Surface tension of aqueous solutions

FIGURE 3.1 Change in surface tension of water as a function of added solutes (inorganic salts such as NaCl, surface-active agents such as butyric acid). 

FIGURE 3.2 Surface tension plot of -butanol solutions. 

The y of water changes slowly as compared to detergent solutions. Methanol-water mixtures gave the following y data (at 20°C)  

FIGURE 3.3 Surface tension data of a homologous series of short-chain acids in water. 

However, it should be noted that such dependence in the case of nonlinear alkyl chains will be different. The effective -CH2- increase in the case of nonlinear chains will be lesser (ca. 50%) than in the case of a linear alkyl chain. The tertiary -CH2-group effect would be even lesser. In general, though, one will expect that the change in y per mole substance will increase with any increase in the hydrocarbon group of the amphiphile. 

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The higher members of the series decrease the surface tension of aqueous solutions well below the point possible with any type of hydrocarbon surfactant, although in practice because of their strong acid character and solubiUty characteristics, more commonly salts and other derivatives are employed. A 0.1% solution of C F COOH has a surface tension of only 19 mN/m (dyn/cm) at 30°C (6). 

Surface Tension. The surface tension of aqueous solutions of PVA varies with concentration (Fig. 10), temperature, degree of hydrolysis, and acetate distribution on the PVA backbone. Random distribution of acetyl groups in the polymer results in solutions having higher surface tension compared to those of polymers in which blocks of acetyl groups are present (74—77). Surface tension decreases slightly as the molecular weight is reduced (Fig. 11). 

Depression of the surface tension of their aqueous solutions and other surface-active properties are given in Chap. 4. When fluorine is changed for hydrogen in the alkyl chain of a phosphonate the compound becomes less heat-sensitive. Often the surface tension of aqueous solutions of these compounds is very low. 

The maximal accessible depression of the surface tension of aqueous solutions of disodium alkanephosphonates is strongly controlled by the length of the carbon chain. There is a similar dependence of foamability on the length of the alkyl chain [188], as is shown in Table 8. 

Monoamidotriphosphate compounds have been evaluated for their combined detergent-sequestrant action [65,66]. Good surfactant properties are also attributed to organoaminodialkylenephosphonic acids. Typical compounds of this kind are the tetra- and trialkali salts of decyl-, dodecyl-, and tetradecylaminodi (methylphosphonate). Values of surface tension and detergency are given in Refs. 118 and 216-219. Wash test results, foam behavior, wetting performance, and surface tensions of aqueous solutions of phosphate esters have been tabulated [12,17,18,33,37,50,52,56,90,220]. 

Retention in HIC can be described in terms of the solvophobic theory, in which the change in free energy on protein binding to the stationary phase with the salt concentration in the mobile phase is determined mainly by the contact surface area between the protein and stationary phase and the nature of the salt as measured by its propensity to increase the surface tension of aqueous solutions [331,333-338]. In simple terms the solvopbobic theory predicts that the log u ithn of the capacity factor should be linearly dependent on the surface tension of the mobile phase, which in turn, is a llne2u function of the salt concentration. At sufficiently high salt concentration the electrostatic contribution to retention can be considered constant, and in the absence of specific salt-protein interactions, log k should depend linearly on salt concentration as described by equation (4.21)... 

Weissenbom PK, Pugh RJ (1996) Surface tension of aqueous solutions of electrolytes relationship with hydration, oxygen solubility, and bubble coalescence. J Colloid Interface Sci 184 550-553... 

Surfactants are well-known protein denaturants. However, when sufficiently dilute, some surfactants (e.g. polysorbate) exert a stabilizing influence on some protein types. Proteins display a tendency to aggregate at interfaces (air—liquid or liquid—liquid), a process that often promotes their denaturation. Addition of surfactant reduces surface tension of aqueous solutions and often increases the solubility of proteins dissolved therein. This helps reduce the rate of protein... 

Measurements of the surface tension of aqueous solutions of various sulphonated and unsulphonated phenylazonaphthol dyes showed that the degree of surface activity (that is, the lowering of surface tension) tended to increase progressively with the degree of alkyl substitution in the series of dyes [7]. The surface-active behaviour of such alkylated dye ions ensures that they become more concentrated at the interface between the dyebath and the fibre surface, just as they do at the air-water interface of the dye solution. Foaming of dyebaths can be a serious practical problem with relatively hydrophobic dye structures solubilised by means of a single ionised group. 

Fig. 3 Surface tension of aqueous solutions of C12H25 (-0-CH2-CH2-)jjj0S03Na at 25°C (purity 98-99.5%)...

The capillary-rise method was employed to measure the surface tension of aqueous solutions of disodlum alkyl phosphate at 25 °C. The cmc values of the solutions were obtained from the discontinuity in the surface tension - concentration curves(7). 

Figure 1, Surface tension of aqueous solutions of C7pNa and lil RDH-CyFNa at 3D C (with NaCl, ionic strength = D.1 m).

