A diaphragm typically refers to a thin film-like material with a microporous or molecular-level filtration structure that is used to separate, filter, or concentrate specific components of a liquid or gas. These membranes can be used in a variety of applications depending on the material, pore size, and structure, including water treatment, food processing, pharmaceutical preparation, chemical production, and other areas. In water treatment, membranes are commonly used in processes such as reverse osmosis, ultrafiltration, and nanofiltration, where impurities, microorganisms, and dissolved solids can be effectively removed from the water through the microporous structure of the membrane, resulting in clean drinking or industrial water. The choice of membrane depends on the requirements of the application, such as the target substance to be filtered, flow rate demand, operating pressure, etc. Common materials include polyester, polycarbonate, and polyethersulfone, while pore sizes can be adjusted as needed, usually including microfiltration, ultrafiltration, and nanofiltration levels.