Highly selective and efficient chelating fiber functionalized by bis(2-pyridylmethyl)amino group for heavy metal ions

Abstract

A bis(2-pyridylmethyl)amino group-modified polyacrylonitrile fiber (BPEN-PANF) was firstly prepared. The BPEN-PANF displays excellent selective complexation affinity in a 1 : 1 binding stoichiometry for the common toxic heavy metal ions, viz. Pb²⁺, Hg²⁺, Cd²⁺, Ag⁺, Zn²⁺, Cu²⁺, Ni²⁺, Co²⁺, and Cr³⁺. Meanwhile, it was significant that a much weaker binding ability was expressed for other light metal ions (Ca²⁺, Al³⁺, and Mg²⁺). Taking Pb²⁺ as an example, the maximum absorption capacity was as large as 303 mg g⁻¹ calculated by the Langmuir isotherm model with an equilibrium time of 60 min. And the BPEN-PANF exhibits high absorption capacities for Pb²⁺ over a wide range of pH values from 3 to 11. Furthermore, it has an absorption limit of 4.76 ppb which is much lower than the drinking water standard of 10 ppb issued by the WHO. More positively, it can be easily recycled by filtration from the metal ion solutions and reused more than 20 times. In summary, the BPEN-PANF has the advantages of having inexpensive raw materials, simple preparation, high selectivity for heavy metal ions, and excellent recyclability and reusability, which surely indicates that the BPEN-PANF is a particularly useful material for rapid and simultaneous removal of heavy metal ions from polluted water.