Journal articles: 'Kinetic Thermodynamic parameters'

1

Zhang, Jin-Ye, and Xiao-Qing Zhu. "Comparison between 1,2-Dihydropyridine and 1,4-Dihydropyridine on Hydride-Donating Ability and Activity." Molecules 27, no. 17 (2022): 5382. http://dx.doi.org/10.3390/molecules27175382.

Full text

Abstract:

In this paper, detailed comparisons of the driving force in thermodynamics and intrinsic force in the kinetics of 1,2-dihydropyridine and 1,4-dihydropyridine isomers of PNAH, HEH, and PYH in hydride transfer reactions are made. For 1,2-PNAH and 1,4-PNAH, the values of the thermodynamic driving forces, kinetic intrinsic barriers, and thermo-kinetic parameters are 60.50 and 61.90 kcal/mol, 27.92 and 26.34 kcal/mol, and 44.21 and 44.12 kcal/mol, respectively. For 1,2-HEH and 1,4-HEH, the values of the thermodynamic driving forces, kinetic intrinsic barriers, and thermo-kinetic parameters are 63.40 and 65.00 kcal/mol, 31.68 and 34.96 kcal/mol, and 47.54 and 49.98 kcal/mol, respectively. For 1,2-PYH and 1,4-PYH, the order of thermodynamic driving forces, kinetic intrinsic barriers, and thermo-kinetic parameters are 69.90 and 72.60 kcal/mol, 33.06 and 25.74 kcal/mol, and 51.48 and 49.17 kcal/mol, respectively. It is not difficult to find that thermodynamically favorable structures are not necessarily kinetically favorable. In addition, according to the analysis of thermo-kinetic parameters, 1,4-PNAH, 1,2-HEH, and 1,4-PYH have a strong hydride-donating ability in actual chemical reactions.

APA, Harvard, Vancouver, ISO, and other styles

2

Vogel, Kristina, Thorsten Greinert, Monique Reichard, Christoph Held, Hauke Harms, and Thomas Maskow. "Thermodynamics and Kinetics of Glycolytic Reactions. Part II: Influence of Cytosolic Conditions on Thermodynamic State Variables and Kinetic Parameters." International Journal of Molecular Sciences 21, no. 21 (2020): 7921. http://dx.doi.org/10.3390/ijms21217921.

Full text

Abstract:

For systems biology, it is important to describe the kinetic and thermodynamic properties of enzyme-catalyzed reactions and reaction cascades quantitatively under conditions prevailing in the cytoplasm. While in part I kinetic models based on irreversible thermodynamics were tested, here in part II, the influence of the presumably most important cytosolic factors was investigated using two glycolytic reactions (i.e., the phosphoglucose isomerase reaction (PGI) with a uni-uni-mechanism and the enolase reaction with an uni-bi-mechanism) as examples. Crowding by macromolecules was simulated using polyethylene glycol (PEG) and bovine serum albumin (BSA). The reactions were monitored calorimetrically and the equilibrium concentrations were evaluated using the equation of state ePC-SAFT. The pH and the crowding agents had the greatest influence on the reaction enthalpy change. Two kinetic models based on irreversible thermodynamics (i.e., single parameter flux-force and two-parameter Noor model) were applied to investigate the influence of cytosolic conditions. The flux-force model describes the influence of cytosolic conditions on reaction kinetics best. Concentrations of magnesium ions and crowding agents had the greatest influence, while temperature and pH-value had a medium influence on the kinetic parameters. With this contribution, we show that the interplay of thermodynamic modeling and calorimetric process monitoring allows a fast and reliable quantification of the influence of cytosolic conditions on kinetic and thermodynamic parameters.

APA, Harvard, Vancouver, ISO, and other styles

3

Barghamadi, Mohammad. "Isothermal kinetics and thermodynamics studies of curing reaction of epoxy-aromatic diamine reinforced with epoxy functional MWCNT." High Performance Polymers 29, no. 7 (2016): 827–35. http://dx.doi.org/10.1177/0954008316660367.

Full text

Abstract:

This study reports the cure kinetics and thermodynamics of an epoxy functional multiwall carbon nanotube-containing epoxy nanocomposite obtained by the polymerization of diglycidyl ether of bisphenol A with diaminodiphenyl sulfone as a curing agent through isothermal technique of differential scanning calorimetry. Isothermal kinetic parameters including reaction orders ( m, n), rate constants ( k1, k2), activation energy ( Ea), and pre-exponential factor ( A) were estimated using Kamal autocatalytic model. The model gives a good description of curing kinetics at various temperatures prior to the onset of vitrification. Thermodynamic parameters such as enthalpy (Δ H#), entropy (Δ S#), and Gibbs free energy (Δ G#) changes were also determined using the rate constants from the isothermal kinetic analysis and transition state theory. The thermodynamic functions were shown to be very sensitive parameters for the evaluation of the cure reaction.

APA, Harvard, Vancouver, ISO, and other styles

4

Yablonsky, Gregory S., Denis Constales, and Guy B. Marin. "Single-Route Linear Catalytic Mechanism: A New, Kinetico-Thermodynamic Form of the Complex Reaction Rate." Symmetry 12, no. 10 (2020): 1748. http://dx.doi.org/10.3390/sym12101748.

Full text

Abstract:

For a complex catalytic reaction with a single-route linear mechanism, a new, kinetico-thermodynamic form of the steady-state reaction rate is obtained, and we show how its symmetries in terms of the kinetic and thermodynamic parameters allow better discerning their influence on the result. Its reciprocal is equal to the sum of n terms (n is the number of complex reaction steps), each of which is the product of a kinetic factor multiplied by a thermodynamic factor. The kinetic factor is the reciprocal apparent kinetic coefficient of the i-th step. The thermodynamic factor is a function of the apparent equilibrium constants of the i-th equilibrium subsystem, which includes the (n−1) other steps. This kinetico-thermodynamic form separates the kinetic and thermodynamic factors. The result is extended to the case of a buffer substance. It is promising for distinguishing the influence of kinetic and thermodynamic factors in the complex reaction rate. The developed theory is illustrated by examples taken from heterogeneous catalysis.

APA, Harvard, Vancouver, ISO, and other styles

5

Gandova, Vanya, and Ivalina Petrova. "Black chokeberry (Aronia melanocarpa) copigmentation reaction: Thermodynamic and kinetic investigations." BIO Web of Conferences 122 (2024): 01001. http://dx.doi.org/10.1051/bioconf/202412201001.

Full text

Abstract:

Two type of parameters (thermodynamics and kinetics) were used to determine thermal stability of copigmentation process in black chokeberry: chlorogenic acid system. According to thermodynamic investigations copigmentation complex was destroyed at high temperature and restored again at low temperature. Different parameters kinetic rate constant, energy of activation and z-factor were presented and the reaction Based on them the order of the reaction was determined as first order.

APA, Harvard, Vancouver, ISO, and other styles

6

Saha, Tapan K., Subarna Karmaker, and Md F. Alam. "Kinetics, mechanism and thermodynamics involved in sorption of meso-tetrakis(4-sulfonatophenyl)porphyrin onto chitosan in aqueous medium." Journal of Porphyrins and Phthalocyanines 18, no. 03 (2014): 240–50. http://dx.doi.org/10.1142/s1088424613501174.

Full text

Abstract:

Sorption of meso-tetrakis(4-sulfonatophenyl)porphyrin ( H 2 tpps ) onto chitosan has been investigated in aqueous medium. Kinetic and isotherm studies were carried out by considering the effects of various parameters, such as pH, initial concentration of H 2 tpps solution, and temperature. The kinetic data obtained from different batch experiments were analyzed using pseudo first-, second-order, intraparticle, and film diffusion kinetic models. The equilibrium sorption data was analyzed by using Tempkin, Langmuir and Freundlich models. The best results were achieved with the pseudo second-order kinetic, Langmuir and Freundlich isotherm models. The intraparticle diffusion and film diffusion are the rate limiting steps. The amount of sorbate adsorbed at equilibrium (qe) increased with increasing the initial concentration of H 2 tpps solution, showing maximum sorption capacity of 445.21 μmol.g-1. The activation energy (Ea) of sorption kinetics was found to be 19.47 kJ.mol-1. Thermodynamic parameters such as change in free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) were evaluated by applying the Van't Hoff equation. Thermodynamic activation parameters such as change in enthalpy of activation (ΔH‡), entropy of activation (ΔS‡), and free energy of activation (ΔG‡) were also calculated. The thermodynamics of H 2 tpps sorption onto chitosan in aqueous medium indicates its spontaneous and endothermic nature.

