Adsorption of Cr(VI) using Natural Magnetite (Fe₃O₄)
Keywords:
Magnetite, Natural, Adsorption, Heavy Metal Cr, Water RemediationAbstract
Heavy metal contamination, particularly hexavalent chromium ions [Cr(VI)] in aquatic environments, has become a serious issue due to its toxic and carcinogenic nature. This study aims to synthesize a composite adsorbent material based on magnetite (Fe₃O₄) modified with polypyrrole (PPy) and evaluate its performance in the adsorption of Cr(VI) ions from aqueous solutions. The PPy–magnetite composite was synthesized via in-situ polymerization and characterized using FTIR, FESEM-EDX, and XRD to identify its morphology, functional groups, and crystallinity. Adsorption experiments were conducted by varying pH (1, 3, and 4), contact time (45, 60, and 90 minutes), initial Cr(VI) concentration (20, 40, and 60 ppm), and adsorbent dose (40, 60, and 100 mg). Characterization results indicated interactions between –NH and –N= groups of PPy and the Fe₃O₄ surface, as well as the formation of a porous structure. Optimal adsorption conditions were achieved at pH 4, 60 minutes of contact time, and an initial Cr(VI) concentration of 40 ppm. The Langmuir isotherm model showed the best fit (R² = 0.9979), with a maximum adsorption capacity (qₘ) of 54.645 mg·g⁻¹ and a removal efficiency of 99.92%. Adsorption kinetics followed the pseudo-second-order model (Ho–McKay) with an R² of 0.9827 and a rate constant (k₂) of 0.007 g·mg⁻¹·min⁻¹, indicating a chemisorption mechanism. AAS analysis confirmed the high effectiveness of the PPy–magnetite adsorbent in removing Cr(VI) ions from solution.
References
Abd El-Monaem, E. M., Eltaweil, A. S., El-Subruiti, G. M., Mohy-Eldin, M. S., & Omer, A. M. (2023). Adsorption of nitrophenol onto a novel Fe₃O₄-κ-carrageenan/MIL-125(Ti) composite: Process optimization, isotherms, kinetics, and mechanism. Environmental Science and Pollution Research, 30(17), 49301–49313. https://doi.org/10.1007/s11356-023-25678-2
Abdel Maksoud, M. I. A., Fahim, R. A., Bedir, A. G., Osman, A. I., Abouelela, M. M., El-Sayyad, G. S., Elkodous, M. A., Mahmoud, A. S., Rabee, M. M., Al-Muhtaseb, A. H., & Rooney, D. W. (2022). Engineered magnetic oxides nanoparticles as efficient sorbents for wastewater remediation: A review. Environmental Chemistry Letters, 20, 767–812. https://doi.org/10.1007/s10311-021-01331-0
Abewaa, J., Kankam, F., & Andoh, R. (2024). Hexavalent chromium removal from industrial wastewater using modified magnetic bio-adsorbents: Recent advances and challenges. Journal of Water Process Engineering, 58, 104972. https://doi.org/10.1016/j.jwpe.2023.104972
Ali, A., & Ismail, A. A. (2023). Facile synthesis of Fe₃O₄@PPy nanocomposites for efficient removal of Cr(VI) from aqueous media. Separation and Purification Technology, 316, 123674. https://doi.org/10.1016/j.seppur.2023.123674
Eltaweil, A. S., El-Monaem, E. M. A., & Omer, A. M. (2024). Recent progress on Fe₃O₄-based nanocomposites for the adsorption and reduction of hexavalent chromium from aqueous solutions: A review. Chemosphere, 351, 141643. https://doi.org/10.1016/j.chemosphere.2023.141643
Juturu, S., Iyer, P., & Karanam, S. R. (2024). Recent developments in adsorbents for heavy metal remediation: From conventional to advanced nanomaterials. Environmental Nanotechnology, Monitoring & Management, 23, 100806. https://doi.org/10.1016/j.enmm.2023.100806
Li, X., Liu, Z., & Chen, L. (2023). Redox-active Fe₃O₄@polypyrrole nanocomposites for enhanced Cr(VI) adsorption and reduction from water. Journal of Hazardous Materials, 452, 131337. https://doi.org/10.1016/j.jhazmat.2023.131337
Liu, Y., Wang, S., Zhao, R., & Zhang, H. (2023). Hybrid Fe₃O₄@PPy/graphene nanocomposite for high-efficiency removal of Cr(VI) from aqueous solutions. Environmental Research, 230, 115519. https://doi.org/10.1016/j.envres.2023.115519
