Congo Red Removal from Aqueous Solution Using 2-Mercaptopropionic Acid Functionalized Fe₃O₄ Magnetic Nanoparticles

Öz

In this study, magnetic Fe₃O₄ nanoparticles were synthesized and were modified with 2-mercaptopropionic acid (MPA). This was done to enhance their adsorption performance toward Congo Red (CR) in aqueous solution. FTIR spectroscopy was used to characterize the resulting MPA-functionalized nanomaterial (Fe₃O₄@MPA), confirming the successful attachment of -SH and -COOH functional groups. To investigate the effects of pH, initial dye concentration, contact period and temperature, the batch adsorption technique was conducted. Since the adsorption capacity was not significantly affected by pH, pH adjustment was continued for minimal chemical and time savings. This finding indicates that the surface charge and functional groups of Fe₃O₄@MPA interact most favorably with CR molecules under near-neutral conditions. The adsorption data were fitted to isotherm models, and the optimal model was found to be the Langmuir model (R² = 0.9901), which shows single-layer adsorption with a maximum capacity of 120.48 mg/g. Analysis of the kinetic data revealed a correlation with the pseudo-second-order kinetic model, confirming the chemical adsorption mechanism with a determination coefficient (R²) greater than 0.99. Thermodynamic parameters further confirmed the process to be spontaneous and endothermic, with negative ΔG°, positive ΔH° (6.92 kJ/mol), and positive ΔS° (0.029 kJ/mol·K). More than 60% removal was achieved in real sample applications. This work presents a new approach using MPA-functionalized Fe₃O₄ nanoparticles, which both increases adsorption efficiency and magnetic recoverability, providing a sustainable and pH-independent method for Congo Red purification from real matrices.

Anahtar Kelimeler

• 2-Mercaptopropionic acid
• Adsorption isotherms
• Congo Red
• Magnetic nanoparticles

2-Merkaptopropiyonik Asit ile Fonksiyonelleştirilmiş Fe₃O₄ Manyetik Nanopartiküller Kullanılarak Sulu Çözeltiden Kongo Kırmızısının Uzaklaştırılması

Öz

Bu çalışmada, manyetik Fe₃O₄ nanopartiküller sentezlenmiş ve 2-merkaptopropiyonik asit (MPA) ile modifiye edilmiştir. Bu, sulu çözeltide Kongo Kırmızısı (CR) üzerindeki adsorpsiyon performansını artırmak için yapılmıştır. FTIR spektroskopisi, elde edilen MPA-fonksiyonelleştirilmiş nanomalzemeyi (Fe₃O₄@MPA) karakterize etmek için kullanılmış ve -SH ve -COOH fonksiyonel gruplarının başarılı bir şekilde bağlandığını doğrulamıştır. pH, başlangıç boya konsantrasyonu, temas süresi ve sıcaklığın etkilerini araştırmak için toplu adsorpsiyon tekniği uygulandı. Adsorpsiyon kapasitesi pH'dan önemli ölçüde etkilenmediğinden, kimyasal ve zaman tasarrufu için pH ayarlaması devam ettirildi. Bu bulgu, Fe₃O₄@MPA'nın yüzey yükü ve fonksiyonel gruplarının, neredeyse nötr koşullar altında CR molekülleriyle en uygun şekilde etkileşime girdiğini göstermektedir. Adsorpsiyon verileri izoterm modellerine uydurulmuş ve optimal modelin, maksimum kapasitesi 120,48 mg/g olan tek katmanlı adsorpsiyonu gösteren Langmuir modeli (R² = 0,9901) olduğu bulunmuştur. Kinetik verilerin analizi, 0,99'dan büyük bir belirleme katsayısı (R²) ile kimyasal adsorpsiyon mekanizmasını doğrulayan, sözde ikinci dereceden kinetik model ile bir korelasyon olduğunu ortaya koymuştur. Termodinamik parametreler, negatif ΔG°, pozitif ΔH° (6,92 kJ/mol) ve pozitif ΔS° (0,029 kJ/mol·K) ile sürecin spontan ve endotermik olduğunu daha da doğruladı. Gerçek numune uygulamalarında %60'ın üzerinde bir giderim oranı elde edildi. Bu çalışma, MPA ile işlevselleştirilmiş Fe₃O₄ nanopartiküllerini kullanan yeni bir yaklaşım sunmaktadır. Bu yaklaşım, hem adsorpsiyon verimliliğini hem de manyetik geri kazanılabilirliği artırarak, gerçek matrislerden Kongo Kırmızısı saflaştırması için sürdürülebilir ve pH'dan bağımsız bir yöntem sağlamaktadır.

