Kinetic Model Research Articles

Magnesium-modified starch cryogels for the recovery of nitrogen and phosphorus from wastewater and its potential as a fertilizer substitute: A novel nutrient recovery approach

Nitrogen (N) and phosphorus (P) are primary pollutants contributing to water quality degradation and eutrophication but are also indispensable resources for agricultural production. In this study, we synthesized porous MgO/Mg(OH)2-modified starch gels (SC-M/SC-OM) to facilitate the simultaneous removal of N and P from wastewater and address the challenges associated with separating and recycling powdered materials. By immobilizing magnesium powder within the matrix of starch gel, with the addition of 1.7 % w/w of MgO and 2.4 % w/w of Mg(OH)₂, the adsorbent can be efficiently recovered from the liquid phase, minimizing material loss. Due to their inherent pH-regulating capabilities, the modified starch gels exhibited excellent removal performance over a wide pH range. At the appropriate adsorbent dose, the maximum recovery of SC-M was 70.072 mg/g P and 25.517 mg/g N, whereas SC-OM was marginally inferior to SC-M. The pseudo-first kinetic model more accurately represented the adsorption of the two materials, showing that N and P concentrations mainly affected the adsorption efficiency, which benefits nutrient recovery at higher concentrations. Starch gels function as carriers for powdered magnesium and contribute to the synergistic removal of N and P, particularly enhancing P removal. SC-OM primarily facilitates the recovery of N and P by forming struvite. At the same time, the adsorption during the hydration process of MgO also plays a crucial role in the recovery with SC-M. Finally, the pot experiment confirmed the feasibility of using the recovered SC as a sustained release fertilizer. This study reveals the significant potential of SC-M/SC-OM for environmentally friendly nutrient removal and recovery, providing a promising approach for wastewater treatment and nutrient recycling.

Synthesis of dihydrocarvone over dendritic ZSM-5 Zeolite: A comprehensive study of experimental, kinetics, and computational insights

This study explores the isomerization of limonene-1,2-epoxide (LE) from kinetic and mechanistic viewpoints, using a dendritic ZSM-5 zeolite (d-ZSM-5) as a highly selective catalyst for the formation of dihydrocarvone (DHC) in the form of diastereoisomers (cis + trans). Ethyl acetate, a green solvent, was used at mild reaction temperatures (50–––70 °C). DHC, which can also be extracted from caraway oil, is widely used as an intermediate for epoxylactone production and as a constituent in flavors and perfumes. Kinetic modeling of LE isomerization was performed using a reaction network with eight parallel reactions and the corresponding rate equations, derived from the assumption of the rate-limiting surface reactions. The large standard errors in the statistical results of some kinetic parameters of the initial data fitting suggested that three of those reactions can be neglected to describe the kinetic model more accurately. This refinement resulted in standard errors in the kinetic parameters lower than ca. 11 %, confirming the statistical reliability of the modified kinetic model. Activation energies of 41.1 and 162 kJ/mol were estimated for the formation of cis-DHC and trans-DHC, respectively. Density Functional Theory (DFT) calculations revealed the preferred pathway for both cis and trans-LE conversion to DHC and carveol. The rate-determining step, carbocation formation (ΔEact = 234 kJ/mol), precedes near-instantaneous dihydrocarvone formation under the studied conditions.

Evaluating the shelf life of strawberries using a portable Vis-NIR spectrophotometer and a Reflectance Quality Index (RQI)

This study aimed to develop a postharvest quality index for strawberry (Fragaria ananassa Duch.) based on Vis-NIR reflectance, using a portable handset spectrometer to assess fruit quality and establish maximum shelf life. Fresh strawberries were stored at different temperatures (5, 15, 25 and 35 °C) and at 60 % relative humidity for up to 15 days. Various quality parameters were evaluated, including colour, firmness, weight loss, appearance, and microbial quality, every three days during storage. Kinetic models were used to describe the changes in weight loss, appearance, colour, and firmness of strawberries during storage under different temperatures. Vis-NIR spectroscopy was employed to establish a Reflectance Quality Index (RQI) for determining fruit quality during storage. This index helped to reduce the high number of wavelengths to a lower set of representative independent variables. Calibration and prediction models were created using the partial least squares (PLS) regression method, incorporating cross-validation, to predict quality indicators of strawberries. These models were developed for predicting appearance, weight loss, L*, a*, b* colour parameters, and firmness. A very good fit was obtained (R2 = 0.95), demonstrating the feasibility of both the RQI and PLS for evaluating strawberry quality. This study presents a novel approach for assessing the shelf life of strawberries based on storage time and temperature using a portable spectrophotometer. This method can be a valuable tool for the food industry to ensure optimal fruit quality and minimize food losses.

