Facile self-assembly of Au nanoparticles on a magnetic attapulgite/Fe3O4 composite for fast catalytic decoloration of dye

In this paper, we employed a simple and efficient electrostatic self-assembly strategy to fabricate superparamagnetic attapulgite/Fe3O4/Au nanoparticles (APT/Fe3O4/AuNPs) nanocomposites with a well-dispersed distribution of AuNPs using natural chitosan (CTS) as a bridge. The toruloid APT/Fe3O4 composite with negative surface charges was firstly prepared by a one-step solvent-thermal reaction between APT, FeCl3 and ethylene glycol, and then the positively charged CTS was used as a double sided tape to tightly adhere APT/Fe3O4 and AuNPs through electrostatic interaction. UV-vis, XRD and TEM analyses proved that the toruloid structure was formed, and AuNPs were successfully attached on the APT surface with good dispersion. The formation of the toruloid composite structure can not only bring stronger magnetism, but also facilitate the attachment of AuNPs. The APT/Fe3O4/AuNPs nanocomposite shows excellent catalytic activity, which can rapidly catalytically decolor a solution of Congo red (20 mg L-1) within 2 min at a low dosage of 0.3 g L-1. In addition, the nanocomposite shows strong magnetism with a maximum magnetization rate of 33.6 emu g(-1). This makes the nanocomposite prone to be magnetically separated and recycled.