Magnetic porous graphene/multi-walled carbon nanotube beads from microfluidics: a flexible and robust oil/water separation material

Abstract

In this paper, magnetic porous graphene/multi-walled carbon nanotube beads (MPGCBs) were fabricated by a modified capillary microfluidic device. Polystyrene (PS) microspheres not only served as the hard templates to form uniform macropores, but were also beneficial for keeping the stability of spherical architecture. In the process of solidification, both graphene oxide (GO) and acidified multi-walled carbon nanotubes (aMWCNTs) enriched with carboxyl functional groups can form stable and uniform dispersion in the droplets. After the calcination treatment, the composite beads had excellent water resistance and robust mechanical properties. Moreover, due to the addition of the Fe 3 O 4 nanoparticles, the beads also possessed the advantage of flexible operation, which can facilitate oriented movement and recycling of the absorbents, and promoted the collection and recovery of the useful pollutants. These multifunctional MPGCBs with interconnected macroporous structures showed high absorption capacity (up to 8-25 times their own weight) for various kinds of oils and organic solvents, relatively high separation efficiency and long-term recycle stability in the oil/water mixture separation process.

Microfluidics-Enabled Soft Manufacture of Materials with Tailorable Wettability

“…Hydrophobic porous microparticles are good oil absorbents for water remediation (Figure ), ,− as they are repellent to water while readily wetted by oils. The porosity of microparticles determines their capacity for oil absorption.…”

“…(d) Separation of water-in-oil (W/O) emulsions using a membrane assembled by hydrophobic porous microparticles. Reproduced with permission from ref . Copyright 2017 The Royal Society of Chemistry under a Creative Commons Attribution 3.0 Unported License.…”

“…Dispersing NPs into single-emulsion droplets produces either microparticles with surface nanocavities 267 and internal porous networks 269 or self-assembled colloidal spheres with structural colors. 286 The produced microspheres have two-tier hierarchical structures: the first tier consists of microspheres and the second tier of self-assembled NPs or nanocavities.…”

“…274 Besides oil absorption, water−oil separation is another functionality of surface assemblies using hydrophobic porous microparticles (Figure 25d). 269 Only oils can pass through the assembled porous membrane, whereas the infiltration of water is prohibited because of surface hydrophobicity. This method allows the separation of water from oils in surfactant-stabilized W/O emulsions.…”

A Review of State‐of‐the‐Art Microfluidic Technologies for Environmental Applications: Detection and Remediation

“…The MCNTBs had uniform diameters of ≈200 ± 10 µm, and possessed superhydrophobic and oleophilic properties which are vital in adsorbing oil and organic pollutants. Graphene was later incorporated into the MCNTBs and magnetic porous graphene/multiwalled carbon nanotube beads (MPGCBs) were obtained by the same group via the same fabrication method . The MPGCBs had been tested on the contaminated water containing pollutants that had been previously carried out on the MCNTBs, and a significant increase in the adsorption capacities was observed.…”