Experimental and numerical study of cadmium fate and transport mechanisms during artificial recharge in agricultural regions

Agricultural Managed Aquifer Recharge (AgMAR) uses agricultural lands and floodwater to enhance groundwater recharge, but its effectiveness can be hindered by heavy metals like cadmium (Cd), which pose risks to groundwater quality. Cd is particularly concerning due to its high mobility and persistence in the environment. This study investigates Cd's fate and transport in agricultural regions during MAR, focusing on sandy loam soils through batch and column experiments. Equilibrium and kinetic batch studies were conducted under varying Cd concentrations and exposure times to quantify the adsorption capacity and rate. HYDRUS-2D was used to simulate Cd's transport in soil under various ponding depths and Cd concentrations. Results showed a maximum Cd adsorption capacity of 439.58 mg/kg, with the Freundlich isotherm providing a better fit (R2 = 0.98) and indicating heterogeneous adsorption sites (n = 0.389). The kinetic experiment indicated chemisorption as the predominant mechanism, with an equilibrium adsorption capacity of 236.49 mg/kg. The pseudo-second-order kinetic model (rate constant 0.0016 h⁻1, R2 = 0.99) suggested that adsorption kinetics are influenced by Cd concentration and available adsorption sites. The column experimental findings supported by HYDRUS-2D modeling successfully explained the fate and transport of Cd within the soil columns. The model fitted parameter values for Freundlich adsorption isotherm coefficient (KF), linearity factor (Nu), and kinetic rate coefficient are (α) 47.37 L/kg, 0.00389 cm³/ppm and 0.0029 min⁻1, respectively. Modeling scenarios further elucidated the transport dynamics of Cd under simulated AgMAR conditions. Modeling scenarios indicated that with constant ponding of 5 cm over a year, Cd at 20 and 40 ppb concentrations in floodwater could potentially migrate below root zone systems. This study highlights the critical role of understanding Cd fate and transport in optimizing AgMAR systems and reducing Cd pollution risks, providing valuable insights for developing effective monitoring and management strategies.

A rigorous model for hydrogen response in industrial propylene polymerization loop reactors: From micro-mechanism to macro-behavior

In spite of playing a chain transfer agent role, the hydrogen activation effect in propylene polymerization with Ti-based Ziegler-Natta catalysts, so called “hydrogen response”, is usually explained by the dormant-site theory in polymer chemistry. However, how the micro-mechanism at the catalyst site scale affects the macro-behavior of industrial processes is unrevealed. This work aims at developing a rigorous model that can accurately describe hydrogen response and predict polymer chain microstructure for an industrial propylene polymerization process consisting of loop reactors in series. The model is comprised of a kinetic model, a thermodynamic model, and a macroscopic non-ideal loop reactor model. To describe hydrogen response, an elaborated kinetic model is established based on a consistent dormant site reactivation mechanism assuming a multi-site model. The model predictions are in good agreement with plant data, after taking the dormant sites reactivated by hydrogen into account. The proposed model is capable of fully assessing the effects of various process conditions, during steady-state and grade transition processes, on the macro-behavior (i.e., production, slurry density) as well as polymer properties (i.e., melt flow index, molecular weight distribution) in the industrial loop reactors. The underlying correlations are also discussed.

Supercritical hydrothermal combustion and enhanced degradation characteristics of phenol

Supercritical hydrothermal combustion is a green combustion technology that produces flames in supercritical water (SCW), which can realize efficient disposal of aqueous wastes. In this study, the typical pollutant phenol is investigated through tubular reactor experiments and mechanism analysis to explore its hydrothermal combustion properties and enhanced degradation effects on refractory species. The results show that 3.06 and 3.41 wt% phenol can be self-ignited in the tubular reactor with a critical preheating temperature of 460 °C. Methanol could improve the ignition and burnout characteristics of phenol. As the COD ratio of methanol was greater than 0.35, the ignition temperature of phenol was reduced to 420 °C, with TOC removal rate achieving 99.9%. At 460 °C, phenol positively influenced the heat release during combustion of phenol/methanol. In oxidation of phenol/ammonia, 1.61 wt% phenol resulted in the reaction temperature rising by around 62.0 °C, allowing a NH4-N removal rate of 92.8% through its synergistic kinetic and thermal effects. Whereas, the nitrogen-containing intermediates from ammonia inhibited phenol oxidation. Finally, a mechanism-based kinetics model for oxidation of phenol in SCW was developed by means of real gas properties and sensitive reaction step modifications, which was viable for simulating the ring-opening path of phenol.

