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Wyszukujesz frazę "surface-active agents" wg kryterium: Wszystkie pola

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    Tytuł:
    Współczesne zastosowania związków powierzchniowo czynnych
    Modern applications of surface active agents
    Autorzy:
    Dywicki, Paweł
    Grabowska, Ola
    Chmurzyński, Lech
    Powiązania:
    https://bibliotekanauki.pl/articles/172143.pdf
    Data publikacji:
    2020
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    związki powierzchniowo czynne
    rolnictwo
    przemysł spożywczy
    przemysł farmaceutyczny
    biosurfaktanty
    surface active agents
    agriculture
    food industry
    pharmacy industry
    biosurfactants
    Opis:
    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.
    Źródło:
    Wiadomości Chemiczne; 2020, 74, 5-6; 391-409
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Zastosowanie polimerowych membran ultrafiltracyjnych do usuwania substancji powierzchniowo czynnych z roztworów wodnych
    Separation of surface active agents from water solutions using polymer ultrafiltration membranes
    Autorzy:
    Kowalska, I.
    Powiązania:
    https://bibliotekanauki.pl/articles/1825969.pdf
    Data publikacji:
    2008
    Wydawca:
    Politechnika Koszalińska. Wydawnictwo Uczelniane
    Tematy:
    związki powierzchniowo czynne
    membrany ultrafiltracyjne
    surfaktanty
    SPC
    dodecylobenzenosulfonian sodu
    SDBS
    membrany płaskie
    Opis:
    Celem przeprowadzonych badań było określenie skuteczności polimerowych membran ultrafiltracyjnych w usuwaniu substancji powierzchniowo czynnych z roztworów wodnych w zakresie stężeń poniżej i powyżej krytycznego stężenia micelizacji. Zbadano również wpływ obecności soli mineralnych będących podstawowym wypełniaczem kompozycji detergentowych na skuteczność eliminacji SPC z roztworów wodnych w procesie ultrafiltracji.
    Surface active agents, also called surfactants, are amphiphilic compounds that contain both a hydrophobic and a hydrophilic portion. In aqueous solutions, surfactant monomers aggregate into structures called micelles with hydrophobic groups in the interior of the micellar structures. The minimum concentration at which micellization occurs is called the critical micelle concentration (CMC). At higher concentrations than CMC, monomers and micelles coexist in equilibrium. Surface active agents are used in large quantities in household products, detergent formulations, industrial application and as additives to improve the effectiveness of agrochemicals. The consumption of surfactants for both industrial and domestic purpose has resulted in a worldwide production of approximately 17 million tonnes in 2000 (including soap), with expected future growth rates of 3-4% per year globally and of 1.5-2.0% in the EU [19]. As a consequence of their widespread use surfactants may persist in wastewater treatment systems at relatively high concentrations [13, 18]. In order to meet legislative requirements and to discharge effluents into communal systems or directly into the river an efficient treatment process must be applied. Due to the diversity of surfactants and their physico-chemical properties it is difficult to develop a single and an effective treatment method of detergent wastewater. From among techniques which were studied in this research area [3, 5, 10, 14, 16] can be listed biodegradation, coagulation, foaming, oxidation, adsorption, ion-exchange and membrane processes. Numerous reports indicate that membrane technology is emerging as one of the leading contenders in the recovery of water and concentrated products from the rinsing waters used in the batch production of surfactants and detergents or as a polishing step before the effluents are discharged. The aim of the study was to evaluate the removal efficiency of anionic surfactant from water solutions by means of ultrafiltration. Polymer membranes made of polyethersulfone and cellulose with molecular weight cut-off of 5, 10 and 30 kDa were used. Both transport and separation properties of the polymers were tested for surfactant solutions in concentration range of 0.1-3.0 CMC in a presence of mineral salt (NaCl). It was found that the surfactant concentration was a crucial parameter determining effectiveness of ultrafiltration process. With the increase in surfactant concentration, the retention coefficients and hydraulic performance decreased, with a rise around the CMC value. The UP005 membrane was found to be very effective in anionic surfactant removal in a wide range of concentrations - the retention coefficient amounted to 82-90%. During the permeation experiments in the presence of mineral salt, the increase in retention coefficient was observed for a given dose of mineral salt along with the increase in surfactant concentration in the feed
    Źródło:
    Rocznik Ochrona Środowiska; 2008, Tom 10; 593-604
    1506-218X
    Pojawia się w:
    Rocznik Ochrona Środowiska
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Metody wyznaczania krytycznego stężenia micelarnego związków powierzchniowo czynnych
    Methods for determining critical micellar concentration of surfactants
    Autorzy:
    Grabowska, Ola
    Dywicki, Paweł
    Chmurzyński, Lech
    Powiązania:
    https://bibliotekanauki.pl/articles/171754.pdf
    Data publikacji:
    2020
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    związki powierzchniowo czynne
    krytyczne stężenie micelarne
    konduktometria
    elektroforeza kapilarna
    izotermiczna kalorymetria miareczkowa
    metoda luminescencyjna
    surface active agents
    critical micelle concentration
    conductometry
    capillary electrophoresis
    isothermal titration calorimetry
    luminescent method
    Opis:
    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.
    Źródło:
    Wiadomości Chemiczne; 2020, 74, 5-6; 371-390
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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