Cahn balance

The Cahn balance design is shown in Figure 5.2. The balance arm is connected at the fulcrum to a platinum taut band... 

Svedberg and Rinde automatic recording sedimentation beam balance Cahn balance Gallenkamp balance Mettler H20E balance Sartorious Recording Sedibel balance... 

Fig. I. Schematic apparatus for experiment (a) adsorption(electtic cahn balance)mBasureinent system and (b) membrane transport system...

Antivibration base 15, sample chamber 16, plexiglas enclosure and 17, Cahn balance... 

Control unit for Cahn balance 19, time derivative computer 20, recorder 21, thermos for thermocouple cold junction and 22, time switch used in conjunction with thermocouple... 

Figure 2.26. Change in mass of platinum sample holder using the Cahn balance (48).

Ethylene adsorption was measured on a CuCl/y-alumina granular particles prepared by sol-gel/wet-impregnation method. A cuprous solution was synthesized by mixing cuprous chloride, ammonia hydroxide, ammonia citrate and deionized water with the composition of 1.98g 8.8ml 0.4g 20ml. About 180 mg of alumina sample was used in each adsorption measurement run by Cahn balance. Before each run, the sample was activated at 250°C for 4 hours in ethylene atmosphere to ensure that the Cu2+ ions, if any, were reduced to Cu" ions. Following that, the sample was exposed to nitrogen at 250°C for 2 more hours to completely remove the residual ethylene adsorbed on the sample. Finally, the sample was cooled down under vacuum (1.0 Pa) to the room temperature for adsorption measurement. 

The interaction of fineparticles in a suspension has been reviewed in detail in Reference 1 B. H. Kaye and C. R. G. Treasure, The Thermal Stability of Sedimenting Suspensions Used to Measure Particle She.Distx sxdxotxd, Materiak Research and Standards, 5 11 (1965). R. Davies and B. H. Kaye, The Effect of Cluster Instability in Suspensions and Particle Size Analysis Measurements with the Cahn Balance Particle Size Analysis Conference 1970, Bradford University, British Society for Analytical Chemistry, London. 

To get more information on the kinetics, isothermal runs were made using a Cahn balance with a controlled furnace and otherwise similar reaction conditions. Isothermal data were collected between 1 and 32 mg and temperatures between 600 and 700 K. Using 18 different functions to represent the data, it was found that Eq. (7) in Fig. 7.18 gives the best fit. This equation can be justified if one assumes that the mass loss is governed by the contracting geometry of the particles. 

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