MEMBRANES FUNCTIONALIZED WITH 1d, 2d and 3d CARBON MATERIALS

Abstract

Modification of polymer and ceramic mem­branes by modern one-, two- and three- di­men­sional carbon nanomaterials (carbon nano­tubes, fullerenes and their derivatives, oxi­dized and reduced graphene) is consi­dered. It is shown that carbon materials can be incorporated into membrane matrices both as independent components and as a part of multicomponent modifier. The main methods of modification are the addition of modifiers to the polymer solution with subsequent making of polymer membranes, incorporation of nanoparticles of carbon nanomaterials into the pristine membranes, deposition on the outer membrane surface, formation of nanoparticles directly in the pores of the ceramic matrix. Composite membranes containing carbon nanoparticles are used for pervaporation, gas separation, baromembrane processes and low-temperature fuel cells. The addition of carbon nanomaterials to polymers provides better mechanical strength of the membranes. Hydrophilic carbon modifiers increase the resistance of membranes to fouling by organic substan­ces and biofouling, improves their separation ability. Ion-exchange membranes modified with fullerenol and oxidized graphene maintain high proton conductivity at elevated temperatures and low humidity. Сarbon additives increase membrane productivity in baromembrane processes. This effect is especially evident for materials modified with nanotubes: their smooth surface ensures fast liquid transport. These carbon nanomaterials are characterized by antibacterial activity. Composites consisting of nanotubes and an ion-exchange biopolymer, and composites with oxidized graphene and inorganic ion exchanger, give to membranes selectivity to inorganic ions. Ceramic membranes modified with carbon nanoparticles that were formed in the pores of matrices by carbonization of synthetic polymers and polysaccharides have the same properties.
 Besides, these composites reject organic dyes too. The separating ability of composite membranes ocuures due to both dimensional and charge effects. Carbon or composite nano­particles block the pores of the membranes. The pores formed by the modifier prevent pene­tration of large particles of organic substances, for example, protein macromolecules. The charge effect is realized due to the functional groups of the modifier. For membranes modified with fullerenols, the retaining of low molecular weight organic substances occurs due to adsorption. Fullerene-modified gas sepa­ration and pervaporation membranes show increased permeability and selectivity.