Incorporating hydrophilic amino-modified UiO-66 nanoparticles into polyphenylsulfone membrane for improved dye/salt separation

This study explores the incorporation of three Zr-based MOFs with varying pore structures (UiO-66, NU-906, and NU-1008) into a polyphenylsulfone (PPSU) matrix for dye and salt separation, highlighting that UiO-66/PPSU membrane exhibits superior permeability and separation performance. To enhance the compatibility of the MOF with the matrix and improve the antifouling performance, hydrophilic diethylenetriamine was grafted onto UiO-66. The strengthened hydrogen bonding between DETA-UiO-66 and PPSU improved its dispersibility in the polymer matrix and increased the mechanical strength of the MMMs. Moreover, the incorporation of hydrophilic DETA-UiO-66 nanoparticles enhanced the pore structures and hydrophilicity of the DETA-UiO-66/PPSU membranes, enabling them to exhibit higher permeability and antifouling performance. The 1.0wt%DETA-UiO-66/PPSU membrane exhibited a substantial increase in water flux to 16.52 LMH·bar −1 , threefold and double higher than the pure PPSU membrane and UiO-66/PPSU membrane. Meanwhile, high rejection rates of 99.3% for reactive orange 16, 99.6% for brilliant blue G, and 99.7% for rose Bengal were demonstrated with low NaCl retention rate of 7.69% at a high salt concentration of 5000 mg/L, achieving a high salt/dye separation factor of 184.6 under the size sieving and the Donnan exclusion mechanisms. Moreover, integrating DETA-UiO-66 significantly improved the antifouling performance with the flux recovery rate increased from 71.6% to 95.2% and the irreversible fouling ratio decreased to 4.8%. DETA-UiO-66/PPSU membrane also exhibited excellent stability where the mechanical integrity and separation performance were maintained in the 100-hour dye/salt separation process. This research highlights the promising application of DETA-UiO-66 in the fabrication of advanced mixed matrix nanofiltration membranes and offers valuable insights into the integration of various modified hydrophilic MOFs for the design of efficient water treatment membranes.