Anahtar Kelimeler

• 2-merkaptopropiyonik asit
• adsorpsiyon izotermleri
• kongo kırmızısı
• manyetik nanopartiküller

Kaynakça

1. S.I. Siddiqui, E.S. Allehyani, S.A. Al-Harbi, Z. Hasan, M.A. Abomuti, H.K. Rajor, S. Oh, Investigation of Congo Red Toxicity towards Different Living Organisms: A Review, Processes, 11, 2023, 807.
2. Y. Su, Y. Wang, L. Ding, Y. Chen, D. Song, An innovative and efficient strategy for removing Congo red using magnetic hollow Zn/Co zeolitic imidazolate framework composite, Environ Res, 264, 2025, 120399.
3. A.K. Verma, R.R. Dash, P. Bhunia, A review on chemical coagulation/flocculation technologies for removal of colour from textile wastewaters, J Environ Manage, 2012, 93, 154–168.
4. D. Mansour, E. Alblawi, A.K.D. Alsukaibi, B. Al Shammari, Removal of Congo red dye by electrochemical advanced oxidation process: optimization, degradation pathways, and mineralization, Sustain Water Resour Manag, 10, 2024, 41.
5. J. Cevallos-Mendoza, C.G. Amorim, J.M. Rodríguez-Díaz, M. Montenegro, Removal of Contaminants from Water by Membrane Filtration: A Review, Membranes, 12, 2022, 570.
6. V. Vignesh, G. Shanmugam, Removal and recovery of hazardous congo red from aqueous environment by selective natural amino acids in simple processes, Process Biochemistry, 2023, 127, 99–111.
7. S. Velusamy, A. Roy, S. Sundaram, T.K. Mallick, A Review on Heavy Metal Ions and Containing Dyes Removal Through Graphene Oxide-Based Adsorption Strategies for Textile Wastewater Treatment, The Chemical Record, 21, 2021, 1570.
8. M. Harja, N. Lupu, H. Chiriac, D.D. Herea, G. Buema, Studies on the Removal of Congo Red Dye by an Adsorbent Based on Fly-Ash@Fe3O4 Mixture, Magnetochemistry 8, 2022, 125.

