Accumulation Of Reaction Products Research Articles

Development of an automated system for the purification of alkanolamine solutions

The alkanolamine solutions used in natural gas purification processes are inevitably degraded over time. This occurs due to accumulation of reaction products from the reactions with carbon dioxide, hydrogen sulphide, oxygen and other impurities present in the gas streams, as well as from thermal degradation. The degradation of solutions leads to the formation of thermostable compounds that not only reduce absorption efficiency, but also increase corrosive activity. Furthermore, part of the amine turns into a bound state and becomes ballast. The necessity of purification of alkanolamine solutions is becoming more and more urgent since the cost of maintaining efficient operation of gas treatment plants grows, and environmental safety requirements increase. Purification of solutions makes it possible to prolong their service life, reduce the cost of purchasing new reagents and reduce the negative impact on the equipment. In this work the method of anion-exchange technology of purification is used. Unlike vacuum distillation and electrodialysis, the considered technology does not require significant energy costs for generation and maintenance of vacuum, and heating of solutions, it can be easily integrated into the existing production process without any significant changes in the infrastructure. The described problem is relevant for Kazakhstan oil refineries, two of which use methyldiethanolamine, and one of which uses diethanolamine, and the existing practice of maintaining the operability of the systems is based on periodic replacement of part of the solution with pure amine. The development of automated systems for purification of such solutions makes it possible to significantly improve process control, minimise manual labour, and improve the overall economic efficiency of production.

The removal mechanisms of HF and HCl gases using Mg-Al adsorbent prepared by sol-gel synthesis method

In this study, a series of Mg-Al mixed oxide adsorbents have been introduced to simultaneously remove hydrogen chloride (HCl) and hydrofluoric acid (HF) in low-temperature environment (100 °C). These adsorbents prepared by the sol-gel method, the effects of Mg loading amount and calcination temperature for adsorbents on their performance were investigated. The optimal adsorbent (modified by 20 wt% Mg and calcined at 500 °C, referred to as Mg20Al80OX-500) exhibited the highest adsorption capacity among all the adsorbents tested. The role of MgO loaded on Mg-Al mixed oxide adsorbent was investigated using various analytical methods, including Brunauer-Emmet-Teller (BET), X-ray diffractometer (XRD), scanning electron microscopy (SEM-EDS), thermogravimetric analysis (TG-DTG), temperature programmed desorption of CO2 (CO2-TPD), X-ray photoelectron spectroscopy (XPS)， in-situ infrared (in-situ IR) and transmission electron microscopy (TEM). These results indicated that MgO and lattice oxygen (Oα) played a crucial role in promoting the adsorption activity of the adsorbents. Mg were highly dispersed, and moderate levels of Mg content and calcination temperature could enhance the performance of adsorbents according to XRD, SEM-EDS and TG-DTG results. BET analysis showed that the modification of Mg did not change the pore type of the γ-Al2O3 largely. CO2-TPD results revealed that the calcination temperature significantly affected the number and strength of the basic sites on the surface of the adsorbent. In addition, XPS, in-situ IR and TEM analysis demonstrated that the consumption of MgO and Oα as well as the accumulation of reaction products on the surface and within the pores of the adsorbent, and they were the main reasons the deactivation. And MgF2 (MgCl2) and H2O were the main products after the inactivation of adsorbent.

Research on the Application and Mechanisms of Electroactive Microorganisms in Toxicants Monitoring: A Review.

A biological treatment is the core process for removing organic pollutants from industrial wastewater. However, industrial wastewater often contains large amounts of toxic and harmful pollutants, which can inhibit the activity of microorganisms in a treatment system, precipitate the deterioration of effluent quality, and threaten water ecological security from time to time. In most of the existing anaerobic biological treatment processes, toxic effects on microorganisms are determined according to the amounts of end-products of the biochemical reactions, and the evaluation results are relatively lacking. When microorganisms contact toxic substances, changes in biological metabolic activity precede the accumulation of reaction products. As sensitive units, electroactive microorganisms can generate electrical signals, a change in which can directly reflect the toxicity level. The applications of electroactive microorganisms for the toxicity monitoring of wastewater are very promising. Further attention needs to be paid to considering the appropriate evaluation index, the influence of the environment on test results, mechanisms, and other aspects. Therefore, we reviewed the literature regarding the above aspects in order to provide a research foundation for the practical application of electroactive microorganisms in toxicant monitoring.

