Kinetic Model Research Articles

Quality variation analysis and rehydration kinetics modeling of yuba subjecting to three different drying process

This study investigated the effects of hot air drying (HAD), microwave vacuum drying (MVD), and vacuum frying drying (VFD) on the quality of yuba and utilized mathematical models (Peleg model, Weibull equation, first-order kinetic model, and exponential association model) to explore the rehydration kinetics of yuba. The results indicated that, compared to HAD, MVD significantly increased yuba's L* value and sensory score, while VFD notably reduced the cooking loss rate and enhanced moisture retention. Significant changes were observed in the texture of yuba before and after cooking, with distinct differences noted under microscopic observation, and a pronounced change in protein secondary structure. The Peleg model can effectively fit the rehydration processes of HAD and VFD yuba, while the first-order kinetic model can effectively fit the rehydration processes of MVD yuba. This study provides a valuable reference for yuba's drying method and rehydration Kinetics model.

Metal heteroatoms significantly enhance efficacy of TiO2 nanomaterials in promoting hydrolysis of organophosphates: Implications for mitigating pollution of plastic additives.

Organophosphate esters (OPEs) are prevalent pollutants in the aquatic environment. OPEs are released from many sources, particularly, from the breakdown and weathering of plastic wastes, as OPEs are commonly used plastic additives. Metal oxide mineral nanoparticles play critical roles in the hydrolytic transformation of OPEs. While natural minerals often contain metal impurities, it is unclear how metal heteroatoms affect the efficiency of mineral nanoparticles in mediating hydrolysis reactions. Herein, we show that transition metal-doped anatase titanium dioxide (TiO2) nanomaterials are more effective in catalyzing the hydrolysis of 4-nitrophenyl phosphate (pNPP), a model OPE compound, with the relative effects of the heteroatoms following the order of Fe > Cr > Mn ≈ Ni > Co > Cu. With multiple lines of evidence based on spectroscopic analysis, kinetics modeling, and theoretical calculations, we show that metal doping increases the Lewis acidity of the TiO2 nanomaterials by increasing the oxidation state of surface Ti atoms, inducing oxygen vacancies, and creating additional Lewis acid sites with stronger acidities. Moreover, the increased amounts of surface hydroxyl groups due to metal-doping enhance inner-sphere complexation of pNPP through ligand exchange. The interesting observation that Fe-doped TiO2 exhibited the highest catalytic efficiency may have important implications for reducing the risks of organophosphate plastic additives, as iron is the most common heteroatom of naturally occurring TiO2 (nano)materials.

Waste biomass-based graphene oxide decorated with ternary metal oxide (MnO-NiO-ZnO) composite for adsorption of methylene blue dye

In this study, a novel approach for the removal of methylene blue (MB) dye is effectively illustrated by using biomass based composite adsorbent. The investigation employed areca nut husk (AH) to produce graphene oxide (GO) by a single step calcination method. Thereafter, AH-GO was incorporated by using ternary metal oxide (TMO) via hydrothermal treatment. The developed AH-GO@MnO-NiO-ZnO composite was characterized by various analytical techniques, including FT-IR, XRD, FESEM, HRTEM, BET surface area and Raman spectroscopy which exhibited promising properties for dye adsorption. To study the adsorption efficiency of prepared composite, optimization experiments were performed for adsorbent dose, initial dye concentration and contact time. The optimized parameters during adsorption phenomenon were found to be 0.5g/L of dose, 20mg/L of initial concentration and 180min of time exhibiting removal efficacy of 93.05 ± 0.93%. Moreover, adsorption isotherm and kinetic models were analysed to explore the adsorption behaviour of AH-GO@MnO-NiO-ZnO towards MB dye. The adsorption isotherm and kinetic studies followed Langmuir isotherm model and pseudo-second-order (PSO) model respectively. AH-GO@MnO-NiO-ZnO has demonstrated a maximum adsorption capability of 127.06mg/g. These findings collectively underscore the potential of AH-based adsorbent as a viable, inexpensive, and environment friendly for the treatment of wastewater contaminated with MB dye.

