Average Enthalpy Research Articles

Hydrogen purification via hydrate-based methods: Insights into H2-CO2-CO hydrate structures, thermodynamics, and kinetics

Hydrate-based H2 purification is promising for removing impurities owing to the cage-like structures formed by water molecules. Understanding the competition mechanism of multicomponent gas molecule in hydrate is critical for improving gas purification efficiency. This study investigated the hydrate structure, thermodynamics, and kinetics of ternary gas mixture (H2–CO2–CO) from natural gas reforming products. The results identified H2–CO2–CO hydrate as type sI and determined the lattice parameters using X-ray diffraction. Raman spectroscopy results confirmed the presence of H2, CO2, and CO gas molecules in the hydrate phase. Increasing pressure, compared to cooling, enhanced CO2 content in hydrate phase. The phase equilibrium conditions and average hydrate dissociation enthalpy (53.47 J/g) were determined using a high-pressure microcalorimeter. Gas chromatography identified that the content of CO2 in the hydrate was the highest, followed by H2, and CO was the least abundant. The molecule dynamics simulation results show CO2 molecule numbers reflected trends in 51262 cages, H2 numbers correlated with changes in 512 cages, while CO numbers showed insignificant variation. Under the gas composition studied, the ability of gas molecules to be incorporated within hydrates decreases in the following order: CO2, H2, and CO.

Evaluation of the synergic effect of amino acids for CO2 hydrate formation and dissociation

Gas hydrate formation is a very challenging problem in the oil and gas industry. The chemical inhibition method is the best practicable hydrate mitigation method by injecting hydrate inhibitors such as Thermodynamic Hydrate Inhibitors (THIs) and Kinetic Hydrate Inhibitors (KHIs) into the pipeline. However, the hydrate inhibitors' biodegradability and limited data on dual functional inhibitor mixtures raise concerns in this study. This study aims to investigate and compare thermodynamic and kinetic inhibition on CO2 hydrate by using biodegradable amino acid inhibitor mixtures of Glycine and Alanine. In this study, the inhibitor mixtures were prepared by mixing Glycine and Alanine in 3 different mixture ratios, followed by the Thermodynamic and Kinetic inhibition tests. Thermodynamic Inhibition Test was conducted by using 10 wt% of inhibitor mixtures in a CO2-water system under pressure of 4.0, 3.5, 3.0 and 2.5 MPa, while Kinetic Inhibition Test was carried out by using 1 wt% of the sample in the CO2-water system at a constant pressure of 4.0 MPa and temperatures at 274.15K. The analysis methods for the Thermodynamic Inhibition Test were Hydrate Liquid-Vapor Equilibrium (HLVE) Curve, Average Depression Temperature and Molar Dissociation Enthalpy, while the Induction Time method, the number of CO2 moles consumed, the formation rate of CO2 gas hydrate and RIP were used in the Kinetic Inhibition Test. In this study, all inhibitor mixtures exhibit dual functional inhibition on the CO2 hydrate. For THI, 50% Gly: 50% Ala shows the best thermodynamic inhibition strength with an average depression temperature of 2.42 K. All the inhibitor mixtures for THI have the dissociation enthalpies within the CO2 hydrate enthalpy range, which show that the inhibition is due to the influence on the water molecules’ interaction only. For KHI, 75% Gly: 25% Ala shows the highest kinetic inhibition strength on CO2 formation with the longest induction time of 115.2 min and the highest RIP of 0.40. In the KHI experiment, there is a drop in the CO2 uptake capacity with the presence of inhibitors used, where the highest difference of CO2 moles consumed is 0.0057 mol. A synergistic effect of inhibitor mixtures was observed in this study on 50% Gly: 50% Ala for THI and 75% Gly: 25% Ala for KHI. However, the “degradation” effect was also exhibited on 75% Gly: 25% Ala and 25% Gly: 75% Ala for THI and 50% Gly: 50% Ala and 25% Gly: 75% Ala for KHI, where the performance of the inhibitor mixtures is poorer than the concentrated amino acids. The “degradation” effect of the inhibitor mixtures at certain ratios was not covered in this study and it requires a further understanding of the chemistry behind the inhibition mechanism.