Expression of the hypoxia-inducible factor as a predictor of the resistance of the organism of laboratory animals to hypoxia

BACKGROUND:One of the key transcriptional regulators that determine the bodys resistance to hypoxia is the hypoxia-inducible factorHIF-1, the study of the role of which in the bodys resistance to extreme influences can justify new directions in medical technologies for its increase.
 AIM:To evaluate the quantitative contribution of the level of expression of the hypoxia-inducible factorHIF-1in various tissues of laboratory animals to the increase in the resistance of animals to the effects of hypoxic hypoxia.
 MATERIALS AND METHODS:The study was carried out on outbred white laboratory rats obtained from the Rappolovo nursery weighing 180220 g. To conduct the study, animals were previously tested for an individual level of resistance to hypoxia, which made it possible to form experimental groups from highly resistant and low resistant animals. Biological material was taken from all animals (whole blood, plasma, tissues of the heart, liver, kidneys, brain), in which the expression of theHIF-1andTSPOgenes (housekeeping gene) was determined by the Real-Time-PCR method. Total RNA was isolated from the test material by affinity sorption,synthesis of the first strand of cDNA, amplification, followed by determination of the expression level of theHIF-1gene in rats was carried out according to the instructions and the manufacturers protocol by PCR with detection of the accumulation of reaction products in real time (Real-Time PCR) using a CFX-96 detecting amplifier (Bio-Rad, USA) and specific primers and probes for theHIF-1gene in rats (DNK-Sintez, Russia). Statistical processing of the obtained data was carried out using the ANOVA analysis of variance.
 RESULTS:It has been established that the level of resistance of animals to hypoxia is largely determined by their genetic characteristics. Even under normoxic conditions, the expression of theTSPOhousekeeping gene in animals with a high level of resistance to hypoxia differed with a high degree of reliability from low-resistance animals (in the kidneys, liver, and brain, on average, by 4060%; in the heart, by 25%). The values of the expression of this gene, determined in whole blood or plasma, make it possible to differentiate groups of animals according to the level of resistance to hypoxia. A similar ratio between animals with high and low resistance is also observed in tissues obtained immediately after hypoxic exposure. An analysis of the reaction of the genomic regulation system to extreme exposure showed that it increased the expression of the TSPO gene by 1.62 times equally in all tissues, regardless of the level of animal resistance. For theHIF-1gene, similar patterns were found, but the severity of their manifestations is more and significant.
 CONCLUSIONS:The main organ that provides a high level of resistance to hypoxia associated with the basic (under normoxic conditions) expression ofHIF-1is the brain. The expression of the hypoxia-inducible factor in it is more than 300 times higher than the expression of the housekeeping genes. The second most important organ is the liver, in whichHIF-1expression activity is more than 15 times higher than the expression of housekeeping genes. Under conditions of moderate hypoxia, a compensatory-adaptive reaction is noted, associated with the activation of hypoxic defense mechanisms in blood and liver cells, and in low-resistant animals, also in the brain tissue. In the myocardium, such a compensatory-adaptive reaction is activated only in the group of highly resistant animals. A high level of basal expression of theHIF-1transcription factor under daily (normoxic) conditions may be a predictor of a high level of resistance to hypoxia in a given animal.

Efficiency Analysis of Hydrogen Fuel Cell Power Systems for Off-Grid Applications

The escalating environmental hazards associated with the use of fossil fuels call for eco-friendly alternative renewable energy conversion sources. One of these renewable energy measures is the development of a hydrogen fuel cell, a device which directly converts the potential of chemical fuel into electrical power without combustion. This study evaluates the efficiency of a hydrogen fuel cell power system for off-grid applications with an aim to show how much energy can be generated from a locally produced hydrogen powered device, and for how long an electrical load (1Ω resistor) in the form of bulbs of varying loading sizes is carried. For the power and performance evaluation of the cell, multimeters equipped with integrated voltmeters and ammeters were employed for their accuracy, with a power generator, functioning through a rectifier, supplying a direct current of 3.45A at a known voltage of 18.2V, providing the means to calculate the energy input into the developed fuel cell. The results assessments, revealed that power levels steadily fall as time progresses, an occurrence caused by the depletion of reactants and the continuous accumulation of reaction products, which ultimately lead to decreasing electrochemical activity and subsequently decreased power generation. The graph readings show the dynamic behaviour of the fuel cell's performance depicted by the distinct pattern followed in the relationship between time and power output.

