Adsorption Modeling of Fatty and Oleic Estolide Esters via Boundary Lubrication Coefficient of Friction Measurements

2005 ◽  
Author(s):  
T. L. Kurth ◽  
S. C. Cermak ◽  
J. A. Byars ◽  
G. Biresaw
Keyword(s):  
Boundary Lubrication ◽  
Adsorption Model ◽  
Fatty Esters ◽  
Cooperative Adsorption ◽  
Interaction Terms ◽  
Adsorption Modeling ◽  
Adsorption Energies ◽  
Friction Measurements ◽  
Negative Adsorption ◽  
Test Regime

The frictional behaviors of a variety of fatty esters (methyl palmitate (MP), methyl laurate (ML), and 2-ethylhexyl oleate (EHO)) and oleic estolide esters (methyl oleic estolide ester (ME) and 2-ethylhexyl oleic estolide ester (EHE)) as additives in hexadecane have been examined in a boundary lubrication test regime using steel contacts. Critical additive concentrations were defined and used to perform novel and simple Langmuir analyses that provide an order of adsorption energies: EHE ≥ ME > EHO > MP > ML. Application of a general adsorption model indicates slight cooperative adsorption of EHE, ME, and EHO. MP and ML data require larger attractive interaction terms (α ≤ −2.3) to be adequately fit. Irrespective of ester functionality increasingly negative adsorption energies appear to correlate with molecular weight. This suggests that multiple site coverage and multiple adsorptive interactions are likely for each of the esters studied.

Non-linear adsorption modeling of fatty esters and oleic estolide esters via boundary lubrication coefficient of friction measurements

Wear ◽  
2007 ◽  
Vol 262 (5-6) ◽  
pp. 536-544 ◽  
Author(s):  
Todd L. Kurth ◽  
Jeffrey A. Byars ◽  
Steven C. Cermak ◽  
Brajendra K. Sharma ◽  
Girma Biresaw
Keyword(s):  
Coefficient Of Friction ◽  
Boundary Lubrication ◽  
Fatty Esters ◽  
Adsorption Modeling ◽  
Non Linear ◽  
Friction Measurements

Adsorption Behavior of Heat Modified Soybean Oil via Boundary Lubrication Coefficient of Friction Measurements

2008 ◽  
Author(s):  
Brajendra K. Sharma ◽  
Girma Biresaw ◽  
Sevim Z. Erhan
Keyword(s):  
Soybean Oil ◽  
Metal Surface ◽  
Boundary Lubrication ◽  
Average Molecular Weight ◽  
Relative Distribution ◽  
Adsorption Model ◽  
Free Energy Of Adsorption ◽  
Soybean Oils ◽  
Modified Soybean Oil ◽  
Friction Measurements

The frictional behaviors of soybean oil and heat modified soybean oils with different Gardner scale viscosities as additives in hexadecane have been examined in a boundary lubrication test regime (steel contacts) using Langmuir adsorption model. The free energy of adsorption (ΔGads) of various heat modified soybean oils were compared with unmodified soybean oil. It was observed, that relative distribution of unsaturation in the molecule, average molecular weight and thus viscosity can affect adsorption on the metal surface. Heat modified soybean oils consistently have a lower ΔGads values compared to unmodified soybean oil. Lower ΔGads corresponds to stronger adsorption on the metal surface. The heat modification thus provides oils with stronger adsorption and higher viscosities, good for use in industrial lubricant formulations. This information can be used to design suitable lubricant molecules that will have optimum structure for effective metal adsorption as well as exhibit excellent boundary lubrication properties.

ADSORPTION SITES OF THE PRODUCTS OF GeH4 ON ASYMMETRIC Si(100)(2×1) SURFACE

2004 ◽  
Vol 18 (08) ◽  
pp. 1191-1202
Author(s):  
ŞENAY KATıRCıOĞLU
Keyword(s):  
Density Functional ◽  
Geometry Optimization ◽  
Density Functional Theory Method ◽  
Adsorption Model ◽  
Functional Theory ◽  
Adsorption Models ◽  
Adsorption Sites ◽  
Asymmetric Dimer ◽  
Adsorption Energies ◽  
Relative Adsorption

The decomposition of GeH 4 on Si (100)(2×1) was investigated on different adsorption models of fragments using density functional theory method. The most probable adsorption model of fragments corresponding to the growth steps of SiGe film has been obtained by geometry optimization and single value total energy calculations. The relative adsorption energies of GeH 3, GeH 2 and GeH have been found to be -5.6, -5.1, and -4.5 eV for their most probable adsorption models respectively. It has been found that, the asymmetric dimer bond rows of Ge on Si (100) surface can be constructed by following the adsorption models corresponding to the relative adsorption energies of GeH 3, GeH 2 and GeH .

scholarly journals How to Extract Adsorption Energies, Adsorbateadsorbate Interaction Parameters, and Saturation Coverages from Temperature Programmed Desorption Experiments

2021 ◽  
Author(s):  
Sudarshan Vijay ◽  
Henrik Høgh Kristoffersen ◽  
Yu Katayama ◽  
Yang Shao-Horn ◽  
Ib Chorkendorff ◽  
...  
Keyword(s):  
Adsorption Energy ◽  
Density Functional ◽  
Configurational Entropy ◽  
Density Functional Theory Calculations ◽  
Temperature Programmed Desorption ◽  
Functional Theory ◽  
Interaction Terms ◽  
Saturation Coverage ◽  
Adsorption Energies ◽  
Temperature Programmed

