Liquid absorption experimental

The influence of pressure on the mass transfer in a countercurrent packed column has been scarcely investigated to date. The only systematic experimental work has been made by the Research Group of the INSA Lyon (F) with Professor M. Otterbein el al. These authors [8, 9] studied the influence of the total pressure (up to 15 bar) on the gas-liquid interfacial area, a, and on the volumetric mass-transfer coefficient in the liquid phase, kia, in a countercurrent packed column. The method of gas-liquid absorption with chemical reaction was applied with different chemical systems. The results showed the increase of the interfacial area with increasing pressure, at constant gas-and liquid velocities. The same trend was observed for the variation of the volumetric liquid mass-transfer coefficient. The effect of pressure on kia was probably due to the influence of pressure on the interfacial area, a. In fact, by observing the ratio, kia/a, it can be seen that the liquid-side mass-transfer coefficient, kL, is independent of pressure. 

Diffusion coefficients are important in the design of mass transfer operations equipment, such as gas absorption, distillation and liquid-liquid extraction. Experimental data for the common systems can be found in the literature, but for most design work, the values will have to be estimated. 

Spectroscopy is basically an experimental subject and is concerned with the absorption, emission or scattering of electromagnetic radiation by atoms or molecules. As we shall see in Chapter 3, electromagnetic radiation covers a wide wavelength range, from radio waves to y-rays, and the atoms or molecules may be in the gas, liquid or solid phase or, of great importance in surface chemistry, adsorbed on a solid surface. 

With a reactive solvent, the mass-transfer coefficient may be enhanced by a factor E so that, for instance. Kg is replaced by EKg. Like specific rates of ordinary chemical reactions, such enhancements must be found experimentally. There are no generalized correlations. Some calculations have been made for idealized situations, such as complete reaction in the liquid film. Tables 23-6 and 23-7 show a few spot data. On that basis, a tower for absorption of SO9 with NaOH is smaller than that with pure water by a factor of roughly 0.317/7.0 = 0.045. Table 23-8 lists the main factors that are needed for mathematical representation of KgO in a typical case of the absorption of CO9 by aqueous mouethauolamiue. Figure 23-27 shows some of the complex behaviors of equilibria and mass-transfer coefficients for the absorption of CO9 in solutions of potassium carbonate. Other than Henry s law, p = HC, which holds for some fairly dilute solutions, there is no general form of equilibrium relation. A typically complex equation is that for CO9 in contact with sodium carbonate solutions (Harte, Baker, and Purcell, Ind. Eng. Chem., 25, 528 [1933]), which is... 

There is convincing experimental evidence for the following important statement. To a degree of approximation satisfactory for most analytical work, the mass absorption coefficient of an element is independent of chemical or physical state. This means, for example, that an atom of bromine has the same chance of absorbing an x-ray quantum incident upon it in bromine vapor, completely or partially dissociated in potassium bromide or sodium bromate in liquid or solid bromine. X-ray absorption is predominantly an atomic property. This simplicity is without parallel in absorptiometry. 

The sampling of solution for activity measurement is carried out by filtration with 0.22 pm Millex filter (Millipore Co.) which is encapsuled and attached to a syringe for handy operation. The randomly selected filtrates are further passed through Amicon Centriflo membrane filter (CF-25) of 2 nm pore size. The activities measured for the filtrates from the two different pore sizes are observed to be identical within experimental error. Activities are measured by a liquid scintillation counter. For each sample solution, triplicate samplings and activity measurements are undertaken and the average of three values is used for calculation. Absorption spectra of experimental solutions are measured using a Beckman UV 5260 spectrophotometer for the analysis of oxidation states of dissolved Pu ions. 

Fig. 7.5. Fitting of the -dependence of the widths for the rotational absorption spectrum of HC1 in liquid noble gases. Experimental data are shown by dots, theoretical calculations by solid curve.

Fig 18. Experimental trickle-bed system A, tube bundle for liquid flow distribution B, flow distribution packing of glass helices C, activated carbon trickle bed 1, mass flow controllers 2, gas or liquid rotameters, 3, reactor (indicating point of gas phase introduction) 4, overflow tank for the liquid phase feed 5, liquid phase hold-up tank 6, absorber pump 7, packed absorption column for saturation of the liquid phase 8, gas-liquid disengager in the liquid phase saturation circuit. (Figure from Haure et ai, 1989, with permission, 1989 American Institute of Chemical Engineers.)... 

This chapter describes use of solid-surface room temperature phosphorimetry (SSRTP) as a detection technique in the liquid chromatographic (LC) analysis of caffeine, theophylline, and theobromine. Measurements were made in a continuous mode, using a 2-nebulizer automatic system for SSRTP analysis (previously optimized for LC detection). Use of SSRTP and UV absorption detection was compared under identical experimental conditions.38... 

Double-resonance spectroscopy involves the use of two different sources of radiation. In the context of EPR, these usually are a microwave and a radiowave or (less common) a microwave and another microwave. The two combinations were originally called ENDOR (electron nuclear double resonance) and ELDOR (electron electron double resonance), but the development of many variations on this theme has led to a wide spectrum of derived techniques and associated acronyms, such as ESEEM (electron spin echo envelope modulation), which is a pulsed variant of ENDOR, or DEER (double electron electron spin resonance), which is a pulsed variant of ELDOR. The basic principle involves the saturation (partially or wholly) of an EPR absorption and the subsequent transfer of spin energy to a different absorption by means of the second radiation, leading to the detection of the difference signal. The requirement of saturability implies operation at close to liquid helium, or even lower, temperatures, which, combined with long experimentation times, produces a... 

The first subnanosecond experiments on the eh yield were performed at Toronto (Hunt et al., 1973 Wolff et al., 1973). These were followed by the subnanosecond work of Jonah et al. (1976) and the subpicosecond works of Migus et al. (1987) and of Lu et al. (1989). Summarizing, we may note the following (1) the initial (-100 ps) yield of the hydrated electron is 4.6 0.2, which, together with the yield of 0.8 for dry neutralization, gives the total ionization yield in liquid water as 5.4 (2) there is -17% decay of the eh yield at 3 ns, of which about half occurs at 700 ps and (3) there is a relatively fast decay of the yield between 1 and 10 ns. Of these, items (1) and (3) are consistent with the Schwarz form of the diffusion model, but item (2) is not. In the time scale of 0.1-10 ns, the experimental yield is consistently greater than the calculated value. The subpicosecond experiments corroborated this finding and determined the evolution of the absorption spectrum of the trapped electron as well. 

In solution, although solute contributions can generally be singled out, difficulties arise sometimes solvent-solute interactions may induce a shift of the solute absorption and consequently of its susceptibility or hydrogen bonded molecular complexes may modify the liquid structure. This situation has been studied both theoretically and experimentally by Zyss and Berthier (10) and by Ledoux and Zyss (13) in the case of urea derivatives in various solvents and in crystal showing the importance of environment considerations and thus the limitations of an oriented gas model for crystals. 

---