Electrospun Polyacrylic Acid-Functionalized Poly-Cyclodextrin Fibers for Efficient Heavy Metal Removal from Water

Electrospun poly-cyclodextrin (poly-CD) fibers grafted with poly(acrylic acid) (PAA) were produced for effective heavy metal removal from water. CD fibers were first fabricated via electrospinning, then subjected to post-heat treatment for esterification, yielding poly-CD fibers. Subsequently, PAA was attached to poly-CD via Cu-catalyzed azide-alkyne cycloaddition. Alternatively, acrylic acid was polymerized directly on poly-CD fibers using reversible addition–fragmentation chain transfer (RAFT) polymerization, yielding PAA/poly-CD fibers. The structure and morphology of the PAA/poly-CD fibers were examined using Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), confirming successful modification while maintaining fibrous structure. The fibers exhibited a strong affinity for heavy metal ions, with removal efficiencies assessed through inductively coupled plasma mass spectrometry (ICP-MS) analysis. Modifying poly-CD with PAA enhanced its adsorption performance by up to 49%. They effectively removed multiple heavy metal ions, including Mn²⁺, Ni²⁺, Cu²⁺, Zn²⁺, and Cd²⁺, with the highest sorption observed for Cu²⁺, followed by Cd²⁺ and Zn²⁺. Notably, the PAA/poly-CD fibers demonstrated very high performance of removal (77%–100%) at lower concentrations for all tested metal ions and retained high efficiency for specific metal ions like Cu²⁺ and Cd²⁺ (73%–89%) even at high concentrations of 50 ppm, highlighting their potential for heavy metal removal from water.