Highly efficient chromium(VI) adsorption with nanofibrous filter paper prepared through electrospinning chitosan/polymethylmethacrylate composite

Chitosan/polymethylmethacrylate (PMMA) composite nanofibrous membrane was prepared by electrospinning technique with a single solvent system. Characterization with Fourier transformation infrared spectroscopy (FT-IR) indicated that there was weak interaction (such as hydrogen bonds) between PMMA and chitosan. Scanning electron microscopy (SEM) measurements illustrated that the average diameter of the composite nanofibers decreased as the chitosan content was increased, while the number of nano/micrometer sized beads increased in the membrane. The composite nanofibrous membrane with chitosan:PMMA ratio of 0.3:1.0 exhibited a maximum adsorption capacity (67.0   mg   g −1 ) of Cr(VI) in static adsorption, which was nearly three times higher than that of chitosan powder (22.9   mg   g −1 ). The adsorption capacity of Cr(VI) via filtration became even higher, where the maximum value was 92.5   mg   g −1 at pH 3.0. Notably, most of Cr(VI) has been removed after the first filtration at all pH values (2.0–6.0) investigated in this report. The adsorption capacity of the composite nanofibrous membrane decreased slightly (17.1%) after three filtration cycles even with the solution of pH 2.0, which shall be attributed to the enhanced mechanical strength and acid fastness of the composite membrane. X-ray photoelectron spectroscopy (XPS) analysis indicated that amino groups played an important role in the adsorption of Cr(VI).