Effect of compressed CO[sub 2] on the properties of AOT reverse micelles studied by spectroscopy and phase behavior

Dongxia Liu; Jianling Zhang; Buxing Han; Jiufeng Fan; Tiancheng Mu; Zhimin Liu; Weize Wu; Jing Chen
September 2003
Journal of Chemical Physics;9/1/2003, Vol. 119 Issue 9, p4873
Academic Journal
Combination of reverse micellar solutions and supercritical or compressed carbon dioxide (CO[sub 2]) is a new and interesting topic. This work conducted the first study on the effect of compressed CO[sub 2] on the micro-properties (e.g., micropolarity, ionic strength, pH) of the sodium bis(2-ethylhexyl) sulfosuccinate reverse micelles in isooctane by phase behavior measurement, Fourier transform infrared and UV–vis spectroscopic techniques. The results show that CO[sub 2] can dissolve in both the organic-continuous phase and the water cores of the reverse micelles. The properties of the reverse micelles can be tuned continuously by changing the pressure of CO[sub 2] because the solubility of CO[sub 2] in the solution and in the water cores depends on the pressure. CO[sub 2] in the water cores can be ionized to produce HCO[sub 3][sup -1] and H[sup +]. The micropolarity and ionic strength of the water cores increase with the pressure of CO[sub 2]. Accordingly, the pH is reduced as the pressure and water-to-surfactant molar ratio (w[sub 0]) are increased. © 2003 American Institute of Physics.


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