Addressing small-scale temperature swing adsorption challenges using intensified fluidised bed technology for carbon capture process development

Polyethylenimine (PEI)-based adsorbents exhibit high CO2 capacities, making them potential candidates for mitigating unavoidable industrial CO2 emissions. However, desorption of CO2 from PEI, and from adsorbents in general, has received far less attention in the literature than adsorption. Whilst Temperature Swing Adsorption (TSA) is simple to conceptualise, it is difficult to implement in small-scale experiments in practice. Here we study the desorption characteristics of a commercial branched PEI adsorbent in a small-scale swirling fluidised bed reactor (TORBED) to improve the small-scale heat transfer rates. Our experimental results show that higher desorption temperatures, higher gas flow rates, and higher CO2 concentrations during adsorption can improve the desorption efficiency (defined as the amount of CO2 removed as a fraction of the initial amount adsorbed). In terms of kinetics, we found that the fractional order kinetic model provided the best fit to the PEI adsorbent, implying that this adsorbent involves multiple simultaneous molecular interactions, physisorption processes, and chemisorption processes, that cannot be described by simpler pseudo 1st or 2nd order models. Desorption rates in the TORBED in this study were 1 order of magnitude faster than fluidised beds, and 2–3 orders of magnitude faster than packed beds.

Biosorption of thorium onto Chlorella Vulgaris microalgae in aqueous media

Thorium biosorption by a green microalga, Chlorella Vulgaris, was studied in a stirred batch reactor to investigate the effect of initial solution pH, metal ion concentration, biomass dosage, contact time, kinetics, equilibrium and thermodynamics of uptake. The green microalgae showed the highest Th adsorption capacity at 45 °C for the solution with a thorium concentration of 350 mg L−1 and initial pH of 4. The amount of uptake raised from 84 to 104 mg g−1 as the temperature increased from 15 to 45 °C for an initial metal concentration of 75 mg L−1 at pH 4. Transformation Infrared Spectroscopy (FTIR) was employed to characterize the vibrational frequency changes for peaks related to surface functional groups. Also, the scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDX) were used to determine the morphological changes and elemental analysis of the biosorbent before and after the sorption process. The Langmuir isotherm was in perfect agreement with the equilibrium empirical data of thorium biosorption and the highest sorption capacity of the Chlorella Vulgaris microalgae was determined as 185.19 mg g−1. Also, the results of kinetic studies show that the thorium biosorption process follows a pseudo-second-order kinetic model. The negative value of ΔG0 indicates spontaneity and the positive values of ΔH0 indicate the endothermic nature of the adsorption process.

Atomistic analysis of the mechanisms underlying irradiation-hardening in Fe–Ni–Cr alloys

This work presents a comprehensive examination of the physical mechanisms driving hardening in irradiated face-centered cubic FeNiCr alloys. The evolution of irradiation-induced defects during shear deformation is modeled by atomistic simulations through overlapping cascade simulations, where the nucleation and evolution of dislocation loops is validated by transmission electron microscopy images obtained from irradiated FeNiCr alloys using tandem accelerator. The effect of different shear rates on the microstructure of irradiated materials with a specific focus on the changes in the density of voids and dislocation loops induced by irradiation was analyzed. Additionally, the fundamental interaction processes between single irradiation-induced defects contributing to irradiation hardening, such as voids and dislocation loops in the alloy are explained. The analysis at atomic level indicates that both the dislocation loops and the voids exhibit strengthening effects. Furthermore, the nanometric voids are much stronger obstacles than dislocation loops of comparable size. The mechanism of cutting the voids leads to an increase of voids density and thus contributes to an increase in irradiation hardening. The mechanism of collapse of small voids into dislocation loops leads to decrease of voids density and at the same time increase of loops density. The coupling effect between the density of voids and dislocation loops is determined. Finally, the novel, physical mechanisms-based model of irradiation hardening and dislocation-radiation defect reaction kinetics are developed, which consider the mechanisms of void cutting, void shrink and void collapse to dislocation loop.

