sodium chloride (NaCl) located on the epidermis of the leaves and stems. Ice plant is an obligatory halophyte that requires NaCl for optimum growth. The objective of this study was to determine the impact of NaCl on growth of ice plant for hydroponic production as an edible leafy green and to quantify the ability of ice plant to take up NaCl from the environment. Four-week-old seedlings of ice plant were transplanted into hydroponic systems, established for 1 week, and given five NaCl treatments [0 M (control), 0.05 M, 0.10 M, 0.20 M, 0.40 M NaCl]. Sequential destructive harvests to determine plant growth occurred at day 7, 14, and 21 after NaCl treatment. The 0.05 M NaCl had the greatest stimulating effect on biomass, increasing total fresh weight (FW) by 173% and shoot FW by 193% compared with the control plants. The 0.10 M NaCl also had stimulating effect as compared with 0 M, but plants were not as large as those receiving 0.05 M NaCl. The 0.20 M NaCl had little effect on plant growth compared with the control. The 0.40 M NaCl had a strong stunting effect on plant growth. All plants treated with NaCl had less root weight than the control, and higher NaCl concentration resulted in greater reduction in root weight. However, for the 0.05 and 0.10 M treatment, the gain in shoot weight exceeded the loss in root weight. Plants gained or lost water in a faster rate than dry mass, which resulted in larger differences among treatments in FW than in dry weight (DW). Plants treated with higher NaCl concentrations developed fewer, smaller, and thicker leaves but contained more EBCs per unit leaf surface area. There was high Na and Cl accumulation in leaf tissues of all salt-treated plants (e.g., 180,507 mg·kg−1 Na and 125,084 mg·kg−1 Cl in the 0.05 M treatment vs. 13,558 mg·kg−1 Na and 12,991 mg·kg−1 Cl in the 0 M treatment). This indicated potential for bioremediation of saline soil or hydroponic water. Concentrations of macronutrients such as nitrogen (N), phosphorus (P), calcium (Ca), magnesium (Mg), and sulfur (S) were reduced when plants received increasing NaCl treatments. In general, this study showed that growth of ice plant benefited from 0.05 and 0.10 M NaCl additions to the hydroponic nutrient solution. Ice plant deserves further work on its ability to reduce Na and Cl from accumulating in recirculating hydroponic nutrient solution.

Kinetic of the Oxygen and Chlorine Evolution Reaction on Platinum Electrodes at Neutral pH

The platinum anode modified by metal oxides electrodes degrades Abidjan wastewater which contains a high concentration of Cl-. During this degradation process, the organic polluants are oxidized, O2 and Cl2 are produced. The purpose of this study is to contribute to the understanding of these reaction mechanisms by studying the kinetics of O2 and Cl2 evolution at neutral pH on Pt. The study was performed by interpreting the voltammograms and Tafel slopes obtained. The voltammetric measurements were carried out using an Autolab Potentiostat from ECHOCHEMIE (PGSTAT 20) connected by interface to a computer. Pt electrode was prepared on titanium (Ti) substrate by thermal decomposition techniques at 400°C. The characterization of the surface of the prepared electrode by scanning electron microscopy and X-ray photoelectron spectrometry showed the presence of platinum on its surface. The results obtained show that the OH· are adsorbed on the active sites of Pt. Then they react to form PtO. Then by reaction between the surface oxygen and PtO, O2 is produced and the active sites are regenerated. In the presence of low Cl- concentration, there is a competition between the Cl2 and O2 evolution reactions. However, Cl2 only is produced for high Cl- concentrations. The kinetics of the evolution reaction of chlorine increases with the concentration of Cl- and remains constant for concentrations greater than 0.5 M. This study also showed that the chlorine reduction reaction produced in solution is a diffusion-controlled reaction for low scan rates.

Acute kidney injury profile of COVID-19 patients and associated risk factors a rural hospital-based retrospective study from Vadodara, Gujarat

Background: Clinical outcome of patients hospitalized with COVID-19 and acute kidney injury (AKI) are not well understood. The clinical significance of abnormal electrolytes and renal outcome in COVID-19 patients have been poorly documented. We aim to exhibit the electrolyte abnormalities, renal outcome and associated risk factors in hospitalized COVID-19 patients in rural tertiary care hospital in Vadodara district, Western India. Method: A hospital record based retrospective study was conducted. Total 994 patients hospitalized with COVID-19 between 1st April 2021 to 30th June 2021 and those meeting inclusion criteria were included for the analysis. The laboratory data of interest included electrolytes reports like Na+, K+, CL-, creatinine and blood urea. Result: Of the total hospitalized COVID-19 patients, 324 patients were eligible. For the criteria for suspected AKI - 279 (86.11%) and no AKI - 45 (13.88%) patients were found. Suspected AKI patients were classified into four conditions: 1) HYPERNATREMIA (14.33%); HYPERKALEMIA (2.15%); BCR ratio >20 (65.59%); HIGH Cl- (17.92%). Out of total AKI patients, (36.91%) died whereas (13.3%) patients died in no AKI group. All patients were provided antibiotics, steroids and anti-viral therapies irrespective of AKI status, which we presume might have contributed in high mortality among suspected AKI.

