Surface Chemical Reactions Research Articles

Spectral insight into the interface evolution of a carbon/carbon composite under high-enthalpy, nonequilibrium flow

Gas–surface interactions between thermal protection materials and high-enthalpy nonequilibrium flow are one of the greatest challenges in accurately predicting aerodynamic heating during supersonic flights. Finer microscopic details of flow properties are required for elaborate simulation of these interactions. Spectral insight, with quantum-state-specific characteristics, is provided in this work to investigate the physico-chemical processes in high temperature interface of a carbon/carbon (C/C) composite. The nonequilibrium air flow is produced by a 1.2 MW inductively coupled plasma wind tunnel at an enthalpy of 20.08 MJ/kg. The duration of each test is up to 100 s, and quartz is also tested for comparison. Spectral insights into the reaction mechanisms of the gas–surface interactions are acquired by the optical emission spectroscopy and laser absorption spectroscopy. Dynamic evolution of the chemical reaction pathways and thermal nonequilibrium are discussed based on the results of optical emission spectroscopy. Temporally and spatially resolved results of the translational temperature and number density of atomic oxygen are quantified by laser absorption spectroscopy. Controlling mechanisms in the surface chemistry are further analyzed in conjunction with the surface temperature, scanning electron microscopy, and energy dispersive spectroscopy. Reaction mechanisms on the C/C composite surface sequentially experience an oxidation-dominant, an intense competitive, a nitridation-dominant, and a recession dominant period. Distributions in the axial direction and dynamic characteristics of the translational temperature and number density of atomic oxygen are found closely related with surface swelling, recession, and chemical reactions. The results herein are consistent with each other and are instructive to further investigate the interface evolution on C/C composites.

The Leaching Behavior of Potassium Extraction from Polyhalite Ore in Water.

The extraction of potassium from polyhalite ore (K2SO4·MgSO4·2CaSO4·2H2O) can help alleviate potassium resource shortages in China. In this study, the leaching behavior of potassium extracted from polyhalite ore in water was investigated using leaching experiments and kinetic analysis. The effects of various factors, such as liquid-to-solid ratio, leaching temperature, leaching time, and polyhalite ore particle size were comprehensively studied. It was found that high temperatures improved the reaction rate and efficiency at the beginning (1-15 min) but reduced the final leaching efficiency of potassium. And this phenomenon is discussed from the aspects of the dissolution-reprecipitation of potassium, newly formed solid products during the leaching process, and leaching thermodynamics. The leaching of potassium followed the Avrami model, with an apparent activation energy of 26.29 kJ/mol. Additionally, it was determined that the mixed controlled step (surface chemical reaction and diffusion) was the controlling step during potassium leaching. This study clarified the leaching mechanism of the polyhalite in water, and the causes of hindering the leaching of potassium were analyzed. The research results can provide theoretical reference and solutions for parameter design for the enhanced leaching process and selection of leaching agents in the future.

Precise Tuning of Bilayer Ultrasmall MoS2 Featuring Inhibition of Carrier Recombination and Fast Surface Chemistry for Green H2 Evolution.

Achieving water splitting to produce green H2 , using the noble-metal-free MoS2 , has attracted huge interest from researchers. However, tuning the number of MoS2 layers precisely while obtaining small lateral sizes to surge the H2 -evolution rate is a tremendous challenge. Here, a bottom-up strategy is designed for the in situ growth of ultrasmall lateral-sized MoS2 with tunable layers on CdS nanorods (CN) by controlling the decomposition temperature and concentration of substrate seed (NH4 )2 MoS4 . Here, the bilayer MoS2 and CN coupling (2L-MoS2 /CN) exhibits the optimum photocatalytic activity. Compared to thicker MoS2 , the 2L-MoS2 has sufficient reduction capacity to drive photocatalytic H2 evolution and the ultrasmall lateral size provides more active sites. Meanwhile, the indirect bandgap, in contrast to the direct bandgap of the monolayer MoS2 , suppresses the carrier recombination transferred to 2L-MoS2 . Under the synergistic effect of both, 2L-MoS2 /CN has fast surface chemical reactions, resulting in the photocatalytic H2 -evolution rate of up to 41.86mmol g-1 h-1 . A novel strategy is provided here for tuning the MoS2 layers to achieve efficient H2 evolution.

