Surfactant Removal from Mesoporous ‎Silica Shell of Core-Shell Magnetic ‎Microspheres by Modified Supercritical ‎CO2‎

Document Type : Research Paper


1 Department of Chemical Engineering, School of Chemical and Petroleum Engineering, Shiraz ‎University, Shiraz 7193616511, Iran‎

2 Department of Chemical Engineering, School of Chemical and Petroleum Engineering, Shiraz ‎University, Shiraz 7193616511, Iran‎.


   In this paper, a kind of core–shell magnetic mesoporous microspheres of Fe3O4@SiO2@meso-SiO2 with high surface areawas prepared, where magnetic Fe3O4 nanospheres were used as the inner core, tetraethyl orthosilicate (TEOS) as silica source, and cetyltrimethylamonium bromide (CTAB) as pore forming agent. Methanol-enhanced supercritical CO2 extraction has been attempted on structurally order mesoporous shell to remove the cationic template of CTAB and the effects of operating conditions i.e. pressure and temperature on the extraction efficiency were investigated. The influence of the methanol-enhanced supercritical CO2 on the structural properties of magnetic mesoporous silica nanocomposites was examined in detail by means of FE-SEM, FTIR, XRD, N2 adsorption/desorption and VSM. The obtained results reflected that the methanol-enhanced supercritical CO2 extraction had well preserved the structural stability of Fe3O4@SiO2@meso-SiO2 with high surface area ca.569 m2/g. The strong magnetization value (60 emu/ g) of the core–shell particles suggests their suitability for magnetic separation in a short time.


  1. Nikje, M. M. A., Sarchami, L.,Rahmani, L. (2015). "Fabrication of 2-Chloropyridine-Functionalized Fe3O4/Amino-Silane Core–Shell Nanoparticles", International Journal of Nanoscience and Nanotechnology, 11: 39-44.
  2. Teng, X., Black, D., Watkins, N. J., Gao, Y., Yang, H. (2003). "Platinum-Maghemite Core−Shell Nanoparticles Using a Sequential Synthesis", Nano Letters, 3: 261-264.
  3. Jiang-Ying Li, S. X., Pan, J., Qian, Y. (May 12, 2010 ). "Hydrothermal Synthesis and Electrochemical Properties of Urchin-Like Core−Shell Copper Oxide Nanostructures", Physics and Chemistry, 114 (21): 9645–9650.
  4. Zhu, C.-L., Zhang, M.-L., Qiao, Y.-J., Xiao, G., Zhang, F., Chen, Y.-J. (2010). "Fe3O4/TiO2 Core/Shell Nanotubes: Synthesis and Magnetic and Electromagnetic Wave Absorption Characteristics", The Journal of Physical Chemistry C, 114: 16229-16235.
  5. Hu, J. Q., Zhan Y. B., J. H., Golberg, D. (2004). "Si∕ZnS and Si∕ZnSe core/shell nanocrystal structures", Applied Physics Letters, 85: 3593.
  6. Cao, J., Hong, J.-Z. S., J., Li, H.-Y., Chen, H.-Z., Wang, M. (January, 2004). "Carbon Nanotube/CdS Core–Shell Nanowires Prepared by a Simple Room-Temperature Chemical Reduction Method", ADVANCED MATERIALS, 16: 84–87.
  7. Jennifer L. Lyon, D. A. F., Stone, M. B., Schiffer, P., Williams, . E. (March 20, 2004 ). "Synthesis of Fe Oxide Core/Au Shell Nanoparticles by Iterative Hydroxylamine Seeding", Nano Letters, 4: 719–723.
  8. Yang, P., Quan, Z., Hou, Z., Li, C., Kang, X., Cheng, Z., Lin, J. (2009). "A magnetic, luminescent and mesoporous core–shell structured composite material as drug carrier", Biomaterials, 30: 4786-4795.
  9. Zhang, M., Wu, Y., Feng, X., He, X., Chen, L., Zhang, Y. (2010). "Fabrication of mesoporous silica-coated CNTs and application in size-selective protein separation", Journal of Materials Chemistry, 20: 5835-5842.
