Fabrication of chitosan/magnetite-graphene oxide composites as a novel bioadsorbent for adsorption and detoxification of Cr(VI) from aqueous solution

Bei Zhang,Yujiang Li,Tao Wu,Dejun Sun,Runtao Hu

doi:10.1038/s41598-018-33925-7

Bei Zhang, Yujiang Li + Show 3 more

Open Access

https://doi.org/10.1038/s41598-018-33925-7

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Abstract

By utilizing the synergistic effect of chitosan (CS), magnetite (Fe3O4) particles, and graphene oxide (GO), a series of efficient and eco-friendly chitosan/magnetite-graphene oxide (CS/MGO) composites were fabricated through a facile chemical route. First, Fe3O4 particles were chemically deposited on the surface of GO to fabricate MGO hybrid. Then, chitosan was attached on MGO sheets, assembling to CS/MGO composites. According to the results of characterization, the covalent Fe-O-C bonds, electrostatic attraction, and hydrogen bonding between GO, Fe3O4, and chitosan ensure excellent structural stability and physico-chemical properties. The adsorption of Cr(VI) onto CS/MGO composites was also carried out under various conditions (content of CS, pH, initial concentration, contact time, and temperature). The CS/MGO composites possess high removal capacity for Cr(VI) from aqueous solution. Moreover, results also suggested that the CS/MGO composites had a strong reducing action for Cr(VI). When adsorption occurred, Cr(VI) and Cr(III) were simultaneously removed by CS/MGO composites. In addition, CS/MGO composites could retain good Cr(VI) removal efficiency after reuse over five cycles. CS/MGO composites are expected to have potential applications as easily regenerative bioadsorbents for Cr(VI) polluted water cleanup.

Highlights

Water pollution by heavy metals constitutes a worldwide environmental concern due to the detrimental effects of many heavy metals on human health and eco-systems
Compared with magnetite-graphene oxide (MGO) composites (Fig. 1a), the Graphene oxide (GO) sheets in chitosan/magnetite-graphene oxide (CS/MGO) composites (Fig. 1b) exhibit some overlapping and agminate, indicating that chitosan can play the role of a bridge between the lamellas
The active sites of chitosan are adequately exposed between GO sheets, which can promote the interaction of CS/MGO composites with target pollutants

Summary

Introduction

Water pollution by heavy metals constitutes a worldwide environmental concern due to the detrimental effects of many heavy metals on human health and eco-systems. Simultaneous adsorption and detoxification of Cr(VI) is considered as the most effective, economical and reliable method[8] Various adsorbent materials, such as activated carbon[9], clay minerals[10], layered double hydroxides[11], carbon nanotubes[12], and nanoscale zero-valent iron[13], have been applied for removing Cr(VI) from aqueous solution. Graphene oxide (GO), one of the most important derivatives of graphene, contains many more polar moieties and oxygen-rich functional groups such as epoxy (C-O-C), hydroxyl (-OH), carboxyl (-COOH), and carbonyl (C=O) groups on its basal planes and at the edges Taking these oxygen-rich functional groups into account, GO can be well dispersed in both water and organic solvents, and provide more possibility for fabrication of graphene-based multifunctional materials[21,22,23,24,25]. Our work may provide a novel understanding of CS/MGO with heavy metals

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