Comparative Kinetic Study Research Articles

Petroleum-Contaminated Soil Isolates: A Comparative Study of Naphthalene Biodegradation Kinetics and Metabolic Pathways

Petroleum-Contaminated Soil Isolates: A Comparative Study of Naphthalene Biodegradation Kinetics and Metabolic Pathways

Exploring enzyme inhibition and comprehensive mechanisms of antioxidant/prooxidative activity of natural furanocoumarin derivatives: A comparative kinetic DFT study

This study aimed to explore the antioxidant and prooxidative activity of two natural furanocoumarin derivatives, Bergaptol (4-Hydroxy-7H-furo [3,2-g] [1]benzopyran-7-one, BER) and Xanthotoxol (9-Hydroxy-7H-furo [3,2-g] [1]benzopyran-7-one, XAN). The collected thermodynamic and kinetic data demonstrate that both compounds possess substantial antiradical activity against HO• and CCl3OO• radicals in physiological conditions. BER exhibited better antiradical activity in comparison to XAN, which can be attributed to the enhanced deprotonation caused by the positioning of the –OH group on the psoralen ring. In contrast to highly reactive radical species, newly formed radical species BER• and XAN• exhibited negligible reactivity towards the chosen constitutive elements of macromolecules (fatty acids, amino acids, nucleobases). Furthermore, in the presence of O2•─, the ability to regenerate newly formed radicals BER• and XAN• was observed. Conversely, in physiological conditions in the presence of Cu(II) ions, both compounds exhibit prooxidative activity. Nevertheless, the prooxidative activity of both compounds is less prominent than their antioxidant activity. Furthermore, it has been demonstrated that anionic species can engage in the creation of a chelate complex, which restricts the reduction of metal ions when reducing agents are present (O2•─ and Asc─). Moreover, studies have demonstrated that these chelating complexes can be coupled with other radical species, hence enhancing their ability to inactivate radicals. Both compounds exhibited substantial inhibitory effects against enzymes involved in the direct or indirect generation of ROS: Xanthine Oxidase (XOD), Lipoxygenase (LOX), Myeloperoxidase (MPO), NADPH oxidase (NOX).

A Comparative Kinetic Study of Uncatalyzed and Ce(IV) Catalyzed Cetrizine Dihydrochloride Oxidation in Aqueous Acid Medium by Chloramine-T

A kinetic study of uncatalyzed and Ce(IV) catalyzed cetrizine dihydrochloride oxidation was carried out in aqueous acid medium using chloramine-T. Both uncatalyzed and catalyzed reactions follows first order kinetics with respect to [CAT] and fractional order kinetics with respect to [substrate]. The reaction follows first order dependence on [CeIV] catalyst. The uncatalyzed reaction shows inverse fractional order for [H+] and [Cl–] whereas catalyzed reaction follows fractional order. The effect of ionic strength is negligible in both cases. The dielectric constant has negative effect on uncatalyzed reaction and positive effect on catalyzed reaction. To compute the thermodynamic parameters the kinetic runs were studied at different temperatures (293-313 K). The stoichiometry of the reaction was studied and the products of oxidation were analyzed. The rate law was also derived by the proposed mechanism.

Recovery of Omega-3-Rich Lipids: Toward the Sustainable Valorization of Sea-Bass Industry Side Streams

This study pertains to the selection of the appropriate process parameters of lipid extraction aimed at the valorization of sea-bass gutting and filleting side stream biomass. A comparative kinetic study between an environmentally friendly polar (ethanol) and a conventional non-polar solvent (hexane) was implemented to determine the effect of temperature, solvent to solid ratio and time, providing insights in terms of the yield recovery and quality of omega-3 fatty acids. Maximum recovery yield (43.8 and 34.0 g/100 g of dried gutting and filleting by-products, respectively) was achieved within 10 min. In gutting by-products, ethanol achieved full lipid recovery at 35 °C and a 50:1 ratio, while for hexane, the maximum yield was 83%. In the case of filleting side-streams, hexane achieved exhaustive recovery at a 50:1 ratio and 20 °C compared with ethanol, where a higher temperature (50 °C) was needed for exhaustive recovery to be achieved. Differences were attributed to the diverse fatty acid profiles among the two by-products, with 27.3% and 40.8% polyunsaturated fatty acids in viscera and fish frames, respectively. All extracts at 20 °C and 35 °C remained below the oxidation limit set by the Codex Alimentarius Commission (peroxide value < 5 meqO2/kgoil; p-anisidine value < 20). Therefore, green solvents could assist conventional extraction, combining high efficiency and an improved environmental impact.

