Separation-Factor Treatment

Constant Separation-Factor Treatment If the valences of all species are equal, the separation factor Oti applies, where... 

Series, No. 107, Nijhoff, Dordrecht, 1986, pp. 119-1451. Constant Separation-Factor Treatment If the valences of all species are equal, the separation factor atJ applies, where atJ = KtJ= Z (16-46) cjn/ FIG. 16-8 Ideal mass-action equilibrium for three-component ion exchange with unequal valences. K AC = 8.06 K B C = 3.87. Duolite C-20 polystyrenesul-fonate resin, with Ca as A, Mg as B, and Na as C. [Klein et al., Ind. Eng. Chem. Fund., 6, 339 (1967) reprinted with permission.]... 

The treatment here is restricted to the Langmuir or constant separation factor isotherm, single-component adsorption, dilute systems, isothermal behavior, and mass-transfer resistances acting alone. References to extensions are given below. Different isotherms have been considered, and the theory is well understood for general isotherms. 

Resolution in capillary gel electrophoresis of DNA sequencing was shown to be directly proportional to the product of the number of bases and the relative peak distance, i.e., to the mean separation of peaks.43 Reformulation of the treatment of the capacity factor has been used to simplify and clarify the interpretation of the separation factor in electrophoresis.44 Peak... 

Effect of membrane treatment conditions on the permeate flux and separation factor of a 5% ethanol/water mbcture at 60 C by silicalite membranes... 

Treatment Treatment temp.(°C) Treatment time (h) Permeate flux OcR/m -h) Separation factor, a... 

Results after annealing of the polymers under vacuum in the dry state at 120°C for 24 h and heating of the polymers at 130°C for 4 h in the mobile phase. The MIP using benzene (C6H6) as diluent was evaluated using acetonitrile/0.05 M potassium phosphate buffer, pH 7 7/3 (v/v) as mobile phase. The separation factor prior to the heat treatment was 4.1 in this mobile phase. Data from [7]... 

Treatment State Swelling Solvent uptake (ml/ml) Retention k h Separation factor a (= k Jk o)... 

In particular the layers prepared by two subsequent hydrothermal treatments showed an optimal quality. Flux and separation factors of single gas, methane, n-butane, isobutane and 2,2-dimethylbutane as well as mixtures of methane/n-butane, n-butane/isobutane and n-hexane/2,2- dimethylbutane were determined. 

For a zeolite T (OFF stmcture, 0.68 nm XRD pore diameter), Tanaka et al. [131], observed that the separation factor of a water/acetic acid (50/50 wt%) measured at 75°C decreased monotonically after the immersion of the membrane into the acetic acid mixmre. Initially, the separation factor and water flux were 182 and 1.46 kg/m h, respectively, and after 32 h these values changed to 86 and 1.77 kg/m h, showing a deterioration of the membrane. Cui et al. [130] also smdied the stability of crystals and membranes of zeolite T in acid medium. The powders were immersed in a 50/50 wt% water/acetic acid mixture for 7 days at 75°C and also in HCl solutions 0.5 and 1 M for 1 h at 50°C. The analysis of the samples after the treatment by ICP and XRD indicated that the sample treated in the acetic acid solution maintained its original Si/Al ratio equal to 4 however, the hydrochloridric acid treatment with the 1 M solution destroyed the zeolite stmcmre and the 0.5 M solution dealuminated the zeolite to a Si/Al equal to 8.9 and the XRD analysis corresponded to zeolite T. The membrane performance, after being used for 1 week at different water/acetic acid concentrations, remains almost unchanged and the separation factor of the membrane treated in HCl dramatically decreased as was expected. 

The pervaporation of water/acetic acid mixmres was also evaluated with ZSM-5 membranes by the Matsukata group [129] the initial values of the separation factors in a 50 wt% acetic acid aqueous solution were around 10 to 20 due to the preferential adsorption of acetic acid which decreased the amount of water adsorbed. To increase the amount of water adsorbed, a surface modification that consisted of an alkali treatment with NaOH was carried out. After the treatment, the water flux and separation factor increased markedly, reaching values up to 381 and 0.783 kg/m h, respectively. 

Zeolite monoliths have been useful for such apphcations as rotatory adsorbers for use as dehumidifiers and desiccant cooling processes [253] or in VOC treatment systems [269]. Alumina-coated sUicon carbide monoliths have also been employed as supports for B-ZSM-5 membranes [270] providing a larger surface area per unit volume, compared to traditional membrane supports. With these membranes, these authors have reported n/f-butane and H2/f-butane separation selectivities of 35 and 77, respectively [85]. Also, silicalite-1 membranes supported on stainless steel grids (Figure 10.29) have shown a good performance in the separation of n/f-butane mixtures, with separation factors as high as 53 at 63°C [255]. 

No retention of a emitters was observed during this treatment, and the separation factors of transplutonium elements in relation to europium are respectively = 11.2 a jU = 1.83 = 1.23. 

The derivations for radial beds include the general reaction-kinetic case with constant separation factor, analogous to the treatment of axial-flow beds in the next section. An equation identical in form with Eq. (121) is obtained by Lapidus and Amundson. 

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