Selective adsorption of arsenic by water treatment residuals cross-linked chitosan in co-existing oxyanions competition system

Selective adsorption of arsenic in co-existing oxyanions competition systems remains a significant challenge in water treatment due to the limitations of adsorbent materials that often overlook competitive adsorption, resulting in an overestimation of their actual purification potential for target contaminants. In this study, a novel hydrogel bead adsorbent, composed of water treatment residuals (WTRs) and chitosan (Chi), was developed to selectively remove arsenic, while minimizing the interference from phosphate, which is the strongest and most representative competitor in multi-oxyanion systems. The WTRs-Chi beads (WCB) adsorbents were optimized by adjusting the ratios of WTRs:Chi, with characterization results indicating that increased WTR doping improved the degree of crosslinking and the formation of bidentate complexes with enhanced electrostatic selectivity. Importantly, the co-existence of phosphate had minimal adverse effects on arsenic removal compared to other reported adsorbents. The maximum adsorption capacity for As (Ⅴ) in the binary system was 34.12 mg/g, and the adsorption behavior was fitted well by the pseudo-second-order kinetic model and the extended Langmuir isotherm model. The experimental results, supported by X-ray photoelectron spectroscopy analysis (XPS), revealed that both As (Ⅴ) and P (Ⅴ) adsorption in the single system were driven by electrostatic attraction and ligand exchange. However, in the binary system, the inhibition of P (V) adsorption was attributed to competitive desorption caused by electrostatic repulsion, which hindered the formation of inner-sphere complexes. This study provides a practical approach for developing selective adsorbents to address arsenic contamination in complex water environments and promotes the recycling of municipal solid waste.

High-performance copper terephthalic acid metal-organic framework/gum Arabic/carrageenan composite beads for efficient lead(II) removal from aqueous solutions

Lead (Pb(II)) contamination poses a significant threat to human health and the environment. This study investigates a new approach for Pb(II) removal from polluted water using copper terephthalic acid metal-organic framework/gum Arabic/potassium carrageenan (MGC) composite beads. We synthesized copper terephthalic acid MOF, potassium carrageenan beads, and MGC composite beads to evaluate their adsorption potential. Characterization of the synthesized adsorbents was performed using TGA, nitrogen adsorption/desorption, ATR-FTIR, zeta potential, SEM, and TEM analyses, revealing that MOF > MGC > KG in thermal stability. The MGC composite exhibited a high specific surface area (398.03 m2/g) with mesopores and diverse functional groups, alongside a pH of zero point charge (pHpzc) of 6.8 and a small particle size (20 nm). The maximum Langmuir adsorption capacity for Pb(II) removal by MGC reached 374.7 mg/g under optimized conditions (20 °C, pH 5, 60 min shaking time, 3.0 g/L adsorbent dosage). The adsorption data fit well with the Pseudo-First-Order kinetic model and Langmuir and Dubinin-Radushkevich isotherm models. The adsorption process was physical, favorable, and endothermic. EDTA was used as a desorption agent, showing that the composite beads retained 97 % efficiency after ten cycles, highlighting MGC's potential as a sustainable strategy for Pb(II) remediation.

Adsorption of crystal violet from wastewater using alkaline-modified pomelo peel-derived biochar

The purpose of this study is to investigate the optimal preparation conditions for alkali-modified pomelo peel biochar and to clarify its adsorption process towards crystal violet (CV). The pyrolysis temperature and the alkali-to-carbon ratio of pomelo peel raw materials with varying epidermal layers were evaluated and optimized. Several characterization techniques demonstrated that alkaline modification enhances the adsorption performance of biochar by modifying its pore structure and functional group composition. Notably, the biochar, derived from the outer epidermis of pomelo, modified with an alkali-to-carbon ratio of 2:1 at 900 °C (KC2), exhibited significant adsorption capacity through mechanisms such as pore filling, hydrogen bonding, π-π interactions, electrostatic interactions, and functional groups including CC and COC. The Freundlich isotherm and the pseudo-second-order kinetic model were determined to be the most appropriate for describing the equilibrium data. Accordingly, KC2 exhibited a maximum adsorption capacity of 805.69 mg/g, which significantly exceeded that of biochar derived from pomelo peel with a basic outer epidermis pyrolyzed at 900 °C (BC-GOP900, 586.7 mg/g). This study ultimately concluded that utilizing pomelo peel biochar, particularly KC2, represents an innovative strategy to address pollution caused by CV while effectively repurposing agricultural waste.

