scholarly journals Ionic and nonionic contributions to the free-energy change in the B-Z transition of alternating polydeoxynucleotides in aqueous solution

Biopolymers ◽  
1987 ◽  
Vol 26 (11) ◽  
pp. 1975-1979 ◽  
Author(s):  
Joāo Ruggiero ◽  
Giorgio Manzini ◽  
Franco Quadrifoglio
Keyword(s):  
Aqueous Solution ◽  
Free Energy ◽  
Free Energy Change ◽  
Energy Change

scholarly journals Batch Sorption of Copper (II) Ions from Simulated Aqueous Solution by Banana Peel

2017 ◽  
Vol 12 (4) ◽  
pp. 117-125
Author(s):  
Lahieb Faisal M. Faisal M.
Keyword(s):  
Aqueous Solution ◽  
Free Energy ◽  
Ph Value ◽  
Entropy Change ◽  
Second Order ◽  
Free Energy Change ◽  
Energy Change ◽  
Banana Peel ◽  
Batch Sorption ◽  
Pseudo Second Order

This research presents the possibility of using banana peel (arising from agricultural production waste) as biosorbent for removal of copper from simulated aqueous solution. Batch sorption experiments were performed as a function of pH, sorbent dose, and contact time. The optimal pH value of Copper (II) removal by banana peel was 6. The amount of sorbed metal ions was calculated as 52.632 mg/g. Sorption kinetic data were tested using pseudo-first order, and pseudo-second order models. Kinetic studies showed that the sorption followed a pseudo second order reaction due to the high correlation coefficient and the agreement between the experimental and calculated values of qe. Thermodynamic parameters such as enthalpy change (ΔH°), entropy change (ΔS°) and Gibbs free energy change (ΔG°) were also investigated. Free energy change showed that biosorption of Cu (II) was spontaneous and nature endothermic at all studied temperatures (25–45 °C).

The enol content of simple carbonyl compounds: a thermochemical approach

1979 ◽  
Vol 57 (2) ◽  
pp. 240-248 ◽  
Author(s):  
J. Peter Guthrie ◽  
Patricia A. Cullimore
Keyword(s):  
Aqueous Solution ◽  
Free Energy ◽  
Carbonyl Compounds ◽  
Free Energy Change ◽  
Energy Change ◽  
Free Energies ◽  
Enol Ethers ◽  
Free Energy Of Formation ◽  
Hydrolysis Of ◽  
Energy Of Formation

From the heats of hydrolysis of enol ethers, the heats of formation of the enol ethers, and thence the free energies of formation of the enol ethers in aqueous solution can be calculated. For this calculation it was necessary to determine the free energies of transfer from the gas phase to aqueous solution. By methods previously published it was possible to estimate the free energy change for the hypothetical hydrolysis reaction leading from the enol ether to the enol, which in turn made possible calculation of the free energy of formation of the enol. Finally the free energy change for enolization in aqueous solution could be calculated using the known free energy of formation of the corresponding keto tautomer. In this way the following were determined: carbonyl compound, pKenol = −log ([enol]/[keto]): acetaldehyde, 5.3; propionaldehyde, 3.9; isobutyraldehyde, 2.8; acetone, 7.2; 2-butanone, 8.3; 3-pentanone, 7.8; cyclopentanone, 7.2; cyclohexanone, 5.7; acetophenone, 6.7.

Modeling of Electrical Resistivity Evolution Using Free Energy Analysis for NiTi Shape Memory Alloy Wires

2011 ◽  
Vol 311-313 ◽  
pp. 2282-2285
Author(s):  
Jian Jun Zhang
Keyword(s):  
Electrical Resistivity ◽  
Free Energy ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Free Energy Change ◽  
Energy Change ◽  
Niti Shape Memory Alloy ◽  
Scanning Calorimetry ◽  
Proposed Model ◽  
Free Energy Analysis

This paper presents a transformation kinetics model of NiTi shape memory alloy (SMA) wires based on electrical resistivity (ER) derivative study under the assumption that the derivative of electrical resistivity with respect to temperature is in linear relationship with the derivative of free energy change with respect to temperature. Free energy change and electrical resistivity properties of SMA are analyzed based on differential scanning calorimetry (DSC) experiments during phase transformation. The simulated evolution of electrical resistivity during thermomechanical transformation is presented using the proposed model.

