Cost effective nanofiber composite membranes for Cr(VI) adsorption with high durability

Poly(ethylene-co-vinyl alcohol) (EVOH) nanofibers were obtained by melt-blending extrusion process. Then polyaniline/poly(ethylene-co-vinyl alcohol) (PANI/EVOH) nanofiber composite membranes were prepared through high-speed flow deposition followed by in situ chemical oxidative polymerization of aniline on the surface of EVOH nanofibers. It was utilized as the cost effective adsorbent of hexavalent chromium [Cr(VI)] in aqueous solutions. The morphology and structure of PANI/EVOH composite membranes were characterized by scanning electron microscopy (SEM), Fourier transform-infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The adsorption experiment indicated that pH value of 2.0 was optimal for the removal of Cr(VI), and the removal efficiency was increased with increasing the load of adsorbent. The study of adsorption process revealed that the adsorption equilibrium time was less than 100 min and the maximum adsorption capacity from the experiment was 93.09 mg g(-1). In addition, the adsorption data was well fitted with pseudo-second-order model and Freundlich isothermal model. More importantly, desorption results demonstrated the excellent reusability for Cr(VI) adsorption, i.e., the removal efficiency of Cr(VI) could be maintained up to 92.79% in the first 5 adsorption-desorption cycles and to 76.7% after 25 cycles.