Visible light photocatalytic reduction of Toxic Chemical Organophosphate Monocrotophos using reduced Graphene Oxide derived from bamboo leaves

In this study, graphene oxide (GO) was synthesized from waste bamboo leaves using a pyrolysis and ultra-sonication technique. UV-visible spectroscopy revealed a prominent absorption peak at 230nm, while Raman spectroscopy confirmed the presence of characteristic D-band (1340cm⁻¹) and G-band (1596cm⁻¹). XRD analysis showed a peak at 11.5°, corresponding to a lattice spacing of 3nm, and SEM/TEM imaging demonstrated the formation of multi-layered graphene sheets. The synthesized GO was evaluated for the photocatalytic degradation of the organophosphate pesticide monocrotophos under visible light. At a concentration of 25mg/L, graphene exhibited a removal efficiency of 98% with a degradation rate of 0.036 ppm/min, following a Langmuir isotherm and pseudo-first-order kinetic model. The significance of this study lies in the potential environmental application, offering an economical and sustainable solution for the decontamination of pesticide-contaminated water sources. The method could contribute significantly for reducing environmental pollution and addressing global water safety challenges.

Synthesis and characterization of novel magnetic metal organic framework for efficient removal of ketoprofen from aqueous solutions: Mechanism of interaction, adsorption and optimization via BOX-Behnken design

This investigation examines the adsorption and elimination of the anti-inflammatory medication ketoprofen (KTP) in relation to a newly developed magnetic thorium metal-organic framework (MTh-MOF). The study found that KTP absorption on MTh-MOF resulted in a reduction in pore volume, pore size, and surface area, as revealed by N2 adsorption/desorption isotherm analysis used to evaluate the characteristics of the MTh-MOF. Scanning electron microscopy (SEM) showed that the pore radius of MTh-MOF decreased from 1.68 nm to 0.82 nm, demonstrating a consistent and uniform structure. Fourier-transform infrared (FT-IR) spectroscopy was employed to identify the functional groups present in MTh-MOF, while X-ray photoelectron spectroscopy (XPS) was used to confirm the compound's structure. The optimal conditions for achieving a high adsorption capacity were found to be at pH 6 and a MTh-MOF dose of 0.02 g. The results indicated that MTh-MOF displayed a high capacity for absorbing KTP, with the adsorption data fitting well with pseudo-second-order kinetic models and the Langmuir isotherm. The adsorption capacity of MTh-MOF for KTP was determined to be 518 mg/g. The adsorption energy of 28.26 kJ·mol–1 suggested that chemisorption was the predominant mode of adsorption. The process of KTP adsorption on MTh-MOF was observed to be spontaneous, endothermic, and random, as evidenced by the temperature-dependent increases in the thermodynamic parameters (ΔGo, ΔHo, and ΔSo). The adsorption process was optimized using Response Surface Methodology and Box-Behnken design (RSM, BBD). Aromatic rings interact via π-π bonding, while chemisorption involves the development of chemical interactions between the adsorbate and adsorbent. Additionally, electrostatic interactions arise from the attraction or repulsion of charges between the adsorbate and adsorbent, and pore-filling occurs when the adsorbate fills the adsorbent's pores. In order to understand the electrical properties, reactivity, and shape of KTP, density functional theory (DFT) was utilized.

