Monte Carlo Dynamics Simulations Research Articles

Highly selective PAN@MOFs composite nanofiber for removal of C4F7N/CO2 harmful decomposition products

Perfluoroisobutyronitrile (C4F7N) mixed with CO2 has emerged as a promising eco-friendly alternative to sulfur hexafluoride (SF6) in gas-insulated equipment (GIE). However, thermal or discharge faults in GIE inevitably lead to the generation of harmful decomposition by-products, necessitating their prompt removal to safeguard equipment operation and personnel safety. In this study, we propose a nanofiber composite material comprising polyacrylonitrile (PAN) as the base and multi-metal organic frameworks (MOFs) as the primary adsorbent material for removing typical decomposition components of C4F7N/CO2 gas mixture. Utilizing grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations, we elucidate the selective adsorption mechanisms. Experimental results show that PAN@HKUST-1(Cu) exhibits superior adsorption efficiency for fluorocarbon gases compared to PAN@MIL-101(Cr), while the latter demonstrates better performance for nitrile gases. The PAN@HKUST-1(Cu)/MIL-101(Cr) composite adsorbent effectively removes eight typical harmful decomposition products while minimally affecting C4F7N. Our findings suggest that PAN@HKUST-1(Cu)/MIL-101(Cr) nanofiber film holds promise as an adsorbent for C4F7N/CO2 based GIE.

Exploring cinnamon extract’s potential as a green corrosion inhibitor for X65 carbon steel in sulfuric acid: a comprehensive investigation

The effectiveness of cinnamon extract as an environmentally friendly corrosion inhibitor for X65 carbon steel (X65CSt) in a 1 mol/L H2SO4 solution was examined using electrochemical, chemical, and computational techniques. This inhibitor has many advantages, it is safe, environmentally friendly, harmless to human health, and economically feasible. The anticorrosion efficacy rises with rising the concentration of the cinnamon extract and reducing temperature and reaches 95.83% at 450 mg l−1 of cinnamon extract using potentiodynamic polarization. All the investigated methods confirm the anticorrosion ability of cinnamon extract as indicated by the reduced the corrosion current density values and mass loss as well as the greater charge transfer resistance. In addition, the values of the pitting potentials were also transformed in a more noble direction implying the resistance of pitting attack. The polarization technique categorized the cinnamon extract as a mixed inhibitor. The mechanism of inhibition was demonstrated in terms of adsorption of the main components of cinnamon extract onto the surface of X65CSt. of the adsorption of the main components of the cinnamon extract on the surface of the X65CSt and this adsorption is of combined type between both physical and chemical modes, as determined by the computed values of free energy of adsorption, which range between −46.96 and −37.42 kJ. mol−1. The adsorption is exposed to Langmuir isotherm. The four components of cinnamon extract were investigated through density functional theory, Monte Carlo, and Molecular dynamic simulation. The quantum parameters and the adsorption of these components on the Fe(110) reveals that cinnamaldehyde and cinnamic acid inhibitors are more effective as corrosion inhibitors.

Stability and Phase Transformations in Au–Pd Nanoparticles Studied by Means of Combined Monte Carlo and Molecular Dynamics Simulations

Stability and Phase Transformations in Au–Pd Nanoparticles Studied by Means of Combined Monte Carlo and Molecular Dynamics Simulations

Clay minerals/sodium alginate/polyethylene hydrogel adsorbents control the selective adsorption and reduction of uranium: Experimental optimization and Monte Carlo simulation study