APA, Harvard, Vancouver, ISO, and other styles

7

Van der Ven, A., J. C. Thomas, B. Puchala, and A. R. Natarajan. "First-Principles Statistical Mechanics of Multicomponent Crystals." Annual Review of Materials Research 48, no. 1 (2018): 27–55. http://dx.doi.org/10.1146/annurev-matsci-070317-124443.

Full text

Abstract:

The importance of configurational, vibrational, and electronic excitations in crystalline solids of technological interest makes a rigorous treatment of thermal excitations an essential ingredient in first-principles models of materials behavior. This contribution reviews statistical mechanics approaches that connect a crystal's electronic structure to its thermodynamic and kinetic properties. We start with a description of a thermodynamic and kinetic framework for multicomponent crystals that integrates chemistry and mechanics, as well as nonconserved order parameters that track the degree of chemical order and group/subgroup structural distortions. The framework allows for spatial heterogeneities and naturally couples thermodynamics with kinetics. We next survey statistical mechanics approaches that rely on effective Hamiltonians to treat configurational, vibrational, and electronic degrees of freedom within multicomponent crystals. These Hamiltonians, when suitably constructed, are capable of extrapolating first-principles electronic structure calculations within (kinetic) Monte Carlo simulations, thereby enabling first-principles predictions of equilibrium and nonequilibrium materials properties at finite temperature.

APA, Harvard, Vancouver, ISO, and other styles

8

Chatterjee, Arobindo, and Vinit Kumar Jain. "Isothermal, Kinetic, and Thermodynamic Studies of Graphene Oxide Adsorption on Silk." AATCC Journal of Research 8, no. 5 (2021): 18–29. http://dx.doi.org/10.14504/ajr.8.5.3.

Full text

Abstract:

The properties of graphene enriched silk depend on the amount of graphene oxide (GO) adsorption on silk. GO dipping parameters include the GO solution pH, initial GO concentration, dipping time and temperature, and the type of substrate. The effects of GO dipping parameters on the sorption process are studied to achieve the maximum GO adsorption on the silk surface for the preparation of an economical graphene/silk-based textile product. In addition, equilibrium isotherms, kinetics, and thermodynamics of GO adsorption on the silk surface in a batch sorption process are examined to understand the adsorption mechanism. The Freundlich isotherm best describes the adsorption of GO onto the silk. A pseudo-second order kinetic model best describes the kinetics of GO adsorption. Thermodynamic studies reveal that GO adsorption is spontaneous and exothermic.

APA, Harvard, Vancouver, ISO, and other styles

9

Xu, Huan Yan, Xue Li, Yan Li, Ping Li, and Wei Chao Liu. "Photocatalytic Degradation of Methyl Orange by TiO₂/Schorl Photocatalyst: Kinetics and Thermodynamics." Applied Mechanics and Materials 713-715 (January 2015): 2789–92. http://dx.doi.org/10.4028/www.scientific.net/amm.713-715.2789.

Full text

Abstract:

An active dye, Methyl Orange (MO) was employed as the target pollutant to evaluate the photocatalytic activity of TiO2/schorl composite and the kinetics and thermodynamics of this process was emphasized in this work. Langmuir–Hinshelwood kinetic model was employed for the kinetic studies and the results revealed that the process of MO photocatalytic discoloration by TiO2/schorl composite followed one order reaction kinetic equation under different conditions. The reaction rate constant (k) increased with initial MO concentration decreasing. When the catalyst dosage or solution pH increased,kvalues increased and then decreased. The possible reasons for these phenomena were discussed. Finally, the thermodynamic parameters ΔG, ΔH, ΔSwere obtained by the classical Van't Hoff equation.

APA, Harvard, Vancouver, ISO, and other styles

10

Giménez-López, Bruno, Cristhian Ronceros, Alejandro Quispe, Rosalio Cusi, Manuel Giménez-Medina, and Carmen Cuba. "Mathematical modeling of the onion drying process: Kinetic and Thermodynamic Parameters." Revista de la Facultad de Agronomía, Universidad del Zulia 41, no. 3 (2024): e244127. http://dx.doi.org/10.47280/revfacagron(luz).v41.n3.07.

Full text

Abstract:

The dehydration processes of onions are governed by a series of kinetic and thermodynamic parameters that, when controlled, facilitate the identification of a mathematical model that will improve the efficiency and quality of the drying process in terms of reducing production costs, environmental sustainability, and the development of innovative products. In this study, various mathematical models were validated to accurately describe the drying process, and from them, the kinetic and thermodynamic parameters governing the dehydration processes were determined. For the experimental development, onions grown in the Ica region of Peru were peeled, cut into pieces, and dehydrated (60, 70, and 80 ºC), and five mathematical models were applied to model the drying kinetics of the process. The Midilli model was the best fit for the experimental curves. Increasing the temperature reduced the enthalpy and increased the entropy, Gibbs free energy, and effective diffusion coefficient in both varieties of onions. Determining the drying kinetics has been essential for establishing operating conditions by understanding how temperature, relative humidity, and other parameters affect the moisture removal rate, allowing for the design of optimal equipment and predicting product behavior during the drying process. Keywords: onion dehydration, mathematical models, kinetic parameters, drying efficiency, environmental sustainability.

APA, Harvard, Vancouver, ISO, and other styles

11

BALJEET, KAUR SATSANGI, and KOTHARI SEEMA. "Kinetics and Mechanism of the Oxidation of some Hydroxy Acids by Bis(2,2 '-bipyridyl)copper(II) Permanganate." Journal of Indian Chemical Society Vol. 74, Jan 1997 (1997): 16–20. https://doi.org/10.5281/zenodo.5876440.

Full text

Abstract:

Chemistry Department, Faculty of Science, Suez Canal University, Ismailia, Egypt Manuscript received 10 April 1995, accepted 6 July 1995 The oxidation of glycollic, lactic, mandelic and nine monosubstituted mandelic acids by bis(2,2'-bipyridyl)copper(II) permanganate (BBCP) in aqueous acetic acid solution leads to the formation of the corresponding oxoacids. The reaction is first order with respect to BBCP. Michaelis-Meten type kinetics have been observed with respect to the hydroxy acid. The formation constants for the hydroxy acid-BBCP complexes and the rates of their decomposition have been evaluated. The rates of decomposition of the complexes show an excellent correlation with Hammett's σ values with negative reaction constants. Thermodynamic parameters for complex formation and the activation parameters for their decomposition have also been calculated. The reaction rate increases with an increase in the concentration of hydrogen ion. The decomposition of α deuteriomandelk acid-BBCP complex exhibited the presence of a substantial kinetic isotope effect. With an increase in the amount of acetic add in the solvent mixture of acetic acid and water, the rate increased. Addition of 2,2"-bipyridyl and acrylonitrile has no effect on the rate. Suitable mechanism have been proposed.

APA, Harvard, Vancouver, ISO, and other styles

12

J.A., Puszkiel, Arneodo Larochette P., and Gennari F.C. "Thermodynamic–kinetic characterization of the synthesized Mg2FeH6–MgH2 hydrides mixture." International Journal of Hydrogen Energy 33, no. 13 (2008): 3555–60. https://doi.org/10.1016/j.ijhydene.2007.11.030.

Full text

Abstract:

The increasing relevance of hydrogen economy has generated interest in finding a safe way to transport hydrogen. In order to contribute to a better comprehension of Mg–Fe–H system's behavior, we have examined thermodynamic and kinetic characteristics of a material originally composed of complex hydride Mg2FeH6 (49 wt%), magnesium hydride MgH2 (18 wt%) and unreacted magnesium and iron. Such material was synthesized via mechanical milling of a 2Mg–Fe elemental powder mixture with a subsequent hydriding process at 673 K and 6 MPa for 15 h. Thermodynamics of the Mg2FeH6–MgH2 hydrides mixture was evaluated by pressure–composition isotherm (PCI) measurements in the range of 573–673 K. The van’t Hoff graph was plotted and the thermodynamic parameters, i.e. decomposition enthalpy and entropy, were calculated. The kinetics of the system was also studied to analyze the dependence of hydrogen absorption rate on the temperature and the rate of hydrogen release at a given temperature.