Atomic Layer Deposition as the Enabler for the Metastable Semiconductor InN and Its Alloys.

Indium nitride (InN) is a low-band-gap semiconductor with unusually high electron mobility, making it suitable for IR-range optoelectronics and high-frequency transistors. However, the development of InN-based electronics is hampered by the metastable nature of InN. The decomposition temperature of InN is lower than the required growth temperature for most crystal growth techniques. Here, we discuss growth of InN films and epitaxial layers by atomic layer deposition (ALD), a growth technique based on self-limiting surface chemical reactions and, thus, inherently a low-temperature technique. We describe the current state of the art in ALD of InN and InN-based ternary alloys with GaN and AlN, and we contrast this to other growth technologies for these materials. We believe that ALD will be the enabling technology for realizing the promise of InN-based electronics.

Facile and complete sulfuric acid leaching of zinc ferrite assisted by copper powder: Leaching mechanism and kinetics investigation

Zinc ferrite is a dominant phase in mass solid wastes generated from zinc or iron production, which causes the obstacle of metal recovery and recycling. A facile and efficient sulfuric acid leaching process of zinc ferrite assisted by copper powder was proposed in this study. The effects of factors on the leaching of zinc ferrite and copper were investigated. The results showed that zinc ferrite and copper were coupled and leached. The complete dissolution of zinc ferrite was obtained with wide ranges of leaching conditions. The shortest time for the complete dissolution of zinc ferrite was 10 min at 80 ℃ under the conditions: copper to zinc ferrite molar ratio of 1.5, sulfuric acid concentration of 100 g/L, liquid to solid ratio of 30 mL/g, and copper powder of + 38.5–20 μm. The least consumption of copper to realize the complete dissolution of zinc ferrite was 27.15%. The leaching kinetics was studied by the shrinking core model. It was found that zinc ferrite leaching assisted by copper was controlled by surface chemical reaction. The apparent activation energies for zinc, iron, and copper are 56 kJ/mol, 56 kJ/mol, and 50 kJ/mol, respectively. Characterization of the leaching residues and determination of iron and copper species in the leaching solution showed galvanic corrosion took place between zinc ferrite and copper, enhancing their acid dissolution.

Statistical in situ scanning electron microscopy investigation on the failure of oxide scales

AbstractOxide scales play a pivotal role in obstructing surface chemical and electrochemical reactions, hence hindering chemo‐mechanical effects such as liquid metal embrittlement of steels. Therefore, the critical conditions and failure mechanism of the oxide film are of major interest in the safe service of steels. Though in situ microscopic methods may directly visualize the failure mechanism, they are often challenged by the lack of statistically reliable evaluation of the critical conditions. Here, by combining in situ scanning electron microscopy with a tapered specimen tensile test in a single experiment, we uniquely achieve a mechanistic study with statistically reliable quantification of the critical strains for each step of the dynamic process of film rupture. This is demonstrated with the oxide films formed on a ferrite–martensite steel in liquid lead–bismuth eutectic alloy at elevated temperatures, with in situ results falling right into the predictions of the statistical analysis. Explicitly, the integrated experimental methodology may facilitate the materials genome engineering of steels with superior service performance.

Enhancement of copper metal dissolution in sulfuric acid solution with oxygen and ultrasound

A new method for copper metal dissolution by simultaneous use of oxygen and ultrasound was proposed to enhance the copper dissolution rate in sulfuric acid (H2SO4). The influence factors such as ultrasonic power, oxygen flow rate, reaction temperature, initial copper ion (Cu2+) and H2SO4 concentration was studied to study the dissolution behaviour of copper metal. The dissolution rate of Cu could reach 7.52 g h−1 L−1 after the ultrasonic strengthening, which is 1.83 times higher than that without ultrasonic irradiation (4.109 g h−1 L−1). The study of leaching kinetics found that the Cu leaching process with and without ultrasound were both controlled by surface chemical reaction. The ultrasound could significantly reduce the apparent activation energy of the leaching reaction from 43.52 kJ mol−1 to 28.40 kJ mol−1. Characteristics revealed that the cavitation effect of ultrasound could increase the specific surface area of copper metal and oxygen bubble, and enhance the oxidizing capability of this leaching system, which is beneficial for the dissolution of Cu. Therefore, ultrasonic-assisted technology has provided novel insights for the hydrometallurgical recovery of copper.

