Stage Of Reaction Research Articles

Ethylene Oligomerization: Unraveling the Roles of Ni Sites, Acid Sites, and Zeolite Pore Topology through Continuous and Pulsed Reactions

AbstractHerein, four catalysts, consisting of either MFI or BEA as the zeolite framework in the presence or absence of Ni, are compared to explore the individual and collective adsorptive and catalytic contributions of pore topology, Ni sites, and acid sites. Both continuous and pulsed chemisorption/reaction experiments are used to obtain a complete picture of the time‐dependent adsorption‐desorption behavior, reaction mechanisms, and deactivation steps. The methodology highlights the effect of acid sites, especially during the initial stages of reaction and in the BEA‐based catalysts, which have higher acidity at a given Si/Al ratio. In addition, Ni accelerates the reaction and improves the selectivity towards intermediate oligomers. However, the tendency for the most active Ni and acid sites to saturate and deactivate more rapidly than the less active ones may lead to misinterpretation when using the continuous reactor alone. Hence, the dominant mechanisms over the different catalyst sites and reaction times are discussed based on the combined steady and dynamic experiments.

Regulating In-MOF derivatives for bidirectionally boosting redox kinetics of sulfur cathodes

Lithium sulfur (Li–S) batteries are regarded as a promising application device due to their high theoretical capacity and energy density. However, the commercialization of Li–S batteries is restricted due to their fast capacity fading caused by the shuttle effect of lithium polysulfide (LiPSs) and slow redox reaction of sulfur cathodes. Designing highly-active bidirectional electrocatalysts is an effective strategy to address the problems caused by complex multi-step reactions. Herein, the phase of In-metal-organic framework (In-MOF) derivatives are regulated by controlling the carbonization temperature, and In–In2O3@C heterostructure composite can be obtained at 800 °C. The results show that the polar In2O3 can not only effectively adsorb LiPSs but also accelerate the conversion from Li2S8 to Li2S4, and In can promote the conversion from Li2S4 to Li2S and simultaneously lower the dissociation energy barrier of Li2S. Due to the different catalytic functions of In and In2O3 for different reaction stages of Li–S batteries, In–In2O3@C shows bidirectionally catalytic effect, and renders the corresponding batteries achieve the best electrochemical properties. The specific discharge capacity of In–In2O3@C/S can reach 1298.5 mAh g−1 at 0.2 C after three cycles of activation, and it keeps 620.9 mAh g−1 after 80 cycles with Coulombic efficiency of approximate 100 %. Regulating the products of MOF derivatives provides a reference for the regulation of catalysts for Li–S batteries.

The effects of energy consumption of alumina production in the environmental impacts using life cycle assessment

PurposeAluminium industry emits around 1–2% of the world’s total greenhouse gas emissions. Up to one-third of those are linked to the thermal energy consumed during its initial process: the alumina refining (Bayer process). Previous studies consider the Bayer process a single stage despite its being made of several reaction stages. This work presents a disaggregated energy analysis of the Bayer process that facilitates to find relationships between the main variables in regular alumina production and the environmental impacts.MethodsTwo different thermodynamic simulations of the Bayer process were carried out using Aspen V11 software. The results of these simulations were validated with referenced data, and afterwards, they were used to perform a life cycle assessment. ISO 14040 and 14,044 standards were followed during the analysis. LCA was implemented on SimaPro 9.0, and ReCiPe 2016 Midpoint (H) method was used to calculate environmental impacts. The influence of bauxite mineral form, type of fuel (energy input), and the distance from the mine to the plant was analysed throughout the study.Results and discussionAs expected, the type of fuel was revealed as the most crucial factor in the environmental impact of alumina production, with potential savings of up to 75.5% of CO2-equivalent emissions. Nonetheless, the tendency is diverse for other indicators, such as marine eutrophication or terrestrial acidification. On the other hand, while bauxite transportation always has the same impact on the different environmental indicators, bauxite mineral form affects differently depending on the fuel, causing variations in the CO2-eq emissions from 7.7 to 51.3%.ConclusionsResults indicated that the electrification of heat-demanding processes and the use of renewable power is the most effective approach for reducing environmental impacts. This strategy, however, must be considered in combination with others, as interdependent effects exist on the type of mineral used. These results provide strong evidence of the potential for environmentally friendly strategies in the metal industry, including new processes, alternative fuels, or mineral switching to promote more sustainable aluminium production.

