Adsorbents magnesium aluminum silicate

Finely divided solid particles that are wetted to some degree by both oil and water can also act as emulsifying agents. This results from the fact that they can form a particulate film around dispersed droplets, preventing coalescence. Powders that are wetted preferentially by water form O/W emulsions, whereas those more easily wetted by oil form W/O emulsions. The compounds most frequently used in pharmacy are colloidal clays, such as bentonite (aluminum silicate) and veegum (magnesium aluminum silicate). These compounds tend to be adsorbed at the interface and also increase the viscosity of the aqueous phase. They are frequently used in conjunction with a surfactant for external purposes, such as lotions or creams. 

Owing to its inert nature, magnesium aluminum silicate has few incompatibilities but is generally unsuitable for acidic solutions below pH 3.5. Magnesium aluminum silicate, as with other clays, may adsorb some drugs. This can result in low bioavailability if the drug is tightly bound or slowly desorbed, e.g., amfetamine sulfate, tolbutamide, warfarin sodium, and diazepam. ... 

Adsorbents are chemically inert powders that have the ability to adsorb moisture, gasses, toxins, and to some extent, bacteria. Some minerals have found extensive use as adsorbents, such as magnesium aluminum silicate, bentonite, attapulgite, talc, calcium carbonate, and kaolin. The activities of kaolin and calcium carbonate were discussed in a preceding section. 

Table I represents the weight variation in each experimental step and dehumidification efficiencies of the adsorbent-impregnated ceramic sheets. The interesting thing was that the dehumidification efficiency increased in a sequence of silica, magnesium silicate, aluminum silicate and titanium silicate-impregnated ceramic sheets. It is evident that the incorporation of aluminum and titanium ions improved the dehumidification efficiency of silica gel-based adsorbent, but the incorporation of Mg ions doesn t affect the dehumidification efficiency of silica gel-based adsorbent.

Figure 3 represents the N2 adsorption-desorption isotherms of the silica, magnesium silicate, aluminum silicate, titanium silicate-impregnated ceramic sheets. In all the adsorbent-embedded ceramic sheets, there were the well-developed micropores which gave the isotherms to the hysteresis phenomena at the relative pressures from 0.4 to 0.8. Also, it was shown that the incorporation of Ti and Al ions have the considerable volume of adsorbed N2, compared with the pure silica and magnesium silicate-impregnated ceramic sheets. 

The ceramic sheets with aluminum silicate or titanium silicate adsorbents showed better dehumidification behavior than the silica and magnesium silicate-impregnated ceramic sheets. The superior dehumidification efficiency originates from the well developed micropores. 

In laboratory studies, silica was adsorbed and precipitated by hydroxides of aluminum, iron, manganese, and magnesium, according to Harder (42). After precipitating 15 ppm Al(OH), from a 3 ppm SiO in solution, the residual silica was 0.8 ppm, whereas with 30 ppm aluminum hydroxide, no measurable silica remained. Willey has given an excellent review of the extensive literature on the interaction of silica and alumina in dilute solutions. The low levels of soluble silica reached (39) depended on the particular solid aluminum silicate phase that was formed or present. She studied the interaction at very low concentrations, generally less than 10 ppm, and found that only I ppm SiO is required to initiate the precipitation of 1 ppm of AljOs from solution, and if more than about I ppm AljO, is in solution the silica concentration becomes exceedingly low. 

PQ Corporation of Valley Forge, Pennsylvania (Seybold, 1992) reported test results using their silica adsorbent, Britesorb-RlOO. In their test, french-fried potatoes were made in a restaurant type fryer. The product was fried for 8h per day. Fresh oil was added to the fryer after so many batches of product. The oil was treated with 0.7% Britesorb R-lOO, mixed for 5-10 min, filtered, and stored overnight to be used the next day. Oil breakdown products, such as polar compounds, polymers and free fatty acids were measured. In addition, oil color and soap content in the oil were also monitored. Most significant differences between Britesorb R-lOO and the other adsorbents were noticed in the soap and polar materials. Results from these tests are listed in Tables 11.3 and 11.4. The results indicate that Britesorb R-lOO is a superior adsorbent compared to other commercially available magnesium and aluminum silicate adsorbents. 

An apparatus for simultaneously coating a plate with two adjacent layers of different adsorbents was accomplished by placing a plastic insert into a commercial spreader, thus forming two independent chambers. For this reason, combinations of two adsorbents, such as cellulose, silica gel, alumina, charcoal, silicic acid, magnesium silicate, etc. as a function of the sample were used. Then, the two eluents systems were optimized for the two development directions, e.g., 2-D separation of some ketones on a bilayer (charcoal/ silicic acid) with benzene-ether-acetic acid (82 9 9, v/v) in the first direction (on charcoal) and with benzene-ether (85 15, v/v) in the second direction (on silicic acid). In another paper, the first adsorbent was silica gel (air-dried) and the second adsorbent was deactivated aluminum oxide. The same solvent system, toluene-ethyl acetate (3 1, v/v), was used in the two directions. In this condition, a mixture of 2,4-dinitrophenylhydrazine derivatives of hydroxycarbonyl compounds was resolved. 

Nanoclays can be categorized into cationic and anionic types. Cationic nanoclays are based on smectite clays. An example is montmorillonite (MMT), a hydrated Al, Mg silicate that may contain cations such as Na+ and Ca++ between the anionic layers. In contrast, anionic clays contain cationic layers and anions such as Cr and in the interlayer space. Typical examples include layered double hydroxides (LDH) and hydrotalcite (HT), a mostly synthetic hydrated magnesium and aluminum carbonate salt. Whereas MMT is commonly used as a nanofiller to improve thermal, mechanical, and barrier properties, LDHs have many attractive properties that lead to application as surfactant adsorbents, biohybrid materials, antacid food formulations, acid neutralizers, and active pharmaceutical ingredients excipients [37, 13, 28, 14, 35]. 

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