Precursors sodium silicate

With chemical treatment, the natural surfactants in crude oil can be activated [1384]. This method has been shown to be effective for highly viscous crude oil from the Orinoco Belt that has been traditionally transported either by heating or diluting. The precursors to the surfactants are preferably the carboxylic acids that occur in the crude oil. The activation occurs by adding an aqueous buffer solution [1382,1383]. The buffer additive is either sodium hydroxide in combination with sodium bicarbonate or sodium silicate. Water-soluble amines also have been found to be suitable [1506]. 

The synthesis of MCM-41 structure in fluoride medium has been reported by Silva and Pastore [10], who used sodium silicate as silica source and carried out crystallization at 150 °C. They suggested the behaviour of Si02-CTMA+-F system was significantly different from that reported previously on the mesophase system. It is known that fluoride ions do influence the nature, activity and polymerizing capacity of silica precursors, and a fluorinated silica surface is much more hydrophobic and more resistant to the attack of water molecules than a silanol silica surface [11]. 

Silica nanoparticles are commonly prepared by polymerization of appropriate precursors such as silicates, silicon alkoxides, or chlorides (Fig. 11.2).2 Besides the industrial methods, which rely mainly on condensation of sodium silicate in water induced by sodium removal through ion exchange, three different synthetic methods are currently used in research labs to prepare silica nanoparticles loaded with organic molecules. In the first method, proposed by Kolbe in 1956s and developed by Stober and coworkers in the late 1960s,6 the particles are formed via hydrolysis and... 

Laundry soap bars are precursors of the chip and the powder forms. They are generally made from tallow or a combination of tallow and coconut oil. Borax and builders, such as sodium silicate and sodium carbonate, are included to improve performance and help soften water [1, 2, 5]. 

Hay R. L. (1968) Chert and its sodium-silicate precursors in sodium-carbonate lakes in East Africa. Contrib. Mineral. Petrol. 17, 255 -274. 

The presence of hydrated TPA silicate in the T-series is quite interesting, as the crystallization rate is consistently higher for the T-series than for the S-series where sodium is also included in the gel. It was shown previously that monomeric TPA ions may lead to the formation of ZSM-5 zeolites (30,31), and that the concentrations of TPA ions required to crystallize ZSM-5 is indeed much higher in the sodium-free system. Sodium has also been shown to reduce the rate of ZSM-5 crystallization. This is due in part to the preferential formation of sodium silicate, which leads to the formation of dense structures (29). Moreover, the hydrophillic interaction of sodium with the precursor silicate gels has an inhibiting effect on the formation of the hydrophobic silicalite framework. The results emphasize the dual role of TPA ions both in their structure directing and space-filling functions. 

The zeolite ZSM-3 was prepared from aluminosilicate hydrogels containing sodium and lithium cations. The crystallization technique consists of first preparing a precursor solution of concentrated sodium aluminosilicate and then mixing it with aqueous sodium silicate and aluminum chloride solutions to form the starting hydrogel slurry. This slurry is filtered to remove excess soluble sodium silicate. Lithium is added to this filter cake as lithium hydroxide solution. This mixture is held at temperatures of 60° to 100 °C until ZSM-3 crystals form. At 60 °C, crystallization requires 5 days while at 100 °C, crystals are formed in 16 hours. In order to obtain the desired SiOo/Al203 ratio in the crystalline product, the aluminum chloride content is varied. 

Parvathy Rao A, Venkastewara Rao A, Pajonk GM (2007) Hydrophobic and physical properties of the ambient pressure dried silica aerogels with sodium silicate precursor using various surface modification agents. Appl Surf Sci 253 6032-6040... 

Rao, A P, Rao, A V, Pajonk, G, Shewale, P M (2(X)7) Effect of solvent exchanging process on the preparation of the hydrophobic silica aerogels by ambient pressure drying method using sodium silicate precursor. J Mater Sci 42(20) 8418-8425. 

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