Role of graphene/metal oxide composites as photocatalysts, adsorbents and disinfectants in water treatment: a review

Abstract

With a rapidly growing population, development of new materials, techniques and devices which can provide safe potable water continues to be one of the major research emphases of the scientific community. While the development of new metal oxide catalysts is progressing, albeit at a slower pace, the concurrent and rapid development of high surface area catalyst supports such as graphene and its functionalised derivatives has provided unprecedented promise in the development of multifunctional catalysts. Recent works have shown that metal oxide/graphene composites can perform multiple roles including (but not limited to): photocatalysts, adsorbents and antimicrobial agents making them an effective agent against all major water pollutants including organic molecules, heavy metal ions and water borne pathogens, respectively. This article presents a comprehensive review on the application of metal oxide/graphene composites in water treatment and their role as photocatalyst, adsorbent and disinfectant in water remediation. Through this review, we discuss the current state of the art in metal oxide/graphene composites for water purification and also provide a comprehensive analysis of the nature of interaction of these composites with various types of pollutants which dictates their photocatalytic, adsorptive and antimicrobial activities. The review concludes with a summary on the role of graphene based materials in removal of pollutants from water and some proposed strategies for designing of highly efficient multifunctional metal oxide/graphene composites for water remediation. A brief perspective on the challenges and new directions in the area is also provided for researchers interested in designing advanced water treatment strategies using graphene based advanced materials.

Facile Synthesis of Vanadium Oxide/Reduced Graphene Oxide Composite Catalysts for Enhanced Hydroxylation of Benzene to Phenol

“…The high specific surface areas, hydrophobic surface, and carbon defect active sites were found to be facilitative for the adsorption and activation of benzene, as well as the enhancement of catalytic activity of catalysts [27,31,35]. However, in spite of the fascinating two-dimensional structure of graphene with huge open π-electron systems, highly specific surface areas, and hydrophobic surface [27,36,37], to the best of our knowledge, few studies on the fabrication of uniform VO x nanoparticles (NPs) on graphene for the hydroxylation of benzene to phenol have been reported so far.…”

Adsorption of hexavalent chromium ions from aqueous solution by graphene nanosheets: kinetic and thermodynamic studies

“…The low adsorption capacity of Cr (VI) ions on the traditional adsorbents like activated carbon and high cost have restricted their wide applications (Dias et al 2007). On the other hand, graphene has been used as an efficient adsorbent to remove heavy metal ions from water or wastewater (Zhu et al 2011) because of its relatively low-cost, theoretically high surface area (*2,630 m 2 g -1 ), and high mesoporous volumes (Upadhyay et al 2014). …”

Preparation of Modified Graphene Oxide Nanomaterials for Water and Wastewater Treatment

“…Various active metal oxides nanoparticles, such as TiO2, ZnO, Cu2O and iron oxides, have been loaded on GO surface by in situ synthesis ( Figure 3) [13]. Bahnemann et aldegraded methylene blue by TiO2 loaded TiO2-GO, the photocatalytic degradation rates of MB by TiO2-GO were 3 times faster than that by P25 [18].…”

“…Recent works have shown that GO can perform multiple roles in water and wastewater treatment including adsorbents, photocatalysts and membrane filtration [13]. …”