Abstract
A hydrophobic, hydrothermally stable metal organic framework (MOF) - zeolitic imidazolale framework-8 (ZIF-8) was successfully incorporated into the selective polyamide (PA) layer of nanocomposite (TFN) membranes for water desalination. The potential advantages of ZIF-8 over classic hydrophilic zeolite used in TFNs include: i) theoretically faster water transport within the framework and ii) better compatibility with the PA matrix. The TFN membranes were characterized with SEM, TEM, AFM, XPS, water contact angle measurements and reverse osmosis tests under 15.5 bar hydraulic pressure with 2000 ppm NaCI solution. Lab-made, nano-sized (similar to 200 nm) ZIF-8 increased water permeance to 3.35 +/- 0.08 L/m(2) . h . bar at 0.4% (w/v) loading, 162% higher than the pristine PA membranes; meanwhile, high NaCl rejection was maintained. The TEN surface was less crosslinked and more hydrophilic than that of the pristine PA. A filler encapsulation mechanism was proposed for the effects of filler on TEN membrane surface morphology and properties. This study experimentally verified the potential use of ZIF-8 in advanced TEN RO membranes. (C) 2014 Elsevier B.V. All rights reserved.