The most known and used sort of desiccant is silica gel. It is a natural occurring mineral known as silicon dioxide which is purified and processed to beaded or granular form. Silica gel has a mean pore size of 24 angstroms and has a strong affinity for moisture molecules. It will absorb moisture at temperatures up to 220°F 105°C. As temperature goes above 100°F, the rate of moisture absorption will slow down but it will still work. Silica gel works best at room temperatures and high humidity 60- 90% RH and will drop the relative humidity in a container down to approximately 40 percent RH. It is widely utilized in pharmaceutical and food applications since it is the only desiccant accepted by FDA for direct contact with these products. Silica gel desiccant has a wide range of pore sizes so it is the capacity to consume not only water but alcohols, aromatics, ammonia, olefins, diolefins and paraffins too.
Indicating silica gel is a silica gel bead or granule that is been washed with a concentration of a heavy metal salt, cobalt chloride that has a deep blue colour when dry but it turns from blue to purple to pink as it becomes saturated with moisture. Indicating silica gel shouldn’t be used in contact with products for consumption such as pharmaceuticals or food due to the inclusion of cobalt chloride. Activated carbon or activated charcoal how it is also called is different from normal charcoal since it moved through an activation process and it is also free of fossil fuels which are poisonous. Its surface area is dramatically increased in the activation process that adds the exceptional absorbing ability. Activated carbon has the capacity to absorb toxins or chemical spills when used in agriculture. It is great medicinal qualities used to treat infections and colic, diarrhea, open wounds, spider bites or bees, ants and scorpion bites, food poisoning. Additionally, it treats drug overdose, gas, diabetic ulcers, heartburns and indigestion.
As it possesses such excellent absorption capacity, activated Carbon can also be used for air and water filters. It will absorb gases and odors, plastic fumes, cigarette smoke, furniture glues, carpet odors, bacteria and viruses. Activated charcoal filters out harmful components from water such as chlorine, copper or carbohydrates. Molecular sieves are porous synthetic oxygen absorber which have a very strong affinity for moisture molecules. When compared with the other desiccants, the distinguishing quality of the molecular sieve arrangement is that the uniformity of the pore size openings in the crystal lattice structure. Part of the production process, the pore size on the Molecular sieve particles is controlled allowing the choice of a product that can absorb water, nevertheless exclude many other molecules, such as volatile organics, which could be present in the bundle or others that may absorb a wide assortment of molecules in addition to moisture.