Thiol-functionalized magnetite/graphene oxide hybrid as a reusable adsorbent for Hg2+ removal

Jian Bao,Zhihao Bao,You Fu

doi:10.1186/1556-276x-8-486

Jian Bao, Zhihao Bao + Show 1 more

Open Access

https://doi.org/10.1186/1556-276x-8-486

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Abstract

A thiol-functionalized magnetite/graphene oxide (MGO) hybrid as an adsorbent of Hg2+ was successfully synthesized by a two-step reaction. It exhibited a higher adsorption capacity compared to the bare graphene oxide and MGO due to the combined adsorption of thiol groups and magnetite nanocrystals. Its capacity reached 289.9 mg g-1 in a solution with an initial Hg2+ concentration of 100 mg l-1. After being exchanged with H+, the adsorbent could be reused. The adsorption of Hg2+ by the thiol-functionalized MGO fits well with the Freundlich isotherm model and followed pseudo-second-order kinetics.

Highlights

Due to the development and expansion of industry, pollution of heavy metals in water supplies increases in the recent years
The TEM image (Figure 2b) of the product showed that Graphene oxide (GO) was decorated with magnetite aggregates with a size of several tens of nanometers
Thiol functional groups were grafted on the magnetite/graphene oxide (MGO) by the reaction between MEA and carboxyl groups on GO activated by ethy-3-(3-dimethyllaminopropyl) carvodiimide hydrochloride (EDC) (Figure 1, step B)

Summary

Introduction

Due to the development and expansion of industry, pollution of heavy metals in water supplies increases in the recent years. Thiol-functionalized adsorbents exhibited a specific binding capability toward highly toxic heavy metal ions including Hg2+ due to the existence of the thiol groups [3,4,5,6]. While for iron oxides, their adsorption mechanism was attributed to the complexation of Hg2+ and surface hydroxyl group at the iron oxide/water interface [7,8,9]. Iron oxide nanocrystals can further enhance the adsorption capacities because of their high specific surface area [6,10]. Another advantage of using iron oxide-based adsorbents is that they can be extracted from wastewater by applying an external magnetic force. The emergence of graphene oxide makes such combination possible due to its abundant functional moieties (hydroxyl and carboxyl groups)

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Conclusion