Molecular sieves generally serve the purpose of blocking large molecules from interacting by preventing them from entering a compound. On the other hand they permit the entry of smaller user friendly molecules. Most of molecular sieves are used as desiccants.
The size of the molecules that are restricted and the ones that are permitted are measured in angstroms or nanometers. The general size of the molecules varies between 2 nm (nanometers) and 20 A (angstroms).
The Types of Molecular Sieves Used as Drying Agents
Molecular sieves that are used as drying agents are a combination of silica and aluminium tetrahedral. In order to be used as a drying agent, the water content has to be removed by heating the relevant substances to form equal cavities that can suitably absorb hydrated molecules of a certain size.
A mesh is used for this purpose and its dimensions will depend on the material that is to be dried. Generally, a 4-8 size sieve is used for the drying of gases, while a mesh size of 8-12 is mostly used for liquids. For powders, the 3A, 4A, 5A, and the 13x types of sieves can be used, depending on the exact composition of the powders in question.
Uses of the Molecular Drying Sieves
Molecular sieves as a drying agent have been known to be very effective in many synthetic organic procedures. Many products can be prevented from the condensation process that can severely damage their composition or the required properties. This is precisely where the molecular drying sieves play a vital role.
Most of these drying agents can remove the harmful effects of water or moisture, including alcohols that can include methanol and ethanol. Importantly, they can also prevent the formation of unwanted substances that can result as a byproduct of water or moisture.
The Importance of Solvent Drying
In the chemical or pharmaceutical industries it is critical that only the required amount of moisture or water is present to produce the ideal composition of drugs. It is important that the process of solvent drying is employed before the material is packed or sealed as the case may be.
Every molecule of a substance or a compound has its own unique structure and molecular size and their critical diameters. It is essential that these are kept in mind when dealing with them, especially for drying solutions.