Coagulation mechanism of cellulose/metal nanohybrids through a simple one-step process and their interaction with Cr (VI)

In this work, the coagulation mechanism of the cellulose/metal nanohybrids and the binding mode with Cr (VI) are deeply described. Nanohybrids with 3D porous networks were prepared from cellulose/Fe2O3-SO3H solutions through a simple one-step coagulation process in NaCl aqueous solutions. The structure and properties of nanohybrids were characterized by SEM, EDS, XRD, FTIR, and XPS. The cellulose/metal nanohybrids have a langmuir maximum adsorption capacity of 11.46 mg/g. The dissolved metal nanoparticles could form strong hydrogen bonding with cellulose by breaking the intermolecular hydrogen bonds between the polymer molecules. The porous networks of cellulose/metal nanohybrids provided multiple adsorption sites for Cr2O72− anion through FeO…Cr interactions. The cooperation between cellulose and Fe2O3-SO3H nanoparticles makes the hybrids exhibiting a satisfactory selectivity and affinity for Cr (VI). The cellulose/metal nanohybrids selectively interacted with Cr2O72− via Fe atom from Fe2O3 and oxygen atom from SO3− groups. The Cr (VI) adsorption occurred via a two-step process, the first of them was the initial adsorption of Cr2O72− on cellulose/metal nanohybrids surface, followed by the rearrangement of Cr2O72− molecules and the consecutive growth of Cr2O72− aggregate layers.