Silica gel (also called silica gel, drying beads, drying beads, etc.) is the most commonly used drying agent in aeration drying. It consists of 99% silicon dioxide (SiO2). Due to its high porosity, narrow-pored silica gel has a large internal surface of up to 850 m²/g. The pore structure is not uniform, the funnel-shaped openings have a diameter of approx. 2 to 12.5 nm. This allows the loading of water molecules in several layers (capillary condensation), which explains the very high absorption capacity of this adsorbent. Due to its extreme hydrophilicity (attraction of polar substances such as water) and simple regeneration by raising the temperature to approx. 120°C, it is preferably used as a drying agent.
Particularly at a relative humidity of approx. 70 %rh, silica gel shows excellent absorption capacity and can therefore adsorb large amounts of water from the air. The maximum capacity is approx. 37 % of the dry weight of the bulk material. The silica gel orange-colorless has a weaker color change, which takes place with a later loading. Thus this silica gel discolours with a water load of approx. 20-25%.
Chemical Composition: Amorphous silicon dioxide
CAS number: 112926-00-8
|Appearance and shape||Orange, solid balls|
|particle size||3 - 5 mm|
|bulk density||0,75 - 0,85 kg/l|
|pore volume||0,35 - 0,45 ml/g|
|breaking strength||> 200 N|
|Specific surface||600 - 800 m²/g|
|Silicon oxide SiO2||99 %|
|trace elements||1 %|
|rate of abrasion||< 2 %|
|water absorption capacity||> 370 ml/kg|