magistrsko delo
Rene Urh (Author), Bojan Šarac (Mentor), Jernej Iskra (Thesis defence commission member), Marija Bešter-Rogač (Thesis defence commission member)

Abstract

V magistrskem delu smo raziskovali mešanice dveh kationskih surfaktantov iz skupine decil-, dodecil- ali tetradeciltrimetilamonijevega klorida. Zanimal nas je vpliv razmerja med surfaktantoma z različno dolžino repa na kritično micelno koncentracijo (cmc), sestavo raztopine oz. micel in termodinamiko procesa nastanka mešanih micel. Vrednosti cmc in stopnje ionizacije micel smo ocenili z meritvami električne prevodnosti raztopin. Podatke o cmc in stopnji ionizacije micel smo nato uporabili za izračun standardne Gibbsove proste energije (proste entalpije), standardne entalpije in standardne entropije micelizacije ter za izračun sestave micel. Vrednosti izračunanih entalpij in ocenjene vrednosti cmc surfaktanta TTAC in mešanic TTAC-DeTAC smo nato primerjali z vrednostmi iz kalorimetričnih meritev. Ugotovili smo, da je cmc mešanic močno odvisna od razmerja med surfaktantoma in da jo določa surfaktant z daljšim repom. Vrednosti proste entalpije micelizacije mešanic se nahajajo med vrednostmi čistih surfaktantov in linearno naraščajo z večanjem deleža surfaktanta DeTAC. Pri primerjavi meritev kalorimetrije in prevodnosti smo ugotovili, da lahko obe metodi uporabimo za določevanje vrednosti cmc mešanic. Izračunane entalpije čistih surfaktantov se v večini primerov dobro ujemajo z izmerjenimi, z nekaj odstopanji pri nizkih temperaturah. Sestavo micel smo izračunali z empirično enačbo, ki povezuje cmc čistih surfaktantov in njihovih mešanic, ter iz rezultatov ugotovili, da micele pri cmc vsebujejo večji delež surfaktanta z daljšim repom.

Keywords

micelizacija;termodinamika micelizacije;kritična micelna koncentracija;molekulska teorija micelizacije;magistrska dela;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL FKKT - Faculty of Chemistry and Chemical Technology
Publisher: [R. Urh]
UDC: 544.77.051.62(043.2)
COBISS: 174351619 Link will open in a new window
Views: 77
Downloads: 5
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Other data

Secondary language: English
Secondary title: Research of aqueous solutions of cationic surfactant mixtures by measuring electrical conductivity and calorimetry
Secondary abstract: In the master’s thesis, we investigated mixtures of two cationic surfactants from the group of decyl-, dodecyl- or tetradecyltrimethylammonium chloride. We were interested in the influence of the ration between surfactants with different tail lengths on the critical micelle concentration (cmc), the composition of the solution and micelles, and the thermodynamics of mixed micelle formation. The cmc values and degree of micelle ionization were estimated by measuring the electrical conductivity of the solutions. The values were then used to calculate the standard Gibbs free energy (free enthalpy), standard enthalpy and standard entropy of micellization, and to calculate the micelle composition. The calculated enthalpies and cmc estimations of the surfactant TTAC and the mixtures TTAC-DeTAC were then compared with calorimetric measurements. From the measurements we concluded that the cmc of the mixtures strongly depends on the ration between the two surfactants and is determined by the surfactant with the longer tail. The mixtures values of the free enthalpy of micellization are between those of the puresurfactants and increase linearly with the mole fraction of DeTAC. When comparing the calorimetry and conductivity measurements we found that both methods can be used to determine the cmc values of mixtures. The calculated enthalpies of pure surfactants are in most cases in good agreement with the measured ones, with some deviations at low temperatures. The micelle composition was calculated numerically using an equation that connects the cmc of pure surfactants and their mixtures, from the results we concluded that the micelles at cmc contain a relatively large mole fraction of the surfactant with the longer tail.
Secondary keywords: surfactants;critical micelle concentration;micellization;Površinsko aktivne snovi;Električna prevodnost;Kalorimetrija;Univerzitetna in visokošolska dela;
Type (COBISS): Master's thesis/paper
Study programme: 1000375
Embargo end date (OpenAIRE): 1970-01-01
Thesis comment: Univ. v Ljubljani, Fak. za kemijo in kemijsko tehnologijo, smer Kemija
Pages: 46 str.
ID: 20386148