Amorphous and porous, silica gel is a type of silicon dioxide (silica) made up of a truncated, three-dimensional framework of alternating silicon and oxygen atoms with gaps and pores on the nanoscale scale. Water or other liquids, gas, or a vacuum may occupy the spaces. Silica xerogel is the correct term to use in the third scenario.
The average pore size of 2.4 nanometers in silica gel price in singapore xerogel gives it a high affinity for water molecules, making it a useful desiccant. It's hard and transparent, but a lot softer than quartz or silica glass of gigantic size, and it retains its brittleness even when doused in water.
Commercial silica xerogel often comes in the form of granules or beads a few millimeters in size. A minor quantity of indicator material may be present in some grains; this ingredient causes a change in color after the grains have absorbed water. Dry food containers commonly include little paper envelopes with silica xerogel pellets, typically with a "do not eat" warning, to soak up any moisture that may cause the food to degrade.
Freshly generated 'wet' silica gel from alkali silicate solutions can have a range of textures, from a soft translucent gel like gelatin or agar to a hard solid, in the form of a xerogel that has been saturated with water. Sometimes it is used in the lab to do things like stop particles from settling out of suspension or to stop liquids from convecting.
As early as the 1640s, silica gel was available to the scientific community as an intriguing novelty.
During World War I, [5] it was employed to absorb harmful fumes and vapors in gas mask containers.
[6] In 1918, Walter A. Patrick, a chemical professor at Johns Hopkins University, was granted a patent for a synthetic method of manufacturing silica gel.
Silica gel was crucial to the war effort during World War II because it was used to preserve penicillin, protect military equipment from moisture damage, produce high-octane gasoline, make carbon disulfide, and produce butadiene from ethanol as a catalyst support.
Silica gel is an excellent desiccant because of its high specific surface area (around 750–800 m2/g (230,000–240,000 sq ft/oz))[7] (drying agent). When the microscopic structure of silica gel is disregarded, as in silica gel packs or other goods, the common description of the gel as "absorbing" moisture is accurate. Silica gel, on the other hand, doesn't absorb moisture; rather, it eliminates moisture by having it adsorb onto the surface of its many pores. After becoming soaked with water, the gel can be revitalized by heating it to 120 degrees Celsius (250 degrees Fahrenheit) for one to two hours. [further references needed] If you put enough water on some forms of silica gel, they can explode. This happens when silica spheres disintegrate upon contact with water.Learn more