Preparation of phosphorylated polyacrylonitrile-based nanofiber mat and its application for heavy metal ion removal

• A P-PAN fibers was prepared by electrospinning and chemical grafting modification.
• The resultant fibers showed high adsorption affinity towards selected metal ions.
• In addition, the P-PAN fibers also showed high recyclable removal efficiency.

A phosphorylated PAN-based nanofiber (P-PAN) mat is prepared by electrospinning technique followed by chemical grafting modification, which is suitable for metal adsorption due to their high adsorption capacity for metal ions. The content of phosphorous in phosphorylated PAN fibers is 5.45 mg/g. Adsorption isotherms and adsorption kinetics are used to examine the fundamental adsorption properties. It is found that the adsorption isotherms of P-PAN nanofibers toward Pb2+, Cu2+, and Ag+ are fitted better with Freundlich isotherm model and the adsorption of Cd2+ is fitted better with Langmuir isotherm model. Kinetics of the Pb2+, Cu2+, Ag+, and Cd2+ ions adsorption are found to follow pseudo-second-order rate equation. Through the analysis of the XPS data, phosphorous and nitrogen containing functional groups play the major role in the complexation with heavy metal ions. In addition, the obtained phosphorylated PAN fibers also show high recyclable removal efficiency through the adsorption/desorption experiments. This study provides a promising adsorbent in heavy metal ions wastewater treatment.