Effect of CH4 Addition on Soot Formation in C2H4 Diffusion Flame

Abstract Studying the effect of co-combustion of multiple fuels on soot formation has become a hot spot in the investigation of soot particles. In this paper, the influence of methane blending on soot formation in ethylene flame combustion is studied experimentally and numerically. The visible spectrum of flame image processing technology was used for the in situ measurement of laminar flame temperature and carbon smoke volume points in the experiment. The effects of different methane blending ratios on particle nucleation, coalescence, surface growth, and oxidation process of soot were analyzed based on the piecewise particle dynamics soot model of polycyclic aromatic hydrocarbons (PAHs) using CoFlame Code. Results indicate that the synergistic effect promoted the increasing rate of nucleation and addition reaction of hydrogen extraction at a low methane blending ratio, and the increase in the total mass of soot was mainly due to the PAH condensation rate. The total amount of soot generation gradually decreases with increasing blending ratio. The overall trend of condensation, surface growth rate, and soot nucleation in the flame decreases with increasing blending ratio. And the nucleation rate gradually shifts from a single peak to a double peak and increases slightly at the initial stage of the flame combustion reaction. It is worth mentioning that the change of three PAH precursors (secondary benzo(a)pyrenyl, benzo(a)pyrene, and benzo(ghi)fluoranthene) and the temperature explains the change of nucleation rate from unimodal to bimodal.

Exploration of a two-stage polymerization mechanism in construction of dense polyester membranes for drinking water treatment

Due to the relatively low reactivity of hydroxyls with acyl chloride groups, the synthesized polyester (PE) membranes commonly have loose structures, only capable of removing large-molecule organics with low rejection of inorganic salts. In this study, the pore size reduction of the synthesized PE membrane was successfully achieved by optimizing the interfacial polymerization (IP) reaction between erythritol and trimesoyl chloride (TMC). The optimized membrane was able to maintain a high xylose rejection (∼60 %) and acceptable water permeance (7.85 L m−2 h−1 bar−1), which was suitable for drinking water treatment. Through comprehensive characterizations, a two-stage membrane formation process was demonstrated regarding the reaction between aqueous monomers with different reactive functional groups and TMC. The highly reactive primary hydroxyls more preferentially participated in the initial reaction stage, leading to a linear cross-linking pattern of polyester. When the molecular diffusion was inhibited, the participation of secondary hydroxyls made the reaction proceed toward partial or full cross-linking. The distinct roles of the two kinds of hydroxyl groups were further verified by the energy barrier differences obtained by density functional theory (DFT) calculation. The exploration of membrane-optimized preparation and formation mechanisms can promote the structural regulation and tailored synthesis of PE membranes for various applications.

Computational study of added H2 impacts on mixture formation, OH radical and unregulated emissions of spark-ignition methanol engine under various boundary parameters