Ultrasound-assisted Adsorptive Desulfurization of Dibenzothiophene from Model Fuel on K2CO3-Activated Biochar

A novel mesoporous activated biochar (ABC) was developed from an equal mix of date and olive stones and implemented in the ultrasound-assisted adsorptive desulfurization (USADS) of model gasoline (300 ppm DBT/n-hexane) and model kerosene (300 ppm DBT/cyclohexane). The biowaste blend was carbonized at 450°C for 75 min at a 10°C/min heating rate, followed by K2CO3-activation. The superior ABC was synthesized at 750°C for 1h using an impregnation ratio of 1:1 K2CO3: biochar. The BET surface area and average pore diameter of the resulting ABC were 1099.70 m2/g and 5.14 nm, respectively. The USADS of both models was achieved at relatively mild experimental conditions (0.20 g of the ABC 30°C, 40 min, and 120 W US power). At these conditions, the USADS of model gasoline amounted to 97.32 % compared to 99.39 % for model kerosene. The USADS process of both models followed the Langmuir model of the adsorption isotherms and the pseudo-2nd-order kinetics model. The ABC was recoverable and effective until the 5th regeneration cycle and reused reasonably. The maximum USADS of real gasoline (88.12 %) was achieved using 1.0 g of the ABC at 30°C for 120 min.

Preparation and characterization of functionally antibacterial multi-layer lignin core-shell structure material with adsorption and high efficiency of photocatalysis for Cr(Ⅵ)

Wastewater with chromium is a common heavy metal pollution in industrial pollution, affecting health of human seriously, while adsorption and photocatalysis are efficient for Cr(Ⅵ) removal. The multi-layer lignin core-shell structure materials were prepared with kraft lignin/polydopamine core-shell structure material, using non-covalent bonding to induce the in-situ induction of TiO2. The hydroxyl group of kraft lignin and the amino group of polydopamine provided abundant adsorption active sites with adsorption capacity being 299mg/g at pH of 2. The adsorption process conformed to the Freundlich isotherm model and the pseudo-second-order kinetic model. The removal rate of Cr(Ⅵ) reached more than 99.9% within 10min under simulated solar light with influence of adsorption and photocatalysis. The multi-layer lignin core-shell structure materials presented excellent antibacterial activity, with the inhibition rate against S.aureus and E.coli being 40% under dark conditions and 99% under simulated solar light because h+ or ·OH producing by TiO2. The antibacterial multi-layer lignin core-shell structure materials showed good universality in water pollution treatment.

Insight into the generation network of reactive oxygen species in H2O under nonthermal atmospheric-pressure plasma irradiation using a kinetic modeling approach

A kinetic model incorporating the dominant generation networks of reactive oxygen species (ROS) in H2O under nonthermal atmospheric-pressure plasma irradiation was developed in this study. In the proposed model, the minimum necessary elementary reactions involving ROS were considered based on the behaviors of the dissolved O2 and H2O2 observed in plasma-irradiated H2O. The ROS included not only OH radicals but also other ROSs such as OOH, O, and these anionic radicals. The model agrees well with the experimental results for various initial dissolved O2 concentrations, pH values, and input power conditions. Further, the model could predict specific behavior under extrapolated conditions, which are in the presence of H2O2 at the initial conditions. In addition, the reaction rates of elementary reactions involving dissolved O2, which are difficult to measure in the experiments, were simulated by the model. It was found that the reaction rates between the consumption and production reactions of dissolved O2 were balanced at later stages of nonthermal atmospheric-pressure plasma irradiation. The model is expected to provide fundamental guidelines for the effective utilization of nonthermal atmospheric-pressure plasma irradiation.

High-effective, convenient and environmental-friendly MOFs-chitosan-glyoxal composite film for ceftizoxime adsorption: Behavior and mechanisms.

