Ultrafiltration is a membrane separation technology. Under a certain pressure (the pressure is 0.07 to 0.7 MPa, the maximum does not exceed 1.05 MPa), water flows on the surface of the membrane. Water and dissolved salts and other electrolytes are tiny particles that can pass through the ultrafiltration membrane, and the relative molecules Larger particles and colloidal materials are blocked by the ultrafiltration membrane, so some particles in the water are separated. Ultrafiltration membranes have pore sizes between tens and hundreds of angstroms. ), Between reverse osmosis and microporous membranes. The pore size of an ultrafiltration membrane is determined by a retention test of a substance having a certain relative molecular mass, and is expressed by a value of the relative molecular mass. In water treatment, ultrafiltration membranes are used to remove suspended and colloidal substances in water. Ultrafiltration membranes are also widely used in the pharmaceutical industry. When the membrane is contaminated or contaminated, it is usually washed with hydrogen peroxide or sodium hypochlorite solution. The membrane surface cannot be cleaned by backwashing. The maximum operating temperature of ultrafiltration is 45 ° C, and the pH is 1.5 ~ 13.0.
Ultrafiltration is a method of removing organics from water. It also removes traces of colloidal matter, organics and resin powder. Ultrafiltration is usually placed after the desalination system or before the reverse osmosis unit to protect the reverse osmosis membrane. The membrane materials used in ultrafiltration membrane modules usually include: diacetate (CA), triacetate (CTA), cyanoethyl acetate (CN-CA), polysulfone (PS), and sulfonated polysulfone (SPSS) , Polysulfone amide (PSA), phenolphthalein side polyarylsulfone (PDC), polyvinylidene fluoride (polyvinylidene fluoride), polyacrylonitrile (PAN), polyimide (PI), methyl methacrylate-propylene Nitrile copolymer (MMA-AN), cellulose, etc. Cellulose acetate (CA), polysulfone (PS), polyacrylonitrile (PAN), polyethersulfone (POS), etc. have been widely used. In addition, there are dynamically formed ultrafiltration membranes.