Numerical simulations of hydrogen (H2) impacts on mixture formation, OH radical generation, and formaldehyde (HCHO) and unburned methanol (CH3OH) emissions of spark-ignition (SI) methanol engine based methanol late-injection strategy under different methanol injection timings (MIT), ignition timings (IT), excess air ratios (λ) and added H2 ratios (RH2) boundary parameters were conducted. The simulation results show that the ideal methanol concentration distribution is obtained at the MIT = 85°CA BTDC. The OH radical plays a dominant role in methanol oxidation. The OHPMF (peak OH radical mass fraction) of RH2 = 9 % ≫ OHPMF of RH2 = 6 % > OHPMF of RH2 = 3 % > OHPMF of RH2 = 0 % at MIT = 85°CA BTDC. Compared with IT and λ, the RH2 is more decisive for the generation of OH radical. The HCHO is a major intermediate and an important unregulated emission of methanol engine. In the initial stage of methanol reaction, added H2 can accelerate the generation of OH radical, further promote the oxidation of methanol, and greatly raise the generation of HCHO. The peak HCHO mass fraction increases with the increase of RH2. At MIT = 85°CA BTDC and exhaust valve opening, the HCHO emission of RH2 = 3 %, 6 %, and 9 % is approximately 51 %, 76.5 % and 89.4 % lower than that of RH2 = 0 %, respectively. The generation and post-oxidation of HCHO mainly depended on average in-cylinder temperature. There is a lowest CH3OH emission at MIT = 85°CA BTDC, IT = 28°CA BTDC, λ = 1.4 and pure methanol. At MIT = 85°CA BTDC, λ = 1.4 and exhaust valve opening, the CH3OH emission of RH2 = 3 %, 6 %, and 9 % is approximately 52.8 %, 75.5 % and 92.5 % lower than that of RH2 = 0 %, respectively.

ReaxFF Molecular Dynamics Study on the Microscopic Mechanism for Kerogen Pyrolysis.

Kerogen is mainly composed of carbon, hydrogen, and oxygen, which are the main components of crude oil and gas. The pyrolysis of kerogen is an efficient method to generate clean energy. In the present work, the pyrolysis reaction process of three types of kerogen is simulated using ReaxFF molecular dynamics (MD) methods to study the microscopic mechanism and the distribution of products. The results indicated that the pyrolysis products of the three types of kerogen significantly depend on the molecular structures, temperature, and reaction time. As the temperature increases, the gaseous hydrocarbon and the light and heavy oil fractions decreased, where small molecular fragments polymerized to form new molecular fragments. For an isothermal temperature, with the reaction proceeding, some component polymerization of the pyrolyzed fragments occurred, resulting in the generation of new light oils and heavy oils. Moreover, quantum chemical analysis was employed to reveal the kerogen pyrolysis mechanism. First, the weak bonds such as C-O, C-N, and C-S structures were decomposed to generate large carbon and some heavy shale oil fragments. Second, the cycloalkanes and long-chain alkanes were decomposed to generate a large amount of light shale oil and gaseous hydrocarbons. Finally, the decomposition of C═C in the aromatic ring, the secondary decomposition of light and heavy shale oils, and the further decomposition of short-chain alkanes occurred. In addition, the production of hydrogen (H2) occurred at the late stage of the pyrolysis reaction. Hydrogen radicals were formed by the decomposition of C-H bonds and subsequently collided with each other, resulting in the formation of H2 molecules. The pyrolysis and chemical analysis of kerogen can clearly determine the type and content of hydrocarbon substances, providing scientific data for exploration, development, and utilization of shale gas and shale oil.

Charging rate effect on overcharge-induced thermal runaway characteristics and gas venting behaviors for commercial lithium iron phosphate batteries

Increasing charging rate is an upgrading direction of electrochemical energy storage, which might induce more heat accumulation, posing a higher risk to cause the battery thermal runaway (TR). Driven by this, an experimental investigation was carried out to study the characteristics of TR and gas venting behaviors in commercial lithium iron phosphate (LFP) batteries that were induced by overcharging under different rates. As the charging rate increases, the growth rate of lithium dendrites accelerates, resulting in the earlier formation of large-scale short circuits and a rapid transition to the next stage of the TR chain reaction. However, the temperature rise and the total heat does not increase in proportion to the charge rates. The electrolyte also accelerates its decomposition, and the reaction between the electrolyte and lithium is the main reason of overcharge heat accumulation. It is worth noting that the charging rate for overcharging is positively correlated with the TR violence of batteries and the explosion risk of the ejected gas. The main gases emitted are H2, CO, and CO2 and various alkanes. Specifically, the content of H2 gas increases significantly with the increase of charging rate. And the H2 contents for 2C, 1.5C and 1C correspond to 61%, 53% and 50%, respectively. The rapid growth of lithium dendrites results in a significant increase in H2 generation and earlier capture. This is accompanied by a higher impact pressure and a lower explosion limit (LEL) of the combustible gas mixture, indicating a severer explosion risk. In short, by comparing the TR characteristics and gas products of LFP batteries with different charging rates, which is of great significance for the fire extinguishing design and emergency response of energy storage systems.