Adsorption of Liquids and Swelling of Wood. Part VI. Saturated Amounts and Some Thermodynamic Values of Adsorption

Holzforschung ◽  
2002 ◽  
Vol 56 (1) ◽  
pp. 91-97
Author(s):  
Kei Morisato ◽  
Yutaka Ishimaru ◽  
Hiroyuki Urakami
Keyword(s):  
Free Energy ◽  
Standard Free Energy ◽  
Molecular Size ◽  
Free Energy Change ◽  
Energy Change ◽  
Multilayer Adsorption ◽  
Monolayer Adsorption ◽  
Wood Part ◽  
Cohesive Interaction

Summary To understand the swelling phenomenon of wood in liquids,the saturated amount of adsorption of liquids onto wood and the standard free energy changes of the adsorption were determined. The saturated amount of adsorption obtained by regression for several liquids decreased with increasing molecular size of the solvents. The mechanism of wood swelling is discussed systematically taking all the liquids examined in previous experiments into account. Since methanol molecules require more energy for release from cohesive interactions within bulk liquids in the adsorption onto pre-swollen wood,the values of free energy change of adsorption for methanol were lower than the values for acetone,although the relative swelling with methanol was higher. These results suggest that although the cohesive interaction within the bulk liquids reduces adsorptivity,the phenomenon of wood swelling is influenced not only by monolayer adsorption but also by multilayer adsorption. Therefore,the cohesive interaction within the bulk liquids reduces adsorptivity but enhances the condensation which strongly influences the swelling of wood.

scholarly journals REMOVAL OF CU (II) FROM DYE EFFLUENT USING NATURAL AND PHOSPHATE-MODIFIED NIGERIAN KAOLINITE CLAY

2019 ◽  
Vol 7 (8) ◽  
pp. 402-414
Author(s):  
S. C. Olu ◽  
P. E. Dim ◽  
J. O. Okafor
Keyword(s):  
Free Energy ◽  
Metal Ion ◽  
Fourier Transforms ◽  
Lattice Structure ◽  
Enthalpy Change ◽  
Free Energy Change ◽  
Energy Change ◽  
Order Model ◽  
Acid Modification ◽  
Kaolinite Clay

This study indicates kaolinite clay as an effective adsorbent for the uptake of Cu (II) from wastewater. The adsorption process was studied with variation of time, temperature and adsorbent dosage at the effluent pH of 6. X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), Brunauer Emmett and Teller (BET) and Scanning electron microscopy (SEM) were used to characterize the adsorbents. XRD spectra showed that modification with KH2PO4 did not significantly change the crystal spacing on the lattice structure of the clay mineral; however, there were shifts in the intensity of the peaks for the modified kaolinite clay. The FTIR spectra showed that certain functional groups are responsible for binding the metal ions from solution. SEM indicated an increase in the porosity of the modified adsorbent as compared with the unmodified kaolinite, which enhances metal ion adsorption on modified kaolinite clay. The BET indicate that acid modification increased the surface area and total pore volume of the kaolinite clay. The kinetic study revealed that the pseudo-first-order model fitted poorly to the equilibrium data, however, the pseudo-second-order model had a good fit for all reaction time at different initial concentrations. The mechanism of the sorption process was evaluated using thermodynamic properties such as enthalpy change (ΔH), Gibbs free energy change (ΔG), and entropy change (ΔS), which were evaluated using Van’t Hoff equations. The negative values of free energy change (ΔG), suggests spontaneity and feasibility of the process. The positive values of enthalpy change (ΔH) indicate endothermic nature of the process.

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