Polydopamine-assisted polyethyleneimine grafting on electrospun cellulose acetate/TiO2 fibers towards highly efficient removal of Cr(VI)

Highly efficiently removing hazardous heavy metal ions from water is very important from a viewpoint of maintaining the sustainable development of ecological environment. In this work, a novel adsorbent based on the cellulose acetate (CA) was developed, which was fabricated through the blend electrospinning of CA and titanium dioxide (TiO2) nanoparticles, surface modification by polydopamine (PDA) and then grafted by polyethyleneimine (PEI). The composite CA/TiO2 electrospun fibers exhibit the porous structure, while the surface modification by PDA-assisted PEI grafting has no apparent effect on morphology of the electrospun fibers. The CA/TiO2@[email protected] composite fibers show the large number of amine groups, and the surface of the fibers can be positively charged in the acidic solution. Adsorption measurements show that the fibrous membrane samples exhibit excellent adsorption ability toward Cr(VI), and the maximum adsorption capacity is as high as 357.1 mg g−1 at solution pH value of 2, solution temperature of 25 °C. Specifically, about 72.1 % Cr(VI) can be directly reduced to harmless Cr(III) during the adsorption measurement, which is much higher than those of the almost adsorbents reported in literatures. The excellent adsorption/reduction ability endows the fibrous membranes with great potential application in removing highly hazardous Cr(VI) from wastewater.