Enhanced chromium (VI) adsorption using nanosized chitosan fibers tailored by electrospinning

•75nm diameter chitosan nanofibers electrospun produced.•Enhanced Cr(VI) adsorption delivered by chitosan nanofibers.•Nanofiber's adsorption by diffusion limited due to fiber packing.•Most Cr(VI) co-anions had little or no effect on the adsorption except for SO42−.•Amino and hydroxyl groups of chitosan were both engaged in the adsorption. Stacked chitosan nanofibers with an average diameter of 75nm were successfully produced by electrospinning using 5wt% chitosan in acetic acid as the spinning solution. The fibers were then cross-linked with glutaraldehyde to remove chromium [Cr(VI)] from water via static adsorption. It was found that the adsorption correlated well with pseudo-second order kinetic model, and followed a mixed isotherm of Freundlich and Langmuir. The maximum nanofibers adsorption capacity was 131.58mg/g, more than doubled that of chitosan powders. Common co-ions such as Cl−, NO3−, Na+, Ca2+ and Mg2+ had little or no effect on the adsorption but SO42− was an exception. Fourier transform infrared spectroscopy and X-ray photoelectron spectrophotometer analyses indicated that both amino and hydroxyl groups of chitosan were engaged in the adsorption.