Enhanced immobilization of mercury (II) from desulphurization wastewater by EDTA functionalized graphene oxide nanoparticles

ABSTRACT

Graphene oxide (GO) is a new promising nanometer material in a superconductor and wastewater heavy metal ions removal for its functionalized groups. Ethylenediaminetetraacetic acid functionalized graphene oxide complexes (EDTA-GO) was produced by a realizable silanization chemical reaction. Characteristics of Hg(II) removal in desulphurization wastewater was also under investigation. The chemical composition and microstructures of the EDTA-GO adsorbents were characterized by X-ray photoelectron spectroscopy (XPS), Transmission electron microscope (TEM), Scanning Electron Microscopy (SEM) analyses. To investigate the performance of EDTA-GO adsorbents on adsorption of Hg(II) in wastewater of wet flue gas desulphurization (WFGD), experiments were performed to optimize the main influence factors such as reaction temperatures (35–70°C), pH values(2–13), contact time (0–120 min), initial Hg(II) concentrations(800 ug/L) and adsorbent doses (20–50 mg/L). The maximum uptake removal efficiency (97.14%) was achieved under the optimal conditions at the pH of 7, the temperature of 70°C, the Hg(II) concentration of 1200 μg/L and the EDTA-GO dose of 40 mg/L. The kinetic data fitting results were well consistent with the pseudo-second-order model (R²= 0.99997) and a spontaneous and endothermic adsorption reaction was elaborated by thermodynamics studies (ΔG < 0, ΔH > 0, ΔS > 0). The experiments of recycled adsorbents by HCl generation were carried out to obtain the performance of the reused EDTA-GO adsorbent, the fourth regenerative adsorption efficiency still maintained 80.4%, which indicated that excellent potential application in desulphurization wastewater treatment.

GRAPHICAL ABSTRACT

KEYWORDS:

• EDTA
• graphene oxide
• mercury
• kinetics
• adsorption isotherm
• regeneration

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (NSFC) (NO.51676101, 51806107) and the Natural Science Foundation of Jiangsu Province (No. BK20161558).