The preparation and characterization of chitosan rods modified with Fe 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.