APA, Harvard, Vancouver, ISO, and other styles

13

Huang, Zai-Yin, Xing-Xing Li, Zuo-Jiao Liu, Liang-Ming He, and Xue-Cai Tan. "Morphology Effect on the Kinetic Parameters and Surface Thermodynamic Properties of Ag3PO4Micro-/Nanocrystals." Journal of Nanomaterials 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/743121.

Full text

Abstract:

Considerable effort has been exerted using theoretical calculations to determine solid surface energies. Nanomaterials with high surface energy depending on morphology and size exhibit enhanced reactivity. Thus, investigating the effects of morphology, size, and nanostructure on the surface energies and kinetics of nanomaterials is important. This study determined the surface energies of silver phosphate (Ag3PO4) micro-/nanocrystals and their kinetic parameters when reacting with HNO3by using microcalorimetry. This study also discussed rationally combined thermochemical cycle, transition state theory, basic theory of chemical thermodynamics with thermokinetic principle, morphology dependence of reaction kinetics, and surface thermodynamic properties. Results show that the molar surface enthalpy, molar surface entropy, molar surface Gibbs free energy, and molar surface energy of cubic Ag3PO4micro-/nanocrystals are larger than those of rhombic dodecahedral Ag3PO4micro-/nanocrystals. Compared with rhombic dodecahedral Ag3PO4, cubic Ag3PO4with high surface energy exhibits higher reaction rate and lower activation energy, activation Gibbs free energy, activation enthalpy, and activation entropy. These results indicate that cubic Ag3PO4micro-/nanocrystals can overcome small energy barrier faster than rhombic dodecahedral Ag3PO4micro-/nanocrystals and thus require lower activation energy.

APA, Harvard, Vancouver, ISO, and other styles

14

Huang, Mouxin, Zongbin Jia, Sanzhong Luo, and Jin-Pei Cheng. "Quantitative Thermodynamic and Kinetic Parameters of Radical." Chinese Journal of Organic Chemistry 41, no. 10 (2021): 3892. http://dx.doi.org/10.6023/cjoc202106018.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Moretti de Almeida, Gabriel, Carlos Miguel Nóbrega Mendonça, Attilio Converti, and Ricardo Pinheiro de Souza Oliveira. "Kinetic and thermodynamic parameters of nisin thermoinactivation." Journal of Food Engineering 280 (September 2020): 109986. http://dx.doi.org/10.1016/j.jfoodeng.2020.109986.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Jabar, Tabarek Abdulsajad, and Khalid M. Mousa Al-zobai. "Removal of Reactive Green Dye from Textile Waste Water by Photo Fenton Process: Modeling, Kinetic, and Thermodynamic." Al-Nahrain Journal for Engineering Sciences 24, no. 2 (2021): 104–11. http://dx.doi.org/10.29194/njes.24020104.

Full text

Abstract:

This work investigated the removal of the reactive green (R.G) dye from wastewater using the photo-Fenton process. Batch experiments were carried out to research the role of the Impacts of operating parameters. The dosage of H2O2; dosage Fe+2; pH; temperature, and irradiation time were examined. Maximum decolorization efficiencies green dye were achieved at the [H2O2]=100 ppm; [Fe2+]=20 ppm; pH 3; temperature=56 °C and irradiation time=90 min. This research focuses on modeling, kinetics and thermodynamics of the removal of pollutant (reactive green dye) of water. The results showed that the decolorization kinetic of R.G followed pseudo-first-order reaction kinetic. Also the thermodynamic parameters ∆G˚, ∆H˚ and ∆S˚ were determined using the Van't Hoff equation for the oxidation processes. The changes in Gibbs free energy showed the oxidation process under normal conditions is non-spontaneous.

APA, Harvard, Vancouver, ISO, and other styles

17

N., Sharma, Bose B., Ar·chana, S. Bhatt S., and C. Chaudhry S. "Synthesis and reactivity of monochlorotetraphenoxoniobium(V) complexes." Journal of Indian Chemical Society Vol. 80, Oct 2003 (2003): 875–78. https://doi.org/10.5281/zenodo.5839257.

Full text

Abstract:

Department of Chemistry, Himachal Pradesh University, Summer Hill, Shimla-171 005, India E-mail : ssbhatt2k @yahoo.com Manuscript received 21 November 2002, revised 6 May 2003, accepted 17 June 2003 Complexes of composition [NbCl(OAri,ii)4] (OAi = OC6H4But-4 and OArii = OC6H4OMe-4) have been synthesized by the reaction of NbCI5 with four equivalents of 4-t-butyl and 4-methoxyphenol in CCI4 and characterized. From the non-isothermal TG data, the kinetic and thermodynamic parameters have been calculated by Coats-Redfern method and the mechanism of decomposition has been computed using non-isothermal kinetic method. The reactions of [NbCl(OAri,ii)4] with a variety of ligands containing labile protons (LH) such as acetylacetone (acacH), dihenzoylmethane (dbmH), benzoin (benzH), 2- hydroxyacetophenone (hapH) and salicylaldehyde (salH) have afforded the complexes of the type [Nb(OAri,ii)4L,] while potassium salts of salicylhydroxamic acid (KSHA) and cinnamylhydroxamic acid (KCH)(L') yielded [NbCl(OAr)3.L) authenticated by chemical analyses and physical data.

APA, Harvard, Vancouver, ISO, and other styles

18

Charity, Aghariagbonse Osagiede and George Chidozie Nwagu. "Characterization, Kinetics, and Thermodynamics Analysis of Palm Kernel Oil Extraction." Journal of Energy Technology and Environment 5, no. 2 (2023): 16–24. https://doi.org/10.5281/zenodo.8018158.

Full text

Abstract:

The inefficiency frequently encountered in oil extractors can be attributed to the insufficient availability of kinetics and thermodynamic data during the design phase. This study examined the kinetics and thermodynamics involved in the extraction of oil from palm kernel seeds. The mass transfer kinetic power model and the laws of thermodynamics were applied to describe the kinetics and the thermodynamics of the oil extraction process, respectively. The physicochemical parameters of the palm kernel oil extracted were determined according to the methods recommended by the Association of Official Analytical Chemists. The results showed that a maximum oil yield of 48.56% was obtained from the dried palm kernels under optimum conditions of 70 °C, a particle size of 2.0 mm, and an extraction duration of 90 min, using 250 ml of n-hexane.  The oil extraction process was found to follow second-order kinetics, whose rate constant is dependent on temperature, and the activation energy (Ea) was 54.69 kJ/mol. The thermodynamic parameters of the extraction process were an enthalpy change (∆H) of 24.94 kJ/mol, an entropy change (∆S) of 0.08 kJ/mol, and negative values of Gibbs’ free energy change (∆G) at each prevailing temperature value. The results of the thermodynamic study implied that the palm kernel oil extraction process is endothermic and requires a constant supply of energy for effective and efficient extraction. Also, the physicochemical properties of the oil showed that it is edible and also suitable for use in soap production, pharmaceutical industries, and as a feedstock in the production of biodiesel.

APA, Harvard, Vancouver, ISO, and other styles

19

A., U. Itodo, E. Khan M., and P. Feka D. "On the Adsorptive Detoxification of Chrome Tan Liquor: Kinetics, Thermodynamics and Mode of Transport." Asian Journal of Chemical Sciences 2, no. 3 (2017): 1–13. https://doi.org/10.9734/AJOCS/2017/32728.