Determination of Protein-Ligand Binding Affinities by Thermal Shift Assay.

Quantification of protein-ligand interactions is crucial for understanding the protein's biological function and for drug discovery. In this study, we employed three distinct approaches for determination of protein-ligand binding affinities by a thermal shift assay using a single ligand concentration. We present the results of the comparison of the performance of the conventional curve fitting (CF) method and two newly introduced methods - assuming zero heat capacity change across small temperature ranges (ZHC) and utilizing the unfolding equilibrium constant (UEC); the latter has the advantage of reducing calculations by obtaining the unfolding equilibrium constant directly from the experimental data. Our results highlight superior performance of the ZHC and UEC methods over the conventional CF method in estimating the binding affinity, irrespective of the ligand concentration. In addition, we evaluated how the new methods can be applied to high-throughput screening for potential binders, when the enthalpy (ΔH L) and molar heat capacity change (ΔC PL) of ligand binding are unknown. Our results suggest that, in this scenario, using the -300 cal K-1 mol-1 assumption for ΔC pL and either -5 kcal mol-1 or the average enthalpy efficiency-based estimation for ΔH L(T) can still provide reasonable estimates of the binding affinity. Incorporating the new methods into the workflow for screening of small drug-like molecules, typically conducted using single-concentration libraries, could greatly simplify and streamline the drug discovery process.

Research on the Potential of Persistent Free Radicals Triggering Open-Pit Coal Oxidation and Spontaneous Combustion

ABSTRACT This study attempts to reveal the triggering pathways of open-pit coal oxidation and spontaneous combustion from the perspective of persistent free radicals (PFRs). To this end, electron spin resonance technology, spin trap technology, and quantum chemical calculations were combined to study the occurrence characteristics of PFRs in coal and their photoreaction characteristics. Based on typical coal molecular fragments, the mechanism of PFRs triggering open-pit coal oxidation was further revealed. The results indicate that coal contains abundant PFRs, which produce reactive oxygen species (ROS) after exposure to sunlight, mainly including hydroxyl radicals (•OH) and superoxide anion radicals (O2 •−). Among them, the higher the initial content of PFRs or the longer the time of sunlight exposure, the more favorable it is for the production of •OH, the concentration of photoinduced •OH remains at the level of 1011 spin/mm3. Compared to O2 in the air, these photoinduced •OH have stronger oxidizing properties and can trigger free radical chain reactions of coal oxidation at room temperature (activation energies ＜ 40 kJ/mol), releasing reaction heat (average enthalpy change is −65.53 kJ/mol). As a common oxidant in coal spontaneous combustion (CSC) process, O2 does not possess these abilities (activation energies greater than 190 KJ/mol and enthalpy change greater than 160 KJ/mol). From the perspectives of thermodynamics and kinetics, PFRs in coal have the potential to indirectly trigger open-pit coal oxidation and spontaneous combustion. Therefore, the efficient quenching of PFRs or inhibiting the production of •OH will be beneficial for preventing the oxidation and spontaneous combustion of open-pit coal. This study provides a new perspective on revealing the mechanism of CSC and developing new inhibitors.

Enhanced methylene blue adsorption using single-walled carbon nanotubes/chitosan-graft-gelatin nanocomposite hydrogels