(Energy Technology Division Graduate Student Award sponsored by BioLogic) Probing and Engineering Electrode-Electrolyte Interfaces in Electrochemical Energy Storage and Conversion

Climate change demands the development of clean energy technologies, where rechargeable batteries and fuel cells promise a bright future by integrating with solar or wind energy. Li-ion batteries and fuel cells also play essential roles in electrifying transportation in replacement of internal combustion engines. Central to these electrochemical systems is the electrode-electrolyte interface, where (electro)chemical surface reactions or intercalation reactions occur, and its thermodynamic and kinetic properties determine the energy density, power density, and lifetime of the electrochemical devices. However, the molecular structures at the interface and how they promote or suppress the desired reactions remain unclear, hindering the rational design of electrode-electrolyte interfaces to improve the performance of electrochemical devices.This talk focuses on the fundamental understanding of the interfacial (electro)chemical reaction mechanisms at the molecular level and charges transfer kinetics at the electrified interfaces. First, an in situ Fourier-transform infrared spectroscopy (FTIR) method was developed to examine the parasitic reactions between carbonate electrolytes and lithium nickel, manganese and cobalt oxides (NMC) in Li-ion batteries, and unique evidence for dehydrogenation reactions on Ni-rich NMC was revealed, which accounted for interface impedance build-up and battery capacity fading. Based on the proposed mechanism, strategies based on electrolyte non-covalent interactions were demonstrated to improve battery lifetime. In the second part of the talk, the research extended in situ FTIR characterization and electrolyte engineering to electrocatalytic reactions central to fuel cell technologies. An interfacial layer of protic ionic liquids with different acid dissociation constants were found to enhance the oxygen-reduction reaction (ORR), attributed to strengthened hydrogen bonding between ORR products and ionic liquids, revealed by in situ surface-enhanced infrared absorption spectroscopy and density functional theory (DFT) calculations. For the hydrogen evolution reaction (HER), similarly, promoting hydrogen bonding between interfacial water molecules also facilitated proton-coupled electron transfer kinetics, resulting in favorable HER in controllable organic confinements. Finally, this talk will introduce fundamental, theoretical aspects of charge transfer processes at the electrode-electrolyte interface - the kinetic mechanism for ion intercalation. Experimental evidence from a charge-adjusted electrochemical method showed that Li-ion intercalation occurs by coupled ion-electron transfer (CIET), which governs the current-dependent maximum capacity and power density of intercalation batteries. these research efforts have laid a solid foundation for the rational design of electrochemical interfaces employing the physical chemistry of electrodes and electrolytes, for next-generation electrochemical storage devices with improved energy and power density and cycle life.

Refining interface compatibility and carrier management via π-π conjugated stacking for efficient and stable perovskite solar cells based on low-temperature processing

ABSTRACT Deficiencies and instability in the ETL, perovskite layer, or their interface contribute to carrier nonradiative recombination losses. To address these issues, we propose an electron collection and injection optimisation strategy that focuses on enhancing the compatibility and charge transfer performance at the ETL-perovskite interface. Our approach involves low-temperature modification TiO2 with pyrimidine-2-carboximidamide acetate (PCA) through π-π stacking, reducing the surface energy and improving the interfacial compatibility. At the same time, a stable organic–inorganic hybrid layer is formed with lead iodide (PbI2) below the perovskite layer. Additionally, we demonstrate long-term ambient stability, with the PSCs retaining approximately 90% of their initial PCE after 100 days. We also fabricate large-area modules, achieving an efficiency of 19.53% with an active area of 36.41 cm2. Highlights The introduction of the π-π stacking multifunctional molecule PCA through a low-temperature process to modify TiO2 film enhances the stability and performance of perovskite solar cells. This novel approach improves interfacial compatibility and reduces defects at the interface, enabling vertically aligned crystal growth of perovskite and increasing the interfacial contact area. By effectively removing two types of Hydroxyl groups over the low-temperature TiO2 film through multiple surface chemical reactions, the strategy mitigates nonradiative recombination, leading to reduced energy losses and improved performance in both small and large-area perovskite solar cell modules.

