ACS Appl Mater Interfaces. 2015 Jan 28;7(3):2124-33. doi: 10.1021/am508565d. Epub 2015 Jan 15.

Noncovalent magnetic control and reversible recovery of graphene oxide using iron oxide and magnetic surfactants.

ACS applied materials & interfaces

Thomas M McCoy, Paul Brown, Julian Eastoe, Rico F Tabor

PMID: 25590575 DOI: 10.1021/am508565d

Abstract

The unique charging properties of graphene oxide (GO) are exploited in the preparation of a range of noncovalent magnetic GO materials, using microparticles, nanoparticles, and magnetic surfactants. Adsorption and desorption are controlled by modification of pH within a narrow window of <2 pH units. The benefit conferred by using charge-based adsorption is that the process is reversible, and the GO can be captured and separated from the magnetic nanomaterial, such that both components can be recycled. Iron oxide (Fe2O3) microparticles form a loosely flocculated gel network with GO, which is demonstrated to undergo magnetic compressional dewatering in the presence of an external magnetic field. For composites formed from GO and Fe2O3 nanoparticles, it is found that low Fe2O3:GO mass ratios (<5:1) favor flocculation of GO, whereas higher ratios (>5:1) cause overcharging of the surfaces resulting in restabilization. The effectiveness of the GO adsorption and magnetic capture process is demonstrated by separating traditionally difficult-to-recover gold nanoparticles (d ≈ 10 nm) from water. The fully recyclable nature of the assembly and capture process, combined with the vast adsorption capacity of GO, presents obvious and appealing advantages for applications in decontamination and water treatment.

Keywords: adsorption; graphene oxide; iron oxide; magnetic nanomaterials; magnetic surfactants

Publication Types

• Journal Article