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Structural changes of viscoelastic solutions of zwitterionic and anionic surfactant mixtures under the influence of simple salt

Różańska Sylwia, Warmbier Ewelina, Wagner Patrycja, Różański Jacek

Chemical and Process Engineering : New Frontiers

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2023

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Vol. 44, nr 2

art. no. e10

EN

The paper presents the effects of sodium chloride on the rheological properties of aqueous solutions of cocamidopropyl betaine (CAPB) and sodium dodecylbenzene sulfonate (SDBS) mixtures. Studies were carried out in the CAPB/SDBS molar ratio range of 0.95 to 3.5, at sodium chloride concentrations varying from 0.03 M to 0.75 M. Continuous and oscillatory flow measurements showed that the impact of sodium chloride concentration on shear viscosity and relaxation time was closely linked to the CAPB/SDBS molar ratio. The maximum shear viscosity and the longest Maxwell relaxation time were obtained at the CAPB/SDBS molar ratio of 2. Based on CryoTEM images, it was determined that the shear viscosity and relaxation time peaks identified at a certain concentration of sodium chloride could be attributed to the transition of the entangled wormlike micellar network into branched wormlike micelles. Changes in the micellar microstructure accompanying modifications of the CAPB/SDBS molar ratio and sodium chloride concentration were accounted for on the basis of the packing parameter.

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Pressure drops during the flow of solutions of cocamidopropyl betaine and cocamide DEA mixtures with the addition of ethylene glycol

Różańska Sylwia, Różański Jacek, Wagner Patrycja, Warmbier Ewelina

Polish Journal of Chemical Technology

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2022

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Vol. 24, nr 4

67--71

EN

The paper presents the results of experimental studies on pressure drops during the flow of cocamidopropyl betaine (CAPB) and DEA cocamide solutions with the addition of ethylene glycol. The degree of drag reduction during the flow of the CAPB/DEA aqueous solution and with the 10% addition of ethylene glycol was similar. A significant reduction in pressure drops was also observed at the 20% concentration of ethylene glycol. However, the increase in the concentration of ethylene glycol resulted in the reduction of flow resistance at higher temperatures. The resistance of the micellar microstructure of CAPB/DEA solutions to mechanical degradation depends strongly on the pH level. Significant changes in flow properties were observed when the initial pH was alkaline. The solution with initial pH close to neutral was stable over time, though reduced resistance to degradation with time was also observed.

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Effects of multiple passes through a dynamic membrane on the properties of w/o emulsions

Frankiewicz Adrianna, Różański Jacek

Chemical and Process Engineering

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2022

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Vol. 43, nr 4

449--459

EN

Conventional membranes used in the process of premix membrane emulsification are prone to fouling, especially when biopolymers are employed as surfactants. An alternative to conventional membranes are dynamic membranes consisting of an unconsolidated porous medium. Dynamic membranes have the advantage of enabling easy cleaning of the inside of the pores. Experimental research carried out to date has focused on the application of hydrophilic dynamic membranes composed of glass microbeads for producing o/w emulsions. The aims of this study were to determine the efficiency of droplet size reduction in a w/o emulsion when passed through a dynamic hydrophobic membrane consisting of a bed of irregular polymer particles, and to assess the effect of multiple membrane passes on the properties of the w/o emulsion. The dynamic membranes evaluated in the tests were found to reduce the diameters of premix droplets when an appropriate pressure level was reached. Higher bed porosity was associated with greater fluxes achieved across the packed bed, but the resulting emulsions were less homogeneous. Multiple passes of the emulsion through the dynamic polypropylene membrane led to a further reduction in droplet size, but it was accompanied by a decline in emulsion homogeneity.