METHOD OF MEMBRANES MODIFICATION FOR ULTRAFILTRATION OF AQUEOUS MEDIA

摘要

FIELD: membrane technologies.;SUBSTANCE: invention relates to membrane technology and can be used for purification and separation of water and aqueous solutions in food, pharmaceutical, petrochemical and other industries, in water treatment and creation of especially pure solutions. Method of modifying membranes for ultrafiltration of aqueous media involves predetermining the cutoff threshold of the initial membrane and taking into account characteristics of separated contaminants and material, from which the initial membrane is made, the required cutoff threshold is set, then depending on characteristics of the initial membrane, a modifier is selected from anisotropic disperse materials selected from the group: nanofibrillar cellulose, halloysite nanotubes, nanocrystalline cellulose with particle size corresponding to the preset cut-off threshold, wherein selected modifier is subjected to chemical treatment to obtain value of zeta-potential corresponding to specified cut-off threshold, wherein when nanofibrilled cellulose is used as a modifier, the aqueous dispersion of nanofibrillar cellulose is mixed with sulfuric acid until its concentration reaches 20–65 wt% and hydrogen peroxide until reaching its concentration of 0.1–10.0 wt% with further washing with treated modifier water to achieve zeta-potential of nanofibrillar cellulose from minus 36 to minus 200 mV, when halloysite are used as a modifier of the nanotubes, the aqueous halloysite dispersion is mixed with the aqueous polymer solution followed by washing the treated modifier with water to achieve the halloysite nanotubes zeta potential from minus 36 to minus 200 mV, when nanocrystalline cellulose is used as a modifier, the aqueous dispersion of nanocrystalline cellulose is mixed with sulfuric acid until its concentration reaches 20–80 wt% and hydrogen peroxide until its concentration reaches 0.1–10.0 wt% with further washing of treated modifier with water to achieve zeta potential of nanocrystalline cellulose from minus 36 to minus 200 mV, after which initial membrane is placed in aqueous medium and hydrophilization of initial membrane is carried out by supplying on its working surface of dispersion of selected and treated by one of said corresponding modifying methods modifier to form hydrophilic layer on membrane working surface during filtration of modifier dispersion through membrane wall.;EFFECT: achieved technical result consists in formation during the modification of the membrane of the hydrophilic separating layer on the working surface of the membrane with controlled specific charge and orientation of anisotropic disperse particles of modifier, which provides high barrier properties of self-assembled charged particles of modifier of hydrophilic separating layer.;1 cl, 2 dwg, 7 ex