Microscopic techniques for fabrication of polyethersulfone thin-film nanocomposite membranes intercalated with UiO-66-SO3H for heavy metal ions removal from water

Environmental remediation of heavy metals from wastewater is becoming popular area in the field of membrane technology. Heavy metals are toxic in nature and have ability to bioaccumulate in water bodies. In current study, zirconium-based metal organic frameworks (MOFs), that is, UiO-66 and UiO-66-SO3H with a mean diameter of 200 nm were synthesized and intercalated into polyethersulfone (PES) substrate to fabricate thin-film nanocomposite (TFN) membranes via an interfacial polymerization (IP) method. TFN membranes exhibit higher selectivity and permeability as compared to thin-film composite (TFC) membranes for heavy metals, such as cadmium (Cd) and mercury (Hg). Zirconium-based MOFs are highly stable in water and due to smaller pore size enhanced hydrophilicity of TFN membranes. In addition, TFN membrane with functionalized MOF (UiO-66-SO3H) performed best as compared to TFC and TFN with UiO-66 MOF. The effect of loading of different weight percentages (wt%) of both MOFs for TFN membranes was also investigated. The TFN membranes with loading (0.2 wt%) of UiO-66-SO3H displayed highest permeability of 9.57 LMH/bar and notable rejections of 90% and 87.7% toward Cd and Hg, respectively. To our best understanding, it is the first study of intercalating functionalized UiO-66-SO3H in TFC membranes by IP and their application on heavy metals especially Cd and Hg.

Automated summary

The study demonstrates the synthesis of zirconium-based MOFs, UiO-66 and UiO-66-SO3H, with a mean diameter of 200 nm and their intercalation into PES substrate to fabricate TFN membranes via IP method. TFN membranes show higher selectivity and permeability compared to TFC membranes, especially for heavy metals such as Cd and Hg.