Electrospun oxime-grafted-polyacrylonitrile nanofiber membrane and its application to the adsorption of dyes

Abstract

Oxime grafted polyacrylonitrile (OX-g-PAN) nanofibers (NFs) membrane was prepared by combining electrospinning and chemical grafting techniques. The membrane was extensively characterized with field emission scanning electron microscopy (FE-SEM) and Fourier transforms infrared (FT-IR) spectroscopy. High percent grafting (79 %) with no change in the physical nature was confirmed by FT-IR spectra. The adsorption kinetics of methylene blue (MB), rhodamine B (RB) and safranin T (ST) onto OX-g-PAN NFs membranes followed a pseudo-second-order model and no change in the intraparticle diffusion pattern was observed. The order of adsorption capacity ((qmax) at equilibrium time) was; MB (102.15 mg/g) < ST (118.34 mg/g) < RB (221.24 mg/g). The adsorption data for the dyes fitted well to Langmuir (r 2 values and varied from 0.950 to 0.985 and Freundlich (r 2 values varied from 0.988 to 0.996) equations. The increased adsorption by OX-g-PAN NFs membrane could be attributed to the increased exposed surface and number of active sites on the membranes. The good fitting to adsorption equations showed that beside condensation (physical adsorption) monolayer adsorption has also occurred. The adsorption capacity values of the present system were higher as compared to the values reported in the literature for conventional adsorbents.