Full text

Abstract:

Aim: The aim of this study is to regenerate spent activated carbon (RGAC) for use as adsorbent and to study the kinetics, thermodynamics and mode of transport of removing chromium from chrome tanning effluent (TEff). Methodology: The chemical regeneration approach was adopted in the recycling. Regenerated adsorbent was characterized using FTIR, SEM and classical methods. A batch adsorption experiment was carefully followed to de-chrome the chrome tan effluent. Equilibrium phase chromium was quantified with Atomic Absorption Spectrophotometer (AAS). Adsorption phenomena were investigated with Kinetic, thermodynamic and transport (diffusion) models to study the behavior of Cr uptake. Kinetic models viz; First order, pseudo-second order, Elovich and Bhattacharya-Venkobachor kinetic models were subjected to three model applicability tests. Thermodynamic parameters which include changes in free energy (ΔG), entropy (ΔS) and enthalpy (ΔH) were monitored in standard states. Prediction of applicable diffusion model was based on comparing linearity of film diffusion, intra-particle diffusion and intraparticulate diffusivity models. Results: Highlights from this study unveiled the influential roles of parametric factors (Initial effluent concentration on vol./vol. bases, solution pH, particle size, adsorbent dose, contact time and temperature). R2 values for models considered showed good fit except for the Bhattacharya-Venkobachor kinetic model. The rate law of the adsorption kinetics is best explained using the Pseudo-second order kinetic model. The chromium adsorption efficiency using both Commercial and regenerated GAC are in good agreement at 95% confidence interval. The regenerant-chromium mode of diffusion, as predicted by the “best-fit’’ transport models, was not suitable for use in the intraparticle diffusion mode (with least R2 and high transport rate) as it does for the film diffusion. In addition, thermodynamic parameters of sorption have also been determined in favour of spontaneity and chemisorptions mechanism. Conclusion: An overall from this study is the recommendation of regenerated adsorbent as a sure economically viable substitute to the commercial activated carbon for chrome tan effluent de-chroming. This generalization was based on statistical test of significance which reports good agreement between the two adsorbents for the investigated adsorption phenomena.

APA, Harvard, Vancouver, ISO, and other styles

20

Nangarthody, Sindhu, and V. Sivasubramanian. "Kinetic and Thermodynamic Analysis of Pyrolysis of Coconut Wood Residue." Asian Journal of Chemistry 35, no. 1 (2022): 39–44. http://dx.doi.org/10.14233/ajchem.2023.24016.

Full text

Abstract:

Physico-chemical properties, kinetics and thermodynamic analysis of biomass are important in designing an efficient pyrolysis process. The current study aims to investigate the physico-chemical behaviour, calorific value and kinetics of thermal decomposition of coconut wood (Cocos nucifera) at 10, 15, and 25 ºC/min using the thermogravimetric analysis (TGA) technique in nitrogen atmospheres. Kinetic parameters were estimated using the Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO), Staring, Tang, Friedman and Coats-Redfern (CR) methods. Average activation energy estimated from Kissinger-Akahira-Sunose (KAS), Starink, Tang and Coats-Redfern (CR) methods was ≈ 100 kJ/mol. The Flynn-Wall-Ozawa (FWO) method predicted a higher value of 104 kJ/mol and Friedman a lower value of 81 kJ/mol. Thermodynamic parameters like change in enthalpy, Gibbs free energy and entropy have also been evaluated.

APA, Harvard, Vancouver, ISO, and other styles

21

Graeser, Kirsten A., James E. Patterson, J. Axel Zeitler, Keith C. Gordon, and Thomas Rades. "Correlating thermodynamic and kinetic parameters with amorphous stability." European Journal of Pharmaceutical Sciences 37, no. 3-4 (2009): 492–98. http://dx.doi.org/10.1016/j.ejps.2009.04.005.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Ashish, Garg, Sharda, Kumar Yogesh, Prakash Meena Om, Sing Mahipat, and Pandey R. "Study of electrode kinetics and thermodynamic parameters of Metronidazole polarographically." Journal of Indian Chemical Society Vol. 89, May 2012 (2012): 619–22. https://doi.org/10.5281/zenodo.5763151.

Full text

Abstract:

Lab. No. 303, Department of Chemistry, University of Rajasthan, Jaipur-302 055, Rajasthan, India E-mail : ashishgarg 101 @gmail. com Manuscript received 04 June 2010, revised 06 September 2011, accepted 19 September 2011 The electrochemical reduction of antibacterial and antiprotozoal drug "Metronidazole" has been carried out in aqueous solution of different pH by direct current (DC) polarography. It exhibits two reduction peaks in acidic medium and one in basic medium. Along with different pH, studies of drug have been carried out with different concentrations of drug and at different temperatures. The reduction of MTZ was found to be irreversible so kinetic parameters (Kº fh, αn) are evaluated using Meites-lsrael and Gaur-Bhargava's methods. Thermodynamic parameters such as ΔHp≠, ΔHv≠, ΔG≠ and ΔS≠ are also evaluated.

APA, Harvard, Vancouver, ISO, and other styles

23

Nor, Norhusna Mohamad, Nur Hidayahtul Nazrah Kamil, Amirul Izan Mansor, and Hawaiah Imam Maarof. "Adsorption Analysis of Fluoride Removal Using Graphene Oxide/Eggshell Adsorbent." Indonesian Journal of Chemistry 20, no. 3 (2020): 579. http://dx.doi.org/10.22146/ijc.43481.

Full text

Abstract:

Graphene oxide with eggshells (GO/ES) adsorbent has been studied for fluoride ions (F–) removal. An adsorption study was conducted in batch experiments at different adsorption parameters, which are initial F– concentration, contact time, and temperature. The effects of these adsorption parameters towards F– removal by using GO/ES adsorbent were investigated. The adsorption parameters were then analyzed with adsorption isotherms (Langmuir and Freundlich), kinetics (pseudo-first-order and second-order) and thermodynamic studies. Under various parameters, GO/ES is proven as an effective adsorbent with an adsorption capacity of F– are up to 48 mg/g. The experimental data were satisfactorily fitted with Langmuir isotherm, which illustrated the monolayer pattern of F– adsorption into GO/ES adsorbent. The adsorption kinetic analysis indicated that the adsorption data could be well described by Pseudo-second-order kinetic model, which indicated the chemisorption process, while thermodynamic studies revealed that the adsorption of F– was an exothermic process.

APA, Harvard, Vancouver, ISO, and other styles

24

MOSOARCA, GIANNIN, COSMIN VANCEA, SIMONA POPA, SORINA BORAN, and MARIA ELENA RADULESCU‑GRAD. "Crystal Violet Dye Adsorption on Raspberry Leaves Powder - Kinetic and Thermodynamic Studies." Buletinul Institutului Politehnic din Iași, Secția Chimie și Inginerie Chimică 68, no. 3 (2022): 123–36. https://doi.org/10.5281/zenodo.7545787.

Full text

Abstract:

In this study, kinetics and thermodynamics of crystal violet dye adsorption onto raspberry leaves powder was investigated. The effect of contact time, temperature and ionic strength was studied. The values of the equilibrium time and the experimental adsorption capacity were better that values for other similar adsorbents obtained from vegetal wastes. The thermodynamic study showed that the adsorption process is endothermic, spontaneous and favourable, and physical adsorption is the main mechanism implied in the dye retention on the adsorbent surface.

APA, Harvard, Vancouver, ISO, and other styles

25

Abourabia, Aly Maher, and Taha Zakaraia Abdel Wahid. "Kinetic and thermodynamic treatments of a neutral binary gas mixture affected by a nonlinear thermal radiation field." Canadian Journal of Physics 90, no. 2 (2012): 137–49. http://dx.doi.org/10.1139/p11-151.

Full text

Abstract:

In the present study, the kinetic and the irreversible thermodynamic properties of a binary gas mixture, under the influence of a thermal radiation field, are presented from the molecular viewpoint. In a frame comoving with the fluid, the Bhatnagar–Gross–Krook model of the kinetic equation is analytically applied, using the Liu–Lees model. We apply the moment method to follow the behavior of the macroscopic properties of the binary gas mixture, such as the temperature and the concentration. The distinction and comparisons between the perturbed and equilibrium distribution functions are illustrated for each gas mixture component. From the viewpoint of the linear theory of irreversible thermodynamics we obtain the entropy, entropy flux, entropy production, thermodynamic forces, and kinetic coefficients. We verify the second law of thermodynamics and celebrated Onsager’s reciprocity relation for the system. The ratios between the different contributions of the internal energy changes, based upon the total derivatives of the extensive parameters, are estimated via Gibbs’ formula. The results are applied to the argon–neon binary gas mixture, for various values of both the molar fraction parameters and radiation field intensity. Graphics illustrating the calculated variables are drawn to predict their behavior and the results are discussed.

