Absorption of solutes

When 1, 3, 3-triethoxypropene was hydrolyzed with IN sulfuric acid, a solution of malonaldehyde whose optical density was perfectly stable at 350 m/x for at least one week was obtained. If the solution was made alkaline, the optical density at the same wavelength increased by a small value and then remained virtually constant for at least one week (56). It was also observed that in these solutions the extinction coefficient at 350 m/x was very low (observed 8.3, 61.5 and 69, for solutions of pH 0.4, 7.15 and 9.4 respectively) compared with previously reported values which varied from 200 ( 40) to 1000 ( 48). On the other hand, the absorption of solutions having a pH of 3 to 5, increased considerably with time (at pH 4.75, the extinction coefficient of malonaldehyde at 350 m/x was initially about 40 after four weeks a value of about 930 was recorded and the optical density of the solution was still increasing). This increase in absorption was accompanied by a marked decrease in the malonaldehyde content of the solution, as measured by the thiobarbituric acid method. As a corollary, it was found that aqueous solutions of malonaldehyde, prepared by autocatalyzed hydrolysis (33) of the same acetal and which had a pH of about 3.5, showed, at the completion of the hydrolysis, considerably higher extinction coefficient values at 350 m/x than did those malonaldehyde solutions which were prepared by hydrolysis with IN acid and subsequently adjusted to pH 4. It appears, therefore, that at pH values at which most of the periodate oxidations are carried out, malonaldehyde is unstable and undergoes a chemical reaction, the nature of which is not, as yet, known. 

Fig. 4.18 represents a countercurrent-flow, packed gas absorption column, in which the absorption of solute is accompanied by the evolution of heat. In order to treat the case of concentrated gas and liquid streams, in which the total flow rates of both gas and liquid vary throughout the column, the solute concentrations in the gas and liquid are defined in terms of mole ratio units and related to the molar flow rates of solute free gas and liquid respectively, as discussed previously in Sec. 3.3.2. By convention, the mass transfer rate equation is however expressed in terms of mole fraction units. In Fig. 4.18, Gm is the molar flow of solute free gas (kmol/m s), is the molar flow of solute free liquid (kmol/m s), where both and Gm remain constant throughout the column. Y is the mole ratio of solute in the gas phase (kmol of solute/kmol of solute free gas), X is the mole ratio of solute in the liquid phase (kmol of...

Figure 15.3 (a) Heat absorption in solutions of native RNase A (trace 1) and RNase A kept in 10% buffered formalin for 2 days (trace 2) and 6 days (trace 3) at pH 7.4 and 23°C. All samples were dialyzed against 75 mM potassium phosphate buffer (pH 7.4) prior to DSC. (b) Dependence of Td of the dialyzed RNase A samples on time of incubation in 10% buffered formalin at pH 7.4 and 23°C. (c) Heat absorption of solutions of formalin-treated RNase A fractions isolated by size-exclusion gel chromatography monomer (trace 1), dimmer (trace 2), and a mixture of oligomers with >5 cross-linked proteins (trace 3). Protein concentrations were 0.5 mg/mL. The thermal denaturation transition temperature (Td) is defined as the temperature of the maximum in the excess heat absorption trace associated with the protein s endothermic denaturation transition. See Rait et al.10 for details. 

Experimental evidence in support of this explanation is the fact that lithium added to a solution of lithium iodide in ethylenediamine dissolves without imparting a blue color to the solution—i.e., reacts immediately to give the amide. By contrast, lithium added to a solution of lithium chloride in ethylenediamine dissolves and imparts a deep blue color to the solution. The catalytic effect of iodide anion may be related to the effect of iodide anion on the electron spin resonance (ESR) absorption of solutions of alkali metals in liquid ammonia. Catterall and Symons (2) observed a drastic change in the presence of alkali iodides but very little change in the presence of alkali bromides or chlorides. They attributed this change to interaction of the solvated electron with the 6 p level of the iodide anion. 

It is often mentioned that when drugs are absorbed paracellularly, they are dragged by a local water flux through the tight junctions. In this context, it is interesting to mention the Pappenheimer hypothesis [169,175,176], which suggests that the absorption of solutes across... 

Absorption of solution by dry soil with varying clay content... 

Penetration enhancers are substances that facilitate absorption of solutes across biological membranes. There are currently five major types of penetration enhancers under investigation ... 

If your school has a spectrometer or colorimeter, you can measure the absorption of light passing through the solutions. By measuring the absorption of solutions of copper(II) sulfate with different concentrations, you can draw a graph of absorption against concentration. 

Nonbonded complexes. The equilibrium constants, enthalpies, and entropies for the weak complexation of pyrazine with dichloromethane, chloroform, or carbon tetrachloride have been determined from changes in the n — 77 absorptions of solutions at various concentrations (in cyclohexane) and temperatures 568 similar data for pyrazine-aromatic hydrocarbon complexes were obtained from variations in the H NMR chemical shift values.1037 The spectral effects of complexation with borane have been studied in the pyrazine diborane adduct and its methyl derivatives.254... 

The UV/Vis absorption of solute molecules can be influenced not only by surrounding solvent molecules but also by other environments, e.g. embedment in solids, polymers, glasses, micelles, or proteins, as well as adsorption on solid surfaces. Therefore, the more general term peri-chromism (from the Greek peri = around and chroma = colour) has been recommended (Prof. E. M. Kosower, Tel Aviv/Israel, private communication to the author). Solvatochromic shifts caused by dye inclusion into protein interiors have been called enzymichromism [438]. 