In the present study, single-walled carbon nanotubes (SWCNTs) incorporating chitosan-graft-gelatin (CS-g-GEL/SWCNTs) hydrogels were fabricated with multiple advantages, including cost-effectiveness, high efficiency, biodegradability, and ease of separation for methylene blue (MB) dye from aqueous solution. To verify the successful formulation of the prepared hydrogels, various characterization methods such as NMR, FTIR, XRD, FE-SEM, TGA, BET, and EDX were employed. The removal efficiency of CS-g-GEL/SWCNTs nanocomposite hydrogel increased significantly to 98.87% when the SWCNTs percentage was increased to 20%. The highest adsorption was observed for pH = 9, an adsorbent dose = 1.5 g L−1, a temperature = 25 °C, a contact time = 60 min, and a contaminant concentration = 20 mg L−1. Based on the thermodynamic results, spontaneous adsorption occurred from a negative Gibbs free energy (ΔG°). In addition, the thermodynamic analysis of the adsorption process revealed an average enthalpy of − 21.869 kJ mol−1 for the adsorption process at a temperature range of 25–45 °C, which indicates its spontaneous and exothermic behavior. The Langmuir isotherm model was successfully used to describe the equilibrium behavior of adsorption. The pseudo-first-order model better described adsorption kinetics compared to the pseudo-second-order, intra-particle, and Elovich models. CS-g-GEL/SWCNTs hydrogels have improved reusability for five consecutive cycles, suggesting that they may be effective for removing anionic dyes from aquatic environments.

Simultaneous removal of diclofenac sodium, cadmium and bacterial inactivation from aqueous solutions by activated MgO nanoparticles

This study investigated whether MgO nanoparticles (NPs) produced via the sol–gel process can simultaneously remove the pharmaceutical diclofenac sodium (DCF) and cadmium ions (Cd2+) from water. The UV spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX) were used to confirm the composition, morphology and particle size of the MgO NPs. The adsorption performance of MgO NPs was compared to that of bentonite-nano zero valent iron (B-nZVI) and activated carbon (AC). The impact of contact time, adsorbate concentration, pH, and temperature on the removal efficacy of DCF and Cd2+ via MgO NPs in aqueous solutions were investigated, and the removal data was best described by the kinetic model of pseudo-second-order and the Langmuir isotherm model (R 2 > 0.996). The maximum removal capacity of MgO for DCF and Cd2+ at pH 7 was 66.2 mg.g−1 (%R = 90) and 50.8 mg.g−1 (%R = 80), respectively. The average adsorption enthalpy for DCF and Cd2+ (ΔH° 50 kJ. mol−1) demonstrates the occurrence of physical adsorption process, while the negative value of ΔG° reveals the spontaneous nature of DCF and Cd2+ adsorption on the surface of MgO NPs. The DCF and Cd2+ adsorbed MgO surfaces were reused against various gram-positive bacteria. Finally, it was shown that MgO and sand column were more effective for removal of persistent substances and heavy metal residues than a column packed by a mixture of B-nZVI and sand.

Analysis of stage parameters of low-temperature oxidation of water-soaked coal based on kinetic principles

Mine fires caused by spontaneous coal combustion are major disasters in coal mines. The staged oxidation kinetic parameters of various coal samples at oxygen concentrations of 21 %, 15 %, 10 %, 5 %, and 3 % were analyzed using a programmed temperature testing system. Herein, the temperature increase rate of coal, the temperature difference between the furnace and coal, and the oxygen consumption characteristics were obtained. Based on the amount of CO produced and the temperature sensitivity coefficient, three characteristic temperatures and four stages of low-temperature oxidation (LTO) were identified. The results showed that at a critical temperature (TC), the amount of CO gas released from the coal samples increased with increasing oxygen concentration, and the difference in the oxygen consumption rate increased. After the limit temperature (Tu), the amount of CO gas increased steadily, and the increase in the oxygen consumption rate stagnated. CO production, the maximum heating rate, and the maximum heat release rate were positively correlated with the oxygen concentration. As the oxygen concentration increased, the activation energy during the oxygen absorption stage gradually decreased. The average reaction enthalpy (ΔH) of pre-oxidized water-immersed coal was 19.37 kJ/kg greater than that of raw coal. The equation for the conservation of energy of the coal oxidation warming process was normalized. The theoretical values of the awakening stage and the stable stage were τν and τν (1-B), respectively. When B was >1, pre-oxidized water-immersed coal at a low oxygen concentration was prone to crossover points during the oxygen absorption stage, which increased the risk of coal spontaneous combustion (CSC). The research results could provide a theoretical basis for the staged control of the spontaneous combustion of water-immersed coal in goaf areas.