APA, Harvard, Vancouver, ISO, and other styles

26

Al-Rufaie, M. M., Z. T. A. Alsultani, and A. S. Waheed. "Adsorption kinetics and thermodynamics of Azure C dye from aqueous solution onto activated charcoal." Koroze a ochrana materialu 60, no. 3 (2016): 80–85. http://dx.doi.org/10.1515/kom-2016-0013.

Full text

Abstract:

Abstract Adsorption thermodynamics and kinetics of Azure C and from the aqueous solution on activated charcoal was examined. The charcoal was activated by concentrated sulphuric acid and the adsorption kinetic and thermodynamic was tested in batch experiment. An experiments used the adsorption batch method to observe the effect of the variable parameters, i.e. concentration of dye, time of contact, pH, temperature and adsorbent dose. The ideal dosage of adsorbent was 0.3 g for Azure C. The equilibrium state was reached within 60 min for dye Azure C at activated charcoal. The isotherms of equilibrium were investigated to characterize the adsorption operation. The data for the kinetics study were adjusted utilizing the equation of pseudo- second-order and the model of diffusion (intra-particle). All data were evaluated by means of equilibrium Freundlich, Langmuir and Temkin isotherm on activated charcoal surface. Based on the adsorption isotherm evaluation on activated charcoal the result was 4S by using Giles classification. The thermodynamic factors like ΔH, ΔG and ΔS were estimated.

APA, Harvard, Vancouver, ISO, and other styles

27

Sargin, İ., and N. Ünlü. "Insights into cationic methyl violet 6B dye–kaolinite interactions: kinetic, equilibrium and thermodynamic studies." Clay Minerals 48, no. 1 (2013): 85–95. http://dx.doi.org/10.1180/claymin.2013.048.4.05.

Full text

Abstract:

AbstractIn this study, adsorption and adsorption kinetics of methyl violet dye from aqueous solutions onto kaolinite were investigated. The effects of adsorbent dosage, pH, ionic strength, contact time, temperature and initial dye concentration were studied. Kinetic and thermodynamic parameters were determined using experimental data. Adsorption capacity decreased with increasing ionic strength. Changes in the initial pH of the dye solution in a range close to the dye's natural pH (i.e. ∼ pH 5.0) values affected adsorption capacity slightly, indicating that adsorption studies could be carried out at the dye's natural pH. The adsorption process followed the Freundlich-type adsorption isotherms and pseudo-second order type adsorption kinetics. However, an intraparticle diffusion process was found to have effects in adsorption processes. Thermodynamic parameters were calculated from the experimental data and enthalpy of the adsorption, ΔH0, was found to be –6.82 kJ mol–1, indicating physisorption nature of the adsorption. Other thermodynamic parameters, ΔS0 and DG0, were also calculated. Negative values of ΔG0 indicated that the adsorption process for methyl violet on kaolinite is spontaneous.

APA, Harvard, Vancouver, ISO, and other styles

28

Aravinthavathani S, Arivoli S., and Hema M. "Removal of Chromium Ions from Aqueous Solution using Activated Pergularia daemia Carbon by Batch Adsorption Method." Ecology, Environment and Conservation 28, no. 04 (2022): 1867–73. http://dx.doi.org/10.53550/eec.2022.v28i04.033.

Full text

Abstract:

In this research, the stems of Pergularia daemia which is a kind of pick over were converted to activated carbon and were used for the removal of hexavalent chromium ion from aqueous solution. The effect of some parameters such as contact time, adsorbent dose, pH of solution, and other ionic strength of Cr (VI) onto the adsorbent. The equilibrium data were analyzed by Langmuir, and Freundlich isotherm models. Kinetic parameters were studied using following manner such as pseudo second order model, Elovich model and intraparticle diffusion model for adsorption process in addition the thermodynamic parameters such as change in free energy (G°), enthalpy (H°) and entropy (S°) were determined. The results revealed that in this process, the adsorption isotherm and kinetics have more conformity with Langmuir isotherm and pseudo-second-order kinetics, respectively and the thermodynamics study provide evidence about nature of adsorption process.

APA, Harvard, Vancouver, ISO, and other styles

29

Ma, Zhijun, Qi Zhang, Xingyuan Weng, et al. "Fluoride ion adsorption from wastewater using magnesium(II), aluminum(III) and titanium(IV) modified natural zeolite: kinetics, thermodynamics, and mechanistic aspects of adsorption." Journal of Water Reuse and Desalination 8, no. 4 (2017): 479–89. http://dx.doi.org/10.2166/wrd.2017.037.

Full text

Abstract:

Abstract Natural zeolite was modified using metal ions, including magnesium(II), aluminum(III) and titanium(IV). The modified zeolite was then used as an adsorbent for the investigation of the adsorption kinetics, isotherms, and thermodynamic parameters of fluoride ions in wastewater at various pHs and temperatures. The kinetics and thermodynamics for the removal of the fluoride ions onto the modified zeolite have also been investigated. The fluoride ion adsorption capacity of the three types of modified zeolites exhibited an increase, then decrease, with rising pH. The fluoride adsorption capacity of the modified zeolites decreased with an increase in temperature. The pseudo-second-order model is more suitable for describing the adsorption kinetic data than the pseudo-first-order model for modified zeolite and the adsorption process of the fluoride ions reveals pseudo-second-order kinetic behavior, respectively. It was found that the adsorption equilibrium data fit the Freundlich isothermal equation better than that of the Langmuir isothermal and Dubinin–Radushkevich (D–R) isothermal equations. Thermodynamic analysis suggests that the negative values of ΔG0 and ΔH0 further indicate that the fluoride adsorption process is both spontaneous and exothermic. The results of competitive adsorption tests suggest that the modified metal zeolite materials adsorb fluoride ions with high selectivity.

APA, Harvard, Vancouver, ISO, and other styles

30

Konicki, Wojciech, Małgorzata Aleksandrzak, and Ewa Mijowska. "Equilibrium and kinetics studies for the adsorption of Ni2+ and Fe3+ ions from aqueous solution by graphene oxide." Polish Journal of Chemical Technology 19, no. 3 (2017): 120–29. http://dx.doi.org/10.1515/pjct-2017-0058.

Full text

Abstract:

Abstract In this study, the adsorption of Ni2+ and Fe3+ metal ions from aqueous solutions onto graphene oxide (GO) have been explored. The effects of various experimental factors such as pH of the solution, initial metal ion concentration and temperature were evaluated. The kinetic, equilibrium and thermodynamic studies were also investigated. The adsorption rate data were analyzed using the pseudo-first-order kinetic model, the pseudo-second-order kinetic model and the intraparticle diffusion model. Kinetic studies indicate that the adsorption of both ions follows the pseudo-second-order kinetics. The isotherms of adsorption data were analyzed by adsorption isotherm models such as Langmuir and Freundlich. Equilibrium data fitted well with the Langmuir model. The maximum adsorption capacities of Ni2+ and Fe3+ onto GO were 35.6 and 27.3 mg g−1, respectively. In addition, various thermodynamic parameters, such as enthalpy (ΔHO), entropy (ΔSO) and Gibbs free energy (ΔGO), were calculated.

APA, Harvard, Vancouver, ISO, and other styles

31

Abubakar, Abdulhalim Musa, Haruna Mavakumba Kefas, Yusufu Luka, and Jimzibea Jehu Kawuwa. "Revolutionizing Biodiesel Synthesis: Kinetic and Thermodynamic Insights with Carbonized Doum-Shell Catalyst." Trends in Ecological and Indoor Environmental Engineering 2, no. 2 (2024): 11–23. http://dx.doi.org/10.62622/teiee.024.2.2.11-23.

