Silica gel [James .C. Bolyan, 1994]
Silica gel is a granular, vitreous, and porous form of the silicon dioxide which is synthetically obtained from the sodium silicate. Silica gel contains a non porous silica micro structure suspension inside a liquid. Most application gel should be dried. Fig: 30. Silica gel
Structure Density : 700 kg/m3
Boiling point: 2.2300C
Molar mass: 60.08 g/mol
Chemical formula: Sio2
Appearance: Transparent beads
Odor : Odourless
Insect repellent gel excipients profile [James .C. Bolyan, 1994]
Gel: Gel is a solid jelly like material that can have properties ranging
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Aqueous solutions of higher molecular-weight grades may form gels. Liquid polyethylene glycols are soluble in acetone, alcohols, benzene, glycerin, and glycols. Solid polyethylene glycols are soluble in acetone, dichloromethane, ethanol (95%), and grades may form gels. Liquid polyethylene glycols are soluble in acetone, alcohols, benzene, glycerin, and glycols. Solid polyethylene glycols are soluble in acetone, dichloromethane, ethanol (95%), and methanol; they are slightly soluble in aliphatic hydrocarbons and ether, but insoluble in fats, fixed oils, and mineral …show more content…
In topical pharmaceutical formulations and cosmetics, glycerin is used primarily for its humectants and emollient properties. Glycerin is used as a solvent or co solvent in creams and emulsions .Glycerin is additionally used in aqueous and non aqueous gels and also as an additive in patch applications. In parenterals formulations, glycerin is used mainly as a solvent and co- solvent. In oral solutions, glycerin is used as a solvent, sweetening agent, antimicrobial preservative and viscosity-increasing agent. It is also used as a plasticizer and in film coatings Glycerin is used as a plasticizer of gelatin in the production of soft-gelatin capsules. Stability and Storage Conditions Glycerin is hygroscopic. Pure glycerin is not prone to oxidation by the atmosphere under ordinary storage conditions but it decomposes on heating with the evolution of toxic acrolein. Mixtures of glycerin with water, ethanol (95%), and propylene glycol are chemically