The structure of CaO–MgO–Al2O3–SiO2 melts and glasses doped with FeOX–NiO

AbstractNeutron and x‐ray diffraction measurements have been performed on CaO–MgO–Al2O3–SiO2 (CMAS) glasses doped with NiO–FeXO at room temperature, along with x‐ray measurements on aerodynamically levitated liquids at ≥2000 K. The disordered structures have been modeled using empirical potential structure refinement to investigate the relation between the aluminosilicate network and the modifying cations. The SiO4 and AlO4 tetrahedra are found to have wider Si–O and Al–O bond distance distributions in the glass, and the first Ca–On coordination shell is highly distorted, redistributing different populations of long and short bonds between the liquid and the glass. The addition of Fe and Ni at low aluminosilicate content increases the number of free oxygens not bonded to AlO4 or SiO4. Mg–O and Fe–O are both found to be predominantly fourfold and fivefold in the liquid and glassy states. Despite these low coordination numbers, their bond angle distributions indicate that they are predominantly in nontetrahedral‐type geometries, with ferrous and ferric iron possessing similar coordination environments. The Ca–O and Mg–O average coordination numbers and enthalpies of solution are consistent with their higher reactivity within relatively acidic aluminosilicate melts.

Enhanced adsorption of Bismark Brown R dye by chitosan conjugated magnetic pectin loaded filter mud: A comprehensive study on modeling and mechanisms

Herein, a polymer-based bioadsorbent was prepared by cross-linking chitosan to filter mud and magnetic pectin (Ch-mPC@FM) for the removal of Bismark Brown R dye (BB-R) from wastewater. Morphological characterization analysis indicated that Ch-mPC@FM had a higher surface area and better pore structure than its components. The Artificial Neuron Network (ANN) and Adaptive Neuro-Fuzzy Inference System (ANFIS) were employed to evaluate the simulation and prediction of the adsorption process based on input variables like temperature, pH, dosage, initial BB-R dye concentration, and contact time. ANFIS and ANN demonstrated significant modeling and predictive accuracy, with R2 > 0.93 and R2 > 0.96, and root mean square error < 0.023 and <0.020, respectively. The Langmuir isotherm and the pseudo-second-order kinetic models provided the best fits to the equilibrium and kinetic data. The thermodynamic assessment showed spontaneous and endothermic adsorption with average entropy and enthalpy changes of 119.32 kJ mol−1 K and 403.47 kJ mol−1, respectively. The study of BB-R dye adsorption on Ch-mPC@FM revealed multiple mechanisms, including electrostatic, complexation, pore filling, cation-π interaction, hydrogen bonding, and π-π interactions. The approximate production cost of US$ 5.809 Kg−1 and excellent adsorption capability render Ch-mPC@FM an inexpensive, pragmatic, and ecologically safe bioadsorbent for BB-R dye removal from wastewater.

A computational study of H-bonded networks in cyclic water clusters, (H2O)n (n = 3-12).

We have performed a detailed MM and DFT investigation of neutral water clusters (H2O)n (n = 3-12). Our results show the trend of interaction energies in these clusters as a function of the size of the cluster. They show that the H-bond strength increases with cluster size and that the model of water is better described if two different partial charges are used on the hydrogen, depending on whether hydrogen is H-bonded or not. The average binding enthalpy change due to the formation of H-bonds between water molecules is found to be - 25.9kJmol-1 at B3LYP/aug-cc-pVDZ level of theory. We observe the formation of cyclic H-bonded networks through the analysis of frontier orbitals and IR vibrational frequencies spectra. For the water cluster with n = 11, we observe an unusual reduction of the bandgap indicative of a cyclic H-bonded network. Calculations were performed with the MMFF94 force field and the B3LYP method using various large basis sets. Molecular orbital diagrams and population analysis were done using standard tools in Gaussian.

