A nanocomplex of graphene oxide (GO) and nitrogen-doped carbon quantum dots (N-CQDs) is utilized for effective stabilization of the toluene–water interface in high surface area oil-in-water emulsions to assist in detection and extraction of Cu(II) ions. CQDs are nitrogen-doped to produce a positively charged material that readily adsorbs to GO through charge interactions, forming a surface-active complex. N-CQDs serve two key purposes: first, to screen the surface charge of GO and thereby lower the electrostatic barrier to adsorption at the toluene–water interface, and second to detect Cu(II) ions via fluorescence quenching. This combined system is far more effective in lowering the interfacial tension between toluene and water, and thus stabilizing toluene-in-water emulsions, than either component alone. The complex comprises cheap and easy to prepare materials, and overcomes the limitations of the individual components through synergistic effects. Additionally, the noncovalent nature and self-assembly of this system allows for facile use and potential recovery of the materials, and therefore enables utilization in industrial applications such as solvent extraction for mineral processing.
- carbon quantum dots
- graphene oxide