A comparative study of macrosegregation evolution kinetics for undercooled Cu60Fe40 immiscible alloy during slow cooling and rapid cooling processes

A comparative study of macrosegregation evolution kinetics for undercooled Cu60Fe40 immiscible alloy during slow cooling and rapid cooling processes

Optimizing alkaline and enzymatic extraction of black bean proteins: a comparative study of kinetics, functionality, and nutritional properties

This work explores the aqueous and enzyme-assisted extraction of black bean proteins with a focus on extraction yields, kinetics, protein functionality, and in vitro protein digestibility.

Competency of sonolysis on PTC induced polymerization of EMA – A comparative kinetic study

Competency of sonolysis on PTC induced polymerization of EMA – A comparative kinetic study

Comparative kinetic study of formic acid decomposition for hydrogen production in supercritical water and gas phase: Effect of water catalysis

Formic acid is attracting increasing attention due to is important role for hydrogen production in different practical scenarios. This work presents a comparative kinetic study of formic acid decomposition in supercritical water (SCW) and gas phase. At first, the decomposition of formic acid in SCW was investigated at a pressure of 25.0 MPa, temperatures of 773–848 K and residence times of 2.1–8.5 s in an isothermal flow reactor. Hydrogen and carbon dioxide were found to be the major gaseous products, indicating that decarboxylation was the predominant reaction pathway. A detailed kinetic model was developed with consideration of water catalysis and was used to interpret the present data as well as data from literature. For gas-phase conditions, the kinetics of formic acid decomposition were well characterized by analyzing different types of experimental data in literature. The Machado model was proved to provide satisfactory description of the kinetic behavior of formic acid decomposition. Based on the developed models, a comparative kinetic analysis was further conducted to explore the differences of characteristics of formic acid decomposition under the two conditions. Water catalysis effectively reduced the onset temperature and facilitated the reaction rate for formic acid decomposition in SCW. Finally, the catalytic mechanism of water was elucidated in detail.

Comparative Study of Adsorption, Kinetics, and Thermodynamics of Selected Cationic and Anionic Surfactants on Ultrasound-Assisted Bagasse

Comparative Study of Adsorption, Kinetics, and Thermodynamics of Selected Cationic and Anionic Surfactants on Ultrasound-Assisted Bagasse

Synthesis of Mono- and Dinuclear Aluminum Complexes Bearing Aromatic Amino-Phenolato Ligands: A Comparative Study in the Ring-Opening Polymerization of Cyclohexene Oxide.

Dinuclear aluminum methyl complexes bearing aromatic diamine-bridged tetra(phenolato) ligands and the mononuclear aluminum methyl complex with the phenylamine-bridged bis(phenolato) ligand have been synthesized and characterized. Structure determination revealed that the Al-Al distances in these dinuclear aluminum complexes are tunable by the choice of the suitable aromatic backbone of the diamine-bridged tetra(phenolato) ligands. The catalytic behaviors of these mono- and dinuclear aluminum complexes for cyclohexene oxide (CHO) polymerization were investigated. The activities of these dinuclear Al complexes were observed to increase with the decrease of Al-Al distances, and the dinuclear Al complexes appeared to have better catalytic activity than the mononuclear Al complex, even if the Al-Al distance is as long as 9.401 Å. Dinuclear aluminum complex 2, with the shortest Al-Al distance (7.236 Å), showed the highest activity toward CHO polymerization with TOFs up to 6460 h-1 in neat CHO at 30 °C. Furthermore, comparative kinetic studies revealed that the polymerization is first-order for CHO concentration, and the reaction orders for initiator concentration are different for the mono- and dinuclear Al complexes. The polymerization mechanism study revealed that both the methyl and phenolate groups were involved in the initiation process.