Advancements of Intense Terahertz Field Focusing on Metallic Nanoarchitectures for Monitoring Hidden Interatomic Gas-Matter Interactions.

With the advancements of nanotechnology, innovative photonic designs coupled with functional materials provide a unique way to acquire, share, and respond effectively to information. It is found that the simple deposition of a 30nm-thick palladium nanofilm on a terahertz (THz) metasurface chip with a 14nm-wide effective nanogap of asymmetric materials and geometries allows the tracking of both interatomic and interfacial gas-matter interactions, including gas adsorption, hydrogenation (or dehydrogenation), metal phase changes, and unique water-forming reactions. Combinatorial analyses by simulation and experimental measurements demonstrate the distinct nanostructures, which leads to significant light-matter interactions and corresponding THz absorption in a real-time, highly repeatable, and reliable manner. The complex lattice dynamics and intrinsic properties of metals influenced by hydrogen gas exposure are also thoroughly examined using systematically controlled ternary gas mixture devices that mimic normal temperature and pressure. Furthermore, the novel degrees of freedom are utilized to analyze various physical phenomena, and thus, analytical methods that enable the tracking of unknown hidden stages of water-forming reactions resulting in water growth are introduced. A single exposure of the wave spectrum emphasizes the robustness of the proposed THz nanoscopic probe, bridging the gap between fundamental laboratory research and industry.

Hydrogen Generation from Waste Aluminum Foil AA 1235 Promoted by Sodium Aluminate in Sodium Hydroxide Solutions

The primary barrier to hydrogen production through the aluminum-water reaction is the oxide layer which forms on the exterior surface of the aluminum. In this work, the passivation was minimized by optimizing the concentration of sodium hydroxide solution (0.3 - 0.5 M) promoted by NaAlO2 at room temperature reaction conditions. The aluminum used is waste aluminum foil AA1235 chips having dimensions of 20 mm x 30 mm. The results showed that the hydrogen production rate increases as the NaOH solution concentration increases. The higher the solution’s pH, the shorter the hydrolysis process of the alumina layer, hence the hydrogen production is faster. Adding NaAlO2 as a promoter could increase the hydrogen production rate compared to sole NaOH, i.e., 11.162 ml/minute and 9.86 ml/minute, respectively. This increase occurred significantly during the fast reaction stage. It indicates that the solution containing NaOH and NaAlO2 work synergistically whereby NaOH can accelerate the reaction rate in the aluminum core and NaAlO2 functions as the booster for producing Al(OH)3.

Stepwise differentiation of follicular helper T cells reveals distinct developmental and functional states

Follicular helper T (Tfh) cells are essential for the formation of high affinity antibodies after vaccination or infection. Although the signals responsible for initiating Tfh differentiation from naïve T cells have been studied, the signals controlling sequential developmental stages culminating in optimal effector function are not well understood. Here we use fate mapping strategies for the cytokine IL-21 to uncover sequential developmental stages of Tfh differentiation including a progenitor-like stage, a fully developed effector stage and a post-effector Tfh stage that maintains transcriptional and epigenetic features without IL-21 production. We find that progression through these stages are controlled intrinsically by the transcription factor FoxP1 and extrinsically by follicular regulatory T cells. Through selective deletion of Tfh stages, we show that these cells control antibody dynamics during distinct stages of the germinal center reaction in response to a SARS-CoV-2 vaccine. Together, these studies demonstrate the sequential phases of Tfh development and how they promote humoral immunity.