ГОМОГЕННО-КАТАЛИТИЧЕСКОЕ АЦЕТОКСИЛИРОВАНИЕ КАМФЕНА

The homogeneous catalytic reaction of camphene acetoxylation in the presence of palladium complexes with the predominant formation of isobornyl acetate was studied for the first time using chromatography-mass spectrometry. The reaction proceeds stoichiometrically, but can be converted to catalytic mode. Ways of formation of some accompanying products were shown and an explanation was found for the inhibition of the process during the accumulation of reaction products in the reaction zone. The obtained results were compared with the results of experiments under acid catalysis and it was shown that at a temperature of 75-80°C it is possible to achieve 99-100% conversion of the substrate with an 89% yield of isobornyl acetate.

Urea-modified Cu-based materials: Highly efficient and support-free adsorbents for removal of H2S in an anaerobic and dry environment

In this work, we report a novel urea-modified copper-based material (XUrea@Cu) obtained by directly calcinating a mixture of urea and copper nitrate. This material enables the efficient purification of H2S under dry and anaerobic conditions. The performance test results showed that the H2S capacity of the optimal adsorbent (2Urea@Cu) could reach 364.2 mg(H2S)∙gsorbent-1, which is much superior to those of other adsorbents in the literature. Further study demonstrates that the ultra-desulfurization performance of 2Urea@Cu is mainly attributed to the extensive alkaline site, the high concentrations of active oxygen, and the abundance of oxygen vacancy; which are quite effective for capturing H2S (acidic and strong reducibility). Interestingly, the deactivation adsorbent (De-2Urea@Cu) is mainly composed of high-purity CuS, which means that the Urea@Cu adsorbent can simultaneously achieve efficient purification of H2S and recovery of sulfur resources since CuS is a valuable product. In addition, in-situ FT-IR and theoretical calculation results indicate that H2S molecules dissociate on the CuO(111) surface by stepwise dehydrogenation, while S combines with adjacent Cu to form CuS. The consumption of active components (CuO) and the accumulation of reaction products (CuS) are the primary reasons for the deactivation of adsorbents. Considering the simple preparation process, low cost, and excellent H2S adsorption activity, these urea-modified copper-based materials are very promising H2S adsorbents.

Critical conditions for laser initiation of a chemical reaction in thin layer placed on substrate

In this work, we propose a model for the laser initiation of a chemical reaction in a film supported by an inert substrate. Materials of the film and the substrate have different thermal and physical properties. The model includes the equations of heat conductivity and chemical kinetics of the overall reaction. The reaction rate depends on the reactant concentration by power law and on the temperature by Arrhenius law. Consideration is given to possible changes in optical properties of the film due to accumulation of reaction products as well as to features of laser absorption and reflection from the film-substrate interface. For a detailed numerical study, the model is presented in dimensionless variables selected by fitting spatial and temporal scales that characterize the model. This reduces the number of variable parameters and gives the most general results. Critical conditions are found between different modes of the process. At the subcritical pulse duration, either no chemical reaction takes place or a reaction stops immediately after it started. At the supercritical pulse duration, complete conversion occurs in the laser hot spot. It is found that the dependence of optical properties of the film on the degree of conversion strongly affects the temperature, conversion dynamics, size of the reaction product zone, and critical conditions. In this work, for the first time, the dependence of the critical conditions separating different modes of process development (sharp temperature rise with complete transformation in the center of the heating spot and extinction, which may be accompanied by partial transformation) on model parameters was investigated. For the first time, the dynamics of the reaction front in the film located on the substrate was analyzed for conditions of changing optical properties. The results of calculations can be useful in discussing the mechanisms of destruction of polymer coatings, in describing methods of protection against external influences, as well as in developing methods for modifying surface structures, creating three-dimensional objects with specified properties, synthesis of intermetallic products in 3D - technologies, etc.

Preparation of MgX/Al2O3-Y sorbent for highly efficient simultaneous removal of hydrogen fluoride and hydrogen chloride under low-temperature environment