Study on non-isothermal pyrolysis of Azadirachta Indica for kinetic triplets and thermodynamics evaluation

Exploring kinetics and thermodynamics of biomass pyrolysis process is imperative for optimizing the process. This study employs various model-free iso‐conversional methods and a model-fitting method to investigate the kinetics and thermodynamics of non-isothermal pyrolysis of Azadirachta indica biomass under four distinct heating rates of 10, 20, 30 and 40 °C/min. Average values of activation energy and pre-exponential factor ranged from 187.613 to 196.635 kJ/mol and 5.068×1014 − 1.178×1022 min−1, respectively, indicating an endothermic and complex nature of reaction. Integral master plots proved superior in revealing the reaction mechanism, although Criado's master plot unveiled a combination of reaction models, aligning with the intricate degradation mechanisms of biopolymers. The average enthalpy change, Gibbs free energy change and entropy change values spanned from 182.425 to 191.638 kJ/mol, from 167.288 to 173.742 kJ/mol and from 0.014 to 0.039 kJ/mol·K, respectively.

Safety analysis of pressurized water reactors with annular fuel during different transients

The dual-cooled annular fuel has two channels, with a shorter heat transfer path and a larger heat transfer area than solid fuel, which can effectively improve the safety of the reactor. It has excellent potential to improve the economy of the pressurized water reactor (PWR) and is considered to have a good development prospect. In this paper, the safety of the reactor with annular fuel assemblies under different transient conditions is analyzed using the system code NUSOL-SYS and the subchannel code NACAF, with the CPR1000 as the reference power plant. The analysis mainly includes the large break loss of coolant accident (LBLOCA), main steam line break accident (MSLB), loss of flow accident (LOFA), and rod ejection accident (REA) under nominal power and higher power density. The flow blockage accident and the combined accidents of LBLOCA and the flow blockage accident are also evaluated. The results show that during LBLOCA, the peak cladding temperature (PCT) of the core is only 833 K, much lower than that of the solid fuel. In addition, the departure from nucleate boiling ratio (DNBR) of annular fuel is larger during MSLB and LOFA, which means a more negligible risk of fuel damage. In REA, the average temperature of annular fuel is below 900 K, and the average enthalpy is below 200 kJ/kg, which is much lower than that of solid fuel. The results at 150 % power show that the performance of the core with annular fuel is still better than that of solid fuel at nominal power, except that the PCT during LBLOCA is slightly higher than solid fuel at nominal power. During the flow blockage accident, the results with different blockage areas show that a small proportion of blockage of the inner channel does not have a significant effect on the cladding temperature and that there is a risk of rupture when the inner channel is completely blocked. Finally, the results of the assumed combined accident show that the blockage of the inner channel before scram will significantly increase the PCT of the core and the time to complete the reflood during LBLOCA.

Studies on solubility measurement of codeine phosphate (pain reliever drug) in supercritical carbon dioxide and modeling

In this study, the solubilities of codeine phosphate, a widely used pain reliever, in supercritical carbon dioxide (SC-CO2) were measured under various pressures and temperature conditions. The lowest determined mole fraction of codeine phosphate in SC-CO2 was 1.297 × 10−5 at 308 K and 12 MPa, while the highest was 6.502 × 10−5 at 338 K and 27 MPa. These measured solubilities were then modeled using the equation of state model, specifically the Peng-Robinson model. A selection of density models, including the Chrastil model, Mendez-Santiago and Teja model, Bartle et al. model, Sodeifian et al. model, and Reddy-Garlapati model, were also employed. Additionally, three forms of solid–liquid equilibrium models, commonly called expanded liquid models (ELMs), were used. The average solvation enthalpy associated with the solubility of codeine phosphate in SC-CO2 was calculated to be − 16.97 kJ/mol. The three forms of the ELMs provided a satisfactory correlation to the solubility data, with the corresponding average absolute relative deviation percent (AARD%) under 12.63%. The most accurate ELM model recorded AARD% and AICc values of 8.89% and − 589.79, respectively.

