High-performance nanofiltration membrane intercalated by FeOOH nanorods for water nanofiltration

Nanofiltration (NF) is considered a promising candidate to improve the separation efficiency in water desalination, and the membranes with incomparable water permeance and great selectivity are urgently requried to reduce the energy consumption. Iron oxohydroxides (FeOOH) nanorods, goethite (α-FeOOH) with a diameter of 30–40 nm and length of about 340 nm, were synthesized and deposited on PES microfiltration (MF) membrane with the pore size of 0.1 μm by the assistance of vacuum filtration. Then a high flux NF membrane intercalated by well-dispersed FeOOH nanorods was fabricated using piperazine (PIP) and trimesoyl chloride (TMC) as monomers. The influence of FeOOH deposition on the surface properties and the nanofiltration performance of the fabricated membranes was studied. XPS, SEM, TEM, AFM, water contact angle (WCA) and NF measurements were utilized to investigate membrane performance. The optimum membranes showed a high water permeability (34.1 L·m−2·h−1·bar−1), high rejection for Na2SO4 (95.0%) and good ion selectivity towards Cl−/SO42− (23.9). Furthermore, the optimized NF membranes are acid-stable to some extent, and showed good stability in long-term NF operations. This work presents a facile and low-cost strategy for constructing high performance NF membranes.