In this work, a novel PCN-222-chitosan-glyoxal (PCN@CSG2) composite film was constructed by loading PCN-222 in chitosan substrate, and used for ceftizoxime adsorption. The results demonstrated that the PCN@CSG not only had excellent adsorption properties for ceftizoxime, but also maintained excellent structural properties in harsh environments (strong acids and alkalis), making it have good recycling performance. Specifically, the adsorption kinetics and isotherms investigation demonstrated that the adsorption process followed the pseudo-second-order kinetic model and Freundlich isotherm model respectively, indicating that it was a multilayer process mainly controlled by chemisorption. The PCN@CSG possesses excellent absorptive capacity of 561.7mg·g-1 and reaches equilibrium rapidly within 60min, which is attributed to the structural advantages of PCN-222 and chitosan. The amino, carboxyl and hydroxyl functional groups of PCN-222 provide numbers of active sites and cationic chitin greatly promoted the electrostatic adsorption with negative ceftizoxime. In addition, the PCN@CSG has the advantages of renewable and environment-friendly for the biodegradation of chitosan. After five consecutive adsorption-desorption cycles, the removal rate was still higher than 90%, confirming the excellent reusability of PCN@CSG. This work provided a great prospect for the design and application of shaped-MOFs composite materials for the removal of cephalosporins in environmental water.

Kinetic analysis and model evaluation for steam co-gasification of coal-biomass blended chars using macro-TGA

Kinetic analysis and model evaluation for steam co-gasification of coal-biomass blended chars using macro-TGA

Enrichment of polyphenols from Cinnamomum camphora seed kernel by macroporous adsorption resins and evaluation of its antioxidant and enzyme inhibitory activities

The Cinnamomum camphora seed kernel (CCSK) has potential as a natural source of bioactive phenolics. However, there is limited information on the recovery and characteristics of polyphenols from the by-product of CCSK after oil extraction. In this study, an efficient macroporous adsorption resin technology was established to enrich polyphenols from CCSK (CCSK-P). HJ-18 resin was found as the most appropriate adsorbent because of its highest adsorption/desorption capacity for CCSK-P. The pseudo-second-order kinetic and Freundlich isotherm models better described the whole adsorption process. The adsorption process was spontaneous, physical, and dominated by multilinear intraparticle diffusion. The optimum enrichment procedure of CCSK-P on HJ-18 resin was as follows: for adsorption, loading flow rate and sample volume were 1.5 BV/h, and 4.79 BV, respectively; for desorption, the eluent type, elution flow rate and volume were 80% ethanol, 3.0 BV/h and 8 BV, respectively. After one-step large-scale enrichment, the total polyphenol content of CCSK-P was increased 7.11-fold with a recovery of 81.07%. Moreover, enriched CCSK-P showed significantly higher scavenging ability against DPPH radical and ABTS radical and higher inhibitory activity against α-amylase and α-glucosidase. In conclusion, CCSK-P was well enriched by HJ-18 resin and exhibited good antioxidant and enzyme inhibition activity, which may be applied in the food, cosmetic and pharmacy industries. This study provides a meaningful guidance for the industrial enrichment of polyphenols from CCSK.

Quantitative mechanisms for the Cd2+ adsorption increased by sewage-sludge biochar but decreased by rice-straw biochar after melamine modification

To explore the relative contributions of different mechanisms to Cd2+ adsorption by melamine (C3H6N6) modified biochars, the adsorption characteristic experiments including adsorption kinetics, isotherms and thermodynamics were performed, and the qualitative and quantitative characterization of adsorption mechanisms were further analyzed by SEM-EDS, XRD, FTIR, XPS and the calculation, respectively. When initial pH increased from 1.0 to 7.0, the adsorption capacities were increased, and began to decline after reaching maximum capacities at pH of 5.0 for both modified biochars. After C3H6N6-modification, the maximum adsorption capacity of sewage-sludge biochar (SSB) increased from 64.20 to 126.75 mg/g, but the maximum capacity of rice-straw biochar (RSB) decreased from 52.03 to 25.65 mg/g. For both pristine biochars, the adsorption process was better described by pseudo-second-order kinetic and Langmuir isotherm models, whereas it did not change the applicability of the adsorption models after modification. The thermodynamics confirmed that all the adsorptions were endothermic process under different temperatures of 293, 303 and 313 K, suggesting higher temperature was more conducive to the adsorption. Such an enhancement was supported by more aromatic structure in modified SSB (N-SSB) compared to SSB, which was qualitatively confirmed by FTIR and XPS observation, and the enhancement was fundamentally caused by the increases in the importance of Cπ-coordination mechanism, accounting for 20.30 % (SSB) to 41.12 % (N-SSB) of total adsorption. While for modified RSB (N-RSB), the reduction was primarily explained by the decreased contribution of cation-exchange mechanism to total adsorption, since the contribution proportion was reduced from 80.16 % to 55.65 % after modification. The present analyses would shed light on the mechanisms underlying the adsorption by similar modified adsorbents, and the application of rice-straw biochar by C3H6N6-modification for the Cd2+ adsorption should be investigated prudently in future.

