Nanocolloidal Hydrogel for Heavy Metal Scavenging.

We report a nanocolloidal hydrogel that combines the advantages of molecular hydrogels and NP-based scavengers of heavy metal ions. The hydrogel was formed by the chemical crosslinking of cellulose nanocrystals and graphene quantum dots. Over a range of hydrogel compositions, its structure was changed from lamellar to nanofibrillar, thus enabling control of hydrogel permeability. Using a microfluidic approach, we generated nanocolloidal microgels and explored their scavenging capacity for Hg2+, Cu2+, Ni2+ and Ag+ ions. Due to the large surface area and abundance of ion-coordinating sites on the surface of nanoparticle building blocks, the microgels exhibited high ion-sequestration capacity. The microgels were recyclable and were used in several ion scavenging cycles. These features, in addition to the sustainable nature of the nanoparticles, make this nanocolloidal hydrogel a promising ion-scavenging material.