Comparative Kinetic Study of the Adsorption Capacity of Walnut Shell and Its Biochar for Chromium Removal from Wastewater

Chromium is a toxic heavy metal that can pollute water from industrial and agricultural activities. Adsorption is a promising method for removing chromium from wastewater, and walnut shell is a sustainable and abundant biomass that can be used to produce biochar for adsorption. This study compares the effectiveness of walnut shell and walnut shell biochar for chromium removal from wastewater using adsorption. The effects of various parameters on chromium adsorption, such as pH, biochar dosage, and contact time, are investigated. The results show that both walnut shell and walnut shell biochar are effective adsorbents for chromium removal. However, walnut shell biochar exhibits a higher adsorption capacity and faster adsorption kinetics than walnut shell. The findings of this study suggest that walnut shell biochar is a promising adsorbent for chromium removal from wastewater. It is a sustainable and low-cost material that can be used to develop effective and efficient wastewater treatment systems. The kinetics of Cr adsorption will examine using pseudo-first-order, pseudo-second-order, and adsorption isotherms. The results demonstrated that the adsorption of Cr onto WS and BC followed pseudo-second-order kinetics, suggesting chemisorption as the rate-limiting step.

Comparative kinetics study of different iron-containing pellets with hydrogen at isothermal conditions

Using hydrogen to produce iron is a promising way for the steel industry to achieve the goal of carbon neutrality. The reducibility of iron-bearing oxides by hydrogen significantly impacts the productivity and energy consumption during the reduction process. This study investigated the competitive kinetics of hydrogen reduction for different iron bearing pellets including iron ore pellets, bauxite residue pellets, and calcium-added bauxite residue sintered and self-hardened pellets at isothermal condition. Various characterization tools, such as X-ray diffraction, electron probe analysis, and X-ray fluorescence, were used to examine the properties of the pellets. These pellets exhibit different porosity, iron bearing oxides and overall composition. The time required to achieve 50 % reduction(R50) at 1000 °C approximately 2 min for bauxite residue and bauxite residue-CaO sintered and self-hardened pellets, while iron ore pellets required approximately 6 min. Moreover, at 700 °C, the R50 value is reduced for sintered bauxite residue CaO pellets as compared to other owing to the diminished reducibility of brownmillerite (Ca2(Alx,Fe(2-x))O5) in contrast to hematite found in the other pellets. It was highlighted that factors such as porosity of the unreduced pellets, types of iron bearing oxides and grainsize significantly influences the reducibility of different pellets. Furthermore, during the reduction process, all pellets were observed with a rapid initial stage, a subsequent transition stage, and a final slow reduction stage.

Comparative study of the densification kinetics of the FCC phase Al0.3CoCrFeNi and BCC phase AlCoCrFeNi high-entropy alloys during spark plasma sintering

The densification kinetics of the FCC-matrix Al0.3CoCrFeNi and BCC-matrix AlCoCrFeNi HEAs at sintering temperatures ranging from 950 ℃ to 1050 ℃ are comparatively studied utilizing the steady-state creep model. The densification activation energy of the Al0.3CoCrFeNi and AlCoCrFeNi powder in their low-stress exponent stage is linearly fitted to be 264.91 and 220.99 kJ/mol, respectively. The densification mechanism of both the two HEAs in the low-stress exponent stage is proved to be atomic diffusion. However, the densification activation of the Al0.3CoCrFeNi in the high-stress exponent stage increases to 554.77 kJ/mol and the densification mechanism changes to creep. The densification activation energy of the AlCoCrFeNi in its high-stress exponent stage cannot be obtained by linear fitting because of the abnormal increase of the stress exponent at the sintering temperature of 1050 ℃. The BCC-FCC transformation in the AlCoCrFeNi reduces its creep resistance because of different deformation behavior in BCC (dislocation cell) and FCC phase (cross-glide and twinning). As a result, dislocation density is higher in the FCC phase (4.3 ×1013/m2) compared with the BCC phase (3.8 ×1013/m2), which benefits the densification in the creep-controlled high-stress exponent stage. Furthermore, the stronger electromigration effect induced by a higher heating rate is demonstrated to further reduce the densification activation energy from 124.20 to 72.53 kJ/mol and accelerate densification in the diffusion-controlled heating period.

Is It Possible to Obtain a Product of the Desired Configuration from a Single Knoevenagel Condensation? Isomerization vs. Stereodefined Synthesis.

The biological activity of compounds directly depends on the three-dimensional arrangement of affinity fragments since a high degree of pharmacophore compliance with the binding site is required. 3-Benzylidene oxindoles are privileged structures due to their wide spectrum of biological activity, synthetic availability, and ease of modification. In particular, both kinase inhibitors and kinase activators can be found among 3-benzylidene oxindoles. In this work, we studied model compounds obtained via oxindole condensation with aldehydes and alkylphenones. These condensation products can exist in the form of E- and Z-isomers and also undergo isomerization in solutions. The factors causing isomeric transformation of these compounds were established. Comparative kinetic studies to obtain quantitative characteristics of UV-driven isomerization were first performed. The results obtained indicate dramatic differences in two subclasses, which should be considered when developing biologically active molecules.

