| 1. |
- Corkery, Robert W., 1967-, et al.
(författare)
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Emulsion inversion in the PIT range: Quantitative phase variations in a two-phase emulsion
- 2010
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Ingår i: Journal of Chemical and Engineering Data. - : American Chemical Society (ACS). - 0021-9568 .- 1520-5134. ; 55:10, s. 4471-4475
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Tidskriftsartikel (refereegranskat)abstract
- The phase-inversion temperature (PIT) phenomenon is for the first time given a quantitative treatment for systems having a sufficiently small surfactant content to be limited to two phases at the PIT. The results show that the early opinion of a phase transfer of the surfactant as the major event in the transversal of the temperature range is not entirely correct; the major phenomenon is instead an expulsion of water from the low-temperature aqueous micellar solution. In addition, the results unexpectedly give an indication of the existence of three phases at temperatures beneath the PIT, in spite of the the fact that system consists of only two phases at the actual PIT.
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| 2. |
- Friberg, Stig E, et al.
(författare)
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Phase inversion temperature (PIT) emulsification process
- 2011
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Ingår i: Journal of Chemical and Engineering Data. - : American Chemical Society (ACS). - 0021-9568 .- 1520-5134. ; 56:12, s. 4282-4290
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Tidskriftsartikel (refereegranskat)abstract
- A quantitative analysis is made of the phase changes during the phase inversion temperature (PIT) emulsification process of an aqueous hexadecane emulsion stabilized by a tetra-ethylene glycol dodecyl ether surfactant. The mechanical dispersion part of the process takes place at the PIT, at which temperature the emulsion contains three phases: (1) water, with only minute fractions of surfactant and hydrocarbon; (2) an inverse micellar solution, with modest fractions of solubilized water; and (3) a bicontinuous microemulsion, with large concurrent solubilization of both water and hydrocarbon. After the mechanical action at the PIT, the emulsion is immediately cooled to temperatures beneath the PIT range, reducing the number of phases in the emulsion to two, an oil/water (O/W) microemulsion with moderate surfactant and hydrocarbon content, and an inverse micellar hydrocarbon solution with a significantly greater surfactant fraction. The emulsion is characterized by its large fraction of extremely small oil drops, significantly smaller than expected from the mechanical process. These drops are commonly assumed to emanate from the hydrocarbon fraction of the original bicontinuous microemulsion, the small size of the oil drops being a rational consequence of the colloidal dispersion prior to the phase separation. The quantitative analysis of the phase fractions versus temperature revealed this assumption to be premature. The original water phase is not the final aqueous phase in the emulsion; this phase is instead formed from the microemulsion phase by absorbing the original water phase, gradually modifying its own structure to become water-continuous with the originally large hydrocarbon fraction reduced to modest levels. In the process, a part of the original microemulsion is separated, forming the small oil drops.
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| 3. |
- Mira, Isabel C., et al.
(författare)
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Foam forming revisited Part I. Foaming behaviour of fibre-surfactant systems
- 2014
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Ingår i: Nordic Pulp & Paper Research Journal. - : SPCI. - 0283-2631 .- 2000-0669. ; 29:4, s. 679-688
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Tidskriftsartikel (refereegranskat)abstract
- The foaming properties of typical chemithermo-mechanical (CTMP) and kraft pulp paper making formulations in the presence of a series of surfactants were investigated using a lab-scale foaming set up. Foamability, foam stability, and bubble size distribution of the generated foam-fibre systems were measured. The foaming behaviour of the fibre/surfactant systems was found to be dependent on the surfactant concentration. Foams fulfilling the target requirements of air content (ca. 65% v/v air) and average bubble size (25 to 75 μm in radius) were obtained with all the seven surfactants tested. Three of the surfactants were found to allow for a rapid foaming in the system, namely sodium dodecyl sulphate (SDS), a commercial mixture of alkyl and ethoxylated alkyl sulphates, (MixSAES) and a commercial mixture of short chain alkyl glucosides (C8/C10Gluc). The rapid foaming is believed to be an intrinsic property of mixtures of surfactants with the right molecular structures and in the right proportion with respect to each other. On the other hand, the minimum surfactant concentrations required to reach the target foam volumes were lowest for surfactants with an anionic character. Further, the type of pulp fibre and the presence of GCC in the surfactant/pulp formulation were found to have very little effect on the foaming performance of the suspensions.
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