The preparation and characterization of chitosan rods modified with Fe3+ by a chelation mechanism

Chitosan composite rods (CS-Fe3+) were prepared via an in situ precipitation method. The relationships among the preparation, structures, and properties of the CS-Fe3+ composite rods have been investigated. The results of Fourier-transform infrared spectroscopy (FTIR) and core electron X-ray photoelectron spectroscopy (XPS) indicate that the CS and Fe3+ are coordinated via a chelation mechanism. The content of Fe3+ in the complex was determined by atomic absorption spectrometry (AAS) and elemental analysis (EA), the results of which suggested that the content of Fe3+ in the complex can be controlled by the concentration of the ferric salts during coordination. The changes in thermal stability and crystallization properties were measured by thermogravimetric analysis (TGA) and X-ray diffraction (XRD) patterns, respectively. Scanning electron microscopy (SEM) was used to observe the morphological change of the CS-Fe3+ complex rod. After coordination with Fe3+, the CS rod had a denser, layered structure. However, the layered structure cannot remain intact when the ratios of -NH2/Fe3+ are 100/15 and 100/20. Moreover, its thermal stability decreased, and its bending strength was improved significantly (from 86 MPa to more than 210 MPa), despite the remarkable decrease in the degree of crystallinity. (C) 2011 Elsevier Ltd. All rights reserved.