Kinetics study on inhibiting battery thermal runaway using an inorganic phase change material with a super high thermochemical storage capacity

Lithium-ion batteries are susceptible to fires and explosions due to thermal runaway, a serious safety hazard. This study explores the potential of using hydrated inorganic salt (TCM40) composite phase change materials to prevent thermal runaway in battery packs. TCM40 composites stand out due to their exceptional thermochemical heat storage capacity, which allows them to effectively absorb excess heat during runaway events. The research investigates how thermal conductivity, thermal storage capacity, and cell spacing influence the propagation of thermal runaway. The findings demonstrate that TCM40 composites, with a thermal storage density exceeding 1000 kJ/kg, are significantly more effective in preventing thermal runaway compared to traditional latent heat storage phase change materials with lower capacities. To gain a comprehensive understanding of thermal runaway mitigation, a combined thermal management model was developed. This model integrates a battery thermal runaway model with a kinetic model describing the decomposition of TCM40 composites. The analysis reveals that the high heat absorption capability of TCM40 composites minimizes heat transfer to neighboring cells during thermal runaway. Furthermore, the model provides valuable insights into the synergistic effects of thermal conductivity and heat storage capacity on runaway propagation. This knowledge can be directly applied to design safer battery packs, even for compact configurations where cell spacing is less than 2 mm. This study offers significant advancements in both thermal protection materials and design strategies for lithium-ion battery packs. These advancements have the potential to significantly improve battery system safety and minimize the risk of explosions.

Metabolic Adaptation in Epilepsy: From Acute Response to Chronic Impairment.

Epilepsy is characterized by hypersynchronous neuronal discharges, which are associated with an increased cerebral metabolic rate of oxygen and ATP demand. Uncontrolled seizure activity (status epilepticus) results in mitochondrial exhaustion and ATP depletion, which potentially generate energy mismatch and neuronal loss. Many cells can adapt to increased energy demand by increasing metabolic capacities. However, acute metabolic adaptation during epileptic activity and its relationship to chronic epilepsy remains poorly understood. We elicited seizure-like events (SLEs) in an in vitro model of status epilepticus for eight hours. Electrophysiological recording and tissue oxygen partial pressure recordings were performed. After eight hours of ongoing SLEs, we used proteomics-based kinetic modeling to evaluate changes in metabolic capacities. We compared our findings regarding acute metabolic adaptation to published proteomic and transcriptomic data from chronic epilepsy patients. Epileptic tissue acutely responded to uninterrupted SLEs by upregulating ATP production capacity. This was achieved by a coordinated increase in the abundance of proteins from the respiratory chain and oxidative phosphorylation system. In contrast, chronic epileptic tissue shows a 25-40% decrease in ATP production capacity. In summary, our study reveals that epilepsy leads to dynamic metabolic changes. Acute epileptic activity boosts ATP production, while chronic epilepsy reduces it significantly.

Kinetic Modeling of In Vivo K+ Distribution and Fluxes with Stable K+ Isotopes: Effects of Dietary K+ Restriction.

Maintaining extracellular potassium (K+) within narrow limits, critical for membrane potential and excitability, is accomplished through the internal redistribution of K+ between extracellular fluid (ECF) and intracellular fluid (ICF) in concert with the regulation of renal K+ output to balance K+ intake. Here we present evidence from high-precision analyses of stable K+ isotopes in rats maintained on a control diet that the tissues and organs involved in the internal redistribution of K+ differ in their speed of K+ exchange with ECF and can be grouped into those that exchange K+ with ECF either rapidly or more slowly ("fast" and "slow" pools). After 10 days of K+ restriction, a compartmental analysis indicates that the sizes of the ICF K+ pools decreased but that this decrease in ICF K+ pools was not homogeneous, rather occurring only in the slow pool (15% decrease, p < 0.01), representing skeletal muscles, not in the fast pool. Furthermore, we find that the dietary K+ restriction is associated with a decline in the rate constants for K+ effluxes from both the "fast" and "slow" ICF pools (p < 0.05 for both). These results suggest that changes in unidentified transport pathways responsible for K+ efflux from ICF to ECF play an important role in buffering the internal redistribution of K+ between ICF and ECF during K+ restriction. Thus, the present study introduces novel stable isotope approaches to separately characterize heterogenous ICF K+ pools in vivo and assess K+ uptake by individual tissues, methods that provide key new tools to elucidate K+ homeostatic mechanisms in vivo.