Selective leaching of Ni from Cd-depleted spent Ni-Cd batteries by glycine-citrate solution

In the present study, the selective leaching of Ni over Fe from Cd-depleted spent Ni-Cd batteries has been presented using a glycine-citrate solution. These findings can be considered experimental proof of our concept of developing an eco-friendly protocol for the green recycling of both Cd and Ni. In the present study, the pertinent factors affecting Ni leaching, including glycine concentration (0.5–1.5 M), citrate concentration (17–51 mM), temperature (25–55 °C), and time (1–36 h), were investigated. It was found that nearly 95% of Ni can be dissolved when glycine concentration = 1.5 M, citrate concentration = 34 mM, and solid-to-liquid ratio = 2.5% at T = 55 °C after 36 h; noticeably, the amount of Fe entered to solution is only 920 (mg/L). The thermodynamics of the leaching system were comprehensively evaluated and the reactions, responsible for the dissolution of Ni, were predicted. Finally, based on semiempirical kinetic modeling, it was found that the Ni dissolution process is governed by the surface chemical reaction with an activation energy of ∼105 (kJ/mol).

Electric field-assisted leaching of valuable metals from spent lithium-ion batteries in a mixture of acetic acid and ascorbic acid

Recovery of valuable metals from spent lithium-ion batteries (LIBs) has great economic and environmental value. In this study, mixtures of acetic acid and ascorbic acid were used to leach valuable metals from the cathode plates of spent LIBs with assistance from an electric field. Thermodynamic analysis showed that the metal oxides of spent LIBs could be dissolved in the form of metal ions by adjusting potential and pH. Leaching conditions, including the concentrations of acetic acid and ascorbic acid, working voltage, reaction temperature, and reaction time, were systematically investigated. Under conditions with acetic acid concentration of 1 mol/L, ascorbic acid concentration of 0.1 mol/L, working voltage of 4 V, reaction temperature 25 °C and reaction time 70 min, the leaching efficiency of Ni, Co, Mn, and Li reached 99.8%, 99.8%, 99.8%, and 99.9%, respectively. A kinetic study revealed that the surface chemical reaction was the rate-controlling step in the leaching process. The infrared spectra indicated that polyhydroxy groups were transformed into carboxyl or aldehyde groups during mixed acid leaching. The complexity of ascorbic acid and low-valent metal ions increased with leaching time in the ultraviolet spectrum. Finally, the leach residue was analysed using X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), which indicated that the metal oxides in the cathode plate were efficiently leached.

Magnetohydrodynamic Mixed Convection Heat and Mass Transfer of Nanofluid Flow Over a Stretching Wedge-Shaped Surface with the Effect of Thermophoresis and Brownian Motion

The present study has been investigated to the consequence of the magnetic parameter, Grashof number, modified Grashof number, Prandtl number, thermal radiation parameter, Brownian motion parameter, thermophoresis parameter, heat generation parameter, Schmidt number, Biot number, stretching parameter, Lewis number, and chemical reaction parameter, respectively, over a stretching wedge of the magnetohydrodynamic (MHD) BL nanofluid flow. The main goal of this paper is to numerically investigate the nature of the MHD BL nanofluid flow along a stretching wedge-shaped surface with radiation, heat source, and chemical reaction parameters. The fundamental equations has been transformed into ordinary differential equations (ODEs) by the usual transformation. The numerical solutions are found by employing Runge-Kutta fourth-order method by exploiting symbolic software MATLAB via the shooting method. The novelty of the current study is implicated in the area of fluid dynamics to solve nonlinear differential equations numerically and is an important contribution to the field of nanofluids flow. Numerical solutions reveal that the concerned physical parameters lead to progress in the skin friction factor, rate of change of heat transfer as well as the rate of change of concentration. Brownian motion and thermophoresis parameters play a crucial role in the variation of temperature and concentration profiles and also in the development of thermal and concentration boundary layers.