Clay minerals formations are potential geological barrier (host rocks) for the long-rerm storage of uranium tailing in deep geological repositories. However, there are still obstacles to the efficient retardation of uranium because of the competition between negatively charged regions at the clay minerals end face, surface and between layers, as well as low mineralization capacity. Herein, employing a simple method, we used sodium alginate (SA), an inexpensive natural polymer material, polyethylene (PE), and the natural clay minerals montmorillonite (Mt), nontronite (Nt), and beidellite (Bd) to prepare three hydrogel adsorbents, (denoted as Mt/PE-@SA, Nt/PE-@SA, and Bd/PE-@SA), respectively. The application of obtained hydrogel adsorbents further extends to uranium(VI) removal from aqueous. Due to the synergistic action of SA group and PE group, hydrogel adsorbents showed select adsorption and mineralization effect on uranium(VI), among which the maximum uranium(VI) adsorption capacity of Nt/PE-@SA was 133.3 mg·g-1 and Mt/PE-@SA exhibited strong selectivity for uranium(VI) in the presence of coexisting metal ions. Cyclic voltammetry studies indicated the mitigation and immobilization of uranium species onto adsorbents by both reduction and mineralization. Besides, the synergistic adsorption of SA and PE on clay minerals was hypothesized, and the idea was supported by structure optimizations results from Monte Carlo dynamics simulation (MCD). Three obtained hydrogel adsorbents structural model was constructed based on its physicochemical characterization, the low energy adsorption sites and adsorption energies are investigated using MCD simulation. The simulation results show that obtained hydrogel adsorbents have a strong interaction with uranium(VI), which ensures the high adsorption capacity of those materials. Most importantly, this work demonstrates a new strategy for preparing mineral-based hydrogel adsorbents with enough stability and provides a new perspective for uranium(VI) removal in complex environment.

Synthesis, structural characterization and anticorrosion properties of a new hexafunctional epoxy prepolymer based on urea and phosphorus trichloride for E24 carbon steel in 1.0 M HCl

Our goal is to set up a synthetic method to produce the hexaglycidyl amine tri-urea phosphoric acid (HGATUP), a novel hexafunctional prepolymer. We created this prepolymer by phosphorylating urea in two processes. Next, to generate the new prepolymer, we added epichlorohydrin. In addition, we focused on its microscopic characterization using FTIR and NMR. The novel HGATUP prepolymer was utilized as a corrosion inhibitor for E24 carbon steel in a 1.0M hydrochloric acid (HCl) solution. PDP, EIS, EFM, DFT, Monte Carlo (MC), and molecular dynamic (MD) simulations were used in this study. SEM/EDS and XPS studies were also used to investigate the surface morphology. These methods allowed us to examine the sample's surface characteristics and chemical composition, which added to our understanding of the adsorption along with corrosion prevention processes. The electrochemical tests' outcomes also showed that the concentration of HGATUP enhanced inhibitory performance. PDP results indicated that HGATUP at a concentration of 10-3M had a corrosion inhibition efficiency of 97.6% at 298K ambient temperature. The polarization curve confirmed that the HGATUP was a mixed type of inhibitor that could inhibit steel anodic and cathodic reactions. The Langmuir model predicted that an epoxy prepolymer protected the surface of E24 carbon steel. Calculated thermodynamic kinetic parameters were used to analyze the inhibitor adsorption processes.

Molecular simulation of [P8883][Tf2N] ionic liquid decorated silica in 6FDA-ODA based mixed matrix membrane for enhanced CO2/CH4 separation.

Mixed-matrix membranes (MMMs) have been reported to have considerable scope in gas separation applications because of their merged inherent strength of a durable polymer matrix and the exceptional performance capabilities of inorganic fillers. The selection of comparatively suitable polymers with fillers that can match each other and boost interfacial compatibility while ensuring uniform dispersion of filler within the polymer is still intensively demanding and is challenging at the experimental scale. Ionic liquids (ILs) are effective in promoting better dispersion and compatibility, leading to improved separation performance. A computational molecular simulation approach is employed in current work to design a hybrid membrane having Trioctapropyl phosphonium bis(trifluoromethylsulfonyl)imide [P8883][Tf2N] IL decorated silica as a filler and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride-4,4'-oxydianiline (6FDA-ODA) polymer for carbon dioxide (CO2) separation from methane (CH4). Thermophysical and gas transport properties under pure and mixed gas condition (30, 50, and 70% CO2/CH4) within the MMMs with varying filler loadings (5, 10, and 15 wt% IL-silica) are examined via Grand Canonical Monte Carlo (GCMC) and Molecular Dynamics (MD) simulations. Membrane characteristics like glass transition temperature (T g), Fractional Free Volume (v f), X-Ray Diffraction (XRD), solubility, diffusivity, permeability, and selectivity for neat and IL-silica filled 6FDA-ODA are computed. The results show that the T g of the composite membrane with 5 wt% IL-silica is found to be considerably higher (with 305 °C) than that of the pure 6FDA-ODA polymer having 298 °C. A higher T g value highlights the effective dispersion and higher adhesion between the filler and polymer membrane. Additionally, CO2 permeability for 5 wt% IL-silica/6FDA-ODA MMM is significantly improved, measuring 319.0 barrer while maintaining a CO2/CH4 selectivity of 16.2. These values are 89% and 56% respectively, greater than the corresponding values of neat 6FDA-ODA membrane. Published data from the literature review is used to validate the findings and guarantee their reliability. The obtained results exhibited an error in the range of 0.7-9%. Hence, it is concluded from the study that molecular simulation can be used to design IL decorated silica incorporated within 6FDA-ODA matrix, which is able to boost the interfacial compatibility, with elevated CO2/CH4 selectivity and CO2 permeability.

