Sulphuric acid impregnated silica

For the selective absorption of Cs-Cg olefins a reactor (2.0 x0.4 cm) containing silica gel impregnated with concentrated sulphuric acid, was used. The adsorbent was prepared by mixing concentrated sulphuric acid and silica gel (fraction of 60-200 mesh) (3 2, w/w). Silica gel is a good filler for sulphuric acid, as it remains friable even on absorption of a larger amount of acid than its own weight. Other supports (cement, refractory brick) were found to be inefficient. The absorbent must be stored in hermetically sealed vessels as the olefins are no longer absorbed quantitatively if the content of water in the sulphuric acid is about 12% or above. 

Air was filtered on a quartz fiber filter and drowned through a polyurethane foams at a flow rate of 100 1 min . The foam was extracted with toluene. The sample was then cleaned by chromatography on silica gel impregnated with sulphuric acid... 

A major difference between the two first synthes of ordered mesoporous carbons using MCM-48 mesoporous silica as template [106,107] was in the nature of the precursor. Thus, Hyeon and coworkers used phenol-fomialdehyde whereas Ryoo and coworkers used sucrose, which was impregnated twice in the presence of sulphuric acid. Carbonization and removal of the silica template led the latter team to obtain the so-called CMK-1 carbon [113], whose periodic ordered structure was ascertained by XRD and by TEM [Fig. 34a)]. CMK-1 has a high BET surface area (1200-1800 m g" ) and uniform mesopores about 3 nm in diameter. 

Fig. 123. Separation of ubiquinones (Q-n), plastoquinones (PO-9), mena-quinones (MK-n) and phyUoquineon (K) on a paraffin oil-impregnated silica gel G layer, using acetone-water (95 + 5), saturated with paraffin oil (CS). 20 jLg of each substance applied. Layer sprayed with cone, sulphuric acid after having heated to 130° C [115]...

Fig. USB. Two-dimensional fractionation of human serum lipids on a layer partly impregnated with silver nitrate [182]. Adsorbents silica gel G and silica gel G-silver nitrate (5%) solvents 1 direction petrol ether (BP 40—60° C)-diethyl ether-acetic acid (85 + 15 + 1), 2 direction petrol ether (BP 40—60° C)-diethyl ether-acetic acid (75 + 25 + 1) visualisation charring by heating with chromic acid/ sulphuric acid amount 300 fxg 26 Thin-Layer Chromatography, 2nd Edition...

Pbey and co-workers [70] have separated glycerol hRf 38) from ethylene glycol (hi / 45) on normal silica gel G layers, using butanol-water (90 + 10) the separation may be improved by impregnation with O.IN boric acid. They used dichromate-sulphuric acid (Rgt. No. 46) for detection, obtaining white spots on a yellow-brown background. 

Acid-resisting Cement. The principal types are as follows 1. Silicate an inert filler bonded with silica gel that has been precipitated in situ from Na- or K- silicate in the presence of Na2SiFg, or from silicon ester. 2. Rubber Latex essentially cement sand mixes impregnated with rubber. 3. Synthetic Resin with an inert filler. 4. Sulphur Cements usually with sand as filler. 5. Bituminous Cements. ASTM specifications for these materials are listed in Vol 4-05 of the Annual Book of ASTM Standards, and number some 25, including specifications for mortars and grouts. 

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