Method for evaluating healing state of self-healing ceramics using acoustic emission

Previous studies have evaluated the volume expansion rate of oxidation products and healing temperature and time. However, the bonding strength between the product and the matrix is yet to be appropriately evaluated. To develop a self-healing agent selection method for ceramics, this study proposed a method for examining the healing state and fracture behavior of self-healing ceramics through acoustic emissions (AE) generated during three-point bending tests. This study fabricated completely and incompletely healed SiC30 vol%/Al2O3 composite specimens by adjusting the healing time, and the crack length was assessed employing linear fracture mechanics, and effect of healing state on cumulative AE energy and AE frequency. The crack lengths were compared with those of the kinetic model of crack healing. The crack lengths of the 5-h healed specimens were estimated by linear fracture mechanics to be 12.5 μm for incomplete and 10.4 μm for complete healing, while that estimated by the kinetic model were 13.5 μm, indicating the usefulness of the kinetic model in the initial stages of crack healing. Furthermore, while the AE frequency at the initial stage of fracture was dominated by peaks below 100 kHz in damaged or incompletely healed specimen, there was a relatively high frequency peak of over 200 kHz in smooth and completely healed specimen, The average cumulative AE energies of smooth, damaged, 5 h-healed (incompletely), 5 h-healed (completely), and 24 h-healed specimens were 395, 0.89, 26.8, 189, and 318 V・μs, respectively. Thus, the AE energy that accumulated until rupture tended to increase as healing progressed, these findings suggest that the AE method can be used to determine healing conditions. These results will help establish a method for selecting self-healing agents according to the environment in which they are used.

Reforming of methane over two-dimensional Mo2C-Ni/γ-Al2O3 catalyst

The impact of two-dimensional Mo2C (2D-Mo2C) on the activity and stability of a Ni/γ-Al2O3 catalyst for the dry reforming of methane (DRM) is reported. 1.1 wt% 2D-Mo2C added to 13 wt% Ni/γ-Al2O3 increased activity by ∼40 %. Characterization results showed an interaction between 2D-Mo2C and Ni that resulted in the formation of a NixMoy bulk phase (XRD) and Ni-Mo-oxycarbide surface species (XPS). The presence of 2D-Mo2C also improved the stability of the catalyst compared to Ni/γ-Al2O3 by reducing coke deposition. H2 space-time-yields (STYs) were independent of CO2 partial pressure and were lower than the CO STYs. Power law kinetic models were consistent with a DRM reaction pathway via CH4 decomposition (MD) and the reverse Boudouard (RBD) reactions.

Chrysophanol‐Loaded Composites with Xanthan Gum/Polycaprolactone for Drug Release Enhancement

AbstractThis work focused on synthesizing novel chrysophanol‐loaded composites with varied ratios of polycaprolactone/xanthan gum to enhance the release of chrysophanol. The characteristics of the obtained composites were analyzed by infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, differential scanning calorimetry, rhermogravimetric analysis and dynamic light scattering methods. The xanthan gum/polycaprolactone/chrysophanol (XPC) composites were obtained in the powdery form with particle sizes ranging from 80–100 nm. The results of hydrophilic and hydrophobic tests of the composites were discussed. Chrysophanol, polycaprolactone and xanthan gum can interact and are compatible to each other. XPC composites exhibit high stability and don't cause the negative effect on cells. Additionally, the chrysophanol release and kinetic model of chrysophanol release from the XPC composites in different pH buffer solutions were investigated and evaluated. Using drug carriers such as xanthan gum and polycaprolactone can enhance the release of chrysophanol in both pH 2.0 and pH 7.4 buffer solutions. In the presence of biopolymers, the distribution ability of chrysophanol in aqueous solutions such as pH 2.0 buffer, pH 7.4 buffer solutions, and 0.9 % NaCl solution was enhanced significantly. This will be favorable for an increase in the absorption of chrysophanol in the human body.