Research on CO2/CH4/N2 competitive adsorption characteristics of anthracite coal from Shanxi Sihe coal mine.

This study aims to solve the problem of unsatisfactory development and utilization of coalbed methane and CO2 storage efficiency. It is focused on the adsorption behavior of CO2, CH4, and N2 in the macromolecular structure model of Shanxi Sihe coal mine anthracite, as well as the competitive adsorption behavior of CO2/CH4 and CH4/N2 binary gas mixtures with different ratios. Experimental analysis such as elemental analysis, solid 13C nuclear magnetic resonance (13C NMR), Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analysis were used to construct the Shanxi Sihe coal mine model of the macromolecular structure of anthracite coal. The Grand Canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulation methods were used to study the adsorption capacity and heat characteristics of CO2, CH4, and N2 at different temperatures using a molecular model of anthracite coal from Shanxi Sihe coal mine, as well as the competitive adsorption characteristics of CO2/CH4 and CH4/N2 binary mixtures. The mechanism of the influence of temperature and gas properties on the adsorption capacity and heat of adsorption was revealed from a microscopic perspective. The results indicated that the aromatic carbon content of anthracite in the Sihe coal mine, Shanxi is 81.19%, and the ratio Xbp of aromatic bridgehead carbon to surrounding carbon is 0.489. The aromatic structure is mainly composed of pyrene and anthracene. The molecular formula of the macromolecular structure model of anthracite in Shanxi Sihe coal mine is C233H157O13N2. The adsorption capacity and equivalent adsorption heat of the macromolecular model for adsorbing single-component gas CO2/CH4/N2 decrease with the increase in temperature. The temperature has the greatest impact on CO2 adsorption capacity and adsorption heat, followed by CH4 and N2. Under the competitive adsorption conditions of CO2/CH4 and CH4/N2 binary mixtures, the higher the partial pressure of a single-component gas in the mixture, the greater the adsorption capacity of the gas. The difference in the adsorption heat of CH4 and N2 is smaller than that of CH4 and CO2. The conclusions obtained from the study can provide technical and theoretical support for formulating reasonable drainage methods for coalbed methane wells.

A comprehensive study on transport behaviour and physicochemical characteristics of PU/based 3-phase mixed matrix membranes: Effect of [HNMP][HSO4] ionic liquid and ZnO nanoparticles

The gas separation industry has witnessed a significant focus on mixed matrix membranes (MMMs) due to their exceptional potential, surpassing the performance of conventional polymeric membranes. This study aimed to develop and evaluate MMMs using polyurethane (PU) as the polymer matrix and zinc oxide (ZnO) and ionic liquids (ILs) as fillers. PU/ZnO, PU/IL, and PU/ZnO/IL MMMs were prepared utilizing the dry-phase inversion method, and their efficacy in separating CO2, CH4, and N2 gases was investigated under various conditions. A comprehensive characterization protocol using FTIR, FESEM, TGA, AFM, and tensile testing was employed for their thorough characterization. The membranes’ transport properties were assessed at different pressures and filler concentrations. Results showed that IL incorporation increased gas permeability by enhancing solubility, diffusion, ionic interactions, swelling, and accessible volume. Incorporating ZnO and IL particles in the PU matrix simultaneously improved transport properties, particularly selectivity. Robeson’s diagram analysis shows that the PU/0.5%ZnO/2%IL MMM performed best. Furthermore, molecular simulation methods, including Monte Carlo and molecular dynamics simulations, assessed adsorption isotherms and physicochemical properties such as free volume, density, and X-ray diffraction. Simulation outcomes were highly reliable with experimental results, affirming the results’ efficiency and validation. Overall, this study demonstrated the efficiency of using ZnO and IL in the MMMs, highlighting their potential in gas separation applications.

