Centrifugal liquid membrane

FIG. 11 Schematic of the centrifugal liquid membrane apparatus. Typically, the organic phase, 0.150 cm, and the aqueous phase, 0.250 cm, are spread as an inner liquid membrane of 79 /xm film thickness and an outer liquid membrane of 145 fim thickness, respectively. (Reprinted from Ref. 61. Copyright 1998, American Chemical Society.)... 

From the beginning of the 1980s, some effective experimental approaches based on new principles have been invented for the study of interfacial reactions in solvent extraction chemistry. Recently, some methods were developed from our laboratory, the highspeed stirring (HSS) method [4,5], the two-phase stopped flow method [6], the capillary plate method [7], the reflection spectrometry [8], and the centrifugal liquid membrane (CLM) method [9]. 

A high specific interfacial area and a direct spectroscopic observation of the interface were attained by the centrifugal liquid membrane (CLM) method shown in Fig. 2. A two-phase system of about 100/rL in each volume is introduced into a cylindrical glass cell with a diameter of 19 mm. The cell is rotated at a speed of 5000-10,000 rpm. By this procedure, a two-phase liquid membrane with a thickness of 50-100 fim. is produced inside the cell wall which attains the specific interfacial area over 100 cm. UV/VIS spectrometry, spectro-fluorometry, and other spectroscopic methods can be used for the measurement of the interfacial species and its concentration as well as those in the thin bulk phases. This is an excellent method for determining interfacial reaction rates on the order of seconds. 

FIG. 2 Schematic drawing of the centrifugal liquid membrane (CLM) cell. 

Fig. 2. Schematic diagram of the centrifugal liquid membrane (CLM) apparatus. The glass cylinder cell (i.d. 19 mm) was rotated at a speed of 7000 10,000 rpm. Introduction of 50-200 pi of the organic and the aqueous phase generated a two-liquid layer with a thickness of 50-100 pm for each phase. Reagents can be injected from a small hole at the end side of the cell.

Fig. 6. Schematic drawing of the apparatus for the centrifugal liquid membrane-resonance Raman microprobe spectroscopy.

FIGURE 10.9. Schematic drawing of the apparatus for the centrifugal liquid membrane resonance Raman microprobe spectroscopy (a) and the centrifugal liquid membrane (CLM) cell with a sample injection hole at the bottom (b). 

Both the requirements of a high specific interfacial area and a direct spectroscopic observation of the interface were attained by the centrifugal liquid membrane (CLM) method... 

H. Nagatani and H. Watarai, Direct spectrophotometric measurement of demetallation kinetics of tetraphenylporphyrinato zinc(II) at the liquid-liquid interface by a centrifugal liquid membrane method. Anal. Chem., 70, 2860-2865 (1998). 

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