Interaction of Porphyrins with Cetyltrimethylammonium Bromide Micelles in Methylene Chloride

1998 ◽  
Vol 02 (04) ◽  
pp. 345-351 ◽  
Author(s):  
NILKAMAL BAG ◽  
ARUNA DHATHATHREYAN ◽  
ASIT BARAN MANDAL ◽  
TIRUMALACHARI RAMASAMI
Keyword(s):  
Free Energy ◽  
Cetyltrimethylammonium Bromide ◽  
Methylene Chloride ◽  
Aggregation Number ◽  
Film Formation ◽  
Cetylpyridinium Chloride ◽  
Standard Free Energy ◽  
Micelle Formation ◽  
Standard Free Energy Change ◽  
Biphasic Model

The formation of micelles of cetyltrimethylammonium bromide (CTAB) in CH 2 Cl 2 solution has been reported for the first time. The critical micelle concentrations (cmc) of CTAB in CH 2 Cl 2 solution were determined using conductivity and fluorescence techniques in both the absence and presence of 1,3,5,7-tetramethyl-2,4,6,8-tetra(2,4,6-triisopropylphenyl)porphyrin (TMTIP). The cmc values obtained by conductivity and fluorescence methods were found to be 75 and 78 mM, respectively. The aggregation numbers (N) of CTAB and porphyrin–CTAB in CH 2 Cl 2 solution were determined using pyrene and N-cetylpyridinium chloride (CPC) as the fluoroprobe and quencher, respectively. The N of CTAB in CH 2 Cl 2 solution was also determined using the porphyrin (in lieu of pyrene) as the fluoroprobe and CPC as the quencher. The N of CTAB obtained by these probes was found to be 134 ± 3 and 140 ± 5, respectively. This suggests that the porphyrin could be used as an excellent fluoroprobe for determination of the aggregation number of CTAB micelles. The results of both cmc and aggregation number suggest that the micelle formation of CTAB in CH 2 Cl 2 solution is favored in the presence of the porphyrin. The standard free energy change for micelle formation of CTAB in CH 2 Cl 2 solution was calculated using a biphasic model. The standard free energy transfer [Formula: see text] of CTAB micelles from CH 2 Cl 2 to porphyrin environment has been found to be −1.0 kJ mol−1 at 25 °C, suggesting that the above transfer is difficult. However, the reverse situation, i.e. binding of the porphyrin to CTAB micelles, is more probable. The Langmuir–Blodgett (LB) film formation of the porphyrin and metalloporphyrins ( Fe , Co , Cu , Zn ) has also been studied and the UV-vis spectra of these films have been analyzed.

The Equilibrium and the Determination of D00 (H—CN)

1975 ◽  
Vol 53 (16) ◽  
pp. 2365-2370 ◽  
Author(s):  
Don Betowski ◽  
Gervase Mackay ◽  
John Payzant ◽  
Diethard Bohme
Keyword(s):  
Free Energy ◽  
Standard Enthalpy ◽  
Transfer Reaction ◽  
Standard Free Energy ◽  
Proton Transfer Reaction ◽  
Enthalpy Change ◽  
Standard Free Energy Change ◽  
Flowing Afterglow ◽  
Standard Enthalpy Change

The rate constants and equilibrium constant for the proton transfer reaction [Formula: see text] have been measured at 296 ± 2 K using the flowing afterglow technique: kforward = (2.9 ± 0.6) × 10−9 cm3molecule−1s−1, kreverse = (1.8 ± 0.4) × 10−10 cm3 molecule1 s−1, and K = 16 ± 2. The measured value of K corresponds to a standard free energy change, ΔG296°, of −1.6 ± 0.1 kcal mol−1 which provides values for the standard enthalpy change, ΔH298°= −1.0 ± 0.2 kcal mol−1, the bond dissociation energy, D00(H—CN) = 124 ± 2 kcal mol−1, and the proton affinity, p.a.(CN−) = 350 ± 1 kcal mol−1.

Adsorption of Liquids and Swelling of Wood IV. Temperature Dependence on the Adsorption

Holzforschung ◽  
1999 ◽  
Vol 53 (6) ◽  
pp. 669-674 ◽  
Author(s):  
Kei Morisato ◽  
Hitoshi Kotani ◽  
Yutaka Ishimaru ◽  
Hiroyuki Urakami
Keyword(s):  
Free Energy ◽  
Temperature Dependence ◽  
Standard Enthalpy ◽  
Cell Walls ◽  
Standard Free Energy ◽  
Isosteric Heat ◽  
Enthalpy Change ◽  
Standard Free Energy Change ◽  
Standard Enthalpy Change ◽  
Low Activity

Summary For the purpose of understanding the swelling phenomenon of wood in liquids, the contributions of enthalpic and entropic terms to the standard free energy change of adsorption have been determined by measuring the temperature dependence of adsorption isotherms. The values of standard enthalpy change of adsorption are smaller for alcohols having both proton-accepting and -donating properties than for acetone having only a proton-accepting property. The results are discussed in terms of the proton-accepting power and the cohesive energy of the respective adsorbate liquids. Methanol showed a larger isosteric heat of adsorption to dried wood than to pre-swollen wood, and the amounts of methanol and acetone adsorbed on dried wood exceeded those on swollen wood within the low activity range. These results indicate the presence of more exothermic sites in dried wood than in pre-swollen wood, and of pre-existing spaces and/or parts loosely hydrogen-bonded between wood constituents in the cell walls of dried wood.

