Poly(sodium-p-styrenesulfonate)-grafted UiO-66 composite membranes boosting highly efficient molecular separation for environmental remediation

The lack of highly permeable and selective separation membranes hampers the application of the energy-efficient membrane separation process for water remediation and CO2 capture in molecular scale. Nanoparticles have been widely applied for tailoring pore structures and surface properties of the molecular separation membranes, thereby enhancing separation performance. However, limited by non-ideal nanoparticle aggregation, it remains a big challenge to fabricate such membranes on a large scale. Herein, we designed a kind of highly dispersed nanoparticles through grafting poly(sodium-p-styrenesulfonate) (PSS) on metal organic frameworks UiO-66 and deployed them for tailoring structure of polyelectrolyte membrane (PEM) for water remediation and Pebax (PEBA) symmetrical membranes for CO2 capture, respectively. Because of electrostatic interaction, the PSS-grafted-UiO-66 (UiO-66-PSS) demonstrated nearly 100% dispersion in water and had an average particle size around 200 nm. Most interestingly, the introduction of the UiO-66-PSS finely tailored the affinity between membranes and target molecules, and the molecular structure of both PEM and PEBA membranes, thereby tripling the permeances of the membranes and slightly improving the selectivity of the membranes meanwhile. The PEM/UiO-66-PSS membranes demonstrated pure water permeance as high as 27.3 L m−2 h−1 bar−1 with MgSO4 rejection above 98.7%. For CO2 capture, the PEBA/UiO-66-PSS membranes exhibited 414.5 barrer with selectivity about 53.8. Taken together, the highly dispersed UiO-66-PSS shows strong promise in constructing molecular separation membranes with high separation performance for environmental remediation. The highly dispersed PSS-grafted-UiO-66 finely tailored membrane structures of PEM membranes and the PEBA membranes and enhanced affinity between the target molecules and the aforementioned membranes, thereby tripling membrane permeances and improving the membrane selectivity slightly. The obtained PEM/UiO-66-PSS membranes and PEBA/UiO-66-PSS membranes show strong promise in water remediation and CO2 capture, respectively.