Fabrication of micro-nano structure nanofibers by solvent etching

Micro-Nano structure nanofibrous affinity membranes of poly(ether sulfones) (PES) blended with a functional polymer poly(ethyleneimine) (PEI) were fabricated by electrospinning technique followed by solvent etching in crosslinking solution. The surface SEM image of the water washed PES/PEI nanofibrous membrane confirmed that PEI was concentrated on the fiber surface. The nanofibrous PES/PEI membranes were crosslinked in a mixture of acetone and water with glutaraldehyde (crosslinking agent, GA), and the micro-nano structural surface of the nanofibrous membranes was created by solvent etching due to the solvation between PEI and the solvent water in the crosslinking solution during the crosslinking process. The influence of the component of the crosslinking bath on the mophology of the resulting PES/PEI nanofibers was investigated. It was found that the relatively uniform micro-nano spherules grew on the surface of the nanofibers when the content of water in crosslinking solution was more than 20 wt%, and the diameters of the spherules were in the range of 50-250 nm. The advantage of the micro-nano structrue for the heavy metal ions removal in wastwater has been demonstrated by taking a series of static adsorption experiments. It was found that the micro-nano structrue of PES/PEI nanofibrous membranes could bring high performance of adsorption capacity for heavy metal ions, indicating that the unique morphology could bring much more large surface area per unit mass and high effectivity for heavy metal ions removal from aqueous solutions.