  10. Won, Y.-H., Aboagye, D., Jang, H. S., Jitianu, A., Stanciu, L. A. (2010). "Core/shell nanoparticles as hybrid platforms for the fabrication of a hydrogen peroxide biosensor", Journal of Materials Chemistry, 20: 5030-5034.
  11. Li, Y., Wu, J., Qi, D., Xu, X., Deng, C., Yang, P., Zhang, X. (2008). "Novel approach for the synthesis of Fe3O4@TiO2 core-shell microspheres and their application to the highly specific capture of phosphopeptides for MALDI-TOF MS analysis", Chemical Communications: 564-566.
  12. Moradian, M., Moradian, M., Boroumand, Z. (2013). "A New and Efficient Method for the Adsorption and Separation of Arsenic Metal Ion from Mining Waste Waters of Zarshouran Gold Mine by Magnetic Solid-Phase Extraction with Modified Magnetic Nanoparticles", International Journal of Nanoscience and Nanotechnology, 9: 121-126.
  13. Khayat Sarkar, Z., Khayat Sarkar, F. (2013). "Selective Removal of Lead (II) Ion from Wastewater Using Superparamagnetic Monodispersed Iron Oxide (Fe3O4) Nanoparticles as a Effective Adsorbent", International Journal of Nanoscience and Nanotechnology, 9: 109-114.
  14. Xu, Z., Li, C., Kang, X., Yang, D., Yang, P., Hou, Z., Lin, J. (2010). "Synthesis of a Multifunctional Nanocomposite with Magnetic, Mesoporous, and Near-IR Absorption Properties", The Journal of Physical Chemistry C, 114: 16343-16350.
  15. Deng, Y., Qi, D., Deng, C., Zhang, X., Zhao, D. (2008). "Superparamagnetic High-Magnetization Microspheres with an Fe3O4@SiO2 Core and Perpendicularly Aligned Mesoporous SiO2 Shell for Removal of Microcystins", Journal of the American Chemical Society, 130: 28-29.
  16. Zhao, L., Chi, Y., Yuan, Q., Li, N., Yan, W., Li, X. (2013). "Phosphotungstic acid anchored to amino–functionalized core–shell magnetic mesoporous silica microspheres: A magnetically recoverable nanocomposite with enhanced photocatalytic activity", Journal of Colloid and Interface Science, 390: 70-77.
  17. Li, W., Zhang, B., Li, X., Zhang, H., Zhang, Q. (2013). "Preparation and characterization of novel immobilized Fe3O4@SiO2@mSiO2–Pd(0) catalyst with large pore-size mesoporous for Suzuki coupling reaction", Applied Catalysis A: General, 459: 65-72.
  18. Yuan, Q., Li, N., Chi, Y., Geng, W., Yan, W., Zhao, Y., Li, X., Dong, B. (2013). "Effect of large pore size of multifunctional mesoporous microsphere on removal of heavy metal ions", Journal of Hazardous Materials, 254–255: 157-165.
  19. Wu, S., Wang, H., Tao, S., Wang, C., Zhang, L., Liu, Z., Meng, C. (2011). "Magnetic loading of tyrosinase-Fe3O4/mesoporous silica core/shell microspheres for high sensitive electrochemical biosensing", Analytica Chimica Acta, 686: 81-86.
  20. Liu, H., Ji, S., Yang, H., Zhang, H., Tang, M. (2014). "Ultrasonic-assisted ultra-rapid synthesis of monodisperse meso-SiO2@Fe3O4 microspheres with enhanced mesoporous structure", Ultrasonics Sonochemistry, 21: 505-512.
  21. Tang, Y., Liang, S., Wang, J., Yu, S.,Wang, Y. (2013). "Amino-functionalized core-shell magnetic mesoporous composite microspheres for Pb(II) and Cd(II) removal", Journal of Environmental Sciences, 25: 830-837.
