Hydrolysis of oxidized polyacrylonitrile nanofibrous webs and selective adsorption of harmful heavy metal ions

Polyacrylonitrile (PAN) nanofibrous webs were prepared by electrospinning, and then stabilized by a heat treatment. Through these processes, oxidized PAN (oxy-PAN) nanofibers were obtained. After the stabilization, the residual nitrile groups on the surface were hydrolyzed using a high concentration NaOH solution; consequently, hydrolyzed oxy-PAN (H-PAN) nanofibrous webs were prepared. Attenuated total reflection infrared spectroscopy (ATR-IR) and X-ray photoelectron spectroscopy (XPS) were used to confirm the chemical conversion on the surface of the H-PAN nanofibrous webs. Also, the initial pH and contact time were varied to examine the adsorption behavior against heavy metal ions. The adsorption amounts on the heavy metal ions of the H-PAN nanofibrous webs were evaluated by an inductively coupled plasma atomic emission spectrometer (ICP-AES), and they depended on the initial pH and contact time. The maximum adsorption amounts of Pb2+ and Cd2+ were 116.2 mg/g and 85.7 mg/g, respectively. Lastly, the adsorption rate of the H-PAN nanofibers followed the pseudo-second order.