Microporous Engelhard titanosilicate based polyamide membrane for water vapor dehumidification with excellent chemical resistance to toluene

Abstract

Herein, we describe microporous Engelhard titanosilicate-4 (ETS-4) based polyamide membranes for water vapor dehumidification. ETS-4 particles have unique properties such as good water affinity, excellent chemical resistance, and size selective or molecular sieve properties (effective pore diameter of ETS-4: 3–4 Å, kinetic diameter of H2O: 2.65 Å, toluene: 5.85 Å). ETS-4 particles were fabricated by a hydrothermal method and ground to obtain a smaller size. The ground particles were dispersed in diethylenetriamine (DETA) solution, followed by interfacial polymerization with trimesoyl chloride (TMC), resulting in thin film nanocomposite (TFN) membranes. The addition of ETS-4 particles on the outer surface of polysulfone (PSf) hollow fibers resulted in improvement of the hydrophilicity and surface roughness of the membrane. The ETS(0.2) membrane with 0.2 wt% ETS-4 concentration showed the highest selectivity (413) and the highest water vapor permeance (1544 GPU) at 25 °C and relative humidity 60 %. In addition, the toluene removal performance of the best ETS(0.2) membrane was tested and demonstrated a rejection efficiency of ca. 94.7 %. The long term stability of the ETS(0.2) membrane was also measured under toluene gas flow for one month and it was confirmed that the ETS-4 based membrane had excellent chemical stability against toluene.