The electrospun polyacrylonitrile (PAN) nanofibers were chemically modified with amidoxime groups by reacting with hydroxylamine hydrochloride into amidoxime-modified PAN (AOPAN).SEM

FTIR and water contact angle test were used to characterize its physicochemical properties

and then AOPAN was applied for Cr(VI) ions adsorption.The results show that AOPAN nanofibers swelled and bended to a certain degree after hydro-thermal treatment at 60℃for 3.5 h.In the FTIR spectra

the double peaks at 3500-3300 cm-1are ascribed to the typical-NH2 absorption peak.And the water contact angle decreased from 114.5° to 29.8°.It suggests that the AOPAN nanofibers were obtained through this method.The Cr(VI) adsorption test shows that the adsorption capacity of AOPAN nanofibers is as high as 102.5 mg/g at pH=2 and the adsorption equilibrium can be quickly reached within 5 h.This is mainly due to the protonation of-NH2 groups under the acid condition

which is benefit for adsorbing HCrO4-.Moreover the AOPAN nanofibers maintained over 50% removal rate after rinsing with dilute NaOH solution by four cycles.Thus

these AOPAN nanofibers have a high recyclable ability and are promising in heavy metal ions adsorption.