Solvent/ligand free synthesis of Mn-doped CsPbCl3 perovskites with enhanced fluorescence for color sensor of bromide ions

For the detection of anions from wastewater, the perovskite materials synthesized should have suitable stability and be as hydrophilic as possible, and it’s not appropriate to introduce organic ligands. Mechanochemical reaction can avoid the use of organic solvents and provide improved stability for the perovskite materials due to their large particle size and compact structure, but their fluorescence is often too weak. To solve this problem, the Mn2+ doping effect was introduced into the CsPbCl3 crystals, and their synthesis doping strategies driven by mechanical grinding were systematic studied. The optimal Mn2+-doped CsPbCl3 (CsPbCl3:Mn) product was obtained by optimizing the synthesis conditions of Mn2+ source, grinding time on each reaction stage, Mn: Pb feeding ratio, and the sintering temperature. CsPbCl3:Mn had the same crystal structure as its undoped counterpart, while an obvious photoluminescence emission peak at 604 nm was obtained, which was originated from the doped Mn2+ ions. CsPbCl3:Mn had good stability against the ethanol environment and there was no organic ligands to hinder the ion exchange between Cl- and Br- from wastewater. Through testing the color difference of the resultant powders, a linear relationship with high correlation coefficient above 0.99 was established between chroma and Br- concentrations, and the Br- concentration in wastewater was accurately determined, demonstrating a promising application prospect of CsPbCl3:Mn in the fast detection of Br- ions.

3D printed cell for the in situ dynamic light scattering monitoring of nanoparticle size distribution in microfluidics

Microfluidic systems offer a reproducible approach for material synthesis at microliter quantities. Automatization of such systems requires development of new approaches for insitu diagnostics, which can provide feedback for the optimization algorithms. The knowledge about size distribution at different reaction stages is of key importance for the nanoparticle synthesis, but most laboratory devices are designed to work with batch systems. In this work we have designed 3d printed devices for dynamic light scattering (DLS) characterization. The combination of backscatter DLS module and microfluidic chips enables insitu monitoring of ultra-low (down to nanoliters) volumes of sample solution even at high concentration. We report several types of microfluidic chips compatible with the commercially available systems with analyzer fiber probe for the measurements in flow and static regimes. The latter option does not contribute with the flow speed to the Brownian motion of nanoparticles and thus does not affect the calculated particle size distribution. 3d-printed cell for DLS measurements on the one hand, probes small sample volume, on the other, enables cheap insitu hydrodynamic size determination. The application of developed instruments is demonstrated for Tb-doped GdF3 nanoparticles, tween micelles, and gold nanoparticles.

Effect of ferrocene as a combustion catalyst on the premixed combustion flame characteristics of Jatropha biodiesel

Fuel additives are widely used to optimize the combustion process, reduce the harmful emissions, and improve the performance of engines. Among the metal-based additives, ferrocene is soluble in most fuels, including biodiesel. Furthermore, it is easily available and has high stability, low toxicity, and high lipophilicity. It can evenly disperse in biodiesel without causing any change in the physicochemical properties. Therefore, it can serve as an effective combustion catalyst for biodiesel. In this study, the effect of ferrocene as a combustion catalyst on the pyrolysis and combustion performance of Jatropha biodiesel is investigated. The coupled technique of thermogravimetry-Fourier transform infrared spectroscopy-mass spectrometry (TG-FTIR-MS) is used to analyze the evolution characteristics of multicomponent gaseous products generated during the pyrolysis and high-temperature oxidation of Jatropha biodiesel (JB100) and Jatropha biodiesel + ferrocene (JBF). The laminar premixed combustion flame and pollutant emissions of JB100 and JBF are examined using a variety of techniques, including OH planar laser-induced fluorescence (OH-PLIF), flue gas analysis, spectral analysis, transmission electron microscopy, etc. The results reveal that after adding ferrocene, the activation energy for the pyrolysis reaction of JB100 decreases by 4.66 kJ/mol and the complete weight loss temperature decreases by 10 ℃. Further, the addition of ferrocene reduces the endothermic heat by 0.38 mW/mg during the initial stage of the high-temperature oxidation reaction of JB100, and the amounts of final products CO2 and H2O are increased. Compared with JB100, JBF shows an enhanced OH group intensity in the combustion flame and a lower soot spectral peak. Furthermore, compared with JB100, under JBF combustion, the pollutant PM2.5 emissions decrease by 13.3 %, PM10 emissions decrease by 13.2 %, PM> 10 particulate matter emissions decrease by 19.3 %, CO emissions decrease by 6.8 %, NOx emissions increase by 21.2 %, and the size of soot particles decreases by 20.8 %.

