Potassium emission from

In a caustic scmbbing system, caustic potash, KOH, is preferred to caustic soda, NaOH, because of the higher solubiUty of the resulting potassium fluoride. Adequate solution contact and residence time must be provided in the scmb tower to ensure complete neutralization of the intermediate oxygen difluoride, OF2. Gas residence times of at least one minute and caustic concentrations in excess of 5% are recommended to prevent OF2 emission from the scmb tower. 

Fig. 13.9 Frequency dependence of potassium atom emission from argon-saturated 2 M KC1 aqueous solutions. Shown are normalized spectra measured at frequencies of 28, 115,...

Fig. 13.10 Sonoluminescence spectrum of potassium-atom emission from helium-saturated KC1 aqueous solution at 148 kHz. The spectrum shows slightly asymmetric broadening toward blue side, which is in contrast with the potassium line in argon-saturated solution...

As a starting point, we will try to quantify the required activity of a new catalyst by simulating the S02 emission from a double absorption plant as a function of 4th bed catalyst activity for a feed gas with 11% S02 and 10% 02 and a 3+1 converter with fixed bed volumes, cf. Fig. 4. With a conventional potassium-promoted catalyst such as VK38 from Haldor Topsoc (relative activity 1), a typical requirement in the 1990ies of minimum 99.7% S02 conversion corresponding to 395 ppm S02 in the stack gas can be achieved in this plant at a 4th bed inlet temperature of 430-435°C. With a 2-3 times more active catalyst in bed 4, the S02 emission in this plant can be reduced to below 200 ppm at a lower optimum inlet temperature. 

Richardson and Young (Proc. Roy. Soc. A, evil. 377,1925) in an examination of the thermionic and photoelectric emission from surfaces of sodium and potassium have observed more than one threshold value for the work functions and suggest that in these cases also there are small patches of the surface associated with a low value of the work function. 

With good fuels (charcoal or active metals), potassium nitrate will burn well. Its use in colored flame compositions is limited, primarily due to low reaction temperatures. Magnesium may be added to these mixtures to raise the temperature (and hence the light intensity), but the color value is diminished by "black body" emission from solid MgO. 

B3 Potassium standards gave the following emission intensities at 404.3 nm. Emission from the unknown was 417. Find [KJ l and its uncertainty in the unknown. 

This instrument has allowed several studies that provide information not obtainable by other means to be conducted. Four examples are presented as follows The first example concerns the question of the mechanism of emission of potassium ions from potassium zeolite [7]. Earlier studies had made the assumption that this was an S-L type of ion formation mechanism [8], implying that there was a neutral potassium atom flux accompanying the flux of atomic potassium cations. Experiments performed on this instrument clearly showed that this is not the case there was no detectable neutral atomic potassium flux accompanying the cation flux. Thus this instrument was used to answer a long-standing question with an experiment conducted in one afternoon and allowed the conclusion to be reached that the mechanism is potassium ions in the solid state subliming into the gas phase. 

In environmental analysis, flame photometry is most widely used for the determination of potassium, which emits at 766.5 nm. It is also often used for the determination of sodium at 589.0 nm, although spectral interference problems (see Chapter 3) then may be encountered in the presence of excess calcium because of emission from calcium-containing polyatomic species. Molecular species are more likely to be found in cooler flames than in hotter flames. Some instruments use single, interchangeable filters, while others have three or more filters, for example for the determinations of potassium, sodium and lithium,... 

Procedure Concomitantly determine the absorbance values of the Test Solutions at the potassium emission line at 766.7 nm with a suitable atomic absorption spectrophotometer equipped with an air-acetylene flame, using water as the blank. Plot the absorbance values of the Test Solutions versus their contents of potassium, in micrograms per milliliter draw the straight line best fitting the three points and extrapolate the line until it intersects with the concentration axis. From the intercept, determine the amount, in micrograms, of potassium in each milliliter of Test Solution A. Calculate the percent potassium in the portion of sample taken by multiplying the concentration, in micrograms per milliliter, of potassium found in Test Solution A by 0.2. 

Potassium is one of the more easily ionized metals and the type of flame used will be of even greater influence than in sodium work. Since the degree of ionization depends also on other solution constituents, i.e., alkali metals, significant interference from sodium can be expected. The relative enhancement of potassium emission and absorption is shown by Baker and Garton (B2). Atomization of potassium in the fiame, however, is not only reduced by ionization but also by compound formation, notably hydroxide. 

Emission spectroscopy has been used recently in an elegant attempt to elucidate the mechanism of the energy transfer process (10). Moulton and Herschbach have examined the emission from a triple molecul2ur beam experiment. Molecular beams of bromine and atomic potassium cross each other, and vibrationally excited KBr is formed, which is then collimated into a further beam. 

The alkali metals are not found free in nature, because they are so easily oxidized. They are most economically produced by electrolysis of their molten salts. Sodium (2.6% abundance by mass) and potassium (2.4% abundance) are very common in the earth s crust. The other lA metals are quite rare. Francium consists only of short-lived radioactive isotopes formed by alpha-particle emission from actinium (Section 26-4). Both potassium and cesium also have natural radioisotopes. Potassium-40 is important in the potassium-argon radioactive decay method of dating ancient objects (Section 26-12). The properties of the alkali metals vary regularly as the group is descended (Table 23-1). 

The apparent threshold for emission of the potassium D-lines in K + Hg collisions is 4 0 (+0-4) eV the absolute size of the emission cross section at 10 eV has been estimated69 to 3 A2. Again no emission from excited potassium states other than 42P has been observed up to 100 eV collision energy upper limits for emission at 4050 and 6930 A are 1 % of that at 7680 A. No emission from excited mercury states at 5440 and 5780 A was observed either. 

It is reported [95] that the reaction of sodium vapour with chlorine produces emission from Na2 including many new bands of the red system of Na2, but that band emission from the sodium chloride does not occur. The flames of halogens burning in potassium emit the visible—UV systems of the potassium halide molecules and also substantial potassium atom emission. The extent of the emission implies that the direct reaction... 

Emission from electronically excited TiO molecules has been observed by Palmer and co-workers from the reaction of titanium tetrachloride or tetrabromide with potassium vapour in the presence of oxygen [277] and of nitrous oxide [278]. The potassium atoms presumably strip the halogen atoms from the titanium tetrahalide, and the titanium atoms then react with the oxygen or nitrous oxide producing electronically excited TiO molecules. 

Prepare aqueous solutions containing amounts of potassium varying from 1.0 to 100.0 ppm of K" ". Aspirate each sample into the flame. Measure the intensity of emission at 766.0 and 404.4 nm. Plot the relationship between the emission intensity of each line and the concentration of the solution aspirated into the burner. 

Merely from the fact that even a true black body would yield less than half this amount (Table 7) at an estimated flame temperature of about 2500it becomes obvious that in intense pyrotechnic radiation thermal grey-body emission is heavily augmented by selective radiation and luminescent phenomena. This can be experimentally demonstrated by a comparison of light emission from binary mixtures where various alkali salts act as oxidizers. Table 9 (from Table 13.7, Shidlovsky ) shows these relations. He uses a fixed ratio of 40 % metal fuel and 60% of the nitrates of sodium, potassium, or barium. It is of course not... 

---