Structural and Adsorptive Characteristics of 2D Multilayer Nanoflakes of NiCo Phosphates for Chromium(VI) Removal: Experimental and Monte Carlo Simulations

Mai M Khalaf; Mohamed Gouda; Kamal Shalabi; Saad Shaaban; Hany M Abd El-Lateef

doi:10.1021/acsomega.2c00529

Structural and Adsorptive Characteristics of 2D Multilayer Nanoflakes of NiCo Phosphates for Chromium(VI) Removal: Experimental and Monte Carlo Simulations

ACS Omega. 2022 Mar 16;7(12):10738-10750. doi: 10.1021/acsomega.2c00529. eCollection 2022 Mar 29.

Authors

Mai M Khalaf^{1

2}, Mohamed Gouda¹, Kamal Shalabi³, Saad Shaaban^{1

3}, Hany M Abd El-Lateef^{1

2}

Affiliations

¹ Department of Chemistry, College of Science, King Faisal University, P.O. Box 400, Al-Ahsa 31982, Saudi Arabia.
² Department of Chemistry, Faculty of Science, Sohag University, Sohag 82524, Egypt.
³ Department of Chemistry, Faculty of Science, Mansoura University, Mansoura 35516, Egypt.

Abstract

Metal phosphates are efficient adsorbent materials for heavy elements present in industrial effluents because of their promising properties. Hexachromium ions are among the most dangerous contaminants owing to their harmful properties and non-degradability. Accordingly, the present work offers a simplified study of the preparation of bimetallic phosphate materials from nickel cobalt phosphate (NiCo-Ph) based on the sol-gel method in an equimolar ratio. Characterization of the bulk, crystal phase, texture profile, and nanosize of NiCo-Ph was carried out using various techniques such as Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption-desorption isotherm measurements, field emission scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. In this regard, the adsorption performance of NiCo-Ph was exemplified through six batch experiments, elucidating the impacts of the sorbent dose, initial concentration of pollutants, sorption time, temperature, pH, and shaking rate. According to UV/vis spectrophotometry measurements and their related calculations of NiCo-Ph, the maximum removal efficiency (RE %) of 92% and adsorption capacity (q _m) of 37 mg/g were achieved at pH = 6, a dose of 5.0 g/L, 100 mg/L of [Cr(VI)], 300 rpm, adsorption time of 60 min, and 298 K. Monte Carlo simulations were also carried out to correlate the experimental data with theoretical calculations that provided a higher negative value (-911.62 kcal mol^-1) for the adsorption energy of Cr(VI) in acidic medium. The adsorbent NiCo-Ph prepared by this direct method is therefore recommended for the quantification of Cr(VI) under slightly acidic solutions and at room temperature, which can maintain its efficiency even up to six cycles.