Modified polyacrylonitrile nanofiber material as a sorbent for some of heavy metal ions extraction

Abstract

Heavy metal pollution is a serious problem, which can cause public health issues because heavy metals are not degradable and accumulate in organisms. Therefore, sensitive and simple determination of metal ions has proved to be extremely important. To increase the sensitivity of existing methods of heavy metal ions determination, solid phase extraction is used followed by spectrophotometric or AAS detection. In the last decade nonwoven materials (nanofibres) obtained from polymer solutions are used as an attractive alternative to traditional sorbents for heavy metals. The simplest and universal way to produce nonfibers is electrospinning. New solid-phase sorbents for some of heavy metal ions (Cu²⁺, Pb²⁺, Mn²⁺) based on nanofiber materials obtained by non-capillary electrospinning technique from polyacrylonitrile (PAN) in dimethylformamide (DMF) solution were proposed.

To improve the sorption properties of the obtained nanofibers a directional chemical modification of initial PAN nanofiber nitrile groups is proposed by two reactions: alkaline hydrolysis with NaOH solution to form hydroxyl and carboxyl groups (PAN-COOH nanofiber); amination reaction with hydroxylamine in the presence of sodium carbonate to form amidoxime groups (PAN-oxime nanofiber). FT-IR spectroscopic identification of synthesized non-woven sorbents was carried out and their structure was studied by scanning electron microscopy. The specific surface areas of the PAN-oxime and PAN-COOH sorbents were 19.9 and 6.20 m²/g respectively. The optimal conditions and the main sorption characteristics for such metals as Cu (II), Pb (II) and Mn (II) under static sorption were established. The values of the sorption capacities for Cu (II), Pb (II) and Mn (II) were 66 ± 1, 72 ± 2, and 6 ± 2 mg/g for PAN-COOH and 121 ± 3), (115 ± 2) and (14 ± 3) mg/g for PAN-oxime.