Fast and effective adsorption of Ce3+ by phosphate-functionalized ZIF-67-derived layered double hydroxides

In this experiment, phosphate (sodium hexametaphosphate) was used as an intercalation modifier and ZIF-67 as a precursor mixed with Al(NO3)3·9H2O Nanolayered double hydroxides P-Co-Al-LDH with hexametaphosphate group intercalation were prepared in a hydrothermal environment and characterized by SEM, FT-IR, XRD, TGA, SEM and XPS. The adsorption performance of P-Co-Al-LDH and control Co-Al-LDH on Ce3+ under different adsorption conditions was firstly investigated by optimization experiments. It was determined that the best adsorption effect of P-Co-Al-LDH was achieved at pH=6, and the fast equilibrium adsorption state was achieved within 30 min, with the adsorption amount reaching 220.98 mg/g and the adsorption efficiency reaching 72.66%. In addition, kinetic, isothermal adsorption and thermodynamic modeling explored the adsorption mechanism of Ce3 + by nanodiamond P-Co-Al-LDH mainly the complexation of functional groups in sodium hexametaphosphate with metal ions greatly improved the adsorption performance. Several regeneration experiments were carried out to evaluate the stability and reusability of the adsorbent. After three cycles of adsorption, the adsorption efficiency was still maintained at 83.26%.

Mentioned Magnesium Oxide Nanomaterials for Effective Adsorption of Congo Red Dye and Fluoride Ions From Aqueous Solutions

This study investigates the synthesis of nanostructured magnesium oxide (MgO) using the auto-combustion method with urea (MgO-U), glycine (MgO-G), and citric acid (MgO-C) as fuels, followed by subsequent calcination. The selection of fuel plays a crucial role in determining the morphology of the nanostructures.X-ray diffraction (XRD) analysis confirms that the samples exhibit a well-crystallized structure with the desired phase and are free of impurities. Field emission scanning electron microscopy (FESEM) shows that MgO-U nanoparticles have diameters ranging from 10 to 20nm, MgO-C nanoparticles from 60 to 80nm, and MgO-G nanoparticles from 80 to 100nm. These MgO nanomaterials are specifically engineered for adsorption applications, aimed at removing toxic organic dyes and fluoride ions from aqueous solutions. Results demonstrate that MgO-G nanoparticles exhibit superior adsorption activity compared to MgO-U and MgO-C nanoparticles, with maximum uptake capacities of 1429 and 14mg/g, respectively. The adsorption processes adhere to second-order kinetic model. These findings highlight the potential application of the synthesized MgO nanoparticles for mitigating water pollution by adsorbing pollutants from aqueous media.

