Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

Browse

Filters

2000 - 200932010 - 20161

Settings

Access type: Open accessSubject: search.filters.subject.Surface active agents

Search Results

Now showing 1 - 4 of 4
  • Article
    Citation - WoS: 13
    Citation - Scopus: 15
    Ancillary Effects of Surfactants on Filtration of Low Molecular Weight Contaminants Through Cellulose Nitrate Membrane Filters
    (Elsevier Ltd., 2016) Olcay, Aybike Nil; Polat, Mehmet; Polat, Hürriyet; Polat, Mehmet; 04.01. Department of Chemistry; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of Technology
    Removal of contaminants with low molecular weight (<800 Dalton) requires the use of advanced separation techniques such as ultrafiltration (UF) or micellar enhanced ultrafiltration (MEUF). However, surface active agents invariably co-exist in waste waters along with these contaminants or they may be added intentionally as part of the separation process as in the case of MEUF. Though it is quite likely that both the filter medium and the contaminants would interact with the surfactant molecules or their micelles, there is not sufficient emphasis in the literature on the concomitant aspects of such interactions.The ancillary effects created by anionic (sodium dodecyl sulfate, SDS), cationic (hexadecyltrimethyl ammonium bromide, CTAB) and non-ionic (ethoxylated octylphenol, TX-100) surfactants on the mechanism and efficiency of the filtration process were investigated in this study. Methylene blue (MB) and cellulose nitrate membrane (CNM) filters were employed as model retentate and the separation medium. A combination of surface tension, contact angle and charge measurements demonstrated that the addition of surfactants had a remarkable effect on the filtration outcome. The effect depended on both the type and concentration of the surfactant and was manifested mainly through the creation of MB-surfactant entities which acted differently than the MB alone; but more importantly, through the interactions of the surfactant molecules/micelles and the MB-surfactant pairs with the separation membrane.
  • Article
    Citation - WoS: 7
    Citation - Scopus: 6
    Surfactant Adsorption and Marangoni Flow in Liquid Jets. 2. Modeling
    (American Chemical Society, 2004) Weiss, Michael; Darton, Richard C.; Battal, Turgut; Bain, Colin D.; 01. Izmir Institute of Technology
    This paper is concerned with the interfacial behavior of surfactant solutions on short time scales. A gravity-driven laminar liquid jet is used to create a rapidly expanding liquid surface, which exposes the surfactant solution to highly nonequilibrium conditions. This expansion causes the surface tension to differ locally from its equilibrium value, generating a (Marangoni) shear stress that acts on the jet surface and retards the surface acceleration. A theory for the flow very near the nozzle shows that the cube-root dependence of the surface velocity on the distance traveled is altered through the adsorption of surfactant. In a boundary-layer treatment, both the surface velocity and the surface concentration increase linearly from the nozzle exit over a short distance, which we term the detachment region. The length of the detachment region is found to vary with the bulk concentration raised to the power 3/2. A numerical model of the surfactant adsorption process in the jet has been developed within the framework of the CFD code FIDAP. The numerical solution confirms the general features of the theory and shows that the maximum reduction in surface velocity occurs very close to the nozzle exit, except at high concentrations. A comparison with experiments on C16TAB at concentrations below the critical micelle concentration, which are described in part 1 of this series of papers, shows good agreement.
  • Article
    Citation - WoS: 22
    Citation - Scopus: 23
    Effect of Some Surfactants on So2-Marble Reaction
    (Elsevier Ltd., 2002) Böke, Hasan; Böke, Hasan; Caner Saltık, Emine N.; 02.01. Department of Conservation and Restoration of Cultural Heritage; 02. Faculty of Architecture; 01. Izmir Institute of Technology
    In the polluted atmosphere, sulphur dioxide (SO2) reacts with calcite (CaCO3) in marble producing calcium sulphite hemihydrate (CaSO3·0.5 H2O) and gypsum (CaSO4·2H2O). Gypsum develops crust at rain-sheltered surfaces and then, being more soluble, accelerates erosion at areas exposed to rain. Eventually, all these lead to significant deformations in the appearance and structure of marble surfaces. Clearly, some precautions must be taken to stop or at least to slow down this deterioration process which destroys our cultural heritage. In this study, we have investigated the possibilities of preventing the SO2-marble reaction by using water-soluble surfactants: Abil Quat 3270 and Tween 20. Experiments for measuring their effects have been carried out at conditions simulating the dry deposition of SO2. Infrared spectrometry and scanning electron microscopy were used to analyze the mineralogical composition and morphology of the reaction products. The extent of sulphation reaction was calculated by determining calcium sulphite hemihydrate and gypsum quantitatively by an IR approach and also by weight increases observed during the progress of SO2-marble reaction. A 10% decrease is observed in the total sulphation with both surfactant applications. The results have been discussed in relation to the possible stages of sulphation reaction and surface reactions of calcite.
  • Article
    Citation - WoS: 20
    Citation - Scopus: 23
    Electrostatic Charge on Spray Droplets of Aqueous Surfactant Solutions
    (Elsevier Ltd., 2000) Polat, Mehmet; Polat, Hürriyet; Polat, Hürriyet; Polat, Mehmet; Chander, Subhash; 04.01. Department of Chemistry; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of Technology
    Electrostatic charges on individual spray droplets were measured using a refined form of the Millikan oil drop method. The measurement system consisted of three main sections; a droplet generation cell, a settling column and a charge measurement chamber. The trajectories required for calculation of charge were determined using a high-speed motion analyzer coupled to a long-focal-length microscope. Charges on droplets were manipulated by the addition of surface-active agents into the spray solution. Droplet charge was a function of the type and concentration of the surfactant added. For ionic surfactants, it showed a maximum at low surfactant concentrations, decreased with further surfactant addition and was constant after the CMC. The charge on cationic surfactants was always more than that observed with the anionic surfactants. Nonionic surfactants displayed a steady increase in droplet charge with increasing concentration. The charges were lower compared to the ionic surfactants. (C) 2000 Elsevier Science Ltd. Electrostatic charges on individual spray droplets were measured using a refined form of the Millikan oil drop method. The measurement system consisted of three main sections; a droplet generation cell, a settling column and a charge measurement chamber. The trajectories required for calculation of charge were determined using a high-speed motion analyzer coupled to a long-focal-length microscope. Charges on droplets were manipulated by the addition of surface-active agents into the spray solution. Droplet charge was a function of the type and concentration of the surfactant added. For ionic surfactants, it showed a maximum at low surfactant concentrations, decreased with further surfactant addition and was constant after the CMC. The charge on cationic surfactants was always more than that observed with the anionic surfactants. Nonionic surfactants displayed a steady increase in droplet charge with increasing concentration. The charges were lower compared to the ionic surfactants.