Preparation of amidoxime modified polyacrylonitrile nanofibers and its application in metal-ion containing waste water treatment

Polyacrylonitrile non-woven mat with nanofibers was fabricated by electrospinning, and amidoxime modified polyacrylonitrile nanofibers which can be used to absorb and recover metal ion from metal ion containing waste water were prepared via in situ amidoxime modification in aqueous solution. The copper chloride solution was used to simulate metal ion containing waste water and the adsorption behavior of amidoxime modified polyacrylonitrile nanofibers with different oximation time was evaluated. The nanofibers after 8 h oximation were calculated to possess the highest adsorption capacity of 56.5 mg/g according to Langmuir equation, and the concentration of metal ion containing waste water can be reduced from 100 mg/L to 13 μg/L after treating with amidoxime nanofibers, which not only reach but also highly exceed the national standard for metal ion containing waste water treatment(<0.5 mg/L, GB8978-1996). On the other side, the metal ions were desorbed from nanofibers in dilute acid solution, and the desorption ratio was more than 98% after 100 min desorption in 1 mol/L HNO₃ solution. Furthermore, the amidoxime nanofibers remain more than 50% of its original adsorption capacity after four adsorption-desorption circles, which showed relative recycling ability of amidoxime nanofiber.