Kinetic and isotherms modeling of methyl orange and chromium (VI) onto hexagonal ZnO microstructures as a membrane for environmental remediation of wastewater

Usman Ghani; Kiran Hina; Meenal Iqbal; Muhammad Kashif Irshad; Imran Aslam; Rashid Saeed; Muhammad Ibrahim

doi:10.1016/j.chemosphere.2022.136681

Kinetic and isotherms modeling of methyl orange and chromium (VI) onto hexagonal ZnO microstructures as a membrane for environmental remediation of wastewater

Chemosphere. 2022 Dec;309(Pt 2):136681. doi: 10.1016/j.chemosphere.2022.136681. Epub 2022 Oct 1.

Authors

Usman Ghani¹, Kiran Hina², Meenal Iqbal¹, Muhammad Kashif Irshad³, Imran Aslam⁴, Rashid Saeed¹, Muhammad Ibrahim⁵

Affiliations

¹ Department of Environmental Sciences, University of Gujrat, Gujrat, 50700, Pakistan.
² Department of Environmental Sciences, University of Gujrat, Gujrat, 50700, Pakistan. Electronic address: kiran.hina@uog.edu.pk.
³ Department of Environmental Sciences, Government College University Faisalabad, Faisalabad, 38000, Pakistan.
⁴ Department of Basic Sciences and Humanities, University of Engineering and Technology, Lahore, NWL Campus, Pakistan.
⁵ Department of Environmental Sciences, Government College University Faisalabad, Faisalabad, 38000, Pakistan. Electronic address: ebrahem.m@gmail.com.

PMID: 36195126
DOI: 10.1016/j.chemosphere.2022.136681

Abstract

Globally, contamination of water by dyes and heavy metals (HMs) is a serious environmental and public health problem due to their carcinogenic and mutagenic nature. It is incumbent to treat innocuously before discharge. It is the first time, hexagonal zinc oxide (ZnO) microstructure are being employeed as a membrane in the simultaneous removal of methyl orange (MO) and chromium (Cr (VI)) from the aqueous solution. The surface chemistry of hexagonal ZnO was characterized for morphology, surface functional groups, crystalline nature, and elemental composition by scanning electron microscope (SEM), Fourier transmission infrared spectroscopy (FTIR), X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). Adsorption capacity and removal efficiency was determined by the laboratory batch adsorption experiments, while nonlinear, linear kinetics and isotherm models were fitted to experimental data to investigate the adsorption process. The results exhibited that the maximum adsorption capacity (q_max) of hexagonal ZnO from the Langmuir isotherm model was 80.39 mg g^-1 and 84.10 mg g^-1 for MO and Cr (VI) respectively. According to the modeling findings, linear langmuir fitted to the experimental data with R² 0.967 and 0.971 for both MO and Cr (VI) which indicates monolayer physical adsorption of both pollutants has taken place. Whereas, kinetic study showed nonlinear pseudo-second order with R² 0.989 and 0.986 for MO and Cr (VI) model best fitted with the experimental data. The values of thermodynamics parameters Gibbs free energy change ΔG°, heat of enthalpy ΔH° and, heat of entropy ΔS° indicate that spontaneous, endothermic, and irreversible adsorption reactions occurred. Overall, it is concluded from our observations that hexagonal ZnO has the potential to be used as an eco-friendly, cost-effective adsorbent for simultaneous remaoval of both MO and Cr (VI) from water. Findings of the current investigation provide valuable insights for the development of an inexpensive, effective and sustainable filtration method for the treatment of MO and Cr (VI) synergistically.

Keywords: Adsorption; Hexagonal ZnO microstructures; Hexavalent chromium; Membranes; Methyl orange; Wastewater treatment.

MeSH terms

Adsorption
Chromium / analysis
Coloring Agents
Environmental Restoration and Remediation*
Hydrogen-Ion Concentration
Kinetics
Thermodynamics
Wastewater
Water
Water Pollutants, Chemical* / analysis
Zinc Oxide*

Substances

chromium hexavalent ion
Waste Water
methyl orange
Zinc Oxide
Water Pollutants, Chemical
Chromium
Coloring Agents
Water