Alumina sodium adsorption

FIGURE 16,3-6 Adsorption density of dodecylsulfonate, electrophoretic mobility, and settling rale or alumina-sodium dndecylsulfoome system as a function of the concent ration of sodium dodecylsulfonate.78 (Courtesy of Academic Press.)... 

El-Shobaky, G.A. Ghozza, A.M., and Hammad, S., Effect of sodium oxide doping on the surface and catalytic properties of the manganese oxide/alumina system, Adsorpt. Sci. Technol., 12(2), 119-128 (1995). 

Surface heterogeneity may be inferred from emission studies such as those studies by de Schrijver and co-workers on P and on R adsorbed on clay minerals [197,198]. In the case of adsorbed pyrene and its derivatives, there is considerable evidence for surface mobility (on clays, metal oxides, sulfides), as from the work of Thomas [199], de Mayo and co-workers [200], Singer [201] and Stahlberg et al. [202]. There has also been evidence for ground-state bimolecular association of adsorbed pyrene [66,203]. The sensitivity of pyrene to the polarity of its environment allows its use as a probe of surface polarity [204,205]. Pyrene or ofter emitters may be used as probes to study the structure of an adsorbate film, as in the case of Triton X-100 on silica [206], sodium dodecyl sulfate at the alumina surface [207] and hexadecyltrimethylammonium chloride adsorbed onto silver electrodes from water and dimethylformamide [208]. In all cases progressive structural changes were concluded to occur with increasing surfactant adsorption. 

Certain chemicals (sorbents) have the ability to absorb moisture from a gas they may be either solid or liquid. Performance of a chemical dehumidifi cation device depends on the sorbent used. The sorbent must t>e able to attract and remove the sorbate, such as water, from the gas stream, Stirbems absorb water on the surface of the material by adsorption or by chemically combining with water (absorption). If the unit is regenerative, the process is reversible, allowing water to be removed. This is achieved by a sorbent such as silica gel, alumina gel, activated alumina, lithium chloride salt, lithium chloride solution, glycol solution, or molecular sieves. In the case of nonregenerative equipment, hygroscopic salts such as calcium chloride, urea, or sodium chloride are used. 

Dasler, W. et al., Ind. Eng. Chem. (Anal. Ed.), 1946,18, 52 Like other monofunctional ethers but more so because of the four susceptible hydrogen atoms, dioxane exposed to air is susceptible to autoxidation with formation of peroxides which may be hazardous if distillation (causing concentration) is attempted. Because it is water-miscible, treatment by shaking with aqueous reducants (iron(II) sulfate, sodium sulfide, etc.) is impracticable. Peroxides may be removed, however, under anhydrous conditions by passing dioxane (or any other ether) down a column of activated alumina. The peroxides (and any water) are removed by adsorption onto the alumina, which must then be washed with methanol or water to remove them before the column material is discarded [1], The heat of decomposition of dioxane has been determined (130-200°C) as 0.165 kJ/g. 

The adsorption isotherm of sodium dodecyl sulfate (SDS) on alumina at pH = 6.5 in 0.1 M NaCI (Fig. 4.11a) is characteristic of anionic surfactant adsorption onto a positively charged oxide. As shown by Somasundaran and Fuerstenau (1966) and by Chandar et al. (1987), the isotherm can be divided into four regions. These authors give the following explanation for the adsorption mechanism ... 

A well-studied and often-cited adsorption isotherm of an ionic surfactant is that of sodium dodecylsulfate at the alumina-water interface at pH 6.5 and 0.1 M NaCl. At pH 6.5 and 0.1 M NaCl the S-F isotherm [23]... 

We know now that dyeing is an adsorption phenomenon but no one has met specifically the two points raised by Witt. The answer has recently been given implicitly in a paper by Weiser and Porter, who showed that alumina takes up alizarin in the form of the ahzarin anion, because one gets the same red lake whether the lake is treated with acid or alkali, whereas solid sodium alizarate is purple and solid alizarinic acid is yellow. 

With hydrous zinc oxide there is a slight adsorption of yellow alizarinic acid and purple sodium alizarate. A variation in the degree of acidity with stannic oxide and zinc oxide will give all variations of color between yellow and purple, while the presence of alumina introduces a red. This accounts for the fact of alizarin being what is called a polygenetic color, because the color varies with the nature of the mordant. Other examples of this class are said to be cochineal and logwood but we have not yet studied these dyes. 

Fuerstenau, D. W., and T. Wakamatsu, Effect of pH on the adsorption of sodium dodecanesulphonate at the alumina/water interface , Faraday Disc. Chem. Soc., 59,157-168 (1975). 

Further evidence for three distinct modes of adsorption can be seen in the electrophoretic behavior of alumina in the presence of sodium dodecyl sulfonate. Below 6 X 10 5M, the electrophoretic mobility is nearly independent of concentration, but at this concentration the slope of the mobility-us.-concentration curve abruptly changes. At 3 X 10"4M dodecyl sulfonate concentration, the electrophoretic mobility reverses its sign, indicating that the charge in the Stem layer now exceeds the surface charge in absolute magnitude. 

Figure 2. Adsorption isotherms for sodium alkylsulfonates of different hydrocarbon chain lengths on alumina at pH 7.2, 25°C., and 2 X 10 3M ionic strength...

Tomida et al. (73) investigated the temperature-programmed desorption of n-butylamine from silica-alumina and alumina. The desorbed amine products were different in the two cases. n-Butylamine and n-butene were obtained from silica-alumina dibutylamine and n-butene were obtained from alumina. In a subsequent paper by Takahashi et al. (73a), the authors conclude that two types of adsorption sites on silica-alumina account for the desorption behavior of n-butylamine. One type chemisorbs the amine and the other catalyzes the decomposition of the amine to lower olefins at temperatures above 300°C. On the other hand, amine decomposition was not observed when pyridine was desorbed from silica-alumina. The effects of sodium poisoning on desorption behavior of n-butylamine and pyridine were also examined. 

Figure 4. Adsorption of Cs(I), Sr(II), and Eu(III) on the sodium form of gamma-alumina. (Trace loading, 60-240 hr equilibration, 0.5 M NaCl).

In August 1952 Breck located the powder x-ray data for mineral faujasite and realized that it was very similar to that of the X zeolite. We obtained about 50 mg. of faujasite and studied it carefully. The x-ray pattern was indeed very similar to that of X. The adsorption capacity was somewhat lower but similar. The silica/alumina ratio was 4.7 compared to 2.5 for X. The cations in faujasite were calcium, magnesium, and barium, not sodium as in X. It was clear that X and faujasite were isostructural but with different compositions. Further similarities and differences could not be studied at that time due to the limited supply of faujasite. 

Study of vapor adsorption on potassium-sodium zeolites of the fau-jasite type (the ratio of silica to alumina n = 2.49) has shown that adsorption capacity for water is decreased and for benzene increased with... 

Cho et al. reported that a-alumina is formed from aluminum hydroxide prepared by precipitation with potassium hydroxide. However, when alkaline hydroxide is used as the precipitation agent, alkali cations are incorporated into the product, and commercial gibbsite samples are always contaminated with a small amount of sodium ions. Therefore their starting material seems to be contaminated with potassium, and the presence of potassium ions in their precursor seems to play an important role in the nucleation of a-alumina. They also reported that hydroxyl ions, acetic acid, and pyridine added to the glycothermal reaction system affect the morphology of the a-alumina particles because of their preferential adsorption to a specific surface. ... 

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