  22. Min, B. U.,Wenzhong, M. (2013). "Study on core–shell–shell structured nanoparticles with magnetic and luminescent features: Construction, characterization and oxygen-sensing behavior", Journal of Luminescence, 141: 80-86.
  23. Ryczkowski, J., Goworek, J., Gac, W., Pasieczna, S., Borowiecki, T. (2005). "Temperature removal of templating agent from MCM-41 silica materials", Thermochimica Acta, 434: 2-8.
  24. Tanev, P. T., Pinnavaia, T. J. (1996). "Mesoporous Silica Molecular Sieves Prepared by Ionic and Neutral Surfactant Templating:  A Comparison of Physical Properties", Chemistry of Materials, 8: 2068-2079.
  25. Lian, L., Cao, X., Wu, Y., Lou, D., Han, D. (2013). "Synthesis of organo-functionalized magnetic microspheres and application for anionic dye removal", Journal of the Taiwan Institute of Chemical Engineers, 44: 67-73.
  26. Ibrahim, A. S. S., Al-Salamah, A. A., El-Toni, A. M., El-Tayeb, M. A., Elbadawi, Y. B. (2014). "Cyclodextrin glucanotransferase immobilization onto functionalized magnetic double mesoporous core–shell silica nanospheres", Electronic Journal of Biotechnology, 17: 55-64.
  27. Huang, Z., Luan, D. Y., Shen, S. C., Hidajat, K.,Kawi, S. (2005). "Supercritical fluid extraction of the organic template from synthesized porous materials: effect of pore size", The Journal of Supercritical Fluids, 35: 40-48.
  28. Kawi, S., Lai, M. W. (2002). "Supercritical fluid extraction of surfactant from Si-MCM-41", AIChE Journal, 48: 1572-1580.
  29. Kawi, S., Goh, A. H., "Supercritical Fluid Extraction of Amine Surfactant in Hexagonal Mesoporous Silica (HMS)," in Studies in Surface Science and Catalysis. vol. Volume 129, S. Abdelhamid., J. Mietek, Eds., ed: Elsevier, 2000, pp. 131-138.
  30. Huang, Z., Xu, L., Li, J.-H., Kawi, S., Goh, A. H. (2011). "Organic template removal from hexagonal mesoporous silica by means of methanol-enhanced CO2 extraction: Effect of temperature, pressure and flow rate", Separation and Purification Technology, 77: 112-119.
  31. Huang, Z., Xu, L., Li, J.-H. (2011). "Amine extraction from hexagonal mesoporous silica materials by means of methanol-enhanced supercritical CO2: Experimental and modeling", Chemical Engineering Journal, 166: 461-467.
  32. Fung, Y. S., Long, Y. H. (2001). "Determination of phenols in soil by supercritical fluid extraction–capillary electrochromatography", Journal of Chromatography A, 907: 301-311.
  33. Chatterjee, M., Hayashi, H., Saito, N. (2003). "Role and effect of supercritical fluid extraction of template on the Ti(IV) active sites of Ti-MCM-41", Microporous and Mesoporous Materials, 57: 143-155.
  34. Huang, Z., Huang, L., Shen, S. C., Poh, C. C., Hidajat, K., Kawi, S., Ng, S. C. (2005). "High quality mesoporous materials prepared by supercritical fluid extraction: effect of curing treatment on their structural stability", Microporous and Mesoporous Materials, 80: 157-163.
  35. Van Grieken, R., Calleja, G., Stucky, G. D., Melero, J. A., García, R. A., Iglesias, J. (2003). "Supercritical Fluid Extraction of a Nonionic Surfactant Template from SBA-15 Materials and Consequences on the Porous Structure", Langmuir, 19: 3966-3973.
  36. Liu, Z., Yang, H., Zhang, H., Huang, C., Li, L. (2012). "Oil-field wastewater purification by magnetic separation technique using a novel magnetic nanoparticle", Cryogenics, 52: 699-703.
