Stable Forward Osmosis Nanocomposite Membrane Doped with Sulfonated Graphene Oxide@Metal–Organic Frameworks for Heavy Metal Removal

Abstract

A sulfonated graphene [email protected]–organic framework-modified forward osmosis nanocomposite ([email protected]) membrane was developed to improve stability and heavy metal removal performance. An in situ growth method was applied to uniformly distribute UiO-66 nanomaterial with a frame structure on SGO nanosheets to form [email protected] composite nanomaterial. This nanomaterial was then added to a polyamide layer using interfacial polymerization. The cross-linking between [email protected] and m-phenylenediamine improved the stability of the nanomaterial in the membrane. Additionally, the water permeability was improved because of additional water channels introduced by [email protected] SGO, with its lamellar structure, and UiO-66, with its frame structure, made the diffusion path of the solute more circuitous, which improved the heavy metal removal and salt rejection performances. Moreover, the hydrophilic layer of the [email protected] membrane could block contaminants and loosen the structure of the pollution layer, ensuring that the membrane maintained a high removal rate. The water flux and reverse solute flux of the [email protected] membrane reached 14.77 LMH and 2.95 gMH, and compared with the thin-film composite membrane, these values were increased by 41 and 64%, respectively. The membrane also demonstrated a good heavy metal ion removal performance. In 2 h, the heavy metal ion removal rate (2000 ppm Cu²⁺ and Pb²⁺) was greater than 99.4%, and in 10 h the removal rate was greater than 97.5%.