Fluorinated Metal–Organic Framework–Polymer Mixed Matrix Membrane with Tunable Hydrophobic Channel for Efficient Pervaporation of Butanol/Water

The permeability–selectivity trade‐off of membrane is a major challenge limiting the development of pervaporation (PV) technology. Rational design of high‐performance mixed matrix membranes (MMMs) has the potential to break off the trade‐off. Herein, a solvent‐assisted linker exchange‐based strategy is reported to introduce fluoroalkyl into metal–organic framework‐808 (MOF‐808). The pore size of fluorinated MOF‐808 can be adjusted with fluoroalkyl of different chain length (like trifluoromethyl and pentafluoropropyl). Then, the fluorinated MOF‐808/polyether block amide (PEBA) MMMs are prepared for the PV of n‐butanol/water. Compared with pristine PEBA membrane, 20 wt% 3F‐MOF‐808(P)/PEBA MMMs (3F = ‐CF3 group; P = postmodification method) exhibit 69% increase in permeation flux and 33% increase in separation factor in the PV of 2.5 wt% n‐butanol aqueous solutions at 70 °C. Based on Grand Canonical Monte Carlo and molecular dynamics simulations, fluorinated MOF‐808 shows better butanol affinity (pull effect) and stronger water repulsion ability (push effect). And the “push–pull effect” between fluorinated MOF‐808 with butanol/water is helpful to enhance the PV performance of MMMs. The application of “push–pull effect” provides a new strategy for the rational design of high‐performance MMMs, which is of great significance for the in‐depth research and application of PV technology.

Monte Carlo dynamics simulation of nanoparticles for enhanced oil recovery

ABSTRACT This research used density functional theory (DFT)-based simulation software to investigate the potential of emerging nanotechnology to alter the physical–chemical interactions of a reservoir system so that a favourable condition for oil displacement could be created. This reservoir was modelled using sandstone (as rock), oil (as any of the hydrocarbon molecules including Decane, Dodecene, Tetradecene and Hexadecene), a particular type of nanoparticles (graphene (GNPs), magnetite (MNPs), zinc oxide (ZNPs), copper oxide (CNPs)) and sodium chloride (NaCl) for nanofluid. From the analysis of adsorption results, we observed that oil adsorption can be reduced to −18.81 from −28.53 Kcal/mol. This was the case for the MNPs in the absence of NaCl. In the presence of NaCl, GNPs showed better performance than others. Arguably, salinity is thus an important factor contributing to the performance of nanofluid as an enhanced oil recovery agent or specifically a wettability modifier. The main mechanisms of the enhanced changes are assumed to be the inhibition of oil adsorption and the profile control capability of GNPs.

Insights into adsorption and diffusion of CO2, CH4 and their mixture in MIL-101(Cr) via molecular simulation

An in-depth comprehension of the adsorption and diffusion properties of CH4, CO2, and their mixture in MIL-101(Cr) is crucial for its application in the highly selective separation of CO2 and CH4 mixtures in biogas. Existing studies often overlook the influence of gas molecular radius and MIL-101 topological structure on adsorption and lack quantitative analysis of the primary and secondary adsorption sites of MIL-101. Additionally, there is a significant gap in research on the adsorption mechanism of gas mixtures. To address these gaps and to provide new knowledge, this study employs Monte Carlo and molecular dynamics simulations to evaluate various factors such as CH4 and CO2 adsorption isotherms, density distribution profiles, self-diffusion coefficients, radial distribution functions (RDF), and CO2/CH4 selectivity within MIL-101 metal-organic framework (MOF). The insightful and comprehensive atomic-level study reveals several unique and new findings, include 1) the RDF analysis shows that the C = C double bond of the benzene ring within MIL-101 primarily governs the adsorption of CH4, while the open metal center (Cr) exhibits significant adsorption effects on CO2; 2) the density distribution profile analysis indicates that CH4 molecules tend to localize in the larger and medium-sized cages, whereas CO2 molecules exhibit relatively uniform distribution. 3) evaluation of self-diffusivity coefficients and diffusion activation energies demonstrated that CH4 diffuses more easily than CO2, and in the CO2 and CH4 two-component gas, the existence of CH4 can further reduce the diffusion coefficient of CO2. This investigation provides a microscopic understanding of adsorption and diffusion phenomena within MIL-101, contributing to the overall comprehension of its behavior in gas separation applications.