Insights into co-pyrolytic behavior, emission, kinetics, synergy of bio-oil distillation residue and waxy product via TG-FTIR-MS

The technology pathways are maturing in the treatment of carbonaceous solid waste, however, there will inevitably be low value by-products downstream, which requires fine management. Herein, bio-oil distillation residue (DR) and waxy product (WP) as by-products contained considerable energy and chemical composition, and their similar thermogravimetric properties enable efficient synergy during co-pyrolysis. The emission decomposition kinetics, thermodynamics and synergy of DR co-pyrolysis with WP were investigated by TG-FTIR-MS. Thermal process of DR and WP occurred at 175.7–539.1 ℃ and 108.9–427.3 ℃. As the DR content increased, the absorption peak intensity of hydrocarbons was decreasing, but oxygenates changed little when the pyrolysis temperature exceeds 242 °C, the blend containing 50% DR presented the strongest synergy at the absorption peaks assigned to hydrocarbons at each blend. Evolved gas-phase species include mainly hydrocarbons, aromatics and small amount of oxygenated fractions, and higher DR share could obtain greater synergistic gain to CH4, benzene, phenol and naphthalene. Eα and ΔH decreased and then increased with increasing DR content. Average activation energy and enthalpy change of blends containing 25%, 50% and 75% DR were 88.9, 64.4 and 99.6 kJ/mol and 84.1, 59.6, 94.7 kJ/mol calculated through FR method, respectively. Order of reaction mechanism, diffusion mechanism nucleation mechanism affected the pyrolysis process of mixtures together, and the order of reaction model that better described the thermal decomposition of each pseudo-component.

Pyrolysis kinetic behaviour and thermodynamic analysis of waste wind turbine blades (carbon fibres/unsaturated polyester resin)

ABSTRACT This research aims to study the pyrolysis characteristics and thermodynamic analysis of waste wind turbine blades (WTBs: composed of carbon fiber/unsaturated polyester resin) using a thermogravimetric analyzer (TG). The distribution of pyrolysis vapor products and their chemical compositions were analyzed. Also, pyrolysis experiments were carried out at various heating conditions to examine its effect on the vapor composition, and their pyrolysis kinetics was simulated using several modeling routes. In addition, all degradation regions of WTBs were mathematically simulated. The results showed that WTBs are rich in carbon element (53–88 wt.%) and volatile matter (26–30 wt.%), whereas TG measurements revealed that WTBs can fully degrade up to 500°C with a mass loss of 31%. Carbonyl (C=O) was the major functional group in the released vapor with a constant intensity even when the heating rate changed, while styrene was the major Gas chromatography-mass spectrometry compound with a significant abundance of 87% (at 30°C/min) versus 84% (at 5°C/min). Finally, kinetic investigations manifested that WTBs with a specific configuration have lower average activation energies (Ea) estimated at 172 kJ/mol (KAS), 220 kJ/mol (FWO), 194 kJ/mol (Friedman), and 159 kJ/mol (Vyazovkin and Cai), and FWO provides the highest R2 of 0.99. This decrease in Ea and the reaction complexity is caused by high conductivity of carbon fibers which helps in increasing the heat transfer and speeding up the reaction. The average enthalpy and Gibbs free energy were estimated in the ranges of 166–215 kJ/mol and 114–226 kJ/mol, respectively. Based on that, resin and carbon fibers can be recovered from WTBs using pyrolysis treatment.