Temperature-dependent NO2/diisopropylamine sensor based on SnO2 squama-wrapped tubes derived from waste bamboo shoot skin

The development of a conductometric sensor with dual-selectivity remains challenging because most sensors were only reported for sensing a given harmful gas. Accordingly, waste bamboo shoot skin (BSS) was selected as biotemplate and simply immersed in SnCl4 aqueous solution. Then, the obtained BSS precursor was calcined at 600 °C to reproduce biomorphic SnO2-6 squama-wrapped tubes, which achieved temperature-controlled dual-selectivity for two different gases. At a low temperature of 92 °C, SnO2-6 sensor has a super-high response (S = 1300) towards 10 ppm NO2, being obviously larger than most reported metal oxide-based sensors. Also it exhibits a good response (S = 46) towards 100 ppm diisopropylamine (DIPA) at 170 °C for the first time. Such excellent dual-sensing capability mainly relates to the synergism of uniform mesopore distribution, relatively large specific surface area and rich oxygen vacancy defects involved in SnO2-6 squama-wrapped tubes, which not only helps to accelerate rapid gas transport, but also efficiently exposes more active sites, increases the contents of adsorbed oxygen species and promotes surface chemical reactions. Meanwhile, the sensor has reversible response-recovery characteristic, good stability and humidity resistance to both gases. In addition, the dual-functional sensing mechanism was also investigated.

High-efficiency leaching of Li and Ni from spent lithium-ion batteries based on sodium persulfate

Herein, the preferential leaching of Li and Ni from spent lithium-ion batteries was put forward for the first time. Firstly, the stable structure of cathode material was destroyed by reduction roasting, and then Li and Ni in roasted product were leached in sodium persulfate solution. Through adjusting the redox potential and pH of the solution, Li and Ni could exist in the solution in the form of Li+ and Ni2+, while Co and Mn remained in the residue mainly in the form of Co3O4 and MnO2. The leaching efficiencies of Li and Ni were 95.07% and 96.02% under the optimized conditions, respectively. Kinetic analysis showed that the leaching process was controlled by surface chemical reaction. In addition, XPS, XRD, thermodynamic analysis, and SEM-EDS were used to explore the mechanism. This method could effectively simplify the recovery and separation process, providing a new thought for the utilization of spent lithium-ion batteries.

Studies on Water–Aluminum Scrap Reaction Kinetics in Two Steps and the Efficiency of Green Hydrogen Production

This work aims to explain aluminum hydrolysis reaction kinetics based on a properly chosen theoretical model with machined aluminum waste chips as well as alkali solutions up to 1M as a promoter and to estimate the overall reaction profit. The purpose of this work is to assess the optimal alkali concentration in the production of small- and medium-scale green hydrogen. To obtain results with better accuracy, we worked with flat Al waste chips, because a flat surface is preferable to maximally increase the time for the created hydrogen bubbles to reach the critical gas pressure. Describing the reaction kinetics, a flat shape allows for the use of a planar one-dimensional shrinking core model instead of a much more complicated polydisperse spheric shrinking core model. We analyzed the surface chemical reaction and mass transfer rate steps to obtain the first-order rate constant for the surface reaction and the diffusion coefficient of the aqueous reactant in the byproduct layer, respectively. We noted that measurements of the diffusion coefficient in the byproduct layer performed and discussed in this paper are rare to find in publications at alkali concentrations below 1M. With our reactor, we achieved a H2 yield of 1145 mL per 1 g of Al with 1M NaOH, which is 92% of the theoretical maximum. In the estimation of profit, the authors’ novelty is in paying great attention to the loss in alkali and finding a crucial dependence on its price. Nevertheless, in terms of consumed and originated materials for sale, the conversion of aluminum waste material into green hydrogen with properly chosen reaction parameters has positive profit even when consuming an alkali of a chemical grade.

