Thermodynamics of the micellization process of carboxylates: A conductivity study

2015 ◽  
Vol 83 ◽  
pp. 117-122 ◽  
Author(s):  
Žiga Medoš ◽  
Marija Bešter-Rogač
Keyword(s):  
Micellization Process

Micellization Behaviour of Cationic Surfactants in the Presence of Food Additives: Conductance and Spectroscopic Investigations

2020 ◽  
Vol 10 ◽  
Author(s):  
Sonika Arti ◽  
Neha Aggarwal
Keyword(s):  
Glutamic Acid ◽  
Cationic Surfactants ◽  
Hydrophobic Interactions ◽  
Food Additives ◽  
Specific Conductance ◽  
Food Additive ◽  
Nmr Studies ◽  
Degree Of Ionization ◽  
Increase With Increase ◽  
Micellization Process

Aim: The micellization behavior of cationic surfactants have been studied in the presence of food additives. Objectives: Micellization behaviour of cationic surfactants, cetyltrimethylammonium bromide (CTAB) and tetradecyltrimethylammonium bromide (TTAB) has been studied in water and in various concentrations of salts (food additives) L-glutamic acid, sodium propionate, sodium citrate tribasic dihydrate and disodium tartrate dihydrate at (298.15, 308.15 and 318.15) K. Methods: Two methods used in the present study are specific conductance measurements and spectroscopy (NMR) studies. Results: From the specific conductance(κ), various parameters such as critical micelle concentration (CMC), degree of ionization of micelle (α), standard Gibbs free energy (ΔGom), enthalpy (ΔHom), and entropy (ΔSom) of micellization have also been calculated. Thermodynamic parameters related to the micellization process were also analyzed through NMR studies. Conclusion: The CMC values are influenced by the presence of food additive. The magnitude of CMC values increase with increase in concentration of food additive. In all the cases, enthalpy of micellization, ∆Hom values are found to be negative whereas entropy of micellization, ∆S om values are positive which indicate that hydrophobic interactions play a major role in the micellization process. Also, NMR studies reveal that tartrate and citrate are more hydrated than glutamic acid and propionate, resulting in more downfield shift.

scholarly journals A Study of Local Anaesthetics. Part 202. Determination of the Critical Micellar Concentration of Carbisocainium Chloride in Water Using Spectral Methods and the Probe Pyrene

2013 ◽  
Vol 60 (1) ◽  
pp. 1-6 ◽  
Author(s):  
J. Gališinová ◽  
F. Andriamainty ◽  
I. Malík ◽  
J. Čižmárik ◽  
J. Karlovská ◽  
...  
Keyword(s):  
Spectral Methods ◽  
Emission Spectroscopy ◽  
Surfactant Concentration ◽  
Fluorescence Emission ◽  
Local Anaesthetics ◽  
Critical Micellar Concentration ◽  
Ratio Data ◽  
Micellization Process ◽  
Second Procedure

The micellization process of the local anaesthetic carbisocainium chloride in water was investigated by two spectral methods using the probe pyrene. First, the absorption spectroscopy in UV/VIS region was based on studying changes in characteristic absorption spectrum of pyrene in presence of surfactant. The resultant plot of the sum of absorbances for all the major pyrene peaks as a function of the total surfactant concentration shows, around the critical micellar concentration, a typical sigmoidal increase. The fluorescence emission spectroscopy in UV/VIS region of spectrum by the probe pyrene, second procedure, was applied for determination of the cmc from the measurements of the pyrene I1 /I3 ratio as a function of the surfactant concentration. The pyrene ratio data were fitted by the Boltzmann-type sigmoid of decreasing character.

scholarly journals Equilibrium and kinetic studies of the aggregation of porphyrins in aqueous solution

1976 ◽  
Vol 153 (2) ◽  
pp. 279-285 ◽  
Author(s):  
S B Brown ◽  
M Shillcock ◽  
P Jones
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Temperature Jump ◽  
Critical Concentration ◽  
Protoporphyrin Ix ◽  
Kinetic Studies ◽  
Aggregation Processes ◽  
Micellization Process ◽  
Increasing Temperature ◽  
Dimerization Process

An investigation of the behavior of protoporphyrin IX, deuteroporphyrin IX, haematoporphyrin IX and coproporphyrin III in aqueous solution revealed extensive and complex aggregation processes. Protoporphyrin appears to be highly aggregated under all conditions studied. At concentrations below 4 μM, aggregation of deutero-, haemato- and coproporphyrin is probably restricted to dimerization. At approx. 4muM each of these three porphyrins exhibits sharp changes in spectra consistent with a “micellization” process to form large aggregates of unknown size. This critical concentration increases with increasing temperature and pH, but is not very sensitive to variation in ionic strength. Temperature-jump kinetic studies on deuteroporphyrin also imply an initial dimerization process, the rate constants for which are comparable with those for various synthetic porphyrins, followed by a further extensive aggragation. The ability of a particular porphyrin to dimerize appears to parallel that of the corresponding iron(III) complexes (ferrihaems), although it is thought that ferrihaems do not exhibit further aggregation under these conditions.

Influence of External Factors on the Micellization Process and Aggregate Structure of Poly(oxy)styrene−Poly(oxy)ethylene Block Copolymers

2008 ◽  
Vol 112 (17) ◽  
pp. 5296-5304 ◽  
Author(s):  
Emilio Castro ◽  
Silvia Barbosa ◽  
Josué Juárez ◽  
Pablo Taboada ◽  
Issa A. Katime ◽  
...  
Keyword(s):  
Block Copolymers ◽  
External Factors ◽  
Aggregate Structure ◽  
Micellization Process

Volumes and heat capacities of transfer of ammonium salts from water to aqueous octyldimethylamine oxide at 25 °C

1988 ◽  
Vol 66 (4) ◽  
pp. 767-773 ◽  
Author(s):  
Daniel Hétu ◽  
Jacques E. Desnoyers
Keyword(s):  
Aqueous Solutions ◽  
Thermodynamic Functions ◽  
Transfer Functions ◽  
Hydrophobic Interactions ◽  
Critical Micellar Concentration ◽  
Heat Capacities ◽  
Ammonium Salts ◽  
Salting Out ◽  
Ionic Systems ◽  
Micellization Process

The effect of an additive on a water–surfactant system can be studied through thermodynamic functions of transfer of the additive from water to aqueous solutions of the surfactant. These thermodynamic functions often go through extrema in the region of the critical micellar concentration (cmc) of the surfactant. As it can be shown with a simple chemical equilibrium model, the general shape of the transfer functions is primarily related to the pair-wise hydrophobic interactions between the additive and the surfactant monomers, to a shift in the monomer–micelle equilibrium and to the distribution of the additive between the aqueous phase and the micelles. Medium and electrostatic effects are also possible, especially with ionic systems. To separate these effects and identify the salts which distribute themselves in the micelles, the volumes and heat capacities of transfer of hydrophobic ammonium salts from water to aqueous solutions of dimethyloctylamine oxide have been investigated. The short chain salts have only a small effect on monomer–micelle equilibrium by salting out the monomers, whereas the more hydrophobic ones participate also to the micellization process, shifting more strongly the surfactant monomer–micelle equilibrium.

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