<p>We present a simple scheme to extract the adsorption energy, adsorbate interaction parameter and the saturation coverage from temperature programmed desorption (TPD) experiments. We propose that the coverage dependent adsorption energy can be fit using a functional form including the configurational entropy and linear adsorbate-adsorbate interaction terms. As one example of this scheme, we analyze TPD spectra of desorption on Au(211) and Au(310) surfaces. We determine that under atmospheric pressure, the <i>steps</i> of both facets adsorb between 0.4-0.9 ML coverage of CO*. We show this result to be consistent with density functional theory calculations of adsorption energies with the BEEF-vdW functional. <b></b></p>

scholarly journals ADSORPTION MODEL OF Mn2+, Cd2+ and Hg2+ IN THE WATER - SEDIMENT SYSTEMS ALONG CODE RIVER, YOGYAKARTA

2010 ◽  
Vol 8 (3) ◽  
pp. 314-319 ◽  
Author(s):  
Muzakky Muzakky
Keyword(s):  
Metal Ions ◽  
Adsorption Energy ◽  
Initial Condition ◽  
Adsorption Model ◽  
River Dynamics ◽  
Binding Strength ◽  
Langmuir Adsorption ◽  
Langmuir Adsorption Model ◽  
Isotherm Adsorption ◽  
Adsorption Energies

Prediction of adsorption model of Mn2+, Cd2+ and Hg2+ in water-sediment systems along Code River, Yogyakarta has been experimentally investigated. The aim of this investigation is to predict the transfer models based on isotherm adsorption of Mn2+, Cd2+ and Hg2+ metal ions from water into sediment. In addition, this investigation is expected to be able to inform the initial condition of Code River, dynamics, and the fate of Mn2+, Cd2+ and Hg2+ ions from upstream to downstream. Based on the investigation the transfer of Mn2+, and Cd2+ ions into sediment follows Langmuir adsorption model, with the coefficient determination (R2) of 0,9916 and 0,9799, while the value of the adsorption energy are 20,95 kJ/mol and 16,85 kJ/mol. The transfer of Hg2+ ion tend to follow Freundlich adsorption model. From the adsorption energies, it is proven  that Mn2+ ion was chemically sorpted into the sediment, while Cd2+ ion will tend to be physically sorpted into the sediment. The binding strength of which ise in the order of Mn2+ > Cd2+ and the adsorption energy of Hg2+ ion could not be determined.   Keywords: adsorption model, chemically sorpted, physically sorpted

scholarly journals A DFT study on the interaction of doped carbon nanotubes with H2S, SO2 and thiophene

2020 ◽  
Author(s):  
Hossein Tavakol ◽  
Hamed Haghshenas
Keyword(s):  
Carbon Nanotubes ◽  
Dft Calculations ◽  
Intramolecular Interactions ◽  
The Other ◽  
Population Analyses ◽  
Energy Gaps ◽  
Si Doped ◽  
Adsorption Energies ◽  
Sulfur Containing ◽  
Negative Adsorption

The interactions of simple and Al, B, N, S, P and Si-doped carbon nanotubes with three sulfur-containing molecules (H2S, SO2 and thiophene) have been investigated to assess their adsorption potencies and sensor abilities. DFT calculations were used to calculate the adsorption energies and NBO parameters. Besides, Population analyses were performed to calculate the energy gaps and reactivity parameters and to obtain DOS plots. The results showed an exothermic interaction of H2S, SO2 and thiophene with simple and doped CNTs while the maximum negative adsorption energies were belonged to Al and B containing complexes. Furthermore, evaluation of second order perturbation energies (obtained from NBO calculations) confirmed that the highest energies were related to B and Al containing intramolecular interactions. The results revealed the favourability of adsorption of SO2 by nanotubes (B and Al doped carbon nanotubes, in particular), in comparing with the other examined adsorbates.

scholarly journals A DFT Study on the Interaction of Doped Carbon Nanotubes with H2S, SO2 and Thiophene

2021 ◽  
Vol 3 (3) ◽  
pp. 366-375
Author(s):  
Hossein Tavakol ◽  
Hamed Haghshenas
Keyword(s):  
Carbon Nanotubes ◽  
Dft Method ◽  
Intramolecular Interactions ◽  
Population Analyses ◽  
Natural Bond Orbitals ◽  
Energy Gaps ◽  
Si Doped ◽  
Adsorption Energies ◽  
Sulfur Containing ◽  
Negative Adsorption

The interactions of simple and Al-, B-, N-, S-, P-, and Si-doped carbon nanotubes with three sulfur-containing molecules (H2S, SO2, and thiophene) were investigated to assess their adsorption potencies and sensor abilities. The DFT method was used to calculate the adsorption energies and natural bond orbitals parameters. In addition, population analyses were performed to calculate the energy gaps and reactivity parameters. The results showed an exothermic interaction of H2S, SO2, and thiophene with simple and doped carbon nanotubes, while the maximum negative adsorption energies belong to Al- and B-containing complexes. Furthermore, evaluation of second-order perturbation energies (obtained from natural bond orbitals calculations) confirmed that the highest energies were related to B- and Al-containing intramolecular interactions. The results revealed the favorability of adsorption of SO2 by nanotubes (B- and Al-doped carbon nanotubes, in particular) compared with the other examined adsorbates.

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