A phase field-based framework for electro-chemo-mechanical fracture: Crack-contained electrolytes, chemical reactions and stabilisation

We present a new theoretical and computational framework for modelling electro-chemo-mechanical fracture. The model combines a phase field description of fracture with a fully coupled characterisation of electrolyte behaviour, surface chemical reactions and stress-assisted diffusion. Importantly, a new physics-based formulation is presented to describe electrolyte-containing phase field cracks, appropriately capturing the sensitivity of electrochemical transport and reaction kinetics to the crack opening height. Unlike other existing methods, this approach is shown to accurately capture the results obtained with discrete fracture simulations. The potential of the electro-chemo-mechanical model presented is demonstrated by particularising it to the analysis of hydrogen embrittlement in metallic samples exposed to aqueous electrolytes. The finite element implementation takes as nodal degrees-of-freedom the electrolyte potential, the concentrations of relevant ionic species, the surface coverage, the concentration of diluted species, the displacement field and the phase field order parameter. Particular attention is devoted to improve stability and efficiency, resulting in the development of strategies for avoiding ill-constrained degrees of freedom and lumped integration schemes that eliminate numerical oscillations. The numerical experiments conducted showcase the ability of the model to deliver assumptions-free predictions for systems involving both free-flowing and crack-contained electrolytes. The results obtained highlight the role of electrolyte behaviour in driving the cracking process, evidencing the limitations of existing models.

Sustainable approach to achieve overall leaching of Li and Co in spent lithium-ion batteries without liberation by overall pyrolysis

Dissociation is generally considered to be a necessary treatment of the electrode sheets before leaching, and the inadequacy dissociation cause the loss of electrode materials. In the present study, the feasibility of overall leaching of the undissociated electrode sheets to achieve satisfactory leaching was verified, which was believed to avoid complex crushing and sieving processes and reduce metal loss. Hence, the enhancement of the overall pyrolysis on the overall leaching of the electrode sheets was also analyzed. The undissociated electrode sheets were pyrolyzed at 480 °C that could remove the PVDF effectively. It was conducive to the infiltration of leaching solution between particles, the complete removal of PVDF was identified by SEM, EDS and XPS. Whereafter, the leaching kinetic behavior of the Li and Co in the pyrolyzed and unpyrolyzed electrode sheets were analyzed by the Aframi model. The morphology and composition of the leaching residue were analyzed by SEM-EDS to verify the characteristics of overall leaching behavior. Leaching results show that the overall leaching is feasible for the undissociated electrode sheets, the leaching rate of Li and Co of the undissociated and unpyrolyzed electrode sheet reaches 80.51% and 74.42% with 50 min leaching at 70 °C. Further, overall pyrolysis can enhance the leaching of the undissociated electrode sheet, the leaching rates of Li and Co can reach 93.25% and 93.31% only with 30 min leaching after pyrolysis at 70 °C. The kinetic results illustrate that the leaching of Li and Co is surface chemical reaction. The SEM analysis reveals that overall leaching process is gradual leaching, and the pores generated by pyrolysis help to penetrate the leaching solution and strengthen the leaching process.

Detoxification and resource utilization of soda ash chromite ore processing residue by copper slag

