A molecular sieve is the most effective option for removing water from liquids and gases. Though older products such as silica gel and alumina desiccants have traditionally been used for such purposes, molecular sieve desiccants can get the job done with purer results. Molecular sieves are uniform pore crystalline structure. Molecular sieves operate on the size exclusion principle. Smaller molecules that fit into the pores are adsorbed while larger molecules pass through. Molecular sieves have regular pore openings of 3, 4, 5, or 10 Angstroms. Polarity of the molecules matter because the highly polarized molecules are adsorbed more readily into the pores than non-polar molecules. Molecules are selectively removed in this manner When a gas or liquid is passed through the mole sieve, smaller pieces are adsorbed while larger molecules pass through. Unlike other filters, the adsorbed substance is then trapped. Therefore, when water is used in the sieve, penetrating water molecules are caught and retained in the pores, leaving the remaining liquid substantially cleared of the water molecules. In all, a mole sieve adsorbs up to 22% of its own weight in water. More than that, these sieves are exceptionally versatile, with adsorption possible based on molecular size, molecular affinity for the sieve crystal surface, or even the shape of the molecule. For these reasons, molecular sieve desiccants can produce gases or liquids that are virtually water free..