Ni’mah, Y. L., Herwin, H., & Suprapto, S. (2022). Optimization of adsorption parameters using Box–Behnken Design for heavy metal removal on magnetite-based composites. Indonesian Journal of Chemistry, 22(3), 450–462. https://doi.org/10.22146/ijc.68839
Nogueira, J. P., Santos, C. S., & Silva, M. M. (2024). Polypyrrole-based conducting polymers for environmental applications: Synthesis, modification, and performance in pollutant removal. Journal of Environmental Chemical Engineering, 12(2), 111512. https://doi.org/10.1016/j.jece.2023.111512
Rahbar, N., Shafiee, A., & Amiri, A. (2016). Application of Box–Behnken design for optimization of Cr(VI) adsorption using magnetic nanocomposites. Journal of Environmental Chemical Engineering, 4(4), 4059–4069. https://doi.org/10.1016/j.jece.2016.09.028
Setshedi, K. Z., Moutloali, R. M., & Mishra, S. B. (2024). Polypyrrole-modified magnetic nanocomposites as multifunctional adsorbents for heavy metal ions and dyes: A critical review. Environmental Science and Pollution Research, 31, 24371–24392. https://doi.org/10.1007/s11356-023-30045-3
Song, Y., Zhang, X., & Liu, C. (2024). Synergistic adsorption–reduction of Cr(VI) by Fe₃O₄@polyaniline nanocomposites: Mechanistic insights and reusability studies. Journal of Environmental Management, 345, 118764. https://doi.org/10.1016/j.jenvman.2023.118764
Valentín-Reyes, J., Rangel-Mendez, J. R., & Bandala, E. R. (2019). Hexavalent chromium removal from aqueous media by adsorption, reduction, and coupled processes: A review. Critical Reviews in Environmental Science and Technology, 49(17), 1659–1710. https://doi.org/10.1080/10643389.2019.1585260
Wang, J., Liu, J., & Chen, S. (2022). Mechanistic study on Cr(VI) removal using Fe₃O₄-based composites: Role of redox-active sites and surface complexation. Chemosphere, 303, 135129. https://doi.org/10.1016/j.chemosphere.2022.135129
Wang, T., Zhou, Q., & Wu, S. (2024). Enhanced removal of Cr(VI) from water using Fe₃O₄@PPy nanocomposites: Isotherm, kinetics, and reusability studies. Journal of Environmental Chemical Engineering, 12(4), 113024. https://doi.org/10.1016/j.jece.2024.113024
Zhang, L., Xu, Z., & Fang, J. (2021). Comprehensive analysis of Cr(VI) adsorption and reduction by magnetic Fe₃O₄-based nanocomposites under acidic conditions. Applied Surface Science, 565, 150498. https://doi.org/10.1016/j.apsusc.2021.150498
Schechter, R. S. (1997). Overtones in Infrared Spectroscopy.
Silverstein, R. M., Bassler, G. C., & Morrill, T. C. (1986). Spectrometric Identification of Organic Compounds. Wiley.
Skoog, D. A., Holler, F. J., & Crouch, S. R. (2007). Principles of Instrumental Analysis (6th ed.). Thomson Brooks/Cole.
Stuart, B. (2004). Infrared Spectroscopy: Fundamentals and Applications. Wiley.
Tiernan, H., Byrne, B., & Kazarian, S. G. (2020). ATR-FTIR spectroscopy and spectroscopic imaging for the analysis of biopharmaceuticals. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 241, 118636. https://doi.org/10.1016/j.saa.2020.118636
Brunauer, S., Emmett, P. H., & Teller, E. (1938). Adsorption of Gases in Multimolecular Layers. Journal of the American Chemical Society, 60(2), 309–319. https://doi.org/10.1021/ja01269a023
Lowell, S., Shields, J. E., Thomas, M. A. , & Thommes, M. (2004). Characterization of Porous Solids and Powders: Surface Area, Pore Size and Density. Springer.
Rouquerol, F., Rouquerol, J., & Sing, K. (1999). Adsorption by Powders and Porous Solids: Principles, Methodology and Applications. . Academic Press.
Sing, K. S. W. (1985). Reporting physisorption data for gas/solid systems with special reference to the determination of surface area and porosity (Recommendations 1984). Pure and Applied Chemistry, 57(4), 603–619. https://doi.org/10.1351/pac198557040603