Chromite ore processing residue (COPR) and copper slag (CS) are industrial waste slags that cause environmental pollution and require effective treatment. This study proposes a new strategy for the co-treatment and resource utilization of COPR and CS. Under the optimal conditions (liquid-solid ratio of 9.99; H2SO4 concentration of 0.85 M; the CS/COPR mass ratio of 9.98%; temperature of 88.20 ℃; and duration of 60 min), the reduction efficiency of Cr(VI) reached 99.48%, and the total Cr leaching concentration of residue reached 1.35 mg/L, which was below the USEPA regulatory limit of 5 mg/L. In addition, the detoxicated slag containing 61.44 wt% Fe2O3 can be used as a raw material in the steel industry. Through kinetic, characterization, and DFT analyses, the effective remediation of Cr(VI) in COPR by CS is a combination of adsorption and reduction. The unreacted shrinkage nuclear reaction model under the control of the surface chemical reaction is the most suitable model to describe the process, and when the apparent activation energy is 63.90 kJ/mol, the apparent rate equation is:1-(1-x)1/3= 1·371×107[CS/COPR]2·35004 [H2SO4]2·3945 [L/S]1·95338 exp(–63·90/RT)This is an important study for waste-waste co-treatment and resource utilization of industrial waste.

Adsorption and Degradation of Methylene Blue Aqueous Solution by Fe‐based Amorphous Alloy

Fe‐based amorphous ribbons with the brand name 1K101 can adsorb methylene blue (MB) solution. The adsorption reaction is multilayer adsorption, in which chemical adsorption plays a major role. There are also some processes like physical adsorption, liquid phase diffusion, and internal diffusion of particles. The adsorption reaction is exothermic and spontaneous, which is more favorable at low temperatures. During the adsorption process, the entropy value decreases, the degree of disorder and freedom of the solution decreases, and the structure also changes. What's more, H2O2, pH, ribbons's dosage, dye's concentration, and temperature affect the degradation performance of 1K101 on MB. Degradation reactions are mainly controlled by surface chemical reactions, including chemical reduction reactions and adsorption. When c(H2O2) is 15 mm, pH is 2, ribbons’ dosage is 0.9 g, c(MB) is 20 mg L−1, temperature is 338 K, the degradation effect is the best. The optimal conditions with lowest overall cost obtained under the orthogonal experiment are: c(H2O2) = 20 mm, pH = 2, ribbons's dosage = 0.7 g, c(MB) = 20 mg L−1, and T = 338 K. Overall, 1K101 amorphous ribbon can be utilized to treat MB solution, and its degradation effect is better than adsorption effect, which can provide new ideas for the reuse of waste amorphous ribbon and the treatment of azo dye wastewater.

Numerical Simulation of a Simplified Reaction Model for the Growth of Graphene via Chemical Vapor Deposition in Vertical Rotating Disk Reactor

The process of graphene growth by CVD involves a series of complex gas-phase surface chemical reactions, which generally go through three processes, including gas phase decomposition, surface chemical reaction, and gas phase diffusion. The complexity of the CVD process for growing graphene is that it involves not only chemical reactions but also mass, momentum, and energy transfer. To solve these problems, the method of numerical simulation combined with the reactor structure optimization model provides a good tool for industrial production and theoretical research to explore the influencing factors of the CVD growth of graphene. The objective of this study was to establish a simplified reaction model for the growth of graphene by chemical vapor deposition(CVD) in a vertical rotating disk reactor (VRD). From a macroscopic modeling perspective, computational fluid dynamics (CFD) was used to investigate the conditions for the growth of graphene by chemical vapor deposition in a high-speed rotating vertical disk reactor on a copper substrate surface at atmospheric pressure (101,325 Pa). The effects of gas temperature, air inlet velocity, base rotation speed, and material ratio on the surface deposition rate of graphene in a VRD reactor were studied, and the technological conditions for the preparation of graphene via the CVD method in a VRD reactor based on a special structure were explored. Compared with existing models, the numerical results showed the following: the ideal growth conditions of graphene prepared using a CVD method in a VRD reactor involve a growth temperature of 1310 K, an intake speed of 470 mL/min, a base speed of 300 rpm, and an H2 flow rate of 75 sccm; thus, more uniform graphene with a better surface density and higher quality can be obtained. The effect of the carbon surface deposition rate on the growth behavior of graphene was studied using molecular dynamics (MD) from a microscopic perspective. The simulation showed that the graphene surface deposition rate could control the nucleation density of graphene. The combination of macro- and microsimulation methods was used to provide a theoretical reference for the production of graphene.