Electrospun PAN + CALF-20 fibers: characterization and removal of Pb(ii) and Cu(ii) ions from aqueous solution

Abstract

This work presents the first report of integrating the Zn-based metal–organic framework (MOF), CALF-20, into electrospun polyacrylonitrile (PAN) nanofibers for wastewater treatment. CALF-20, previously explored for CO₂ capture, is applied here for the first time in fiber-based composite form manufactured via direct electrospinning, with MOF loadings ranging from 0 to 70 wt%. These resulting mats are promising for Pb(II) and Cu(II) removal. The PAN + CALF-20 mats, which have uniform morphology, were systematically characterized. They showed good mechanical integrity (up to 60 wt% CALF-20) and high removal capacities for Pb(II) and Cu(II) ions from aqueous solutions, 248.3 mg g⁻¹ and 128.2 mg g⁻¹, respectively. Structural analyses (SEM, XRD, and FTIR) confirmed that the dominant removal mechanism is not adsorption but surface-induced precipitation, with distinct crystalline phases forming post-treatment. These results introduce a novel and scalable platform for heavy metal remediation using electrospun MOF-based composites and establish PAN + CALF-20 mat as a promising candidate for multifunctional environmental applications.