Mussel-inspired fabrication of halloysite nanotube-based magnetic composites as catalysts for highly efficient degradation of organic dyes

Abstract

In this work, heterogeneous catalysts based on halloysite nanotubes (HNTs) were fabricated through mussel-inspired chemistry that could be used in situ to generate Fe3O4 nanoparticles on HNTs. HNT-based magnetic composites (HNTs@PDA-MNPs) were examined as catalysts for the Fenton reaction. The characterization results demonstrated that Fe3O4 nanoparticles could be well-dispersed on HNTs with polydopamine (PDA) as the linkage. Various experimental parameters, such as the concentrations of HNTs@PDA-MNPs and H2O2, reaction temperature and solution pH, of the degradation efficiencies were investigated in detail. The results demonstrated that the degradation efficiencies of methylene blue were greater than 97% under optimized conditions. Moreover, HNTs@PDA-MNPs also exhibited excellent degradation efficiencies for other organic dyes (such as rhodamine B, methyl orange, and Congo red). Electron spin-resonance spectroscopy suggested that free radicals such as •OH and •O2− were generated during the Fenton reaction, which could destroy the structure of the organic dyes. Taken together, a biomimetic method based on the self-polymerization of dopamine and the in situ generation of Fe3O4 nanoparticles on HNTs is developed for the fabrication of HNTs@PDA-MNP composites, which exhibit excellent degradation efficiencies towards different organic dyes through the Fenton reaction. This method can also be extended for the preparation of other multifunctional composites with potential for different applications.