Study of the reaction mechanism for preparing powdered activated coke with SO2 adsorption capability via one-step rapid activation method under flue gas atmosphere

In this study, the impact of different reaction times on the preparation of powdered activated carbon (PAC) using a one-step rapid activation method under flue gas atmosphere is investigated, and the underlying reaction mechanism is summarized. Results indicate that the reaction process of this method can be divided into three stages: stage Ⅰ is the rapid release of volatiles and the rapid consumption of O2, primarily occurring within a reaction time range of 0–0.5 s; stage Ⅱ is mainly the continuous release and diffusion of volatiles, which is the carbonization and activation coupling reaction stage, and the carbonization process is the main in this stage. This stage mainly occurs at the reaction time range of 0.5–2.0 s when SL-coal is used as material, and that is 0.5–3.0 s when JJ-coal is used as material; stage Ⅲ is mainly the activation stage, during which activated components diffuse to both the surface and interior of particles. This stage mainly involves the reaction stage of CO2 and H2O (g) activation, and it mainly occurs at the reaction time range of 2.0–4.0 s when SL-coal is used as material, and that is 3.0–4.0 s when JJ-coal is used as material. Besides, the main function of the first two stages is to provide more diffusion channels and contact surfaces/activation sites for the diffusion and activation of the activated components in the third stage. Mastering the reaction mechanism would serve as a crucial reference and foundation for designing the structure, size of the reactor, and optimal positioning of the activator nozzle in PAC preparation.

Modeling stages of domino reaction of thiopyrano[4,3-b]indole-3(5H)-thiones and dimethyl acetylenedicarboxylate: a new synthetic route to γ-carbolines with thione group

Modeling stages of the cascade reaction of thiopyrano[4,3-b]indole-3(5H)-thiones and dimethyl acetylenedicarboxylate were studied. Alkylation of thiones with alkyl halides or dimethyl sulfate affording to thiopyrano[4,3-b]indole-2-ium salts models the first stage of the process. The attack at the 3-position of the obtained salts by secondary amines can serve as a model for the second stage of the cascade transformation; it gives 3-benzoylindoles with thioamide-group. Reactions of thiopyrano[4,3-b]indole-2-ium salts with primary amines lead to a series of γ-carbolines with thione group. The action of ammonia on these salts causes dealkylation and gives thiopyrano[4,3-b]indole-3(5H)-thiones.

Mechanistic Insight into Acceptorless Dehydrogenation of Methanol to Syngas Catalyzed by MACHO-Type Ruthenium and Manganese Complexes: A DFT Study.

The acceptorless dehydrogenation of methanol to produce carbon monoxide (CO) and dihydrogen (H2) mediated by MACHO-type 1-Ru and 1-Mn complexes was theoretically investigated via density functional theory calculations. The 1-Ru-catalyzed process involves the formation of active species 4-Ru through a methanol-bridged H2 release pathway. Methanol dehydrogenation by 4-Ru yields formaldehyde and 1-Ru, followed by H2 release to regenerate 4-Ru (rate-determining step, ΔG‡ = 32.5 kcal/mol). Formaldehyde further reacts with methanol via nucleophilic attack of the MeO- ligand in the Ru complex (ΔG‡ = 9.6 kcal/mol), which is more favorable than the traditional methanol-to-formaldehyde nucleophilic attack (ΔG‡ = 33.8 kcal/mol) due to the higher nucleophilicity of MeO-. CO is ultimately produced through the methyl formate decarbonylation reaction. Accelerated H2 release in the early reaction stage compared to CO results from the initial methanol dehydrogenation and condensation of formaldehyde with methanol. In contrast, CO generation occurs later via methyl formate decarbonylation. The 1-Mn-catalyzed reaction has reduced efficiency compared to 1-Ru for the higher Gibbs energy barrier (ΔG‡ = 34.1 kcal/mol) of the rate-determining step. Excess NaOtBu promotes the reaction of CO and methanol, forming methyl formate, significantly reducing the CO/H2 ratio as the catalyst amount decreases. These findings deepen our understanding of the methanol-to-syngas transformation and can drive progress in this field.