Study on the Pyrolysis Kinetic Behaviors of Different Vegetable-Tanned Sheepskin Leathers

The pyrolysis behaviors of leathers tanned with hydrolyzable tannins (Tara and Chestnut extracts), and condensed tannins (Quebracho and Mimosa extract) were studied by Thermogravimetric (TG) analysis in the present work. The TG/derivative thermogravimetry (DTG) results showed that the thermal stability of Tara- and Chestnut-tanned samples is poorer than that of Quebracho- and Mimosa-tanned ones. In order to study pyrolysis kinetics, TG experiments at different heating rates were carried out. Two methods of Flynn-Wall-Ozawa (FWO) and Friedman (FR) were employed to calculate the pyrolysis activation energy (Eα) of the samples. It was found that the average Eα of the vegetable-tanned samples is located at the range of 191.7-206.1 kJ/mol. The thermodynamic parameters (pre-exponential factor, Gibbs free energy, enthalpy, and entropy) of the samples were subsequently calculated based on the average Eα by the FR method. The Gibbs free energies of the Chestnut-, Tara-, Quebracho-, and Mimosa-tanned leathers were 176.9 kJ/mol, 179.8 kJ/mol, 179.3 kJ/mol, and 178.2 kJ/mol, respectively. The difference between the average enthalpies and the Eα is less than 5 kJ/mol, which indicated that the pyrolysis process is conductive to the product formation. The mean entropy (ΔS) of the four vegetable-tanned samples is all positive, which suggested that the pyrolysis of the samples could easily take place. This work might provide theoretical guidance for the optimization of vegetable-tanned leather waste pyrolysis.

Canarium schweinfurthii stone-derived biochar: A promising adsorbent for crystal violet dye removal

In this study, the effectiveness of C. schweinfurthii biochar (CSSB) for the adsorption of aqueous crystal violet dye (CVD) was investigated. Batch mode experiments were conducted to examine the influence of different process variables on the dye adsorption capacity of the CSSB. The surface chemistry and morphology of the adsorbent were elucidated using the Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy/energy dispersion X-ray (SEM/EDX), respectively. At optimum adsorption conditions (50 mg/L adsorbate concentration, 303 K and 35 min), a maximum removal efficiency of 90.04% was achieved. The experimental equilibrium and kinetic data were best fit to the Freundlich isotherm and Elovich kinetics models, respectively. The thermodynamic evaluation showed average Gibbs free energy (ΔGo), entropy change (ΔSo) and enthalpy change, (ΔHo) values of −1647.18 KJ/mol, −58.69 KJ/mol K and −173.10 KJ/mol, respectively. These thermodynamic data demonstrated that CVD adsorption onto CSSB was favourable, spontaneous, and exothermic. Any doubts about the adsorbent's economic viability were allayed by its projected cost of 0.0003 USSD/g per gram of adsorbate. Thus, according to the experimental results, the CSSB is considered an economical, effective, and environmentally friendly adsorbent for aqueous CVD adsorption.

Pyrolysis kinetics and thermal degradation characteristics of coffee, date seed, and prickly pear wastes and their blends

This study's objective was to emphasize the renewable lignocellulosic biomasses' energy potential by thermally describing them. The TG/DTG/DTA procedures were used to examine the thermal pyrolysis behavior of coffee wastes (CW), date seeds (DSM), prickly pears (PP), and two blends (50%CW/50%DSM and 33.3%CW/33.3%DSM/33.3%PP by weight), and their physico-chemical compositions were identified and assessed. The activation energy (E) of all tested samples was predicted using iso-conversional models like Friedman (FR), Starink (ST), Kissinger-Akahira-Sunose (KAS), and Ozawa-Flynn-Wall (OFW), and the frequency factor (A) was calculated based on the acquired (E) values utilizing the chemical reaction mechanisms (C1–C8). SEM, EDX, and FTIR techniques were used to examine the microstructure, mineralogy, and functional group present in the studied samples. Every DTG profile displayed a rightward shift when the heating rate (β) rose to higher temperatures. The difference in the average activation energy (Eav) values between the ST, OFW, and KAS models, except for the blend (1), does not surpass 5 kJ/mole. Increases in the (β) value, particularly for blends, were significantly correlated with increases in the maximum pyrolysis rate (−RP), pyrolysis index (CPI), pyrolysis stability index (RW), and volatile release index (Ddev). The ΔGav discrepancies between the results from all kinetic models for all samples varied from 1 to 7 kJ/mole. A little potential energy barrier was noticed when comparing the (Eav) to the average enthalpy (ΔHav).

