Thin-film nanocomposite forward osmosis membrane with polydopamine @UiO-66-NH2-modified polypropylene support and its antifouling property

Polypropylene (PP) porous flat membrane is ultrathin and has high porosity, which is suitable for the support of forward osmosis (FO) membrane. However, its high hydrophobicity is its Achilles heel. In this study, dopamine and UiO-66-NH2 were co-deposited onto the surface of PP support, and then interfacial polymerization was performed to fabricate a thin-film nanocomposite (TFN) FO membrane. The reaction-generated polydopamine improved the hydrophilicity of PP membrane, and at the same time enhanced the adhering of UiO-66-NH2 to the support. The experimental results indicated that the UiO66-NH2 nanoparticles were anchored evenly on the surface of the support, which improved the water flux of FO membrane from 11.1 LMH (TFC, TFN-0 without UiO-66-NH2) to 20.7 LMH (TFN-0.1, with 0.1 wt% UiO-66-NH2) using 1 mol/L NaCl as the draw solution in FO mode. Compared with TFC membrane, TFN-0.1 membrane also exhibited relative lower specific salt flux (similar to 0.252) and structural parameter (similar to 379 pm). When separating sodium alginate foulant, the normalized water flux recovery ratio of TFN-0.1 was remained 0.89, and most of the fouling was reversible, as for TFC membrane the data decreased to 0.76 after 2 cycles of operation. These results suggested that UiO-66-NH 2 modified FO membrane exhibited good permeation and antifouling property.

Automated summary

In this study, a thin-film nanocomposite (TFN) forward osmosis (FO) membrane was fabricated by co-depositing dopamine and UiO-66-NH2 onto a polypropylene (PP) support and performing interfacial polymerization. The TFN membrane exhibited improved hydrophilicity and water flux compared to a traditional thin-film composite (TFC) membrane, as well as lower specific salt flux and structural parameter. Furthermore, the TFN membrane showed good antifouling property when separating sodium alginate foulant.