Centrifuge, liquid

Figure 11-21B. Packaged hermetic open drive two-stage centrifugal liquid chiller with flash economizer. (Used with permission Cat. 521-727, 1995. Carrier Corporation, a United Technologies Company.)...

Apples, sorghum 5.0 ACN-H2O (4 1) Homogenization Shaking Centrifugation Liquid-liquid partitioning with dichloromethane Evaporation Cyclohexyl SPE 0.003 0.01... 

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. 

Coal Products Isotopic Distribution by Structural Position. Other workers have also investigated deuterium uptake in coal pro-ducts by structural position. Schweighardt, et al. (26) examined a centrifuged liquid product from a Synthoil run which was heated to 450°C with deuterium gas, Kershaw and Barrass (27) examined the products from the reaction of coal with deuterium gas using SnCl2 as catalyst, and Franz (10) examined the products from the reaction of a subbituminous coal with Tetralin-1,l-d2 at 427°C and 500°C. 

TABLE III.- Analyses of centrifuged liquid product samples... 

Figure 2. Fractionation scheme for centrifuged liquid product (CLP)...

The increase in viscosity of the product oil during a run is due primarily to an increase in asphaltenes and possibly pyridine sols content and not to a change in the molecular weight of the asphaltenes or to an increase in the viscosity of the heavy oil. This may be seen by comparing batches 7 and 88 of run FB-40 in tables VII and VIII. The viscosity of the centrifuged liquid product increases from 59 to 1,433 with an increase in asphaltene content from 22 to 40 and an increase in pyridine sols content from 2 to 5. In contrast, the viscosity of the heavy oil increases only from 12 to 17. There is no increase but rather a slight decrease in the molecular weight of asphaltenes from 459 to 416. 

The increase in viscosity of centrifuged liquid product with asphaltene content is shown in figure 4, where viscosities for runs FB-39 and FB-40 are plotted against asphaltene content. 

The extension of the use of centrifugal fields into the commonplace of chemical processing had its start in 1945 with the commercial application of a centrifugal liquid extractor to the recovery of penicillin (1). The liquid extractor, based on earlier patents by Podbielniak (2), employed perforated concentric plates for contacting the two countercurrent liquid streams. 

Passive capillary burst valves were fabricated on a plastic disk in which centrifugal liquid pumping was used to transport fluids, as shown in Figure 3.29. When the angular velocity (co) is less than the critical value (coc), the liquid cannot enter the big chamber. When co > coc, the liquid then bursts into the chamber. A wider channel would require less force to burst through and hence a lower rotation rate or a lower centrifugal force was used for the valve to burst open [226,453,454,1042],... 

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). 

Recommendations for Centrifugal Liquid Sedimentation Methods for Powders and Suspensions. 

BS 3406, Part 6, (1985), Determination of particle size distribution. Recommendations for centrifugal liquid sedimentation methods for particle size distribution,425... 

Ireland Mine hvAb coal was used in the coal pyrolysis studies. The method of heat treatment was essentially that reported by Petrakis and Grandy (8), Ireland Mine coal was also the feed coal used to obtain most of the coal liquefaction products. The coal-derived liquids investigated were centrifuged liquid products (CLP) and their subfractions from selected runs in the Pittsburgh Energy Technology Center s 400-lb coal/day coal liquefaction process development unit (PDU) (9). 

Determination of these compounds is carried out frequently in biological fluids. Analysis in urine requires a previous filtration to remove cells and other particulate matter then, the samples are diluted and directly injected onto the column. With cerebrospinal fluid, the samples are obtained by lumbar puncture each ahquot is centrifuged and decanted before analysis. Often in plasma or semm, some form of protein removal is needed because the presence of these compounds in injected samples can cause modifications of the column and bias in chromatographic results. Protein removal can be performed by various methods such as protein precipitation, ultrafiltra-tion, centrifugation, liquid-phase or solid-phase extraction, and column-switching techniques. 

---