9. N. Alsawaftah, W. Abuwatfa, N. Darwish, G. Husseini, A Comprehensive Review on Membrane Fouling: Mathematical Modelling, Prediction, Diagnosis, and Mitigation, Water, 13, 2021, 1327.
10. M. Abbas, M. Trari, Mass transfer process in the removal of Congo Red (CR) onto Natural Clay (NC): Kinetic, isotherm modeling, and thermodynamic study, Journal of Water and Climate Change, 2023, 14, 2755–2772.
11. A.M. Badran, U. Utra, N.S. Yussof, M.J.K. Bashir, Advancements in Adsorption Techniques for Sustainable Water Purification: A Focus on Lead Removal, Separations, 10, 2023, 565.
12. S. Muthu Prabhu, N.R. Rane, X. Li, S.V. Otari, S.D. Girawale, A.R. Palake, K.M. Kodam, Y.K. Park, Y.H. Ha, K.K. Yadav, M.A. Khan, B.H. Jeon, Magnetic nanostructured adsorbents for water treatment: Structure-property relationships, chemistry of interactions, and lab-to-industry integration, Chemical Engineering Journal 468, 143474, 2023.
13. N. Zhu, H. Ji, P. Yu, J. Niu, M.U. Farooq, M.W. Akram, I.O. Udego, H. Li, X. Niu, Surface Modification of Magnetic Iron Oxide Nanoparticles, Nanomaterials 8, 810, 2018.
14. B. Sabzi Dizajyekan, A. Jafari, M. Vafaie-Sefti, R. Saber, Z. Fakhroueian, Preparation of stable colloidal dispersion of surface modified Fe3O4 nanoparticles for magnetic heating applications, Sci Rep, 14, 2024, 1296.
15. P. Pączkowski, B. Gawdzik, Studies on Preparation, Characterization and Application of Porous Functionalized Glycidyl Methacrylate-Based Microspheres, Materials, 14, 2021, 1438.
16. D. Hanaor, M. Michelazzi, C. Leonelli, C.C. Sorrell, The effects of carboxylic acids on the aqueous dispersion and electrophoretic deposition of ZrO2, J Eur Ceram Soc, 2012, 32, 235–244.
17. R. Valenzuela, M.C. Fuentes, C. Parra, J. Baeza, N. Duran, S.K. Sharma, M. Knobel, J. Freer, Influence of stirring velocity on the synthesis of magnetite nanoparticles (Fe3O4) by the co-precipitation method, J Alloys Compd, 2009, 488, 227–231.
18. K.L. Muedi, V. Masindi, J.P. Maree, N. Haneklaus, H.G. Brink, Effective Adsorption of Congo Red from Aqueous Solution Using Fe/Al Di-Metal Nanostructured Composite Synthesised from Fe(III) and Al(III) Recovered from Real Acid Mine Drainage, Nanomaterials, 12, 2022, 776.
19. Ü.C. Erim, M. Gülfen, A.O. Aydın, Synthesis and selective Au(III) adsorption properties of poly(2-aminothiophenol) chelating polymer: equilibrium, kinetics and thermodynamics, International Journal of Environmental Science and Technology, 2025, 22, 4307-4320.
20. Y.S. Ho, G. McKay, A comparison of chemisorption kinetic models applied to pollutant removal on various sorbents, Process Safety and Environmental Protection, 1998, 76, 332–340.
21. M.A. Al-Ghouti, M.A.M. Khraisheh, M.N. Ahmad, S.J. Allen, Adsorption behavior of methylene blue onto Jordanian diatomite: A kinetic study, J Hazard Mater, 2009, 165, 589-598.
22. N. Öztürk, D. Kavak, Adsorption of boron from aqueous solutions using fly ash: Batch and column studies, J Hazard Mater, 2005, 127, 81–88.
23. Ü.C. Erim, M. Gülfen, A.O. Aydın, Separation of gold(III) ions by 1,8-diaminonaphthalene-formaldehyde chelating polymer, Hydrometallurgy, 2013, 134, 87–95.
24. H.S. Kusuma, D.E.C. Jaya, G.I. Al Lantip, D.K. Afifah, A.C. Kirani, M. Mahfud, H. Darmokoesoemo, A.N. Amenaghawon, T.A. Kurniawan, Theoretical perspectives and recent advances in palm-based adsorbents for sustainable heavy metal removal from aqueous systems, Desalination Water Treat, 323, 2025, 101315.
25. A. Çiçekçi, F. Sevim, M. Sevim, E. Kavcı. Adsorption Capacity, Reaction Kinetics and Thermodynamic Studies on Ni(II) Removal with GO@Fe₃O₄@Pluronic-F68 Nanocomposite, Polymers, 17, 2025, 2141.
26. K.E. Alsamhary, Optimizing the process conditions for the biosorption of chromium (VI) by Bacillus subtilis in artificial wastewater, Electronic Journal of Biotechnology, 2025, 6, 22-38.
27. T. Turna, A. Solmaz, A. Baran, Rapid adsorption of methylene blue by synthesizing zinc oxide nanoparticles from Ocimum basilicum L. waste, Int J Environ Sci Technol, 2025, 22, 10049–10066.
28. P. Sethi, S. Basu, S. Barman, Innovative CuBTC/gC₃N₄ materials for tetracycline mitigation: adsorption, photocatalysis, and mechanistic perspectives, New Journal of Chemistry, 2025, 49, 8454-8471.
