Fabrication and characterization of a toughened spherical chitosan adsorbent only through physical crosslinking based on mechanism of Chain Rearrangement.

Chitosan extracted from natural products has gained tremendous attention in the field of adsorption and separation due to its inherent biocompatibility and potential applications. In this research, we synthesized a new type of spherical chitosan adsorbent (SCA) by controlling the mass transfer rate of the entanglement of the polymer chains in the recombination process. This SCA is a highly crystalline polymer material with outstanding mechanical strength, high adsorption capacity, a porous surface and suitable particle size distribution. The value of the sphericity of attrition of this SCA was 89.8%, which is the same as that of the commercial macroporous resin with a polystyrene matrix. The X-ray diffraction (XRD) patterns and differential scanning calorimetry (DSC) curves showed a significant change from powder to spherical structure and confirmed that the SCA is highly ordered and crystalline. Optical microscopy (OM) and scanning electron microscopy (SEM) demonstrated that the SCA was composed of a tightly stacked fiber structure, indicating the homogeneity of the polymerization. The porous structure of the surface provided a channel for mass transfer, which was indicated by a test of the ion exchange capacity and the adsorption performance of the SCA with Cu(ii) as the adsorbed subject. The adsorption capacity was higher than those of all reported non-composite chitosan materials. Therefore, we have successfully synthesized a completely green, nontoxic and environmentally friendly adsorbing resin equipped with excellent mechanical properties and adsorption capacity for future applications in many new fields.