ABSTRACT In this study, a series of Mg-modified γ-Al2O3 sorbents have been introduced to simultaneously remove HCl and HF in a low-temperature environment. These sorbents were prepared by impregnation, and the effects of Mg loading amount and calcination temperature on the performance of the sorbent were investigated. The optimal sorbent (modified by 15 wt% Mg and calcined at 400℃, Mg15/Al2O3-400) exhibited the highest adsorption capacity of all the sorbents tested, 37.89 mg(HF)•gsorbent −1 and 34.54 mg(HCl)•gsorbent −1, respectively. Taking into account an excellent HF(HCl) capacity of the Mg15/Al2O3-400, these sorbents are very promising HF(HCl)sorbents usable in a low-temperature environment. The role of MgO loaded on γ-Al2O3 was investigated by Brunauer−Emmet−Teller (BET) method, X-ray diffractometer (XRD), scanning electron microscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption of CO2 (CO2-TPD), and thermogravimetric analysis (TG-DTG). The results revealed that MgO acted as a ‘leading role’ to promote the adsorption activity of the sorbents. BET analysis demonstrated that the Mg modification process did not seriously change the pore type of the γ-Al2O3. CO2-TPD results revealed that the calcination temperature will significantly affect the number and strength of the basic sites on the surface of the sorbent. In addition, XRD and XPS analysis indicated that the consumption of MgO and the accumulation of reaction products on the surface and pores are the main reasons for the deactivation of the sorbent.

Combined chemoresistive and in situ FTIR spectroscopy study of nanoporous NiO films for light-activated nitrogen dioxide and acetone gas sensing

The chemoresistive sensor response of nanoporous NiO films prepared by advanced gas deposition was investigated by combined resistivity and in situ FTIR spectroscopy, with and without simultaneous light illumination, to detect NO2 and acetone gases. The sensitivity towards NO2 increased dramatically under UV irradiation employing 275 nm light. Improved sensitivity was observed at an elevated temperature of 150 °C. In situ FTIR measurements were performed to record the transient gas adsorption/desorption processes. The sustained sensitivity and repeatability for NO2 sensing could be attributed to reversible surface-nitro and nitrate species formation, which are stable on the surface at relative humidity up to 40%. In contrast, acetone sensing results in irreversible decomposition and accumulation of reaction products on the NiO sensor surface, covering the surface and limiting gas sensing. Implications of the study for improved and sustained NiO gas sensor properties in gas mixtures are discussed.

Synthesis by spray pyrolysis of gold nano species confined in iron oxide nanospheres effective in the reduction of 4-nitrophenol to 4-aminophenol

The highly effective Au/Fe2O3-@Au/Fe2O3 nanoreactors for the 4-nitrophenol (4-NP) reduction are successfully obtained by one-pot synthesis using the spray pyrolysis (SP) technique. The Au/Fe2O3-@Au/Fe2O3 nanoreactors manifest superior catalytic activity in the reduction of 4-NP in the presence of sodium borohydride (NaBH4) compared to gold-iron oxide nanoreactors prepared via a colloidal approach. The negative effect of the reaction product accumulation, the 4-aminophenol (4-AP), on the catalytic reduction of 4-NP over Au/Fe2O3-@Au/Fe2O3 is examined by a direct pre-injection of 4-AP to the reaction media. To the best of our knowledge, it is the first experimental evidence of gold active sites blocking by 4-AP. All obtained samples are characterized by the yolk-shell spherical hollow structure mainly consisted of two embedded hollow nanospheres. The reduction of iron oxide precursor concentration diminishes the diameter of final iron oxide nanospheres. According to STEM-EDS analysis and STEM, Au nano species are uniformly dispersed on both iron oxide nanospheres. The SP technique presently used to synthesize Au/Fe2O3-@Au/Fe2O3 nanoreactors manifests high potential for the one-pot fabrication of a large variety of nanoreactors with various active materials applied as heterogeneous catalysts in numerous catalytic processes.

In situ scanning tunneling microscopy study of 2-mercaptobenzimidazole local inhibition effects on copper corrosion at grain boundary surface terminations

New insight on local inhibition effects of 2-mercaptobenzimidazole (MBI) on early stage intergranular corrosion of copper in hydrochloric acid solution is reported from in situ analysis at the nanometer scale and comparison with 2-mercaptobenzothiazole (MBT) effects in the same pre-adsorption and corrosion testing conditions. Macroscopic cyclic voltammetry analysis, including grains and grain boundary (GB) network, showed a passivation-like behavior in the Cu(I) oxidation range, specific to MBI since not observed with MBT and assigned to the anodic formation of a surface film of Cu(I)-MBI reaction products protecting against dissolution. Electrochemical scanning tunneling microscopy analysis revealed net intergranular dissolution, mitigated by the imperfect protection provided by the anodically formed MBI layer. It also showed local accumulation of reaction products in the GB surface regions, blocking preferential dissolution. For random GBs, blocking by local accumulation of reaction products was dominant, in agreement with the expected higher reactivity of these GBs generating more Cu(I) ions under anodic polarization and thus less efficiently protected by the anodically formed MBI layer. For Coincidence Site Lattice (CSL) boundaries, mitigated net dissolution was more frequently observed. Coherent twins showed equally efficient inhibition in the GB surface region than on adjacent grains. MBI inhibition was less efficient than MBT inhibition with more Cu(I) reaction products generated on the grains to form a surface film and their preferential local accumulation more frequently observed in the GB surface regions.

