Single-step One-pot Synthesis of Graphene Foam/TiO2 Nanosheet Hybrids for Effective Water Treatment

Weilin Wang,Zhengguo Zhang,Luyi Sun,Jingjing Liu,Zhaofeng Wang

doi:10.1038/srep43755

Weilin Wang, Zhengguo Zhang + Show 3 more

Open Access

https://doi.org/10.1038/srep43755

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Abstract

Millions of tons of wastewater containing both inorganic and organic pollutants are generated every day, leading to significant social, environmental, and economic issues. Herein, we designed a graphene foam/TiO2 nanosheet hybrid, which is able to effectively remove both chromium (VI) cations and organic pollutants simultaneously. This graphene foam/TiO2 nanosheet hybrid was synthesized via a facile single-step one-pot hydrothermal method. The structure of the hybrid was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The hybrid was evaluated for both chromium (VI) and organic pollutants (using methyl blue (MB) as an example) removal, and the removal mechanism was also investigated. During water treatment, graphene and TiO2 nanosheets function complimentarily, leading to a significant synergy. The hybrid exhibited outstanding chromium (VI) and MB removal capacity, much superior to the performance of the individual pure TiO2 sheets or pure graphene foam. The hybrid could also be easily separated after water treatment, and exhibited excellent recycle stability. Considering the very facile synthesis of this graphene foam/TiO2 nanosheet hybrid, and its excellent water treatment performance and recycle stability, such a hybrid is promising for large scale production for practical applications where both chromium (VI) cations and organic dyes are the main pollutants.

Highlights

Environmental crisis has attracted much attention these decades
The morphology and structure of the G/TiO2 hybrid was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM)
The results showed that TiO2 nanosheets can remove a small amount of methyl blue (MB) even at dark (Fig. 6), which suggests that TiO2 nanosheets can remove MB by physical adsorption as well

Summary

Results and Discussion

This result is expected and is consistent with our initial hypothesis. Graphene can help speed up the electron transfer rate in the photo-catalysis process[37] Such coherent synergy between the physical adsorption by graphene sheets and the photo-catalyzed reduction by TiO2 nanosheets lead to very effective MB removal by the G/TiO2 hybrid. The result of MB removal capacity of the G/TiO2 hybrid under room light and dark shows that a large percentage of MB molecules were removed by physical adsorption of both TiO2 nanosheets and graphene foam while not applying the light. This results suggests that the G/TiO2 hybrid are promising for practical applications where both chromium (VI) ions and organic pollutants present

Conclusions

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