Zwitter ionic modification of cobalt-ferrite nanofiber for the removal of anionic and cationic dyes

In this paper, cobalt ferrite nanofiber was produced using electrospinning technique and the surface of prepared nanofiber was modified with L-arginine. We used [3-(2,3-Epoxypropoxy)-propyl]trimethoxysilane as coupling agent. Bonding behavior, surface morphological and topography, crystalline phase, isoelectric point and chemical composition of nanofibers were investigated by FTIR, SEM, AFM, XRD, zeta potential and XPS analyses, respectively. FTIR spectra illustrated the formation of amino acid layer on the surface of nanofibers. Also, the average roughness of nanofiber surface and the amount of amorphous phase increased after surface grafting. XPS analyses showed a relatively large amount of nitrogen atoms due to the incorporated amine groups on the nanofiber surface. We examined the dye removal ability of prepared nanofibers for both anionic and cationic dyes using Direct red 80 (DR80) and Basic red 46 (BR46) as the model compounds. The effects of operational parameters such as adsorbent dosage, initial dye concentration, and solution pH on dye removal were evaluated. In order to determine the best fit isotherm for each system, two error analysis methods, namely, chi-square (chi(2)) and composite functional error (HYBRD) were used. It was found that adsorption of dyes onto modified nanofibers are based on Langmuir isotherm. Finally, the pseudo-second-order kinetic model can be used to describe the adsorption behavior. (C) 2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.