In silico analysis of Design of Experiment methods for metabolic pathway optimization

Microbial cell factories allow the production of chemicals presenting an alternative to traditional fossil fuel-dependent production. However, finding the optimal expression of production pathway genes is crucial for the development of efficient production strains. Unlike sequential experimentation, combinatorial optimization captures the relationships between pathway genes and production, albeit at the cost of conducting multiple experiments. Fractional factorial designs followed by linear modeling and statistical analysis reduce the experimental workload while maximizing the information gained during experimentation. Although tools to perform and analyze these designs are available, guidelines for selecting appropriate factorial designs for pathway optimization are missing. In this study, we leverage a kinetic model of a seven-genes pathway to simulate the performance of a full factorial strain library. We compare this approach to resolution V, IV, III, and Plackett Burman (PB) designs. Additionally, we evaluate the performance of these designs as training sets for a random forest algorithm aimed at identifying best-producing strains. Evaluating the robustness of these designs to noise and missing data, traits inherent to biological datasets, we find that while resolution V designs capture most information present in full factorial data, they necessitate the construction of a large number of strains. On the other hand, resolution III and PB designs fall short in identifying optimal strains and miss relevant information. Besides, given the small number of experiments required for the optimization of a pathway with seven genes, linear models outperform random forest. Consequently, we propose the use of resolution IV designs followed by linear modeling in Design-Build-Test-Learn (DBTL) cycles targeting the screening of multiple factors. These designs enable the identification of optimal strains and provide valuable guidance for subsequent optimization cycles.

Dynamic strain ageing of L12-strengthened Ni-Co base high-entropy alloy and unraveling its deformation mechanisms in strain ageing process

Dynamic strain ageing (DSA) of L12-strengthened Ni-Co base high-entropy alloy (HEA) was examined at temperatures varying from 20 to 600 °C with strain rates between 10–2 to 10–4 s-1. In normal DSA regimes, elevating temperature or lowering strain rate advances the DSA behavior, resulting in the lowered critical strain and raised amplitude of serrations. Based on strain-rate jump tests, the negative strain-rate sensitivity induced by DSA was observed at the elevated temperature regime, and high apparent activation volumes ranging from 97∼ 737b3 correspond to the strong obstacles effect from the precipitates and the additional pinning strengthening of solute atoms. Transmission electron microscopy evidence suggests that stacking faults prevailed at all testing temperatures, while the serration changes are the outcomes of their dynamic interactions with precipitates and condensed Cr, Co-rich solute cloud. Subsequently, in normal DSA regimes, activation energies required for the onset of type A, a mixture of type A and type A + C, and a mixture of type A + B and type C serrations are 30.6, 65.8, and 101.1 kJ/mol determined by strain ageing model at strain rates of 10–2, 10–3, and 10–4 s-1, respectively. Lastly, a two-time parameter-based Cottrell-Bilby strain aging kinetic model that considers the solute-dislocation interaction in a pipe diffusion manner is applied to evaluate the DSA strengthening concerning strain, strain rate, and temperature.

Adsorption equilibria and kinetics of CO2 and N2 on silica-alumina gels for reducing gas production by CO2 removal from iron flue gases

In industrial fields, hydrogen-containing flue gases generally contain a certain amount of CO2 and N2. After removing CO2, the raffinate gases can be used in various applications to mitigate carbon emissions. Furthermore, the concentrated CO2-rich extract contributes to efficient CO2 capture. Silica-alumina gel can be a high potential adsorbent because of its high CO2 adsorption capacity and energy-saving desorption. Three different silica-alumina gels with different amounts of alumina (FJ, KD, and WS) were compared to study the impact of the alumina content on the adsorption characteristics. The adsorption behaviors of CO2 and N2 were measured at 293K, 308K, and 323K at pressures up to 1000 kPa. The isotherms correlated with the dual-site Langmuir model, showing that the adsorption capacity for CO2 was much higher than that for N2 across all the adsorbents. The surface areas and adsorption capacities followed the opposite order of alumina content: FJ > KD > WS. However, the difference intervals in the isotherms did not align consistently with the alumina content, but the micropore volume changed by alumina contributed highly to the adsorption capacity. In the adsorption kinetic analysis, the diffusional time constants and kinetic parameters in a non-isothermal adsorption kinetic model showed minor dependence on pressure and temperature. The adsorption rate was higher for N2 than for CO2. It increased with alumina content, following the order WS > KD >> FJ. The results contribute to the establishment of guidelines for the selection of silica-alumina gel and the design of the adsorption process.