Characterization,separation performance,and model analysis of STPP‐chitosan/PAN polyelectrolyte complex membranes

Polyelectrolyte complex membranes (PCMs) were prepared using sodium tripolyphosphate (STPP) solution surface‐crosslinking chitosan/polyacrylonitrile (PAN) composite membranes. Fourier transform infrared (FTIR) was used to characterize the surface‐crosslinking. The effects of different surface‐crosslinking time on morphologies, element distribution, and crystal structures were investigated by scanning electron microscopy (SEM), energy dispersion of X‐ray (EDX), and X‐ray diffraction (XRD). The effect of crosslinking ratio on swelling ratio was analyzed. The separation performances of PCMs in terms of permeation flux and separation factor were measured by dehydrating ethyl acetate aqueous solutions. A kinetic model of crosslinking reaction was proposed to investigate the effect of crosslinking agent concentration and surface‐crosslinking time on the crosslinking ratio of PCMs. It was found that the membrane possessed the excellent performance when surface crosslinked for 15 min. The permeation flux and separation factor were 336 g/(m² h) and 6270 in 97 wt % ethyl acetate aqueous solution at 313 K. The crosslinking ratio of PCM exponentially increased as time increased, while linearly increased as concentration and diffusion coefficient of crosslinking agent STPP solution increased. And the effect of crosslinking agent concentration on crosslinking ratio was inversely proportional to surface‐crosslinking time. The experimental results matched well with the kinetic model when STPP concentration was lower than 5 wt %. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011