A theoretical and experimental study of the adsorptive removal of hexavalent chromium ions using graphene oxide as an adsorbent

Ardhmeri Alija,Veprim Thaçi,Arianit Reka,Rilinda Plakaj,Sefer Avdiaj,Drinisa Gashi,Avni Berisha,Admir Omaj

doi:10.1515/chem-2020-0148

Abstract

AbstractThis study is focused on the adsorption of hexavalent chromium ions Cr(vi) using graphene oxide (GO). The GO was prepared by chemical oxidation (Hummers method) of graphite particles. The synthesized GO adsorbent was characterized by Fourier transform infrared spectroscopy and UV-Vis spectroscopy. It was used for the adsorption of Cr(vi) ions. The theoretical calculations based on density functional theory and Monte Carlo calculations were used to explore the preferable adsorption site, interaction type, and adsorption energy of GO toward the Cr(vi) ions. Moreover, the most stable adsorption sites were used to calculate and plot noncovalent interactions. The obtained results are important as they give molecular insights regarding the nature of the interaction between GO surface and the adsorbent Cr(vi) ions. The found adsorption energy of −143.80 kcal/mol is indicative of the high adsorptive tendency of this material. The adsorption capacity value of GO toward these ions is q = 240.361 mg/g.

Highlights

As a result of human activity, water resources are partially contaminated to some extent, and this problem continues to be present
The experimental results show that the graphene oxide (GO) has fast adsorption and high adsorption capacity toward the Cr(VI) ions
The high adsorption energy values as evidenced by theoretical calculation show that these ions strongly interact with the groups in the graphene surface, with the hydroxyl ones

Summary

Introduction

As a result of human activity (mining, chemical industry, manufacturing, agriculture, etc.), water resources are partially contaminated to some extent, and this problem continues to be present. Heavy metals contribute to this variety of chemical pollutants, as effluent products or by-products of the industry [1,2,3]. These pollutants are of great and long-lasting concern for environmental and health safety due to their properties such as nonbiodegradability and bioaccumulation ability in living organisms [1,4]. Cr(VI) ions in the forms of chromate, dichromate, and chromium trioxide are considered the most toxic forms of chromium In this form, they possess an increased oxidizing potential, solubility, and mobility in the environment and living organisms. The most costeffective process for the removal of Cr(VI) from wastewater is the adsorption process [8]

Methods

Results

Conclusion