PERCUTANEOUS ABSORPTION OF SOLUTIONS WITH TIME AND SITE... 

Figure 13 displays MSFTIR spectra [51] of CO adsorbed on an nm-Ru/GC electrode in 0.1 M NaOH solution. Three positive-going bands can be observed. The strong band near 1400 cm is assigned to IR absorption of solution carbonate species, which are formed according to Eqs. (7)-(9) due to oxidation of COad at Er. The other two bands are located near 1960 and 1780 cm and may be ascribed to IR absorption of COl and COr species. The centers of COl and COr bands have been red-shifted about 50 and 60cm , respectively, in comparison with CO adsorption on the nm-Ru/GC electrode in 0.1 M H2SO4 solution (Figure 11). From results of...

The normal glomerular filtration rate (GFR) is 100-120 mL/min about 150 L of fluid passes through the renal tubules each day. Since the average daily urine volume is 1 -1.5 L, 99% of the glomerular filtrate is reabsorbed. Approximately 80% of the water is reabsorbed in the proximal tubule, a consequence of active absorption of solutes. Reabsorption in the rest of the tubule varies according to the individual s water balance, in contrast to the obligatory reabsorption that occurs in the proximal tubule. 

Consider a general-type absorber as diagrammed in Figure 13.6. Gas and liquid flow counter-currently through real or imagined stages. The usual specifications include (a) fraction of absorption of solute in the feed gas, (b) maximnm allowable concentration of solute in the exit gas, and (c) optimal ratio of solvent to feed gas. Based on mass balances,... 

If we assume "plug flow" for both phases, setting up a material balance on a differential height of a packed column for absorption of solute A into a liquid containing dissolved reactant gives ... 

In the case of irreversible chemical reaction of type A+zB Product, the specific rate of absorption of solute gas A by the liquid reactant B, can be expressed by... 

The knowledge of total flux of absorption of solute gas allows the determination of the gas liquid interfacial area a as. 

The absorption of solution containing Na+ and Ca" " ions (artifidal blood) is significantly high, irrespective of fibre type and structure. 

Equation (10.8-1) can be used to correct existing data for absorption of solute Aina. gas on a specific packing to absorption of solute E in the same system and the same mass-flow rates. This is done by Eq. (10.8-2). 

Certain species of plants have been found to accumulate very high concentrations of certain trace elements and these are referred as hyperaccumulator species. Plants can also intercept significant amounts of some elements through foliar absorption. Foliar absorption of solutes depends on the plant species, its nutritional status, the thickness of its cuticle, the age of the leaf, the presence of stomata guard cells, the humidity at the leaf surface, and the nature of the solutes. 

Fig. 1 Ultrasonic absorption of solutions of BMV, BMV protein capsids and subunit-dimers. See text and reference (3).

Fisher RB, Gardner ML. A kinetic approach to the study of absorption of solutes by isolated perfused small intestine. J Physiol 1974 241 211-234. 

Optical fiber detectors are usually utilized as ether miniature spectrophotometers or fluorimeters, because of the availability of indicator dyes that can be detected by absorbance or fluorescence methods. Figure 12 shows the absorption spectrum for phenol red, a dye commonly used as pH indicator. By measuring the absorption of solutions of phenol red at two wavelengths, the isobestic point where absorption is virtually independent of pH and at 600 m u where the intensity of absorption is very pH sensitive, one... 

The ultrasonic absorption of solutions of the EDTA complexes of Ca(II), Sr(II), Ba(II), and Co(II) has been ascribed to the configurational change of the complex in which the pentacoordinated structure is converted (with loss of the final water molecule from the inner coordination sphere of the metal) into the hexacoordinated structure. The values of A /(3.6 x 10, 9.2 x 10, 1.45 X 10 , and 9 x 10 s, respectively) are proportional to, but about one order of magnitude smaller than, the water-exchange rate constants at the unsubstituted... 

Unfortunately, many commercially important absorption operations do not follow Henry s Law for equilibrium values and do not operate at constant gas rates or liquid rates. The concentration of solute in the entering gas stream may represent a significantly large percentage of that stream, so that after absorption of solute, the exit gas flow rate is reduced. Likewise, the liquid rate leaving the tower exceeds the entering liquid rate by the amount of solute absorbed. This statement assumes no vaporization of the solvent and zero solubility of the inert gas phase in the solvent. Equation 3-28 gives the mass balance across such an absorber ... 

In this event, Equation 3-31 for absorption of solute from a lean entering gas stream becomes approximately ... 

Mass transfer driving forces are intermediate between vertical concurrent scrubbers and countercurrent scrubbers [1]. If the absorbed solute obeys Henry s Law in the liquid phase, the mass transfer driving force will limit maximum solute removal efficiency to about 90% of that obtained in a countercurrent scrubber for typical chemical fumes—assuming scrubbing water flow is limited. However, if the absorption of solute is followed by a rapid chemical reaction in the liquid phase, so that there is no appreciable vapor pressure of solute above the solution, the mass transfer driving force will be the same as for a countercurrent scrubber. 

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