What is Desiccant Silica Gel

What is Desiccant Silica Gel?

Silica gel is anamorphous yporous form ofsilicon dioxide (silica), consisting of an irregular tridimensional framework of alternatingsilicon yoxygen atoms withnanometer-scale voids and pores. The voids may contain water or some other liquids, or may be filled by gas orvacuum. In the last case, the material is properly called silica xerogel.

Silica xerogel with an average pore size of 2.4 nanometers has a strong affinity for water molecules and is widely used as adesiccant. It is hard andtranslucent, but considerably softer than massivesilica glass orquartz; and remains hard when saturated with water.

Silica xerogel is usually commercialized as coarse granules or beads, a fewmillimeters in diameter. Some grains may contain small amounts of indicator substance that changes color when they have absorbed some water. Small paper envelopes containing silica xerogel pellets, usually with a “do not eat” warning, are often included in dry food packages to absorb anyhumidity that might causespoilage of the food.

‘Wet’ silica gel, as may be freshly prepared fromalkali silicate solutions, may vary in consistency from a soft transparentgel, similar togelatin oragar, to a hard solid, namely a water-logged xerogel. It is sometimes used in laboratory processes, for example to suppressconvection in liquids or preventsettling of suspended particles

Types

· Type A – clear pellets, approximate pore diameter: 2.5 nm, drying and moistureproof properties, can be used as catalyst carriers, adsorbents, separators and variable-pressure adsorbent.

· Type B – translucent white pellets, pore diameter: 4.5⁠–⁠7.0 nm, liquid adsorbents, drier and perfume carriers, also may be used as catalyst carriers, cat litter.

· Type C – translucent, micro-pored structure, raw material for preparation of silica gel cat litter. Additionally dried and screened, it forms macro-pored silica gel which is used as drier, adsorbent and catalyst carrier.

Silica alumina gel – light yellow, chemically stable, flame-resistant, insoluble except in alkali or hydrofluoric acid. Superficial polarity, thermal stability, performance greater than fine-pored silica gel.

Stabilizing silica gel – non-crystalline micro-porous solid powder, nontoxic, flame-resisting, used in brewery of grains for beer to improve taste, clearness, color, and foam and for removal of non-micro-organism impurities.