Nanofibers of chitosan-polycaprolactone blends as active support for photocatalytic nanoparticles: Outstanding role of chitosan in the degradation of an organic dye in water

Abstract

Hybrid nanofibers of a chitosan-polycaprolactone blend containing titanium dioxide nanoparticles TiO₂NPs, were prepared through electrospinning to study their adsorption and photocatalytic degradation capabilities of the model organic water pollutants, rhodamine B, RhB. To obtain uniform and bead-free nanofibers, an optimization of the electrospinning parameters was performed. The optimization was carried out by systematically adjusting the solution conditions (solvent, concentration, and polymer ratio) and instrumental parameters (voltage, needle tip-collector distance, and flow). The obtained materials were characterized by FT-IR, TGA, DSC, SEM, TEM, mechanical tensile test, and water contact angle. The photoactivity was investigated using a batch-type system by following UV-Vis absorbance and fluorescence of RhB. TiO₂NPs were incorporated ex-situ into the polymer matrix, contributing to good mechanical properties and higher hydrophilicity of the material. The results showed that the presence of chitosan in the nanofibers significantly increased the adsorption of RhB and its photocatalytic degradation by TiO₂NPs (5, 55 and 80 % of RhB degradation with NFs of PCL, TiO₂/PCL and TiO₂/CS-PCL, after 30 h of light irradiation, respectively), evidencing a synergistic effect between them. The results are attributed to an attraction of RhB by chitosan to the vicinity of TiO₂NPs, favouring initial adsorption and degradation, phenomenon known as "bait-and-hook-and-destruct" effect.

Keywords: Electro-spinning; Hybrid composites; Nano composites; Nano particles; Polymer fibers; Synergism.