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Title of Thesis

Bushra Naeem
Institute/University/Department Details
Department of Chemistry/ Quaid-i-Azam University Islamabad
Physical Chemistry
Number of Pages
Keywords (Extracted from title, table of contents and abstract of thesis)
micellar system, dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, cetyltrimethylammonium bromide, sodium dodecylsulfate, potassium dodecylsulfate, sodium dodecylbenzenesulfonate, hemicyanine dyes, micellization, solubilization, polynuclear aromatic hydrocarbons, amphiphilic hemicyanine dyes

Surfactants are known for their ability to form self-assembled aggregates called micelles. Micellization phenomenon is important industrially as well as biologically and is very interesting chemically. The micelles in aqueous solution have a profound effect on the solubility of organic substances otherwise sparingly soluble in water. The present work €œSolubilization of different organic compounds in micellar system€ has been divided into two parts.

The first part deals with the study of micellization of surfactants at different temperatures ranging from 293 K to 313 K by using conductivity method. The various surfactants used were cationic in nature, dodecyltrimethylammonium bromide (DT AB), tetradecyltrimethylammonium bromide (TT AB), and cetyltrimethylammonium bromide (CT AB) and anionic in nature, sodium dodecylsulfate (SDS), potassium dodecylsulfate (KDS), and sodium dodecylbenzenesulfonate (SDBS). Using the CMC values, the thermodynamic parameters of micellization such as free energy change (”Gº), enthalpy change (”Hº) and entropy change (”Sº) of micellization are also computed. To study the solubilization of additives on micellization of surfactants and thermodynamics of these systems, the additives used were hemicyanine dyes with varying alkyl chain length Different concentrations of dyes are used and it has been observed that the CMC of the surfactants decreases linearly with an increase in the concentration of added dyes which is more prominent in the case of dye having longer alkyl chain. The rate of CMC depression is obtained by plotting CMC Vs. concentration of additives (dyes).

The second part deals with the study of interactions between different additives and surfactants by UV-visible absorption spectroscopy. Three types of compounds were used as additives namely hemicyanine dyes, the flavonoids and polycyclic hydrocarbons and their derivatives. The simple absorption spectra were recorded to study the interaction between additives and surfactants (concentration ranging below CMC to above CMC). This simple absorption data is also used to determine the approximate number of additive molecules incorporated per micelle of surfactant. The hemicyanine dyes are sensitive to pH, so their interaction with the surfactants has been studied in different media (aqueous, acidic, and basic) too. The partition coefficient Kx, of additives between the bulk water phase and micellar phase of surfactants were determined at 298 K by differential spectroscopic method. The standard free energy change of solubilization, ”Gºp and relative solubility St/Sº are also determined for all additives by using partition coefficient values. The effect of different concentrations below and above micellization of surfactants on the UV-visible spectra of additives is discussed qualitatively. Incorporation of additive molecules in micelle shifts the spectra of additives, which depends upon both hydrophobic and electrostatic interactions between the surfactants and additives. These models of qualitative and quantitative studies of interactions and solubilization of surfactants and additives may be used to mimic these interactions with those in biological processes in cell membranes.

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8830.32 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
722.01 KB
2 1 Introduction 1
304.15 KB
  1.1 Motivation Work 3
  1.2 References 5
3 2 Colloidal System Solubilization 9
2610.47 KB
  2.1 Colloidal Systems 9
  2.2 Micellization 12
  2.3 Solubilization Of Organic Compounds 14
  2.4 Organic Additives 15
  2.5 Micellization Process 20
  2.6 Solubilization Process 38
  2.7 Theoretical Approaches 46
  2.8 References 56
4 3 Experimental Procedure 66
286.98 KB
  3.1 Chemicals 66
  3.2 Solution Preparation 67
  3.3 Conductance Measurements 67
  3.4 Ultraviolet Visible Spectroscopic Measurements 69
  3.5 References 71
5 4 Results And Discussion 72
5189.15 KB
  4.1 Conductometric Studies 72
  4.2 Amphiphilic Hemicyanine Dyes 120
  4.3 Polynuclear Aromatic Hydrocarbons 160
  4.4 Flavonoids 186
  4.5 References 225
  4.6 Conclusions 230