Corrosion product film formation mechanism of 110H-13Cr casing steel in simulated ultra-high-temperature gas environment for shale oil production

This study investigated the corrosion film formation mechanism of 110H-13Cr at 350 °C in the coexistence of four gases, including H2, H2S, CO2 and H2O, by using techniques such as SEM, EDS, XRD and RAMAN, along with thermodynamic calculations. The results indicate that the average corrosion rate of 110H-13Cr is only 0.0573 mm/a. In this environment, the 110H-13Cr steel spontaneously reacts with H2S and H2O. The corrosion products consist of an easily removable outer Fe(1-x) S film and a dense inner Fe-Cr oxide film. The corrosion film formation process comprises an interfacial reaction stage and an element diffusion stage.

Hydrogen storage and capacity degradation mechanism of superlattice La-Y-Ni-based hydrogen storage alloy

New La-Y-Ni-based hydrogen storage alloys exhibit key technological advantages for energy storage; however, several challenges arise because of their insufficient cycle life. In this study, we design a non-stoichiometric structure and present a scheme for obtaining a stable superlattice structure by optimizing multi-component elements and understanding the structural evolution and anti-degradation mechanism for increasing the cycle life. The rationality of the scheme is verified by designing AB3.67-type La1.4Ce0.5Y4.1-xSmxNi20Mn1.2Al0.8 (x = 0, 0.2, 0.3, and 0.4) alloys. Substituting Y with an appropriate amount of Sm reduces capacity degradationin both in electrochemistry and solid/H2 reactions because it effectively inhibits the transition of the stable phase and this regulation reduces the mismatch of subunits in the Gd2Co7-type phase, especially the control [A2B4] subunit instead of the [AB5] subunit. Further, a capacity degradation mechanism is illustrated and the entire process is divided into three stages. The corrosion resistance of synergistic elements in the first stage (<100 cycles) of the electrochemical reaction is a decisive factor controlling the long-term cyclic stability of alloys. Although the amorphous phase in the solid-H2 reaction is the main factor responsible for decay, the La1.4Ce0.5Y3.8Sm0.3Ni20Mn1.2Al0.8 alloy shows better electrochemical properties, with a maximum discharge capacity, H2-absorption capacity, and capacity retention rate S100 of 377.7 mAh g−1, 1.64 wt%, and 90.9 %, respectively. After 500 cycles, the capacity retention rate is enhanced from 42 % to 60.9 %. The proposed scheme is expected to prom.

Self-acclimation mechanism of pyrite to sulfamethoxazole concentration in terms of degradation behavior and toxicity effects caused by reactive oxygen species

Pyrite has been extensively tested for oxidizing contaminants via the activation of water molecule or dissolved oxygen, while the changing of oxidation species induced by contaminant’s concentration has been largely underestimated. In this study, we revealed a self-acclimation mechanism of pyrite in terms of •OH conversion to 1O2 during the sulfamethoxazole (SMX) degradation process under oxic conditions. Two reaction stages of SMX degradation by pyrite were observed. The SMX concentration decreased by 70% rapidly in the first 12 h after the reaction was initiated, then, the removal rate began to decrease as the SMX concentration decreased. Importantly, •OH and O2•− were the dominant oxidizing species in stage one, while 1O2 was responsible for the further degradation of SMX in stage two. The self-acclimated mechanism of pyrite was proven to be caused by the conversion of oxidative species at the surface of pyrite. This process can overcome the shortages of •OH such as ultrashort lifetime and limited effective diffusion in the decontamination of micropollutant. Moreover, different reactive oxygen species will lead to different degradation pathways and environmental toxicity while degrading pollutants. This finding of oxidizing species’ self-acclimation mechanism should be of concern when using pyrite for water treatment.