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2 Wiadomości Chemiczne

2 2020

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Współczesne zastosowania związków powierzchniowo czynnych

Dywicki Paweł, Grabowska Ola, Chmurzyński Lech

Wiadomości Chemiczne

2020

[Z] 74, 5-6

391--409

Surfactants have been known to mankind since the dawn of time. They have been used primarily as washing and cleaning agents. However, today they are used much more often in many fields of industry. This work focuses on two areas of surfactants use, the agriculture and the food industry due to the direct relationship between these two issues. In agriculture, surfactants play a number of important roles. One of the problems of modem agriculture is the low efficiency of spraying, associated with the low absorption of liquid utility for plants. This problem is solved by surfactants, as demonstrated by the example of glyphosate and the organosilicon compound Silwet® L-77. Nowadays, substitutes for conventional surfactants are being sought. Compounds produced by microorganisms are under great interest of scientists. It has been shown that they are characterized by the lower toxicity as well as high biodegradability, while maintaining the characteristics and properties of synthetic compounds. Directly related to the agriculture, the food industry also often uses surfactants. In the production and processing of food surfactants play the role of such compounds as emulsifiers, stabilizers, additives improving the texture of products and increasing the durability of products. Sorbitan esters, e.g. sorbitan monolaurate, their ethoxylated derivatives, e.g. Polysorbate 20, as well as sucrose esters, e.g. sucrose monostearate, are readily used for this purpose. Great emphasis is placed on the safety of compounds used in the food industry. As in the case of agriculture, biosurfactants and compounds of natural origin are tested for use in the food industry. Their use is not limited to being ingredients of products. They can play a biocidal, as well as a protecting role against surface colonization by microorganisms.

Metody wyznaczania krytycznego stężenia micelarnego związków powierzchniowo czynnych

Grabowska Ola, Dywicki Paweł, Chmurzyński Lech

Wiadomości Chemiczne

2020

[Z] 74, 5-6

371--390

Surface active agents, also known as surfactants, are a group of chemical compounds that are used in various products of the chemical industry. These compounds are components of medicines, detergents, motor oils and many others. The multitude of uses of surfactants makes it important to know their aggregation behaviour in solution. There are many methods used to analyse surfactants behaviour in liquid phase. The choice of a particular technique usually depends on the chemical structure of the surfactant. An example of a method that is used in studies of ionic surfactants is conductometry. This technique allows to study the dependence of specific conductivity on surfactant concentration, enabling determination of critical micellar concentration (CMC). Capillary electrophoresis is another example of the method used to determine the critical micellar concentration. It allows to make measurements in conditions where other methods fail, including conductometric method. Surfactant solutions differ in viscosity, which changes with the appearance of micelles in solution. Measurement of marker compound migration time through surfactant solutions of various concentrations allow to determine critical micellar concentration. Isothermal titration calorimetry (ITC) allows to study the thermal effects associated with the aggregation of surfactants into micelles. Based on the energy changes that occur during titration, the critical micellar concentration of surfactant can be precisely determined. ITC is very sensitive method, so basically it can be used to examine all types of surfactants. In addition, the ITC method allows to determine the thermodynamic parameters of the undergoing micellization process. The use of several measuring methods gives a more complete picture of the phenomena occurring in solutions. It allows to understand aggregation process more accurately. Therefore, CMC measurement are often made with the use of several complementary methods.