Inorganic filler selection in PDMS membrane for acetone recovery and its application in a condenser-gas membrane system

Abstract

PDMS mixed matrix membranes (MMMs) with inorganic fillers - TS720 and TS530 silica, NaY type zeolite and multiwalled carbon nanotube (MWCNT) - were prepared by solvent evaporation and then tested for pure gas (N 2 , O 2 ) and acetone/N 2 mixed gas permeability at various pressures at 35°C. The membranes were also tested for thermal stability. Results showed that the presence of the inorganic fillers improved the thermal stability of the PDMS membrane. Based on permeability and selectivity results, PDMS/TS720 MMM exhibited better performance, thus, it was chosen as the coating material in the fabrication of the thin film composite (TFC) membrane to be integrated into the condenser-gas membrane hybrid system. The TFC membrane was prepared by coating a thin layer of PDMS solution containing 20% (w/w) TS720 filler on the flat-sheet ultrafiltration polysulfone support membrane using a roller coating machine. Acetone/N 2 mixed gas permeation experiment was conducted at 35°C and 5 bars to ensure that the TFC membrane was defect-free. Results showed that the TFC membrane has an acetone permeance and selectivity of 964.3 GPU and 8.5, respectively. The condenser-membrane hybrid experiment was performed at various stage cuts (SCs) under controlled operating conditions (pressure, temperature, flow rate and acetone concentration). Results of the hybrid experiment showed an over-all acetone recovery as high as 91.9% at 60% SC.