Effect of a Fast Potential Change on the Early Stage of Zinc Passivation in a Saturated Calcium Hydroxide Solution

The fast and sharp corrosion potential change from the active state to the passive state, that pure zinc plates immersed in calcium hydroxide saturated solutions with and without chlorides spontaneously exhibit at the early stage of passivation, was studied. The corrosion behavior was investigated by corrosion potential monitoring, anodic polarization curves and electrochemical impedance spectroscopy. The zinc surface was characterized by scanning electron microscopy and X-ray energy dispersive spectroscopy. Experimental results show that the presence of chlorides increases the rate of change of potential by 10-fold in the early stage of passivation, producing a porous passivating film of corrosion products mainly made of calcium hydroxy-zincate Ca(Zn(OH)3)2·2 H2O, with a less protective barrier effect than the non-porous film formed without chlorides. On the other hand, a modeling approach was achieved by solving the transient 2D Nernst–Planck equations and considering 12 chemical species. Numerical results confirm that the composition of the chemical products generated on the Zn surface certainly depends on the concentration of Cl¯ ions: Simonkolleite and hidroxides become unstable in the presence of high Cl¯ concentrations, whereas calcium hydroxyl-zincate is the main chemical compound generated on the Zn surface. However, the presence of the latter compound is much more important in electrolytes with very low concentration of Cl¯ ions.

Intelligent Evaluation of Marine Corrosion of Q420 Steel Based on Image Recognition Method

Marine engineering materials are prone to serious corrosion damage, which affects the efficiency and reliability of marine equipment. The diversity of corrosion morphology makes it difficult to achieve the quantification and standardization of the microscopic local information on the corroded surface, which is of great significance to reveal the multi-scale corrosion mechanism. In this paper, an image intelligent recognition method for the corrosion damage of Q420 steel in seawater is established, which is based on the gray level co-occurrence matrix, binary image method and fractal model. Through the feature extraction of corrosion morphology, the quantitative analysis of corrosion morphology and the microscopic evaluation of corrosion characteristics are achieved. The image recognition data are consistent with the electrochemical result for most cases, which confirms the validity of this image intelligent recognition method. The average gray value and energy value of corrosion morphology reduces with the Cl− concentration, indicating that the corrosion damage aggravates gradually. The increasing standard deviation and entropy reflects that the randomness of the pit distribution increases. The pitting ratio increases from 20.19% to 51.64% as the Cl− concentration increases from 50% to 200% of the standard solution. However, there exists a discrepancy for high Cl− concentration because of the irregular corrosion morphology and various pit depth. The fractal dimension increases with the complexity of the corroded surface at low Cl− concentration, but the fractal dimension decreases at high Cl− concentration because the corrosion complexity is interfered by the interconnection of corrosion holes due to the accelerated pit evolution.

Advanced anion-selective membranes with pendant quaternary ammonium for neutral aqueous supporting redox flow battery

Neutral aqueous organic redox flow battery (NAORFB) stands out as one of the most prospective mass energy storage options. The main limitations of large-scale storage regarding the NAORFB lie in the low Na+/Cl− conductivity of membrane in pH7 systems, which leads to a lower voltage efficiency. Herein, quaternary ammonium functionalized fluorinated poly (arylene ether) (QAFPAE-x) anion exchange membrane with hydrophilic and hydrophobic blocks was designed successfully. The results demonstrated that the grafting of quaternary ammonium and fluorine-containing block enables QAFPAE-x membrane low swelling, high Cl− conductivity, and promising chemical stability characteristics. The voltage efficiency of QAFPAE-100 membrane (93.8%–60.7%) is much higher than the AMVN membrane (88.4%–37.8%) at 20–160 mA cm−2. Furthermore, the NAORFB with the QAFPAE-100 membrane steadily runs at 60 mA cm−2 over 1500 cycles. Therefore, the ionic highway induced excellent performance of QAFPAE-100 membrane to render this material a promising candidate for practical NAORFB applications.