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Nature of Surfactants

The term surfactants covers water-soluble, surface-active compounds which are used for wetting, washing, emulsifying and dispersing. Surfactants are characterised in that they concentrate at surfaces and reduce the surface tension. The term tensides, the German word for surfactants, is derived from the Latin It is based on the root tensio . A prerequisite for this surface activity is an asymmetric structure of the surfactant molecule which consists of a water-repellent = hydrophobic and a water-attracting = hydrophilic part [4]. [Pg.164]

In soap, the hydrophobic group is a relatively long aliphatic hydrocarbon radical the carboxyl group, characteristic of acids and neutralised with an alkali, acts as the hydrophilic group. In order to obtain new surfactants with improved properties, these two groups are varied, at first empirically and then systematically. The hydrophilic and hydrophobic parts of the surfactant molecule are in a balanced mutual relationship. Depending on the molecular structure, the character of the [Pg.164]

Acylamino Alkylamino polyglycolethers (Ethoxylates) Polyol esters [Pg.165]


The aim of this work was to study the influence of a second ligand, the concentration and nature of surfactants on flumequine-sensitized fluorescence of lanthanides and the usage of such a mixed-ligand complex for fluorimetric determination of flumequine in hen meat tissues. [Pg.380]

TRADE NAME SUPPLIER CHEMICAL FORMULA OF MAJOR SYNTHESISED PRODUCT % SURFACTANT ACTIVITY NATURE OF SURFACTANT COMPOSITION INORGANIC SALT CONTENT/ WATER CONTENT/ ... [Pg.309]

As the nature of surfactants varies from relatively apolar, non-ionic to essentially highly polar or ionic species, with, in addition, varying specific characteristics such as persistence towards (bio)chemical or physical degradation, the sample treatment may also vary considerably. [Pg.444]

The actual solubilization limit depends on the temperature, the nature of surfactant, the concentration of water, and on the nature of the acid. Irrespective of size or the specific properties of the solubilized molecules, very little is known about the thermodynamics or the kinetics of the solubilization process. The association of the solute with the interface can be checked using techniques capable of yielding detailed microscopic information at the molecular level (e.g. NMR, ESR, fluorescence, hydrated electrons). [Pg.86]

It can be seen that for the A/W interface y decreases from the value for water ( 72 mN m-1), reaching about 25-30 mN m-1 near the cmc. For the O/W interface y decreases from 50 mN m-1 (for a pure hydrocarbon-water interface) to l-5 mN m-1. Clearly the rate of reduction of y with log C below the cmc and the limiting y reached at and above the cmc depend on the nature of surfactant and the interface. [Pg.510]

Surfactants play a major role in the preparation of suspensions of polymer particles by heterogeneous nucleation. In emulsion polymerization, the monomer is emulsified in a nonsolvent (usually water) using a surfactant, whereas the initiator is dissolved in the continuous phase. The role of surfactants in this process is obvious since nucleation may occur in the swollen surfactant micelle. Indeed, the number of particles formed and their size depend on the nature of surfactant and its concentration (which determines the number of micelles formed). [Pg.513]

The prediction of r and as a function of the natures of surfactant, cosurfactant, and hydrophobic phase requires the derivation of expressions for y and C that should account for, among other things, their dependence on the curvature. Such expressions are not yet available. [Pg.274]

Clearly, neutron reflectivity has contributed much to our understanding of the nature of surfactant adsorption at the solid-solution interface. It has already been successfully applied to an extensive range of systems, as illustrated in this chapter. [Pg.112]

Widom has recently formulated a lattice model that takes into account the amphiphilic nature of surfactant and introduces molecular interactions that explicitly affect curvature of surfactant sheetlike structures [25]. [Pg.188]

The percent recovery of the extracted substances in these systems has been found to be dependent on the solution pH (for ion-izable analytes), presence of additives, nature of surfactant, etc. [Pg.54]

I) then a steep, almost vertical, rise Just below the c.m.c. (regime 11). The final, slower Increase in 111 would, on a linear plot, almost look like a plateau. Other Investigators have essentially confirmed these three regimes, with certain modifications. In isotherms reported In the literature, data In region 1 are not always available and the rise in 11 may be less steep, depending on the natures of surfactant and surface, including surfactant heterodlsperslty and surface homogeneity, respectively. [Pg.230]

Gross and coworkers examined the influence of surfactants on the peroxidase-initiated polymerization of acrylamide [21]. Irrespective of the nature of surfactant (cationic, anionic, neutral), they found a significant rate acceleration,... [Pg.152]

In the case of liquid adsorption layers, the deformation by shear occurs at any small load (Fig. 11-29, line 2), and the shear rate, e, is proportional to the applied stress, xs (the torque angle of the thread). The latter allows one to estimate the surface viscosity of the adsorption layer, which is strongly dependent on the nature of surfactants. The adsorption layers may also reveal more complex rheological behavior, intermediate between that of liquids and solids (Fig. 11-29, curve 3). [Pg.124]

The nature of surfactant adsorption on solid surfaces depends on the polarity and solubility of the surfactant. Thus, when an aqueous surfactant solution is in contact with non-polar coal particles, adsorption layers are formed which have polar groups oriented towards the aqueous phase. In contrast, surfactant solutions in oils (hydrocarbons, vegetable oil oxidation products etc.) in contact with polar materials or powders (carbonates, silicates) the polar groups are on the solid phase surface. [Pg.515]

The main advantages of this technique are easy processing, cheap, time saving, and no need of expert for fabrication of organogels through the same. However, its quality is mainly dependent upon the nature of surfactant and the cosurfactant. Maintaining the formed reverse micelles for longer... [Pg.707]


See other pages where Nature of Surfactants is mentioned: [Pg.414]    [Pg.2591]    [Pg.148]    [Pg.293]    [Pg.325]    [Pg.665]    [Pg.423]    [Pg.658]    [Pg.63]    [Pg.227]    [Pg.148]    [Pg.134]    [Pg.85]    [Pg.87]    [Pg.65]    [Pg.88]    [Pg.8]    [Pg.92]    [Pg.253]    [Pg.342]    [Pg.503]    [Pg.105]    [Pg.796]    [Pg.347]    [Pg.2591]    [Pg.148]    [Pg.227]    [Pg.92]    [Pg.125]    [Pg.535]    [Pg.18]    [Pg.54]   


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