Full text

Abstract:

Background: Conventional methods of biodiesel (FAME) synthesis often involve transesterification processes that are catalysed by homogeneous catalysts, which present challenges in terms of catalyst recovery, environmental impact, and production cost. Heterogeneous catalysts, particularly those derived from agricultural waste, have emerged as promising alternatives due to their reusability, environmental friendliness, and cost-effectiveness. Objectives: The study aims to bridge gaps by providing a comprehensive kinetic analysis of biodiesel production using a synthesized and novel, doum-shell catalyst. It incorporates first, second, and third-order rate model kinetics, alongside the determination of some energy parameters. Methods: Doum palm shell (DPS) was characterized by Fourier Transform Infrared (FTIR) and Atomic Force Microscope (AFM), and then carbonized, ground, and sulfonated to create a biochar catalyst, which was then used in the esterification of palmitic acid (PA) with methanol. Kinetic modelling of the esterification process was performed, followed by deriving thermodynamic parameters using Arrhenius and Eyring-Polanyi equations. Results: Kinetic modelling identified the First-Order reaction as the most appropriate for describing the esterification process at an optimum performing temperature of 55 °С, 180 min reaction time and rate constant, k = 7 · 10-4 min-1. Thermodynamic parameters were derived from the Arrhenius and Eyring-Polanyi equations, providing a deeper understanding of the energy changes involved in the esterification reaction. The activation energy, pre-exponential factor, entropy, enthalpy and free energies obtained for the First-Order, describe the catalysing of the synthesis process by DPS as robust, reversible, non-spontaneous, feasible and energy efficient. In both kinetics and thermodynamics carried out, the Second- and Third-Order of reaction analysis described the experimental data poorly due to lower R2 values comparative to the First-Order rate at 45, 55 and 65 °С. FTIR analysis confirmed the successful conversion of feedstock to biodiesel, with distinct ester functional groups such as, –OH, –SO3H and –COOH groups, identified in the DPS catalyst. Conclusions: This research lays the groundwork for future studies and large-scale implementation of this catalyst in biodiesel production, particularly in regions with abundant doum palm resources. Through comprehensive experimentation and analysis, the carbonized doum-shell catalyst was demonstrated to be a viable and efficient option for FAME synthesis from PA and methanol.

APA, Harvard, Vancouver, ISO, and other styles

32

Llusco, Aleksei, Mario Grageda, and Svetlana Ushak. "Kinetic and Thermodynamic Studies on Synthesis of Mg-Doped LiMn2O4 Nanoparticles." Nanomaterials 10, no. 7 (2020): 1409. http://dx.doi.org/10.3390/nano10071409.

Full text

Abstract:

In this work, a first study on kinetics and thermodynamics of thermal decomposition for synthesis of doped LiMn2O4 nanoparticles is presented. The effect of Mg doping concentration on thermal decomposition of synthesis precursors, prepared by ultrasound-assisted Pechini-type sol–gel process, and its significance on nucleation and growth of Mg-doped LiMn2O4 nanoparticles was studied through a method based on separation of multistage processes in single-stage reactions by deconvolution and transition state theory. Four zones of thermal decomposition were identified: Dehydration, polymeric matrix decomposition, carbonate decomposition and spinel formation, and spinel decomposition. Kinetic and thermodynamic analysis focused on the second zone. First-order Avrami-Erofeev equation was selected as reaction model representing the polymer matrix thermal decomposition. Kinetic and thermodynamic parameters revealed that Mg doping causes an increase in thermal inertia on conversion rate, and CO2 desorption was the limiting step for formation of thermodynamically stable spinel phases. Based on thermogravimetry experiments and the effect of Mg on thermal decomposition, an optimal two-stage heat treatment was determined for preparation of LiMgxMn2−xO4 (x = 0.00, 0.02, 0.05, 0.10) nanocrystalline powders as promising cathode materials for lithium-ion batteries. Crystalline structure, morphology, and stoichiometry of synthesized powders were characterized by XRD, FE-SEM, and AAS, respectively.

APA, Harvard, Vancouver, ISO, and other styles

33

Mohammed, Dr Thamer J. Mohammed, Saif I. Habeeb Habeeb, Zaydoun K. Kreamid Kreamid, and Ali A. Ali Ali. "Treatment of Refinery Industry Wastewater Using Ion Exchange Technology and Studies Kinetics and Thermo-dynamic Parameters." Journal of Petroleum Research and Studies 8, no. 3 (2021): 97–112. http://dx.doi.org/10.52716/jprs.v8i3.254.

Full text

Abstract:

A batch system has been used for removal of chloride, sulfate and sodium pollutantsfrom wastewater of Daura refinery. The fine grained resin lewatit was used in this study,batch experiments were performed to examine the effects amount of resin and mixing timeon the removal efficiency and residual of pollutants. The kinetics and thermodynamics ofadsorption were also analyzed. Various thermodynamic parameters such as enthalpy (ΔH◦),free energy (ΔG◦) and entropy (ΔS◦) showed that the adsorption was endothermic,spontaneous and feasible. The removal efficiency of sulfate, chloride and sodium is (91%,88%, 82%), respectively. The optimum mixing time is (12min) for sulfate and sodium, and(14 min) for chloride. Sulfate adsorption on lewatit fitted well to the pseudo-second-orderkinetic model, but adsorption of chloride and sodium on lewatit behaves to the pseudofirst-order kinetic model.

APA, Harvard, Vancouver, ISO, and other styles

34

Hao, Han, Jian Guo Feng, Wei Tao Chen, Wen Jun Liu, and Xue Min Wu. "Adsorption Characteristics of Methacrylic Acid-Styrene Copolymer onto Azoxystrobin Particles Surfaces." Advanced Materials Research 936 (June 2014): 859–63. http://dx.doi.org/10.4028/www.scientific.net/amr.936.859.

Full text

Abstract:

In order to investigate the feasibility of using methacrylic acid (MAA)-styrene (St) copolymer as dispersants to disperse azoxystrobin particles in aqueous suspension, the adsorption kinetics, isotherm and thermodynamics of MAA-St copolymer onto azoxystrobin particle surfaces were studied by batch equilibrium experiments. The results showed that the adsorption process followed the pseudo-second-order kinetic model with the entire adsorption, adsorption rate decreased with the initial concentration of MAA-St copolymer increasing. The equilibrium data were fitted with Langmuir isotherm equation better. The thermodynamic parameters were calculated, which indicated that the adsorption was a spontaneous and exothermic process in nature, and higher temperature is not beneficial to that adsorption process.

APA, Harvard, Vancouver, ISO, and other styles

35

Mariyam, Sabah, Tareq Al-Ansari, and Gordon McKay. "Multibiomass and Natural Marine Waste Catalyst Copyrolysis: Exploring Synergy, Isoconversional Kinetics, Thermodynamics, and Mechanism." International Journal of Energy Research 2023 (September 19, 2023): 1–18. http://dx.doi.org/10.1155/2023/2140032.

Full text

Abstract:

This study presents the copyrolysis of three biomasses (date pits, cow manure, and coffee waste) and explores the potential of utilizing natural waste catalysts—seashell (SS) and cuttlebone (CB)—to improve the kinetics and thermodynamics of the process. Mixing the feeds led to positive synergistic effects, particularly at a heating rate of 10 K/min or higher. By employing three model-free kinetic methods, the estimated activation energy (Ea) was lower for the ternary feed than the single feeds, and 20 wt.% of the feed with SS and CB catalysts was added. The Ea reduced from 162 kJ/mol for the ternary feed by 25.6% (~121 kJ/mol) and 21.6% (154 kJ/mol) in the presence of SS and CB, respectively. The thermodynamic parameters were positive for all the noncatalytic feeds, resulting in endothermic, nonspontaneous reactions and increased disorder or randomness. Catalysts influenced the thermodynamic parameters, making the process more energy efficient. The results are the utilization of cheap, eco-friendly feeds and catalysts for sustainable energy production using copyrolysis.

APA, Harvard, Vancouver, ISO, and other styles

36

Ickes, Luisa, André Welti, Corinna Hoose, and Ulrike Lohmann. "Classical nucleation theory of homogeneous freezing of water: thermodynamic and kinetic parameters." Physical Chemistry Chemical Physics 17, no. 8 (2015): 5514–37. http://dx.doi.org/10.1039/c4cp04184d.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Hao, Han, Jian Guo Feng, Teng Fei Fan, Wen Jun Liu, and Xue Min Wu. "Adsorption Studies of Methacrylic Acid-Styrene-Acrylic Polyethers Copolymer on Imidacloprid Particles." Advanced Materials Research 936 (June 2014): 854–58. http://dx.doi.org/10.4028/www.scientific.net/amr.936.854.

