Adsorption of Lead and Nickel on to Expanded Graphite Decorated with Manganese Oxide Nanoparticles

Quoc Cuong Do,Hyojeon Kim,Seoktae Kang,Seonmi Choi

doi:10.3390/app9245375

Quoc Cuong Do, Hyojeon Kim + Show 2 more

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https://doi.org/10.3390/app9245375

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Abstract

In this study, expanded graphite (EG) was decorated with manganese oxide nanoparticles (MONPs) by the hydrothermal method, and the newly formed composite (MONPs-EG) was applied as adsorbent for the removal of heavy metals from aqueous solutions. The comparative and competitive adsorption of Pb2+ and Ni2+ (0.01–1.00 mM) on MONPs-EG was investigated. Data from isothermal adsorption of single and binary systems suggested that both Pb2+ and Ni2+ were well described by the Langmuir isotherm, and the maximum adsorption capacities at 298 K were calculated at 0.278 and 0.113 mmol/g for Pb2+ and Ni2+, respectively. In binary systems, a dramatic decrease in adsorption capacity of Ni2+ was observed, while the adsorption capacity of Pb2+ was almost stable, indicating the favorable adsorption of Pb2+ over Ni2+ onto the prepared adsorbent. Kinetics studies of single and binary systems showed that a pseudo-second order model could explain the adsorption processes well. Thermodynamic analysis results demonstrated that the adsorption of these metal ions on the prepared adsorbent is spontaneous and exothermic in nature. The adsorption capacity of MONPs-EG increased significantly in the presence of humic acids. Overall, the results of this study suggest that MONPs-EG can be used effectively as an adsorbent for heavy metals removal from aqueous solutions.

Highlights

With the growth of human activities, heavy metal contamination of soil and groundwater has become a great concern
Manganese oxides were successfully decorated onto the surface of expanded graphite, and the newly formed composite manganese oxide nanoparticles (MONPs)-EG was employed as adsorbent for the removal of heavy metals from aqueous solution
The adsorption isotherms were well described by the Langmuir model, and the maximum adsorption capacity of MONPs-EG in a single metal system at 298 K can attain values of

Summary

Introduction

With the growth of human activities, heavy metal contamination of soil and groundwater has become a great concern. Lead can accumulate in human organs, causing anemia and severe damage to the nervous system, reproductive system, liver, brain, and kidneys [1]. Nickel is another toxic metal ion commonly present in steel and battery wastewater, causing vomiting, chest pain, and shortness of breath [2]. Various methods for heavy metal removal have been developed including reverse osmosis, ion exchange, electrodialysis, electrolysis, and adsorption. Among these technologies, adsorption has been acknowledged as a fast, inexpensive, and widely applicable technique [3,4,5,6].

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