MODIFICATION OF TUBULAR CERAMIC MEMBRANES WITH PYROCARBON AND SILICA

The tubular ceramic membranes of clay minerals were modified with silica and pyrocarbon, which was obtained by carbonizing of polymer precursors at 750 ° С in an argon flow. The precursors to carbonation were polymers formed from the polyisocyanate and sodium carboxymethylcellulose (membrane II) and polyisocyanate and sucrose (membrane III). Silicon dioxide was formed at high temperature from liquid glass. As a result of the modification, the membranes became black with a metallic luster. The composition and structure of the membranes were studied by XRF and SEM. The modifier of the membranes is located in the pore space in the form of separate particles and sintered agglomerates. The particle size of the modified membrane filler varies from 30 nm to ~ 1 μm depending on the modifier composition. The apparent density and open porosity for the unmodified membrane are 1.80 g/cm3 and 21.9 %, for membrane II - 1.83 g/cm3 and 19.7 %, for membrane III - 1.82 g/cm3 and 18.9 %. Testing of modified membranes was carried out by water purification from Ca2+ and Fe3+ using the baromembrane method at a working pressure of 0.6 MPa. The concentration of Ca2+ in aqueous solutions of CaCl2 was 100 mg/dm3, the concentration of Fe3+ in aqueous solutions of FeCl3 was 100 and 36 mg/dm3. The period of time until the establishment of dynamic equilibrium in systems during water purification is 4 hours. The unmodified membranes does not inhibit Ca2+ and Fe3+ at all. After reaching equilibrium the retention factor (R) of Ca2+ during water purification with modified membranes pressure vary from 20 to 28 % and the specific productivity – from 22 to 40 dm3/(m2×h). The retention coefficient of Fe3+, depending on the membranes modifier and concentration of the FeCl3 solutions being purified,  is 78 - 99.9 %. The specific productivity in this case is 15 - 52.3 dm3/(m2×h).