Study of the Aniline and Acetone Condensation Reaction under Electrospray Ionization Conditions

The present paper deals with the study of condensation reaction of aniline with acetone under electrospray ionization (ESI) conditions . An experimental setup is described for conducting reactions under ESI conditions with a possibility of the accumulation of reaction products. The aniline and acetone condensation products were analyzed by gas chromatography–mass spectrometry. Spraying this mixture with high concentration of formic acid, results in the formation of N-phenylformamide, N,N'-diphenylmethaneimidamide, and 1,2-dihydro-2,2,4-trimethylquinoline; the last one is the only product of the reaction of aniline with acetone. Thus, the Schiff base formation reaction radically changes its direction. The results obtained using the proposed experimental setup open up new prospects both for studying chemical reactions in charged microdroplets and for the use of ESI as a preparative method for the synthesis of organic compounds.

A kinetic model for equilibrium binding of intercalation dye with DNA during its amplification

Recently, a number of models of polymerase chain reaction (PCR) have been proposed. In such models, the kinetics of a reaction product and a fluorescence reporter used are usually identified. An intercalation dye is one of the two ways for “real time” detection of reaction product accumulation. In this work a PCR model is proposed, with using of intercalation dye to obtain a PCR curve. The concentration of bound intercalation dye was calculated at the end of each PCR cycle. This calculation is based on an equilibrium equation for intercalation dye binding with DNA. An analysis of simulation results demonstrates a significant difference between the accumulation kinetics of the reaction product and the fluorescent signal of the bound intercalation dye.

Local Inhibition by 2-mercaptobenzothiazole of Early Stage Intergranular Corrosion of Copper

Corrosion inhibition by 2-mercaptobenzothiazole (MBT) at the surface termination of various types of grain boundaries (GBs) was studied at the nanometer scale on microcrystalline copper in HCl acid solution using in situ electrochemical scanning tunneling microscopy (ECSTM). Macroscopic electrochemical analysis by cyclic voltammetry showed highly effective inhibition of Cu(I) active dissolution blocked by MBT pre-adsorption in a potential range of 0.15–0.2 V. ECSTM analysis of the initial stages of intergranular corrosion confirmed the mitigation of net intergranular dissolution by the pre-adsorbed MBT surface layer but also revealed the local accumulation of reaction products in the GB regions. For Coincidence Site Lattice boundaries other than coherent twins, intergranular dissolution, mitigated by the pre-adsorbed MBT layer, and protection by intergranular formation of a film of reaction products were observed. For random GBs, protection by reaction products was dominant, in agreement with their more reactive intrinsic character, generating more Cu(I) ions under anodic polarization and thus promoting the formation of a protective film of reaction products. Coherent twins did not show preferential intergranular reactivity compared to adjacent grains, indicating equally strong efficiency than on grains. These results bring new insight on how inhibition operates locally at various types of GBs.

Microbial ecology and biogeochemistry of hypersaline sediments in Orca Basin

In deep ocean hypersaline basins, the combination of high salinity, unusual ionic composition and anoxic conditions represents significant challenges for microbial life. We used geochemical porewater characterization and DNA sequencing based taxonomic surveys to enable environmental and microbial characterization of anoxic hypersaline sediments and brines in the Orca Basin, the largest brine basin in the Gulf of Mexico. Full-length bacterial 16S rRNA gene clone libraries from hypersaline sediments and the overlying brine were dominated by the uncultured halophilic KB1 lineage, Deltaproteobacteria related to cultured sulfate-reducing halophilic genera, and specific lineages of heterotrophic Bacteroidetes. Archaeal clones were dominated by members of the halophilic methanogen genus Methanohalophilus, and the ammonia-oxidizing Marine Group I (MG-I) within the Thaumarchaeota. Illumina sequencing revealed higher phylum- and subphylum-level complexity, especially in lower-salinity sediments from the Orca Basin slope. Illumina and clone library surveys consistently detected MG-I Thaumarchaeota and halotolerant Deltaproteobacteria in the hypersaline anoxic sediments, but relative abundances of the KB1 lineage differed between the two sequencing methods. The stable isotopic composition of dissolved inorganic carbon and methane in porewater, and sulfate concentrations decreasing downcore indicated methanogenesis and sulfate reduction in the anoxic sediments. While anaerobic microbial processes likely occur at low rates near their maximal salinity thresholds in Orca Basin, long-term accumulation of reaction products leads to high methane concentrations and reducing conditions within the Orca Basin brine and sediments.