Figure 5, Surface tension of aqueous solutions of CaNBr-C/FIMa system at SO C (with NaBr, ionic strength = 0.1 mj C = CCgNBr except curve 2).

Figure 4.10 Surface tension of aqueous solutions of alcohols at 20°C...

The surface tensions of aqueous solutions of sodium dodecyl sulphate at 20°C are as follows ... 

Chen, Y., and Schnitzer, M. (1978). The surface tension of aqueous solutions of soil humic substances. Soil Sci. 125, 7-15. 

Very small amounts of type 3 solutes produce a dramatic lowering of the surface tension of aqueous solutions. A substance with this property is called a surfactant. Usually, they consist of hydrocarbon chains, with n = 10-20 connected to polar groups (such as -OH, -CN, -COOH, -COOR, or -CONH2) or ionic groups (such as -SO,, -OSO,, or -NR3+). They exclusively concentrate at the water-air interface. A monolayer of this type of... 

It was recently suggested that the van der Waals interactions of the ions with the system can explain the ion specific effects [13], and it was shown that by accounting for this interactions one can successfully predict the dependence of surface tension of aqueous solutions of electrolytes on their concentration [14,15], In the first pad of this article [7], it was shown that the ion-hydration interaction can also explain the surface tension behaviour. 

First let us note that experiment revealed long ago that not all ions prefer the bulk to the interface [8]. Gibbs adsorption equation predicts that the surface tension increases with the electrolyte concentration when the total surface excess of ions is negative. The conventional picture, that the ions prefer the bulk, is probably due to Langmuir, who noted that the increase in the surface tension of aqueous solutions of simple salts with increasing concentration can be explained by assuming a surface layer of pure solvent with a thickness of about 4 A [9]. However, because the aqueous solutions of some simple acids (such as HC1) possess surface tensions smaller than that of pure water [8], Gibbs adsorption equation indicates a positive total... 

Kollicoat IR is a unique polymer for pharmaceutical applications prepared by a graft polymerization process of polyethylene glycol (25%) with polyvinyl alcohol (75%). Kollicoat IR dissolves quickly in water and aqueous solutions of acid and alkali and reduces the surface tension of aqueous solutions to allow the solutions to have high spray rates. The polymer film is very flexible, not tacky, and easily colored. The polymer can be used as instant release coating, pore former, binder, protective colloid, etc. 

Traube,1 in an extended investigation of the surface tension of aqueous solutions of many organic compounds, established several important points, of which the significance for the structure of the adsorbed films has been pointed out by Langmuir.2... 

Surface Tension of Aqueous Surfactant Solutions. The 25-26-mN / m range is the best range that methylsilmethylene- and methylsilane-based surfactants can lower the surface tension of aqueous solutions, as demonstrated by the work of Maki and co-workers at the University of Osaka (82-85). Some selected data relevant to the comparison of methylsilmeth-... 

Attenuated total reflection infrared critical micelle concentration electron spectroscopy for chemical analysis hydrophilic-lipophilic balance poly(chlorotrifluoroethylene) poly(dimethylsiloxane) poly(tetrafluoroethylene) poly(trifluoropropylmethylsiloxane) glass transition temperature critical surface tension of wetting Owens-Wendt solid surface tension surface tension of aqueous solution surface tension of liquid... 

Surface Tension of Aqueous Solutions (updated guideline, adopted July 27, 1995)... 

Materials. Sodium lauryl sulfate was purchased from Aldrich Chemical Company, Inc. and its constitution has been reported in detail (14). The material is a blend of C-12, C-14 and C-16 sodium sulfates. It was purified by extraction with diethyl ether and then by recrystallization from absolute ethanol. The surface tension of aqueous solutions of this material was measured as a function of concentration. A curve with a single break resulted indicating a CMC... 

Permprasert, J. and Devahastin, S. 2005. Evaluation of the effects of some additives and pH on surface tension of aqueous solutions using a drop-weight method. Journal of Food Engineering 70 219-226. 

The surface tension of binary mixtures of water + monoethanolamine and water + 2-amino-2-methyl-l-propanol and tertiary mixtures of these amines with water from 25 to 50°C have been reported. = The surface tension of aqueous solutions of diethanolamine and triethanolamine from 25 to 50°C have been analyzed. ... 

FIGURE 5-4 Surface tension of aqueous solutions of isomeric p-dodecylbenzenesulfo-nates at 75°C as a function of their concentration. Reprinted with permission from W. Greiss, Fette, Seifen, Anstrichm. 57, 24, 168, 236 (1955). 

Theories concerning the mechanisms of operation of this film elasticity depend on two observations concerning the surface tension of aqueous solutions of surface-active solutes (1) its increase in value with decrease in concentration of the surface-active solute, at concentrations of the latter below the CMC, and (2) the time required for it to obtain its equilibrium value (the fact that the initial value of these surface tension at a new surface is always greater than the equilibrium... 

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