Adsorption and Kinetics Studies of Cr (VI) by Graphene Oxide and Reduced Graphene Oxide-Zinc Oxide Nanocomposite

Taiba Naseem; Fozia Bibi; Saira Arif; Muhammad Waseem; Sirajul Haq; Mohamad Nor Azra; Taavi Liblik; Ivar Zekker

doi:10.3390/molecules27217152

Adsorption and Kinetics Studies of Cr (VI) by Graphene Oxide and Reduced Graphene Oxide-Zinc Oxide Nanocomposite

Molecules. 2022 Oct 22;27(21):7152. doi: 10.3390/molecules27217152.

Authors

Taiba Naseem¹, Fozia Bibi², Saira Arif², Muhammad Waseem², Sirajul Haq³, Mohamad Nor Azra⁴, Taavi Liblik⁵, Ivar Zekker⁶

Affiliations

¹ School of Engineering, Macquarie University, Sydney 2109, Australia.
² Department of Chemistry, COMSATS University Islamabad, Islamabad 46000, Pakistan.
³ Department of Chemistry, University of Azad Jammu and Kashmir, Muzaffarabad 13100, Pakistan.
⁴ Institute of Marine Biotechnology (IMB), Universiti Malaysia Terengganu (UMT), Kuala Terengganu 21030, Malaysia.
⁵ Department of Marine Systems, Tallinn University of Technology, 19086 Tallinn, Estonia.
⁶ Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia.

Abstract

In this work, graphene oxide (GO) and its reduced graphene oxide-zinc oxide nanocomposite (rGO-ZnO) was used for the removal of Cr (VI) from aqueous medium. By employing a variety of characterization techniques, morphological and structural properties of the adsorbents were determined. The adsorption study was done by varying concentration, temperature, pH, time, and amount of adsorbent. The results obtained confirmed that rGO-ZnO is a more economical and promising adsorbent for removing Cr (VI) as compared to GO. Kinetic study was also performed, which suggested that sorption of Cr (VI) follows the pseudo-first-order model. For equilibrium study, non-linear Langmuir was found a better fitted model than its linearized form. The maximum adsorption capacity calculated for GO and rGO-ZnO nanocomposite were 19.49 mg/g and 25.45 mg/g, respectively. Endothermic and spontaneous nature of adsorption was detected with positive values of ΔS (change in entropy), which reflects the structural changes happening at the liquid/solid interface.

Keywords: adsorption; chromium VI; graphene oxide; nanocomposites.

MeSH terms

Adsorption
Chromium / chemistry
Graphite* / chemistry
Hydrogen-Ion Concentration
Kinetics
Water Pollutants, Chemical* / chemistry
Zinc Oxide*

Substances

graphene oxide
Zinc Oxide
Chromium
Water Pollutants, Chemical
Graphite

Grants and funding

This research was funded by project nr T190087MIMV and European Commission, MLTKT19481R “Identifying best available technologies for decentralized wastewater treatment and resource recovery for India, SLTKT20427” Sewage sludge treatment from heavy metals, emerging pollutants and recovery of metals by fungi and by project KIK 15392 and 15401 by European Commission and by Tartu University development fund PLTKT ARENG53 and from SCANDIUM project.