Investigating the impact of sea surface temperature on the development of the Mediterranean tropical-like cyclone “Ianos” in 2020

This study aims to unravel and quantify the impact of sea surface temperature (SST) on the formation, intensity, structure and track of the Mediterranean tropical-like cyclone (medicane) Ianos occurred on 15–20 September 2020 at the central Mediterranean. This study, thus, demonstrates how Ianos would be in past and future climate conditions, assuming that SST changes over the years, but preserving the same atmospheric conditions. To investigate the SST impact, the medicane was simulated using the Advanced Weather and Research Forecasting (WRF-ARW) model. The numerical experiments were initialized either with SST analysis data (control experiment) or applying a uniform decrease and increase to SST analysis by 1 °C and 2 °C (four sensitivity experiments). In this way, the past and future climatic SSTs were concisely approximated. Analysis of various thermodynamic parameters in combination with phase space diagrams, revealing the thermal symmetry and the warm core structure of the cyclone, indicated that Ianos was very sensitive on SST. Thus, SST changes especially by ±2 °C had significant impact on its intensity, changing the period of tropical features while also determining the track and the landfall location. Overall, the average enthalpy flux (i.e., the sum of sensible and latent heat fluxes) in Ianos changed by approximately −39% and + 50% when SST changed by −2 °C and + 2 °C, respectively. This, in turn, affected the characteristics of Ianos causing changes for example in the average wind speed (approximately −15% and + 15%) and the average precipitation (approximately −56% and + 44%). This study quantifies the impacts of SST on Ianos medicane that have important research and socioeconomic implications with a view to a changing future. Therefore, it could support scientists, decision-makers and civil protection in the adaptation to extreme weather phenomena by building climate resilience and sustainability.

Atomistic insights into the H2 adsorption and desorption behavior of novel Li-functionalized polycrystalline CNTs

At present, hydrogen storage by physisorption is being investigated on novel polycrystalline carbon nanotubes (PCNTs) in order to utilize them for large-scale applications. Large-sized nanotubes are susceptible to structural flaws known as polycrystallinity, which evolve owing to the inherent constraints of growth kinetics and purification during the synthesis process. In this study, molecular dynamics simulations (MDS) were used to analyze the adsorption and desorption behavior of PCNTs employing hybrid grand canonical Monte Carlo (GCMC) simulations coupled with microcanonical ensembles. Moreover, a distinctive potential energy distribution technique was used to compute the adsorption metrics. We further investigated the size dependency effects, including curvature, length, and grain boundaries (GBs), on hydrogen adsorption functionalities. The MDS revealed that PCNTs with a moderate grain size of 4 nm are energetically stable and adsorption compatible with maximum gravimetric densities of 8.22 and 1.03 wt% at 77 and 300 K, respectively. Furthermore, the optimized PCNTs were functionalized with Li adatoms of varied concentrations and simulated at various temperatures and pressures. Afterward, adsorption/desorption kinetics and isosteric enthalpies of Li-functionalized PCNTs (Li-PCNTs) were computed to assess the synergistic impacts of Li adatoms and GBs. Li-PCNTs have shown remarkable performance in terms of hydrogen storage and deliverability. Consequently, at 77 and 300 K, Li-PCNTs doped with a 25% adatom concentration exhibited the maximum hydrogen uptake of 10.36 wt% and 2.13 wt%, respectively. Additionally, at 300 and 77 K, the averaged isosteric enthalpy of adsorption, estimated from the adsorption isotherms, was about 7.07 kJ/mol and 4.03 kJ/mol, respectively. Therefore, despite their ability to prevent metal clustering, PCNTs have a modest impact on adsorption metrics. Our findings open up new avenues for the utilization of PCNTs in large-scale hydrogen storage applications with suitable functionalization strategies.