Full text

Abstract:

The adsorption of methacrylic acid-styrene-acrylic polyethers (MAA-St-APEG) copolymer on the insecticide imidacloprid particles was studied to calculate the kinetic, isotherm and thermodynamic parameters. The kinetic data followed the pseudo-second order kinetic model, and the equilibrium data were well fitted by the Langmuir isotherm model with the maximum adsorption amount of 7.610 mg·g-1 at 298 K. The calculated thermodynamic parameters including ΔG, ΔH and ΔS, demonstrated that this adsorption was a spontaneous and exothermic process in nature. Therefore, MAA-St-APEG copolymer are eligible for the dispersion of imidacloprid particles in aqueous solution as a effective dispersant.

APA, Harvard, Vancouver, ISO, and other styles

38

Desnelli, Desnelli, Delisa Rizkiani, Daniel Alfarado, et al. "Adsorption Study on Phenol from Bentonite doped with Zinc oxide: Synthetis, Characterization, Equilibrium, Kinetics, and Thermodynamic." Indonesian Journal of Fundamental and Applied Chemistry 9, no. 2 (2024): 82–95. http://dx.doi.org/10.24845/ijfac.v9.i2.82.

Full text

Abstract:

This study modified current bentonite with zinc oxide (ZnO) and investigated the performance of phenol adsorption. The material bentonite-ZnO was successfully synthesized and characterized with XRD, SEM-EDX, and FT-IR. The adsorption performance was determined by adsorption equilibrium, kinetics, and thermodynamic parameters. The adsorption, kinetic, and thermodynamic parameters were compared alternatively. The phenol adsorption capacity was obtained from Langmuir and Freundlich adsorption isotherm models, which for bentonite-ZnO was fit with both isotherm models (Langmuir R2 = 0.997 and Freundlich R2 = 0.9515) and was favourable than activated bentonite (n value bentonite-ZnO = 2.389; activated bentonite = 0.898). A kinetic model was tested with pseudo-first-order, pseudo-secondorder, and intraparticle diffusion models which bentonite-ZnO and activated bentonite fit in the pseudo-second-order with an excellent agreement (R2 = 0.999). Several thermodynamic parameters such as enthalpy, Gibbs free energy, and bentonite-ZnO have an entropy more than zero (ΔS = 0.008 J/mol.K), which demonstrated the feasibility and spontaneity (ΔG<0) and endothermic nature (ΔH = 3.056 kJ/mol) of the phenol adsorption process. Several thermodynamic parameters such as enthalpy, Gibbs free energy, and bentonite-ZnO have an entropy more than zero (ΔS = 0.008 J/mol.K), which demonstrated the feasibility and spontaneity (ΔG < 0) and endothermic nature (ΔH = 3.056 kJ/mol) of the phenol adsorption process. Based on the result data in this article, modified bentonite with ZnO has increased the ability for phenol adsorption than currently activated bentonite

APA, Harvard, Vancouver, ISO, and other styles

39

Rejali, Nick A., Felix D. Ye, Aisha M. Zuiter, Caroline C. Keller, and Carl T. Wittwer. "Nearest-neighbour transition-state analysis for nucleic acid kinetics." Nucleic Acids Research 49, no. 8 (2021): 4574–85. http://dx.doi.org/10.1093/nar/gkab205.

Full text

Abstract:

Abstract We used stopped-flow to monitor hypochromicity for 43 oligonucleotide duplexes to study nucleic acid kinetics and extract transition-state parameters for association and dissociation. Reactions were performed in 1.0 M NaCl (for literature comparisons) and 2.2 mM MgCl2 (PCR conditions). Dissociation kinetics depended on sequence, increased exponentially with temperature, and transition-state parameters inversely correlated to thermodynamic parameters (r = −0.99). Association had no consistent enthalpic component, varied little with temperature or sequence, and poorly correlated to thermodynamic parameters (r = 0.28). Average association rates decreased 78% in MgCl2 compared to NaCl while dissociation was relatively insensitive to ionic conditions. A nearest-neighbour kinetic model for dissociation predicted rate constants within 3-fold of literature values (n = 11). However, a nearest-neighbour model for association appeared overparameterized and inadequate for predictions. Kinetic predictions were used to simulate published high-speed (&lt;1 min) melting analysis and extreme (&lt;2 min) PCR experiments. Melting simulations predicted apparent melting temperatures increase on average 2.4°C when temperature ramp rates increased from 0.1 to 32°C/s, compared to 2.8°C reported in the literature. PCR simulations revealed that denaturation kinetics are dependent on the thermocycling profile. Simulations overestimated annealing efficiencies at shorter annealing times and suggested that polymerase interactions contribute to primer-template complex stability at extension temperatures.

APA, Harvard, Vancouver, ISO, and other styles

40

Fuentealba, Patricio, Jorge David, and Doris Guerra. "Density functional based reactivity parameters: Thermodynamic or kinetic concepts?" Journal of Molecular Structure: THEOCHEM 943, no. 1-3 (2010): 127–37. http://dx.doi.org/10.1016/j.theochem.2009.11.014.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Beezer, Anthony E., Richard J. Willson, John C. Mitchell, et al. "Thermodynamic and kinetic parameters from isothermal heat conduction microcalorimetry." Pure and Applied Chemistry 70, no. 3 (1998): 633–38. http://dx.doi.org/10.1351/pac199870030633.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Ibrahim Hamadamin, Shireen. "Effect of the dried limes (Citrus aurantifolia) on the caffeine kinetic extraction in black tea leaves (kinetic and thermodynamic study)." Bulletin of the Chemical Society of Ethiopia 36, no. 3 (2022): 697–705. http://dx.doi.org/10.4314/bcse.v36i3.18.

Full text

Abstract:

ABSTRACT. The kinetic and thermodynamic parameters were studied for the extraction of caffeine in black tea leaves and tea leaves containing antioxidant dried limes (Citrus aurantifolia). Caffeine is widely used in human consumption and is present in any liquid suitable for drinking except water. However, the health and environmental demerits make it significant to reduce caffeine to much less concentration or decaffeination. Therefore, the effect of the dried antioxidant Citrus aurantifolia on caffeine concentration followed by pseudo-first-order reaction, kinetic parameters (pseudo-first-order rate constant (k), equilibrium absorbance (A∞)), and thermodynamic activation parameters, the activation energy (Ea), change in enthalpy of activation (ΔH#), the change in entropy of activation (ΔS#) and change in activation Gibbs free energy (ΔG#) was calculated at four different temperatures 30, 60, 80, and 100 °C. Using the spectroscopic method the activation energy of the caffeine concentration in free black tea leaves solution (Ea = 13.32 kJmol-1) was higher than the black tea leaves mixed with lime solution (Ea = 9.89 kJmol-1), the higher collision of molecules A-factor (1.96 min-1), and large correlation factor (R2 = 0.95). The thermodynamic activation parameters ΔH#, ΔS#, and ΔG# demonstrate less heat absorption, irreversible, and more spontaneous interaction of lime with caffeine.  KEY WORDS: Caffeine, Tea leaves, Citrus aurantifolia, Thermodynamic parameters, Kinetic Bull. Chem. Soc. Ethiop. 2022, 36(3), 697-705.  DOI: https://dx.doi.org/10.4314/bcse.v36i3.18

APA, Harvard, Vancouver, ISO, and other styles

43

Patil, Dilip B., Vijendra Batra, and Sushil B. Kapoor. "Kinetic Studies on Saponification of Poly(ethylene terephthalate) Waste Powder Using Conductivity Measurements." Journal of Polymers 2014 (August 25, 2014): 1–7. http://dx.doi.org/10.1155/2014/321560.

