High-speed stirring measuring kinetics

Recent research on the solvent extraction mechanism revealed that the role of liquid-liquid interface has to be taken into account for understanding the extraction mechanism, especially in the extraction kinetic mechanism. Breakthrough research has been attained with the invention of a high-speed stirring (HSS) method that made it possible to measure the interfacial concentration of extractant (Lewis base) and extraction rate of the complex. Thus, this technique could determine a rate law for the interfacial reaction for the first time [1],... 

Fig. 5.10 Computer-assisted extraction kinetics-measuring apparatus for highly stirred phases (A) high-speed stirrer (B) stirrer shaft (C) sample inlet (D) Teflon stirring har (E) Teflon phase separator (F) water hath (G) flow-cell (H) spectrophotometer (I) peristaltic pump (J) chart recorder (K) A/D converter (L) clock (M) minicomputer (N) dual-floppy disk drive (O) printer, (P) plotter. (From Ref. 16.)...

Tipnis and Carberry (1984) and Carberry et al. (1985) used this concept to design, construct and demonstrate a gradientless gas-liquid-solid catalytic reactor of well-defined interface. With the use of high-speed wipers, a continuously fed liquid film is sustained upon a catalytic wall in the presence of a continuously fed, well-stirred gas phase. This design allows the measurement of intrinsic kinetics of gas-liquid-solid catalytic systems. 

A polymerization is carried out in a continuous stirred reactor, with a volume of 500 ml, and a mean residence time of 300 s. The viscosity of the reaction medium is very high. The empirical constant c = yin 1. Further data are inlet tube dmmeter is 15 mm, diffusivity of monomer 1.0. 10 m7s. At a stirrer speed of 1 s the conversion of the monomer is 0.85. From eq. (4.20b) and the data it follows that volumetric rate constant for instantaneous reaction would be s 0.018 s If the reaction would obey apparent first order kinetics (with respect to the monomer), with this value of the rate constant, and T = 300 s, it would follow from eq. (3.38) that the conversion was 0.84. This fits well with the measured conversion. On scale-up to a volume of 0.5 m, the stirrer speed is reduced to 0.5 s A higher residence time (x) will be applied, such that the same degree of conversion is obtained. The inlet tube diameter is now 50 mm. What will T have to be to get the same conversion Let us apply both models presented in section 4232. When l z has to be the same, it follows from both eqs. (4.20b) and (4.21b) that T has to increase proportionally with (d /ny. ... 

---