Adsorption of hexavalent chromium from water using graphene oxide/zinc molybdate nanocomposite: Study of kinetics and adsorption isotherms

Abstract

Hexavalent chromium is one of the most hazardous contaminants that threaten the environment. The present research work involves the synthesis of Graphene Oxide/Zinc molybdate (GO/ZM) nanocomposite by wet chemical route. The structure and morphology of the synthesized samples were analysed by various characterization techniques such as X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), UV-Vis Spectroscopy, and High-Resolution Transmission Electron Microscopy (HR-TEM), Brunauer-Emmett-Teller (BET) surface area analysis, Barrett-Joyner-Halenda (BJH) pore size analysis and Raman Spectroscopy. The efficiency of the prepared samples for removing hexavalent chromium from the water was investigated by performing batch adsorption studies. The maximum adsorption capacity was optimum at using 6 mg adsorbent, under conditions pH 2 with contact time for 120 min and temperature 283 K. Two isotherm models and two kinetic models were used to study the adsorption mechanism of Cr(VI) ions adsorption on the surface of GO/ZM nanocomposite. The results of isotherm and kinetic modelling shows that the adsorption of Cr(VI) using GO/ZM nanocomposite was well described by Freundlich Isotherm model with higher correlation coefficient (R2 = .985) and follows pseudo second order kinetic model.

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“…The study of adsorption kinetics provides valuable insights into the rate and mechanisms involved in adsorption, including mass transfer, diffusion, and surface reactions on the adsorbent material (KS et al 2023 ; Qi et al 2023 ). Furthermore, understanding the kinetics is critical for establishing the minimal contact time required between the adsorbent and adsorbate to attain steady-state or pseudo-equilibrium in the system (Gao et al 2022 ).…”

“…Recently, research has focused on sustainable and environmentally friendly methods to remove pollutants from wastewater to protect human health and natural resources for the next generations (Bhavya et al 2021 ; Saravanan et al 2022 ). Various techniques have been used to remove Cr(VI) from aqueous solutions, such as adsorption (KS et al 2023 ), chemical precipitation (Qasem et al 2021 ), ion exchange (Bashir et al 2019 ), electrocoagulation (Ayub et al 2020 ), and electrodialysis (Wan et al 2019 ). According to a literature review, the adsorption technique is a workable, low-cost, simple, and promising method for removing Cr(VI) from aqueous solutions (Rajapaksha et al 2022 ).…”