Interaction of cationic surfactant with acid yellow dye in absence/presence of organic and inorganic additives: conductivity and dye solubilization methods

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Md. Ariful Haque ◽  
Shamim Mahbub ◽  
Mohammad Majibur Rahman ◽  
Md. Anamul Hoque ◽  
Dileep Kumar ◽  
...  
Keyword(s):  
Free Energy ◽  
Cationic Surfactant ◽  
Cetyltrimethylammonium Bromide ◽  
Micelle Formation ◽  
Aqueous System ◽  
Nacl Solution ◽  
Solubilization Capacity ◽  
Delta G ◽  
Free Energy Of Micellization ◽  
Dye Solubilization

Abstract In the present study, the conductometric and dye-solubilization techniques have been utilized to investigate the interaction between an anionic dye (acid yellow 23 [AY]) and a cationic surfactant (cetyltrimethylammonium bromide [CTAB]) in presence of organic (ethanol)/inorganic (NaCl) additives. From the conductometric method, two critical micelle concentrations (cmc) were found for AY + CTAB mixture in an aqueous system and the cmc values were found to undergo a change with the variation of AY concentrations. The cmc values of AY + CTAB systems were observed higher in the alcoholic medium, while the same was found to be lower in the NaCl solutions. The change in cmc of AY + CTAB systems shows an U-like curve with an increase of temperature. The negative free energy of micellization ( Δ G m o ${\Delta}{G}_{m}^{o}$ ) for the AY + CTAB systems has indicated a spontaneous micelle formation in all of the cases studied. The enthalpy ( Δ H m o ${\Delta}{H}_{m}^{o}$ ), as well as the entropy of micellization ( Δ S m o ${\Delta}{S}_{m}^{o}$ ) for the AY + CTAB systems, were assessed and discussed with proper reasoning. Additionally, the enthalpy-entropy compensation parameters were also investigated and illustrated. The solubility of AY and C D was observed to rise linearly with an increase in the concentration of CTAB/NaCl solution. The solubilization capacity (χ) of AY, the molar partition coefficient (K M) amongst the micellar and the aqueous phase, and free energy of solubilization ( Δ G S o ${\Delta}{G}_{S}^{o}$ ) were evaluated and discussed in detail. The former parameters undergo an increase with an increase of NaCl concentrations.

scholarly journals The dependence of the free energy of micelle formation on aggregation number and critical micelle concentration

1978 ◽  
Vol 31 (4) ◽  
pp. 919 ◽  
Author(s):  
SD Hamann
Keyword(s):  
Free Energy ◽  
Critical Micelle Concentration ◽  
Aggregation Number ◽  
Micelle Formation ◽  
Free Energy Of Formation ◽  
Energy Of Formation ◽  
The Way

It is shown that a formula proposed recently, to express the way in which the free energy of formation of molecular micelles depends upon the aggregation number of the micelles, is incorrect. The correct relationship is derived.

THE EXTRACTION OF PLUTONIUM FROM NEUTRON-IRRADIATED URANIUM BY URANIUM TRICHLORIDE AND BY MAGNESIUM CHLORIDE

1958 ◽  
Vol 36 (9) ◽  
pp. 1233-1240 ◽  
Author(s):  
D. E. McKenzie ◽  
W. L. Elsdon ◽  
J. W. Fletcher
Keyword(s):  
Free Energy ◽  
Magnesium Chloride ◽  
Standard Free Energy ◽  
Standard Free Energy Change ◽  
Magnesium Metal ◽  
Equilibrium Reaction ◽  
Rate Of Reaction ◽  
Uranium Trichloride ◽  
Preliminary Study ◽  
Kinetics Of

The extraction of plutonium from neutron-irradiated uranium by uranium trichloride and by magnesium chloride has been examined in the temperature range 1150° to 1250 °C. The results of the uranium trichloride experiments have been used to evaluate the standard free-energy change of the equilibrium reaction [Formula: see text] These free-energy values have been used to predict the plutonium extraction in the magnesium chloride experiments on the assumption that the uranium trichloride, continuously formed from the non-equilibrium reaction [Formula: see text] rapidly established the above equilibrium with the plutonium in the uranium. Agreement between predicted and experimental results supports this assumption.A preliminary study of the kinetics of the MgCl2–U reaction showed that the initial rate of reaction is controlled by the distillation of magnesium metal from the reaction zone.

scholarly journals The equilibrium constants of the glutamate dehydrogenase systems

1967 ◽  
Vol 105 (2) ◽  
pp. 691-695 ◽  
Author(s):  
P. C. Engel ◽  
K. Dalziel
Keyword(s):  
Free Energy ◽  
Ionic Strength ◽  
Glutamate Dehydrogenase ◽  
Thermodynamic Data ◽  
Equilibrium Constants ◽  
Standard Free Energy ◽  
Free Energy Change ◽  
Energy Change ◽  
Heat Of Reaction ◽  
Standard Free Energy Change

1. Equilibrium constants for the oxidation of glutamate by NAD+ and NADP+, catalysed by glutamate dehydrogenase, have been measured in phosphate buffers of different ionic strengths and at several temperatures. 2. The equilibrium constants for both systems vary markedly with ionic strength. Thermodynamic values for the two systems obtained by extrapolation to zero ionic strength differ significantly from one another. The standard free-energy change for NADP+ reduction has been calculated from that for NAD+ reduction. 3. The heat of reaction has been estimated and is the same with both coenzymes. 4. The thermodynamic data are discussed in relation to earlier data.

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