29. E. Birinci, M. Gülfen, A.O. Aydın, Separation and recovery of palladium(II) from base metal ions by melamine–formaldehyde–thiourea (MFT) chelating resin, Hydrometallurgy, 2009, 95, 15–21.
30. L. Tofan, I. Bunia, C. Paduraru, C. Teodosiu, Synthesis, characterization and experimental assessment of a novel functionalized macroporous acrylic copolymer for gold separation from wastewater, Process Saf Environ Prot, 2017, 106, 150–162.
31. L. Wang, L.M. Housel, D.C. Bock, A. Abraham, M.R. Dunkin, A.H. McCarthy, Q. Wu, A. Kiss, J. Thieme, E.S. Takeuchi, A.C. Marschilok, K.J. Takeuchi, Deliberate Modification of Fe3O4 Anode Surface Chemistry: Impact on Electrochemistry, ACS Appl Mater Interfaces, 2019, 11, 19920–19932.
32. Q. Deng, X. Wang, M. Shao, L. Fang, X. Zhao, J. Xu, X. Wang, Synthesis of chitosan-modified magnetic metal-organic framework and its adsorption of Congo red and antibacterial activity, Microporous and Mesoporous Materials, 342, 2022, 112042.
33. H.Y. Zhu, Y.Q. Fu, R. Jiang, J.H. Jiang, L. Xiao, G.M. Zeng, S.L. Zhao, Y. Wang, Adsorption removal of congo red onto magnetic cellulose/Fe3O4/activated carbon composite: Equilibrium, kinetic and thermodynamic studies, Chemical Engineering Journal, 2011, 173, 494–502.
34. L. Wang, J. Li, Y. Wang, L. Zhao, Q. Jiang, Adsorption capability for Congo red on nanocrystalline MFe2O4 (M = Mn, Fe, Co, Ni) spinel ferrites, Chemical Engineering Journal, 2012, 181–182, 72–79.
35. S. Laurent, D. Forge, M. Port, A. Roch, C. Robic, L.V. Elst, R.N. Muller, Magnetic iron oxide nanoparticles: Synthesis, stabilization, vectorization, physicochemical characterizations and biological applications, Chem Rev, 108, 2008, 2064–2110.
36. C.T. Yavuz, J.T. Mayo, W.W. Yu, A. Prakash, J.C. Falkner, S. Yean, L. Cong, H.J. Shipley, A. Kan, M. Tomson, D. Natelson, V.L. Colvin, Low-field magnetic separation of monodisperse Fe3O4 nanocrystals, Science, 314, 2006, 964–967.
37. P. Pietrzyk, N.T. Phuong, S.J. Olusegun, N.H. Nam, D.T.M. Thanh, M. Giersig, P. Krysiński, M. Osial, Congo Red removal with superparamagnetic iron-oxide nanoparticles doped with zinc, Magnetochemistry, 8, 2022, 91.
38. H.Y. Zhu, Y.Q. Fu, R. Jiang, J.H. Jiang, L. Xiao, G.M. Zeng, S.L. Zhao, Y. Wang, Adsorption removal of congo red onto magnetic cellulose/Fe3O4/activated carbon composite: Equilibrium, kinetic and thermodynamic studies, Chemical Engineering Journal, 2011, 173, 494–502.
39. C. Ling, D. Yimin, L. Qi, F. Chengqian, W. Zhiheng, L. Yaqi, C. Ling, L. Bo, Z. Yue-fei, L. Yan, W. Li, Fabrication of magnetic targeted cellulose/poly (acrylic acid-co-2-methacryloyloxyethyl trimethylammonium chloride) composites for adsorbing Congo red dye from aqueous solution, J Mater Sci: Mater Electron, 33, 2022, 5750–5762.
40. N. Mahmud, A. Benamor, Magnetic Iron Oxide Kaolinite Nanocomposite for Effective Removal of Congo Red Dye: Adsorption, Kinetics, and Thermodynamics Studies. Water Conserv Sci Eng, 8, 2023, 35.
41. H. Wang, W. Luo, R. Guo, D. Li, B. Xue, Effective adsorption of Congo red dye by magnetic chitosan prepared by solvent-free ball milling, Mater Chem Phys, 292, 2022, 126857.
42. C.R. Lin, O.S. Ivanova, D.A. Petrov, A.E. Sokolov, Y.Z. Chen, M.A. Gerasimova, S.M. Zharkov, Y.T. Tseng, N.P. Shestakov, I.S. Edelman, Amino-Functionalized Fe3O4@SiO2 Core-Shell Magnetic Nanoparticles for Dye Adsorption, Nanomaterials 11, 2021, 2371.
43. A. Saberi, E. Alipour, M. Sadeghi, Superabsorbent magnetic Fe3O4-based starch-poly (acrylic acid) nanocomposite hydrogel for efficient removal of dyes and heavy metal ions from water, J Polym Res, 26, 2019, 271.
44. P. Koohi, A. Rahbar-kelishami, H. Shayesteh, Efficient removal of congo red dye using Fe3O4/NiO nanocomposite: Synthesis and characterization, Environ Technol Innov, 23, 2021, 101559.
45. S. Chatterjee, N. Guha, S. Krishnan, A.K. Singh, P. Mathur, D.K. Rai, Selective and Recyclable Congo Red Dye Adsorption by Spherical Fe3O4 Nanoparticles Functionalized with 1,2,4,5-Benzenetetracarboxylic Acid, Sci Rep, 10, 2020, 111.
46. A.O. Nasser, S.L. Kareem, Removal of Congo red from aqueous solution using lemon peel-Fe3O4 nanocomposite adsorbent, Biomass Convers Biorefin, 14, 2024, 23183–23193.