Low-temperature phase separation of a binary liquid mixture in porous materials studied by cryoporometry and pulsed-field-gradient NMR.
نویسندگان
چکیده
The low-temperature liquid-liquid phase separation of the partially miscible hexane-nitrobenzene mixture imbibed in porous glasses of different pore sizes from 7 to 130 nm has been studied using 1H NMR (nuclear magnetic resonance) cryoporometry and pulse field gradient NMR methods. The mixture was quenched below both its upper critical solution temperature (T(cr)) and the freezing point of nitrobenzene. The size distribution of frozen nitrobenzene domains was derived through their melting point suppression according to the Gibbs-Thompson relation. The obtained data reveal small initial droplets of nitrobenzene surrounded by hexane, which are created as the temperature is decreased below T(cr) and which thereafter coalesce by a droplet-diffusion mechanism. The inter-relation between the pore size and the found size distribution and shapes of nitrobenzene domains is discussed, as well as several aspects of molecular self-diffusion.
منابع مشابه
Experimental and Theoretical Study of Phase Equilibria in Aqueous Mixtures of Lactic Acid with Benzyl Alcohol and p-Xylene at Various Temperatures
Liquid-liquid equilibria for the (water + lactic acid + benzyl alcohol or p-xylene) ternary systems were investigated at atmospheric pressure and in the temperature range from 298.15-318.15 K. The studied systems exhibit two types of liquid-liquid equilibrium (LLE) behavior. The system consisting of benzyl alcohol displays type-1 LLE behavior, while a type-2 behavior is exhibited by th...
متن کاملNuclear Magnetic Resonance Cryoporometry
Nuclear Magnetic Resonance (NMR) cryoporometry is a technique for non-destructively determining pore size distributions in porous media through the observation of the depressed melting point of a confined liquid. It is suitable for measuring pore diameters in the range 2 nm – 1 μm, depending on the absorbate. Whilst NMR cryoporometry is a pertabative measurement, the results are independent of ...
متن کاملSeparation of Formic Acid from Aqueous Solutions by Liquid Extraction Technique at Different Temperatures
In this study, the separation of formic acid from aqueous solutions was investigated. Liquid-liquid equilibrium (LLE) data including tie-lines was reported for water + formic acid + 2-methylpropyl ethanoate ternary mixture at (293.15 to 323.15) K and atmospheric pressure. The system shows type-I phase behavior based on Treybal’s classification because only one partially miscible binary mixture ...
متن کاملFreezing and melting transitions of liquids in mesopores with ink-bottle geometry
Freezing and melting behavior of nitrobenzene in mesoporous silicon with different pore size and with different porous structure have been studied using 1H NMR cryoporometry. With the bulk phase surrounding the porous monoliths, in materials with uniform channel-like pores distinct poresize-dependent freezing and melting transitions have been measured. These data were further used for the analy...
متن کاملSeparation of Somatropin and Its Degradation Products by High-Performance Liquid Chromatography Using a Reversed-Phase Polymeric Column
The accurate prediction of protein stability is one of the most challenging goals in protein formulation and delivery. In this study, a gradient RP-HPLC method is described for the separation of human growth hormone (hGH) variants as deamidated and oxidized forms. The methodology employed a polymeric poly (styrene-co-divinylbenzene) column and a 1mL/min flow rate of a linear gradient of 0.1% v/...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Physical review. E, Statistical, nonlinear, and soft matter physics
دوره 66 3 Pt 1 شماره
صفحات -
تاریخ انتشار 2002