  37. Aboufazeli, F., Lotfi Zadeh Zhad, H. R., Sadeghi, O., Karimi, M., Najafi, E. (2013). "Novel ion imprinted polymer magnetic mesoporous silica nano-particles for selective separation and determination of lead ions in food samples", Food Chemistry, 141: 3459-3465.
  38. Li, Z., Huang, D., Fu, C., Wei, B., Yu, W., Deng, C., Zhang, X. (2011). "Preparation of magnetic core mesoporous shell microspheres with C18-modified interior pore-walls for fast extraction and analysis of phthalates in water samples", Journal of Chromatography A, 1218: 6232-6239.
  39. Zhao, X., Wang, J., Wu, F., Wang, T., Cai, Y., Shi, Y., Jiang, G. (2010). "Removal of fluoride from aqueous media by Fe3O4@Al(OH)3 magnetic nanoparticles", Journal of Hazardous Materials, 173: 102-109.
  40. Huang, L., Kawi, S., Poh, C., Hidajat, K., Ng, S. C. (2005). "Extraction of cationic surfactant templates from mesoporous materials by CH3OH-modified CO2 supercritical fluid", Talanta, 66: 943-951.
  41. Passos, C. P., Silva, R. M., Da Silva, F. A., Coimbra, M. A., Silva, C. M. (2010). "Supercritical fluid extraction of grape seed (Vitis vinifera L.) oil. Effect of the operating conditions upon oil composition and antioxidant capacity", Chemical Engineering Journal, 160: 634-640.
  42. Macías-Sánchez, M. D., Serrano, C. M., Rodríguez, M. R.,Martínez de la Ossa, E. (2009). "Kinetics of the supercritical fluid extraction of carotenoids from microalgae with CO2 and ethanol as cosolvent", Chemical Engineering Journal, 150: 104-113.
  43. Salgın, U., Döker, O., Çalımlı, A. (2006). "Extraction of sunflower oil with supercritical CO2: Experiments and modeling", The Journal of Supercritical Fluids, 38: 326-331.
  44. Fan, F.-L., Qin, Z., Bai, J., Rong, W.-D., Fan, F.-Y., Tian, W., Wu, X.-L., Wang, Y., Zhao, L. (2012). "Rapid removal of uranium from aqueous solutions using magnetic Fe3O4@SiO2 composite particles", Journal of Environmental Radioactivity, 106: 40-46.
  45. Hu, H., Wang, Z., Pan, L. (2010). "Synthesis of monodisperse Fe3O4@silica core–shell microspheres and their application for removal of heavy metal ions from water", Journal of Alloys and Compounds, 492: 656-661.
  46. Lan, S., Wu, X., Li, L., Li, M., Guo, F., Gan, S. (2013). "Synthesis and characterization of hyaluronic acid-supported magnetic microspheres for copper ions removal", Colloids and Surfaces A: Physicochemical and Engineering Aspects, 425: 42-50.
  47. Khosroshahi, M. E., Ghazanfari, L. (2012). "Synthesis and functionalization of SiO2 coated Fe3O4 nanoparticles with amine groups based on self-assembly", Materials Science and Engineering: C, 32: 1043-1049.
  48. Xu, Y., Zhou, Y., Ma, W., Wang, S., Li, S. (2013). "Highly sensitive and selective OFF-ON fluorescent sensor based on functionalized Fe3O4@SiO2 nanoparticles for detection of Zn2+ in acetonitrile media", Applied Surface Science, 276: 705-710.
  49. Zhang, J., Zhai, S., Li, S., Xiao, Z., Song, Y., An, Q., Tian, G. (2013). "Pb(II) removal of Fe3O4@SiO2–NH2 core–shell nanomaterials prepared via a controllable sol–gel process", Chemical Engineering Journal, 215–216: 461-471.
  50. Ren, Y., Abbood, H. A., He, F., Peng, H., Huang, K. (2013). "Magnetic EDTA-modified chitosan/SiO2/Fe3O4 adsorbent: Preparation, characterization, and application in heavy metal adsorption", Chemical Engineering Journal, 226: 300-311.