Study of peak Laminar Burning Velocity of several syngas compositions at different temperatures

In the context of the current energy transition, the use of biomass-derived syngas (BDS) is often recognized as a fundamental path towards decreasing fossil fuel dependency and greenhouse gas emissions. However, hydrogen-containing BDS are prone to flame instability problems. More efforts are being carried out aiming at efficiently adopting BDS in industrial combustors with CH4 co-firing or inert gas dilutions by exploring accurate knowledge of burning velocity. To do so, a deeper knowledge of the syngas combustion behaviour is strictly necessary. The objective of this study fits in this framework: in particular, a computational study has been carried out to evaluate kinetic models and present fresh insights on the effects of varying syngas mixtures such as CO/H2, CO/H2/CO2 and CO/H2/CH4 on Laminar Burning Velocity (LBV) and peak LBV location (ΦLBV=max). In-detail chemical kinetic simulations of equimolar (CO: H2 = 1:1) forestry waste syngas were systematically carried out taking advantage of the open-source CANTERA solver. Three detailed kinetic models i.e., newly released FFCM-2, USC mech II, and modified GRI mech III were implemented to report accurate flame parameters at 1 bar and different temperature levels (from 300 K up to 450 K). On comparing the results with experiments, FFCM-2 proved to be a good kinetic model for the considered syngas mixtures CO/H2, CO/H2/CO2 and especially for CO/H2/CH4 for mixtures containing a limited share of 30 % methane at normal and moderately elevated temperature at 0.4 ≤ Φ ≤ 2.1. The USC mech II performed very well for CO/H2, and CO/H2/CO2, while the modified GRI mech III model also gave agreeable predictions for CO/H2/CH4 mixture having rich methane content. Additionally, when varying syngas composition analysis was conducted at different temperatures, the progressive CO2 dilution and CH4 addition of up to 30 % reduced the peak LBV and moved the peak LBV locations (ΦLBV=max) towards lean ER conditions with 9 % and 40 % reductions, respectively; however, only the latter effect was enhanced at the elevated initial temperature. Furthermore, sensitivity analysis of respective syngas mixtures is reported at normal and elevated temperatures to explore the most sensitive intermediate reactions relative to LBV. The shift of peak LBV locations and their enhancement at elevated temperatures also open the research path to study the underlying impacts on the flame modes/regimes and structure, especially CO emissions pathways in syngas with 30 % of CH4 and CO2 additions.

Kinetic insights into double-branched acyclic ether: Methyl tert-butyl ether and 2,2-dimethoxypropane

This study presents the first kinetic mechanism for methyl tert-butyl ether (MTBE) containing low-temperature chemistry, as well as the first mechanism for 2,2-dimethoxypropane (DMP). The mechanisms have been validated against ignition delay time experiments conducted in a high-pressure shock tube and rapid compression machine. The rapid compression machine conditions were set to 20 and 40 bar for MTBE, and 10 and 20 bar for DMP in a temperature range of 584 to 946 K. Shock tube experiments have been performed for DMP at 20 and 40 bar for stoichiometric and fuel-lean conditions in air at temperatures ranging from 913 to 1173 K. A pronounced negative temperature coefficient regime with two-stage ignition has been observed for both fuels. The developed mechanism consists of reaction rate constants that were primarily modeled in analogy to iso-octane and dimethoxymethane, and calculated thermodata on the G4//B3LYP-D3BJ/def2-TZVP level of theory. Simulations have been performed to analyze the fuel oxidation at different temperatures. Over the full temperature range, H-atom abstraction occurs mainly on the α-side for DMP and on the β-side for MTBE. At low temperatures, both fuels isomerize to the peroxy radical. The dominant MTBE radicals then tend to produce cyclic ether, while the DMP radicals react with O2, enabling significant chain branching and explaining the higher reactivity of DMP. With rising temperature, β-scission of the fuel radicals and unimolecular elimination reactions start to dominate the oxidation process.Novelty and Significance StatementThe novelty of this research is the first observation of a two-stage ignition of methyl-tert butyl ether (MTBE) in an RCM and a discussion of its fundamental ignition chemistry, which is based on a developed detailed kinetic mechanism. In addition, 2,2-dimethoxypropane (DMP) has been investigated experimentally and theoretically to explain the difference in reactivity to MTBE despite their strong molecular similarity. The experiments include RCM and shock tube experiments. The kinetic model is based on rate constant analogies and newly calculated thermo data on the G4//B3LYP-D3BJ/def2-TZVP level of theory. This work is significant, as MTBE is still a widely used octane booster and the developed model could help to improve engine simulations. Furthermore, the findings of DMP provide insights into future fuel design.