Electrocatalytic dehalogenation of aqueous pollutants by dealloyed nanoporous Pd/Ti cathode

In this study, commercial Ti-0.15Pd alloy could be activated by selective dissolution of Ti using simple HF treatment, to catalyze electrochemical dehalogenation of aqueous pollutants. The surface of dealloyed cathodes was characterized with a Pd-enriched nano-porous structure, as confirmed by scanning electron microscopy, glow discharge spectroscopy and transmission electron microscopy with energy-dispersive X-ray spectroscopy. With respect to the surface loading of Pd and 2-chlorophenol (2-CP) hydrodechlorination rate, the [HF] and exposure time were optimized to be 0.5 M and 5 min, respectively. 2-CP removal was maximized at the lowest values of current density (2.5 mA/cm2) and pH (1.8). The activation energy and energy consumption for 2-CP dechlorination were estimated to be 30.7 kJ/mol and 47 kW h/kg for the nanoporous Pd/Ti cathode. Scavenging experiments for the electron (e−) and hydrogen radical (H·) confirmed that adsorbed H· was the active mediator responsible for the dechlorination, which was active for reductive removal of other brominated and iodinated organic compounds. Owing to an accumulation of reaction products inside the pores, periodic regeneration of the catalytic electrodes was necessary, with a proper cycle to minimize the loss of precious Pd component.

Carbon dioxide chemical absorption in non-aqueous solvents by the presence of water

Abstract Present work analyzes the role of water in a gas–liquid–liquid absorber using a non-soluble amine (octylamine) in water. The presence of water causes an enhancement in carbon dioxide loading and absorption rate in comparison with the use of the organic solvent. Several issues have been analyzed in present research work: influence of gas flow-rate, water and amine concentration, type of organic solvent and solvent regeneration. The analysis of experimental data and speciation studies by using nuclear magnetic resonance allows to understand the overall behavior with the accumulation of reaction products in the organic phase by the formation of water-in-oil microemulsion. The accumulation of reaction products allows to decrease the solvent flow rate that must be regenerated and it can decrease the cost of this type of operation.

Deformation behaviour of concrete materials under the sulfate attack

Abstract This study developed an integrated computational model to predict the time-dependent elastic deformation behaviour of concrete materials under external sulfate attack. The reactive-transport process of ions, pore size dependent diffusion coefficient and internal stress development induced by the ettringite formation inside the concrete pores are all considered in the model. Experiments of longitudinal expansion of specimens under different concentration of sulfate ions are carried out to validate the model predictions. Results show that the model can reproduce the experimental observed elastic deformation behaviour of concrete by using one set of model parameters and the relationship between ettringite generated pressure and ettringite concentration could be described by Hill Function. It indicates that the internal stress induced by ettringite formation initially increases at a relatively slow rate until its concentration reaches 20% of the maximum allowable concentration cEtt_max, at which a significant increase of internal expansive stress is triggered, and finally the change of the internal stress gradually keep a stable state when ettringite concentration is over 50% of cEtt_max. Furthermore, it demonstrates that under the influence of accumulation of reaction product, the diffusion coefficient of sulfate ion decreases with time and a relatively high sulfate concentration reduces the time required for concrete to reach its elastic limits.

A high-energy-density and long-stable-performance zinc-air fuel cell system

Metal-air fuel cells are regarded as potential alternatives of power supply due to their high specific energy. However, the excessive accumulation of reaction products leads to performance degradation, low energy density, and short service life, hampering more widespread application. This study focuses on enormously increasing the fuel cell system energy density by electrolyte isolation and management. Filters are used to isolate metal oxide (including ZnO, MgO, and Al2O3) from supersaturated electrolyte solutions in fuel cells. The filtration efficiency is close to 100%. The flow field is optimized to suppress the anode passivation. In zinc-air fuel cells (ZAFCs), the ratio of discharge capacity to electrolyte volume (electrolyte capacity) is up to 1025 Ah L−1, and the discharging voltage still remains stable. The zinc-air fuel cell system (ZAFCS) exhibits high energy density, high stability, and low cost, rendering this type of metal-air fuel cell a promising energy storage in electric vehicles.