C. Gomez Herrera

Specific viscosity of Newtonian aqueous solutions containing an anionic surfactant and an alkaline pyrophosphate

The effects that both temperature and solute concentrations exert on specific viscosity are studied in this paper. The products used were sodium or triethanolammonium dodecylsulfates or dodecylbenzenesulfonates, as surfactants, and tetrasodium or tetrapotassium pyrophosphates, as electrolytes. All are of technical quality. As temperature decreases, within the temperature range studied, a phase separation or an appearance of non-Newtonian behavior is noted in many solutions. The solutions studied fit, within the accuracy range for experimental measurements, an empirical equation that agrees with what is called the activated diffusive relaxation model. For this model, the relative viscosity is a linear superposition of stresses coming from hydrodynamic interactions and from activation energy due to structural relaxation of the uniform distribution of micelles in the quiescent micellar solution. Solutions containing a dodecylsulfate show very slight hydrodynamic effects. Their activation energy, which is independent of temperature, becomes greater by increasing the concentrations of surfactant and pyrophosphate. The specific viscosities of these solutions also increase by replacing the triethanolammonium counter-ion with sodium. Solutions containing sodium dodecylbenzenesulfonate show considerable hydrodynamic effects, which increase with the addition of tetrasodium pyrophosphate. The activation energy is independent of temperature. Solutions containing triethanolammonium dodecylbenzenesulfonate show decreasing activation energy values when temperature is increased. Consequently, a maximum for specific viscosity appears at a certain temperature. This maximum diminishes progressively with the addition of pyrophosphate, while the corresponding temperature becomes higher. From the investigation carried out, the necessity for further basic studies remains clear. Research should be done on concentrated aqueous solutions containing surfactants and electrolytes, taking into consideration the variations that their dynamic viscosities present along with composition and temperature. All of this, naturally, must be carried out before developmental research on manufacturing, commercialization and usage of such solutions proceeds.

Some characteristics of the membranes protecting oil emulsions in protein solutions

Expressed olive juice contains emulsified globules of olive oil. Electron photomicrographs of these globules show a rough membrane protecting them against coalescence. Some features of the membranes, such as the existence of “poles” and deposited microcrystals, are disclosed by the photographs and by electron diffraction patterns. Heavy metals appear to concentrate in the membranes and not in the aqueous medium.

SYNTHESIS, IDENTIFICATION AND SURFACE ACTIVITY OF 2-AMINE-2-DEOXY-3-O-n-OCTYL-D-GLUCOPYRANOSE HYDROCHLORIDE

Abstract The synthesis and identification of this product are described. Variations of surface tension of its aqueous solutions versus concentration (ranged between 3 and 95 mmol/L) and temperature (ranged between 20.0 and 47.5°C) are studied. The isothermal plots of surface tension versus the logarithm of the concentration show a continous decrease, with a sharp change of slope at a concentration about 6.5 mmol/L, for all the studied temperatures. A second change of slope, less pronounced, appears for a higher concentration. This concentration value increases from 28 to 42 mmol/L when temperature is raised from 20.0 to 47.5°C. The changes of slope can be attributed mainly to micellization of neutral amine molecules resulting from hydrolysis of surface active cations, which present a weak electrolytic character.

Effects of builder addition on characteristics of aqueous systems containing surfactant and other ingredients of detergent formulations

ABSTRACT The builders tested were: pentasodium triphosphate, trisodium nitrilotriacetate, trisodium citrate, and tris(triethanolammonium) citrate. The characteristics measured were: stability in hard water, foaming power, wetting power for raw cotton cloth, soil removal efficiency, and redeposition effects. The results of the preliminary exploratory phase show that these builders modify positively or negatively (with different statistical significance)the values of the measured characteristics. Therefore a clear and single behaviour pattern cannot be established without more extensive research. Modifications of the measured