Modificação de membranas inorgânicas e seu uso na separação de compostos orgânicos voláteis, através da técnica de pervaporação.

Abstract

The pervaporation became an atractive separation process in the last years, mainly after the discovery of new membranes. However, to project and improve pervaporation system is important to develop membranes with a good thermaland chemical estability and high selectivities and permeabilities. In this work it was used two types of ceramic membranes: alumina and zirconia membranes. These membranes was submited to a modification process with the aim to became dense and permeable. It was used two polymers: polydimethylsiloxane and polymethylmetacrilate. It was used infra-red spectroscopy to confirm the presence of the siloxane on the surface of the membrane. After the modification of the membranes it was a pervaporation system to measure the selectivity and flux of the membranes by using mixtures of ethanol-water and isopropanol-water as a feed solution. It was observed after alumina membranes modifications with PDMS and zirconia membrane modification with PDMS and PMMA both membranes presents hydrophilic characteristics, i.e., with water afinity. All membranes showed an increasing in the flux with the increasing of water content in the feed solution. To alumina membrane modified by PDMS and using ethanol with 95%, 48% and 23% in concentration, it was observed flux of 3.3, 5.6 and 10.4 Kg.h"1.m"2, respectively. For isopropanol with 95%, 53% and 33% in concentration, the flux were 1.3, 1.6 and 3.8Kg.h"1.m'2, respectively. For zirconia membrane modified by PDMS and using ethanol as a feed solution with 95%, 52% and 30% in concentration, it was obtained a flux of 3.8, 8.8 and 8.7Kg.h~1.m"2, respectively. For isopropanol with 95%, 48% and 26% in concentration, it was obtained flux of 5.3, 7.8 and 9.8Kg.h"1.m"2, respectively. For zirconia membrane treated with PMMA and using ethanol as feed solution with 95%, 48% and 27% in concentration it was obtained a flux of 2.9, 4.6 and 7.6 Kg.h"1.m"2, respectively. For isopropanol with 95%, 38% and 17% in concentration it was obtained flux of 4.7, 5.6 and 6.3 Kg.h'Vm"2, respectively. Alumina membranes modified by PDMS presented high selectivity to water in relation to ethanol, with value of 200. The same behavior was obtained to zirconia membrane modified by PMMA. For zirconia membrane modified by PDMS it was observed no selectivity for ethanol-water and isopropanol-water. This happen due to some cracking found on the zirconia surface by scanning electron microscopy.