Metal–organic frameworks supported on nanofibers to remove heavy metals

Abstract

Fe(III) and Zr(IV) based metal–organic frameworks (MOFs) were enmeshed in polyacrylonitrile (PAN) and polyvinylidene fluoride (PVDF) electro-spun nanofibers to produce nanofibrous MOF membranes (NMOM). The pristine MOFs showed high adsorption capacity for lead ions and mercury ions from aqueous solution. The Fe(III) based MOFs with PAN based NMOM exhibited a high flux of 348 L m⁻² h⁻¹ with a permeance of 870 L m⁻¹ h⁻¹ bar⁻¹. At room temperature, the NMOM could treat 395 mL of 100 ppb Pb(II) solution, while maintaining a drinking water standard of <10 ppb of permeate Pb(II) concentration. Due to the high compatibility between MOF and PVDF nanofibers, MOF was not detected in the permeate even after four cycles of filtration and desorption experiments and more than 90% of the NMM adsorption capacity was retained. The excellent filtration performance and re-generability of the membrane coupled with the hydro-stability of the MOFs suggests that the NMOMs have potential for water treatment through the process of membrane adsorption.