Equilibrating provincial carbon increments for residential buildings in China under carbon peaking constraints

The speedy raise of residential buildings' carbon emissions is a hindrance to achieving China's 2030 carbon peak goal. This study constructs an assessment framework for comprehensive consideration of 30 Chinese provinces' socioeconomic circumstances, energy demand, and emissions reduction technology to meet the consistent coupling degree of equity and efficiency (CDEE). This study is the first to propose an allocation scheme for equilibrating provincial carbon increments for rural and urban residential buildings in 2030 under carbon peaking constraints. The relevant results are fourfold. (1) Residential building's floor area per capita and energy carbon emissions coefficients are the soliddest drivers to facilitate and inhibit the raise of carbon emissions during 2010–2020. (2) Through dynamic Monte Carlo simulation from 2021 to 2030, we demonstrate that provinces with the most gamey carbon emissions in urban and rural areas include Shandong, at 121.52 (± 5.50) Mt. and Hebei, at 61.34 (± 3.08) Mt. in 2030, respectively. (3) A CDEE of 52.3% (biased equity) in urban areas and 34.5% (biased efficiency) in rural areas indicates equilibrated allocation of provincial carbon increment. (4) In the final 2030 allocation scheme, the greatest carbon mitigation pressures are in Beijing (11.34 Mt) and Heilongjiang (3.23 Mt), and the provinces with the largest carbon increment in urban areas include Hebei, Henan, and Guangdong, while the largest carbon increments in rural areas are in Hebei, Henan, and Guangdong. Overall, this study furnishes a targeted and valuable decision making reference for the government to determine provincial carbon peak goals for Chinese residential buildings.

Transport property of hydrogen sulfide in amorphous polyethylene using grand canonical Monte Carlo and molecular dynamics simulations

H2S corrosion poses a significant hurdle to safely transporting sulfur-containing natural gas through metal gathering pipes. Reinforced thermoplastic composite pipes have emerged as a solution, using the polyethylene inner lining layer that resists H2S corrosion. However, the permeation of H2S in the polyethylene may lead to the failure of reinforced thermoplastic composite pipes, resulting in natural gas leakage and environmental pollution. Therefore, it is crucial to investigate the gas transport properties of H2S in polyethylene materials to ensure the reliable functioning of gathering pipes. In this study, the dissolution behavior of H2S for pure H2S and H2S/CH4 mixture in amorphous PE is investigated using the grand canonical Monte Carlo method in conjunction with the NPT, with consideration given to the swelling effect. In addition, the diffusion characteristic is explored through the NVT on the amorphous PE adsorbing H2S. Subsequently, the permeability coefficient is calculated based on the obtained data. The findings reveal that with as the temperature increases, the solubility coefficient decreases, while both the diffusion and permeability coefficients increase. With increasing pressure, both the diffusion and permeability coefficients increase. Additionally, the above three coefficients all increase with increasing H2S mole fraction. The relationships between solubility, diffusion, and permeability coefficients & temperature all conform to the Arrhenius law. Finally, the diffusion mechanism of H2S in amorphous PE is revealed at the microscopic level as the “jumping” mechanism by tracking the diffusion pathway of H2S molecule.

Exclusion processes on a roundabout traffic model with constrained resources.

Motivated by the vehicular traffic phenomenon at roundabouts, we examine how the limited availability of resources affects the movement of two distinct types of particles on bidirectional lanes connected by two bridges, with each bridge specifically designated for the transportation of one species. To provide a theoretical ground for our findings, we employ a mean-field framework and successfully validate them through dynamic Monte Carlo simulations. Based on the theoretical analysis, we analytically derive various stationary properties, such as the particle densities, phase boundaries, and particle currents, for all the possible symmetric as well as asymmetric phases. The qualitative as well as quantitative behavior of the system is significantly affected by the constraint on the number of resources. The complexity of the phase diagram shows a nonmonotonic behavior with an increasing number of particles in the system. Analytical arguments enable the identification of several critical values for the total number of particles, leading to a qualitative change in the phase diagrams. The interplay of the finite resources and the bidirectional transport yields unanticipated and unusual features such as back-and-forth transition, the presence of two congested phases where particle movement is halted, as well as shock phases induced by boundaries and the bulk of the system. Also, it is found that spontaneous symmetry-breaking phenomena are induced even for very few particles in the system. Moreover, we thoroughly examine the location of shocks by varying the parameters controlling the system's boundaries, providing insights into possible phase transitions.

