Porous and Hydrophobic Graphene-Based Core-Shell Sponges for Efficient Removal of Water Contaminants.

Water pollution which is a global environmental problem has attracted great concern, and functional carbon nanomaterials are widely used in water treatment. Here, to optimize the removal performance of both the oil/organic matter and dye molecules, we fabricated a kind of porous and hydrophobic core-shell sponges by growing graphene on three-dimensional (3D) stacked copper nanowires. The interconnected pores among the 1D nanocore-shells construct the porous channels within the sponge, and the multilayered graphene shells equip the sponge with a water contact angle over 120oeven under acidic and alkaline environments, which enables fast and efficient cleanup of oil on or under the water. The core-shell sponge could absorb oil or organic solvents with different densities 40 to 90 times to its own weight, and its oil-sorption capacity is much larger than the other porous materials like activated carbon and loofah. On the other side, the adsorption behaviour of the core-shell sponge to dyes, another common water pollutant, was also measured including methyl orange (MO), malachite green (MG) and so on. Dynamic adsorption of MG under cyclic compression demonstrated a higher adsorption rate than that in static state, and an acidic environment was favorable for the adsorption of MO molecules. Finally, the adsorption isotherm for MO molecules was analyzed and fitted with the Langmuir model, and the adsorption kinetics was studied in depth as well.