Facile preparation of lignosulfonate-based superparamagnetic colloidal nanocrystal clusters (CNCs)

Abstract

Colloidal nanocrystal clusters (CNCs) are hierarchical nanostructure formed by clustering several nanocrystals into one nano-ensemble. In this work, novel lignosulfonate (LS)-based superparamagnetic CNCs were prepared for the first time. The strategy based on electrostatic interaction between LS, nanocrystals and charge control agent, and included multistep of surface modification, precipitation and self-assembly. With the protection of LS and blocking of CTAB, individual γ-Fe2O3 nanocrystals in the colloidal particles can keep monodisperse to form the cluster morphology. The superparamagnetic γ-Fe2O3 endowed superparamagnetic property to the CNCs, and the saturation magnetization value of CNCs increased with the increase number of nanocrystals in the LS spheres. Furthermore, the LS-based superparamagnetic CNCs showed excellent dye adsorption efficiency for different dyes, especially for positive charged cationic dyes.