Effect of kinetic properties of zeolites on the gas-sensing performance of zeolite-covered SnO2 sensors

ABSTRACT Zeolite additional layers coating on metal oxide surfaces to improve the selectivity and response values of the sensors are effective and widely used. The specific adsorption and diffusion of gas molecules in the zeolite are recognised to play an important role in gas sensing improvement. In this work, the adsorption and diffusion behaviours of formaldehyde and acetone in H-Y and H-A zeolites were calculated by Monte Carlo and molecular dynamics simulations. The loading of acetone is greater than formaldehyde in these two kinds of zeolites under the same temperature and pressure, and the water load is lower. The simulation results show that the effects of the nature of the guest molecule and steric hindrance of the diffusing molecule on diffusivity are significant. The diffusivity in H-A zeolite decreases by several orders of magnitude than that in H-Y zeolite However, in H-A zeolite, the internal diffusion dominates, and only the smaller diameter formaldehyde can diffuse between the pores, which is beneficial to improving the sensing properties of formaldehyde. In addition, in the competition diffusion with water molecules, formaldehyde dominates than acetone. The H-Y/SnO2 and H-A/SnO2 sensors were prepared to verify the reliability of the molecular simulations. Research highlights The adsorption and diffusion behaviour of formaldehyde and acetone in H-Y and H-A zeolites were investigated using molecular simulation. Molecular diameter mainly influences the kinetic behaviour. The sensitisation mechanism of H-Y/SnO2 sensor to acetone and H-A/SnO2 sensor to formaldehyde was proved. Focuses on the relationship between gas-sensing the performance of zeolite-covered SnO2 sensors and the adsorption.

Mechanism of elemental segregation around extended defects in high-entropy alloys and its effect on mechanical properties

Elemental segregation around extended defects is common in high-entropy alloys (HEAs) composed of multi-principal elements, which profoundly impacts their mechanical properties. In HEAs, the driving force for segregation usually competes with chemical short-range ordering (CSRO) formation, making it challenging to elucidate the segregation mechanisms. In this study, we systematically investigate the chemical composition changes around extended defects, including dislocations, stacking faults, and grain boundaries (GBs) in CoNiCrFe HEAs, to explore the chemical-structure-mechanical relationship utilizing hybrid Monte Carlo and molecular dynamic (MC/MD) simulations and theoretical analysis. We find a pronounced Cr enrichment and Co/Ni/Fe depletion around all defects considered in this work. A correlation between the degree of structural disorder and the chemical segregation/depletion phenomenon in the proximity of extended defects has been uncovered. Our results show that due to the extreme chemical complexity in HEAs, CSRO inevitably contributes to the elemental rearrangement and affects segregation. Consequently, the segregation behavior in HEAs is mainly controlled by interactions between different atomic pairs, and the segregation entropy also plays a dominant role. By decoupling the strengthening contribution from elemental segregation and CSRO, we demonstrate and highlight that the strengthening in HEAs can be modulated by elemental segregation. The positive impact of element segregation on interfacial properties - improved ultimate tensile strength and elongation, has been evidenced through experimental comparisons of CoNiCrFe with different Fe additions. This work elucidates the mechanism of heterogenous elemental distributions in HEAs where elemental segregation and CSRO coexist, paving the way for manipulating their mechanical properties by modulating the compositional variations.

DFT and MCDS Outcome for a Comparative Analysis of NO, NO2, SO, SO2 and SO3 Gas Adsorption onto a NaMgPO4 (033) Surface

