Nanocomposites and nanomaterials

Ultrafiltration membranes modified with nanocomposite containing graphene oxide
Dzyazko Yu.S.1, Rozhdestvenska L.M.1,  Bildukevich A.V.2, 
Plisko T.V.2,  Borisenko Yu.V.3, Zmievskii Yu.V.4, Zakharov V.V.4
1 V.I. Vernadskii Institute of General and Inorganic Chemistry of the NAS of Ukraine, 32/34 Palladin ave., 03142 Kyiv, Ukraine 
2 Institute of Physical Organic Chemistry of the NAS of Belarus, Surganov str. 13, 220072, Minsk, Belarus 
3 Kyiv National University of Technologies and Design, Nemirovich-Danchenko str.2 , 01011, Kyiv, Ukraine
4 National University of Food Technologies, Volodymyrska str. 48, 01601, Kyiv, Ukraine
e-mail: saharoff.911@gmail.com

Polymer ultrafiltration membranes were modified by embedding of nanoparticles of hydrated zirconium dioxide and graphene oxide into pores. TEM and SEM techniques as well as impedance spectroscopy and potentiometric measurements were applied to membrane test. As opposed to pristine membranes, the modified polymers show membrane potential in NaCl solutions. The dependencies of the membrane potential on the solution concentration have been plotted. The sign and value of the derivative of appropriated polynomial function give the information about counter-ions, and reflect rejection. The membranes modified with hydrated zirconium dioxide are amphoteric, the rejection of Ca2+ and Mg2+ ions reaches 8-20 % during baromembrane desalination of water. The membranes containing this carbon nanomaterial show permeability mainly towards cations. These membranes reject SO4- anions, which are usually contained in water. The retention of hardness ions (15-69 %) is due to electroneutrality of the solution. The strongest effect of the modifier on rejection shows the materials that are characterized by the smallest size of pores of polymer active layer. These composite membranes demonstrate the slowest ion transport. 
The electrochemical approach could be useful for express-test of materials for baromembrane separation. The development of this method, which is based on potentiometric measurements under different concentration of solutions, is possible after accumulation of a large array of experimental data.