A comparative catalytic kinetics study for exploring dye degradation potential of silver, gold and palladium nanoparticles

A comparative catalytic kinetics study for exploring dye degradation potential of silver, gold and palladium nanoparticles

Enhancing Photocatalytic Efficiency of Spent Tea Leaf Powder on ZnIn2S4 Incorporation: Role of Surface Charge on Dye Degradation.

Photocatalytic degradation of dye contaminants using nanocomposite adsorbents has emerged as a promising solution for wastewater treatment. Owing to its abundant availability, eco-friendly composition, biocompatibility, and strong adsorption activity, spent tea leaf (STL) powder has been extensively explored as a viable dye-adsorbent material. In this work, we report spectacular enhancement in the dye-degradation properties of STL powder on incorporation of ZnIn2S4 (ZIS). The STL/ZIS composite was synthesized using a novel, benign, and scalable aqueous chemical solution method. Comparative degradation and reaction kinetics studies were performed onto an anionic dye, Congo red (CR), and two cationic dyes, Methylene blue (MB) and Crystal violet (CV). The degradation efficiencies of CR, MB, and CV dyes were obtained to be 77.18, 91.29, and 85.36%, respectively, using the STL/ZIS (30%) composite sample after the 120 min experiment. The spectacular improvement in the degradation efficiency of the composite was attributed to its slower charge transfer resistance (as concluded by the EIS study) and optimized surface charge (as concluded by ζ potential study). Scavenger tests and reusability tests deciphered the active species (•O2-) and reusability of the composite samples, respectively. To the best of our knowledge, this is the first report to demonstrate improvement in the degradation efficiency of STL powder on ZIS incorporation.

Comparative kinetics studies of ribose and galactose as eco-friendly reductants for leuco dye formation

Comparative kinetics studies of ribose and galactose as eco-friendly reductants for leuco dye formation

Comparative kinetics studies of ribose and galactose as eco-friendly reductants for leuco dye formation

Comparative kinetics studies of ribose and galactose as eco-friendly reductants for leuco dye formation

An exclusive kinetics of long chain fatty alcohol oxidation administered by CMC in anionic micellar media and in their binary mixture

This work thrives an organic oxidative transformation of long chain fatty alcohol, decanol, by hexavalent chromium in anionic micellar assisted aqueous medium at 25 °C. The spectrophotometrically studied kinetics of the oxidation has been recorded in a comparative mode in single and mixed micellar media of anionic surfactants (SDSʹ and SDS) of varying chain length. Moreover, another unprecedented comparative kinetic study of promoted (Phen and Bpy promoters) and unpromoted reactions has been shown in both the micellar system. A direct connection of reaction rate with CMC of the surfactants has been shown here. Some necessary spectral analyses (IR and 1H NMR) have been carried out to elucidate the product formation.

Comparative Kinetic and Pyrolytic Studies of d-Glucose Using Formulated Red Mud, Sand, and HZSM-5

The catalytic pyrolysis of d-glucose (DG) was conducted using a thermogravimetric analyzer (TGA) and formulated red mud (FRM) as the catalyst to determine the kinetic parameters of DG decomposition in the presence of the catalyst. The FRM reduced the overall activation energy (45.58–87.35 KJ/mol) of DG conversion compared to sand (45.27–112.00 KJ/mol). The trend of the frequency factor (A) for the catalytic pyrolysis (first-order reaction: 78.1–1.14 × 108 s–1) and non-catalytic pyrolysis (first-order reaction: 7.10–2.08 × 107 s–1) of DG was different, which indicated different reaction mechanisms. Compared to the sand and HZSM-5 catalyst, the FRM altered the thermal decomposition profile of the DG and promoted its decomposition at lower reaction temperatures. The thermogravimetric analyses showed that at 260 °C, the FRM catalyst converted more DG (50% conversion) than the HZSM-5 (44% conversion) and sand (35% conversion), which was in agreement with its activation energy. Furthermore, the DG decomposition was studied in a fixed-bed reactor using catalytic and non-catalytic pyrolysis conditions. The FRM promoted the formation of low-molecular-weight compounds (acetic acid and formic acid, CO2, formaldehyde, and CO) and hindered the formation of furans. The HZSM-5 catalyst promoted the formation of furans.