The research purpose of this work is to examine the adsorption interaction of gaseous molecules (GMs), such as NO, NO2, SO, SO2, and SO3, with the surface of sodium magnesium phosphate NaMgPO4 (033), in a neutral medium, using two different computational methods: density functional theory (DFT) and Monte Carlo dynamic simulation (MCDS). Various quantum and dynamic descriptors, such as global and local quantum descriptors and the radial distribution function (RDF), are also evaluated and discussed. The data obtained revealed that the NO2 molecule has a small energy gap (0.363 eV) when compared to the other molecules, which means that it is highly reactive and is liable to adsorb, or stick, to the surface of NaMgPO4 (033). Furthermore, this NO2 molecule exhibits good adsorption in aqueous media, returning to the lowest global hardness value (0.1815 eV). MCDS predicted adsorption energies of −874.03, −819.94, −924.81, −876.33, and −977.71 kcal/mol for NO, NO2, SO, SO2, and SO3, respectively. These energies are negative, implying that adsorption occurs spontaneously. Thus, the side views indicated which SO, NO, and SO3 molecules are adsorbed in parallel to NaMgPO4 and the other SO2 and NO2 molecules are adsorbed horizontally. Eventually, the theoretical results reveal that the studied gaseous molecules interact strongly with NaMgPO4. The result obtained by radial distribution function (RDF) analysis for all complexes below 3.5 Å confirm that the adsorption is of the chemi1cal type.

DFT , Monte Carlo and Molecular Dynamics modeling of the Carvacrol, Camphor and Linalool /Al(111) Interaction

In this work, the interaction of three natural compounds: carvacrol (Inh-1), camphor (Inh-2), and linalool (Inh-3) on the Al(111) surface have been studied using DFT/B3LYP/6-31G(d,p), to understand adsorption behavior on the metal surface. The results obtained show a strong correlation between the inhibitory efficiency (IE%) of aluminum corrosion and the quantum chemical parameters of reactivity derived from DFT. In addition, the interactions between the three natural inhibitors and the aluminum surface were studied using Monte Carlo (MC) and molecular dynamics simulations, as a result, the three molecules have strong interactions with the metal surface and thus have excellent predictive power for inhibition against metal corrosion, the three corrosion inhibitors have higher inhibitory efficiency and can be used as inhibitors to minimize the corrosion rate of the metal, therefore, the efficiency of Inh-1 is more important than the efficiency of Inh-2 and Inh-3.

Analysis of the influence of different pore ratios on methane adsorption characteristics of coal

The diverse pore structures in coal are pivotal in coalbed methane storage and transportation, making it highly significant to explore methane adsorption characteristics across varying pore sizes for effective prevention and control of coal mine gas disasters. Using the proposed graphene nanotube filling method, eight coal molecule models with varying pore size ratios were constructed, including four different pore radii: 0.35 nm, 0.55 nm, 0.75 nm, and 2 nm. Methane adsorption amount, methane density, and methane concentration distribution were obtained through Monte Carlo (GCMC) and molecular dynamics (MD) simulation methods. The research results show that coal consisting of multiple pore sizes had a better methane adsorption capacity than a single pore size. Combining pore sizes of 0.35 nm, 0.55 nm, and 0.75 nm in a 1:2:1 ratio resulted in the highest excess methane adsorption capacity in coal, reaching 5.623 mmol/g. The single pore size of 0.55 nm in coal had the lowest excess adsorption amount of methane, which was 2.236 mmol/g. The presence of mesopores weakened the methane adsorption capacity of coal, and this weakening effect increased with the increase of mesopore proportion. In the model composed of single pore size micropores, the methane concentration inside the pores was uniformly distributed. The coexistence of multiple micropores may lead to methane filling in the micropores in a monolayer adsorption form. The coexistence of micropores and mesopores does not alter methane filling in the micropores and monolayer adsorption in the mesopores. The research results provide new insights into our understanding of the impact of pores on methane adsorption in coal.

Experimental and Computational Studies of Nitric Acid Treated Natural Sargassum Algae for Efficient Removal of Crystal-Violet Dye

In this work, crystal-violet (CV) dye was removed using a chemical carbonization process to create carbonized sargassum algae (CSA), which poses less environmental danger. The produced CSA is examined using a scanning electron microscope and a Fourier-Transform Infrared spectrometer. The following parameters were measured: pH, contact duration, temperature, adsorbent concentration, and starting CV dye concentration. The highest removal % was recorded as 91.17%. at pH 7, 3 hours, 25 °C, 0.01 g of adsorbent dosage, and 100 mg/L initial dye concentration. The kinetic testing indicated that pseudo-second-order was the most effective kinetic model for CV adsorption. According to the isotherms for the adsorption of CV dye, the Langmuir constant (K) was used to measure thermodynamic properties like free enthalpy (H), entropy (S), and energy (G). The Freundlich model, followed by Temkin models, best described the data. The earlier research is supported by computational studies like molecular dynamics (MD) simulation and Monte Carlo (MC) simulation.