Full text

Abstract:

Conductometric measurement technique has been deployed to study the kinetic behavior during the reaction of poly(ethylene terepthalate) (PET) and NaOH. A laboratory made arrangement with facility of continuous stirring was used to carry out experiments at desired temperature. With conductometry, the determination of kinetic as well as thermodynamic parameters becomes more simple and faster as compared to gravimetry. Chemical kinetics of this reaction shows that it is a second order reaction with reaction rate constant 2.88×10-3 g−1 s−1 at 70°C. The specific reaction rates of the saponification reaction in the temperature range at various temperatures (50–80°C) were determined. From the data, thermodynamic parameters such as activation energy, Arrhenius constant (frequency factor), activation enthalpy, activation entropy, and free energy of activation obtained were 54.2 KJ g−1, 5.0×106 min−1, 90.8 KJ g−1, -126.5 JK−1 g−1, and 49.9 KJ g−1, respectively.

APA, Harvard, Vancouver, ISO, and other styles

44

Maugis, Philippe, Frédéric Soisson, and Ludovic Lae. "Kinetics of Precipitation: Comparison between Monte Carlo Simulations, Cluster Dynamics and the Classical Laws." Defect and Diffusion Forum 237-240 (April 2005): 671–76. http://dx.doi.org/10.4028/www.scientific.net/ddf.237-240.671.

Full text

Abstract:

We test the main approximations of the classical laws for nucleation, growth and coarsening by comparison with atomistic simulations of the kinetics of precipitation. We investigate the kinetics of phase separation in dilute A-B solid solutions by precipitation of B atoms in the Arich matrix. Classically, the kinetics is represented by the time evolution of the total number of particles and their mean radius. In this work, the kinetics is predicted by three types of models: (a) an Atomic-scale Kinetic Monte Carlo (AKMC) model based on a vacancy diffusion mechanism, (b) a Cluster Dynamics model, and (c) the MultiPreci model, based on the coupling of the classical laws of nucleation, growth and coarsening. Cluster Dynamics and the Multipreci model have been parameterized such that the thermodynamic and kinetic parameters (solubility, diffusion coefficient, interface energy) be identical to that of the AKMC. Under these conditions we find that the classical laws are in good agreement with the atomistic simulations as long as the thermodynamics of the solid solution remains strictly regular. As expected, Cluster Dynamics compares better with the atomistic simulations, especially if a precise description of the energetics of the smallest clusters is applied.

APA, Harvard, Vancouver, ISO, and other styles

45

Shifera, Leta. "Thermodynamics and kinetics studies of Phenol adsorption on to Anchote peel activated carbon adsorbent." Technium: Romanian Journal of Applied Sciences and Technology 10 (June 29, 2023): 131–45. http://dx.doi.org/10.47577/technium.v10i.8691.

Full text

Abstract:

Thermodynamic and kinetics (pseudo first, pseudo second) of phenol adsorption were investigated. Anchote peel (coconia Abysinica peel) was carbonized and activated by treating with KOH solution followed by heating in an electrical furnace at 800 for 2 hrs. Kinetic studies of the data showed that the adsorption follows the pseudo-second-order kinetic model. Thermodynamic parameters showed that adsorption on the surface of APAC was feasible, spontaneous in nature, and exothermic. The equilibrium data better fitted the Freundlich isotherm model. Maximum adsorption efficiencies of Phenol were 97% at optimum pH 6 and optimum contact time 210 min., adsorbent dose 0.25 g and initial conc. 0.025 mg/l respectively. Maximum adsorption capacity of APAC was observed to 43.75 mg/g of Phenol at 25 and 5 mg/L. Key words:

APA, Harvard, Vancouver, ISO, and other styles

46

Nyong, B. E., F. E. Abeng, O. A. Ushie, B. J. Bassey, and M. M. Edim. "Kinetics Mechanism and Thermodynamic Study of the Oxidation of Iodide Ion by Dichromate Ion in Acidic Medium." Journal of Applied Sciences and Environmental Management 24, no. 5 (2020): 821–26. http://dx.doi.org/10.4314/jasem.v24i5.14.

Full text

Abstract:

This work introduces a newly developed kinetic mechanism and thermodynamic study that gives a clear theoretical insight between the iodine and chromium in acid solution. The paper mainly focuses on evaluating kinetic mechanism and thermodynamic properties of the oxidation of iodide by dichromate ion in acidic medium. This study was investigated using iodometric method. The rate has been studied by appropriate choice of concentrated conditions at constant temperature and ionic strength. The kinetic studies revealed half order reaction with respect to dichromate ion, first order for iodide ion and second order for hydrogen ion concentration. The dependence of reaction rate on the temperature was monitored in order to generate some thermodynamic parameters, which can be used in predicting the direction and spontaneity of the reaction. The thermodynamic studies of this reaction revealed negative values for ΔG, ΔS and positive values for ΔH which is an indication that the reaction wasspontaneous and endothermic. The oxidant chromium (vi) exist in acidic media as H2CrO4. The effect of ionic strength on the rate of redox reaction was investigated. The ionic strength was adjusted by varying the concentration of the nitrate to maximum. The effect of temperature was also studied to evaluate the thermodynamic parameters. Transition metals should be use as catalyst for future purpose to monitor the rate of redox reaction. The techniques employed on this research are very useful in determining the rate of a redox reaction. Keywords: Kinetic, thermodynamic, oxidation, iodometric method

APA, Harvard, Vancouver, ISO, and other styles

47

Nugraha, Mawan, Meng-Che Tsai, Wei-Nien Su, Hung-Lung Chou, and Bing Joe Hwang. "Descriptor study by density functional theory analysis for the direct synthesis of hydrogen peroxide using palladium–gold and palladium–mercury alloy catalysts." Molecular Systems Design & Engineering 3, no. 6 (2018): 896–907. http://dx.doi.org/10.1039/c8me00057c.

Full text

APA, Harvard, Vancouver, ISO, and other styles

48

Hao, Yi Nan, Xi Ming Wang, Li Jun Ding, and Da Yan Ma. "Ultrasonic Treatment of Activated Carbon Used in Adsorption of Basic Fuchsin." Materials Science Forum 704-705 (December 2011): 486–91. http://dx.doi.org/10.4028/www.scientific.net/msf.704-705.486.

Full text

Abstract:

Xanthoceras Sorbifolia Bunge hull activated carbon (XSBHAC) developed by phosphoric acid activation for removing basic fuchsin (BF) has been investigated. Experiments were carried out as function of contact time, pH (4-10) and temperature (303,313 and 323K). Adsorption isotherms were modeled with the Langmuir and Freundlich isotherms. The data fitted well with the Langmuir isotherm. The Langmuir monolayer saturation capacities of BF adsorbed onto activated carbon were 351.35, 354.96 and 355.94 mg/g at 303,313, and 323 K, respectively.The kinetic models were also studied .The rates of adsorption were found to conform to the pseudo-second-order kinetics with good correlation.Using the equilibrium concentration contents obtained at different temperatures, various thermodynamic parameters,such as △G,△H and △S, have been calculated. The thermodynamics parameters of system indicated spontaneous and endothermic process. Key words: Xanthoceras sorbifolia bunge hull;biosorption; basic fuchsin

APA, Harvard, Vancouver, ISO, and other styles

49

Komorsky-Lovrić, Š., and M. Lovrić. "Theory of staircase cyclic voltammetry of two electrode reactions coupled by a chemical reaction." Bulgarian Chemical Communications 51, no. 3 (2019): 348–57. http://dx.doi.org/10.34049/bcc.51.3.4983.

Full text

Abstract:

Two reversible electrode reactions that are connected by either reversible or totally irreversible chemical reactions are theoretically analysed by staircase cyclic voltammetry. The dependence of peak potentials on the thermodynamic and kinetic parameters is calculated. If the mechanism is permanently in equilibrium, the stability constant of the reversible chemical reaction can be determined. Furthermore, the critical kinetic parameter is determined and its application to the measurement of the forward rate constant of the chemical reaction is demonstrated. Also, the influence of the kinetics of electrode reactions is discussed. Keywords: ECE mechanism; Cyclic voltammetry; Theory

APA, Harvard, Vancouver, ISO, and other styles

50

Ahmad, Khurshid, Aamir Hassan Shah, Bimalendu Adhikari, et al. "pH-dependent redox mechanism and evaluation of kinetic and thermodynamic parameters of a novel anthraquinone." RSC Adv. 4, no. 60 (2014): 31657–65. http://dx.doi.org/10.1039/c4ra04462b.

Full text

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Kinetic Thermodynamic parameters'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles