2.3.2. Preparation of thin-film composite and nanocomposite membranes
All thin composite films on the HPAN membrane surface were obtainedin situ using an interfacial polymerization route, as presented in Scheme 1. First, the HPAN membranes were immersed in a 1.0% (w/v) DETA aqueous solution. After 30 min, the membranes were pulled out of the solution and the excess DETA solution on them was removed using a rubber roller. Subsequently, UiO-66(Zr/Ti)-NH2 powder was dispersed in a 0.1% (w/v) solution of TMC in n -hexane via ultrasonication for 1 h at 25 °C and was poured onto the surface of the amine-saturated HPAN substrate to react for 3 min. The obtained UiO-66(Zr/Ti)-NH2-containing TFN membrane was denoted as TFN-(Zr/Ti) membrane. We fabricated TFN-(Zr/Ti)-1 and TFN-(Zr/Ti)-2 membranes with UiO-66(Zr/Ti)-NH2 loadings of 0.01% and 0.03% (w/v) in 50 mL of n -hexane solution, respectively. For comparison, we also prepared thin-film composite (TFC) membranes that did not contain MOF nanoparticles and TFN-(Zr) membranes with UiO-66(Zr)-NH2 nanoparticles. Using the same strategy, we fabricated TFN-(Zr)-1 and TFN-(Zr)-2 membranes with UiO-66(Zr)-NH2 nanoparticle loadings of 0.01% and 0.03% (w/v), respectively. All MOF-based membranes were dried and subsequently stored in DI water for further use.