Synthesis of Some Eco-Friendly Materials for Gold Recovery.

The aim of this study was to develop new materials with adsorbent properties that can be used for the adsorption recovery of Au(III) from aqueous solutions. To achieve this result, it is necessary to obtain inexpensive adsorbent materials in a granular form. Concomitantly, these materials must have a high adsorption capacity and selectivity. Other desired properties of these materials include a higher physical resistance, insolubility in water, and materials that can be regenerated or reused. Among the methods applied for the separation, purification, and preconcentration of platinum-group metal ions, adsorption is recognised as one of the most promising methods because of its simplicity, high efficiency, and wide availability. The studies were carried out using three supports: cellulose (CE), chitosan (Chi), and diatomea earth (Diat). These supports were functionalised by impregnation with extractants, using the ultrasound method. The extractants are environmentally friendly and relatively cheap amino acids, which contain in their structure pendant groups with nitrogen and sulphur heteroatoms (aspartic acid-Asp, l-glutamic acid-Glu, valine-Val, DL-cysteine-Cys, or serine-Ser). After preliminary testing from 75 synthesised materials, CE-Cys was chosen for the further recovery of Au(III) ions from aqueous solutions. To highlight the morphology and the functionalisation of the material, we physicochemically characterised the obtained material. Therefore, the analysis of the specific surface and porosity showed that the CE-Cys material has a specific surface of 4.6 m2/g, with a porosity of about 3 nm. The FT-IR analysis showed the presence, at a wavelength of 3340 cm-1, of the specific NH bond vibration for cysteine. At the same time, pHpZc was determined to be 2.8. The kinetic, thermodynamic, and equilibrium studies showed that the pseudo-second-order kinetic model best describes the adsorption process of Au(III) ions on the CE-Cys material. A maximum adsorption capacity of 12.18 mg per gram of the adsorbent material was achieved. It was established that the CE-Cys material can be reused five times with a good recovery degree.

Use of Modified Gompertz Kinetic Modelling to Predict Biogas Production from Co-Digestion of Two Substrates and Other Treatments

This research was conducted with the aim of using Gompertz kinetic model to predict biogas production. The substrates used are the co-digestion of pig and poultry dungs. Batch culture of anaerobic digestion was used while MgSO4, Bovine blood, Charcoal water and water of pH 8 were used as various treatments. Three batches of digestions were done. From the results and statistical kinetic modelling, magnesium sulphate which serve as source of water hardness proved to enhance biogas production. This is because it serves as both salt and catalyst. Bovine blood also showed the same effect. For the charcoal water, it enhanced methane production by the increase of carbon level in C:N ratio. The research recommends as follows. That the quantity of the substrates should be enough to ensure more gas yield. The volume of blood should not be more than the water used in the slurry formation as this could affect proper mixing. The carbon content of the lignocellulose should be increased using charcoal water in slurry preparation to ensure formation of Methane (CH4) which is the main biogas. And finally that measured amount of bovine blood, Magnesium Sulphate and Charcoal can be used as additive in biogas production.

Nanostructured layered double hydroxide (NLDH) - Zn/Al-based materials: strategy to improve performance for zirconium sorption from acidic sulfate solution.

Zirconium is a highly stable radionuclide commonly used in various nuclear operations. However, removing zirconium from wastewater streams is crucial to protect the environment and human health. To achieve this, a zinc and aluminum nanostructured layered double hydroxide (Zn/Al-NLDH) was prepared and investigated for effective removal of zirconium from aqueous solutions. This study examined the prepared Zn/Al-NLDH's structural and textural properties and the impact of various factors on its adsorption performance. The Langmuir isotherm and Pseudo-second order kinetic models were found to be the best fit for the adsorption process of Zr(vi). This suggests that the adsorption process is uniform, involves the formation of a monolayer, and is chemisorption in nature. The maximum uptake capacity was 117.6 mg g-1, and the process was endothermic, spontaneous, and feasible. About 96% of Zr(vi) was successfully desorbed from the loaded sorbent using 1.0 M hydrochloric acid, and the Zn/Al-NLDH sorbent remained stable for six consecutive sorption/desorption cycles. These findings emphasize the high potential of Zn/Al-NLDH to act as a remarkable sorbent for efficiently tackling water contaminants.