Preparation and characterization of APTES modified magnetic MMT capable of using as anisotropic nanoparticles

Highlights: • Magnetic MMT modified by APTES have been prepared for the first time. • APTES were both chemically bonded onto Fe₃O₄ and MMT. • Ultrasonication was firstly used to test the interaction between Fe₃O₄ and MMT in Magnetic MMT. • Fe₃O₄/APTES/MMT possesses stable and high magnetism. Montmorillonite (MMT) based anisotropic magnetic nanoparticles (Fe₃O₄/APTES/MMT) with high anisotropy and reliable magnetism were prepared by using Fe₃O₄ as magnetic nanoparticles and γ-aminopropyltriethoxysilane (ATPES) as modifier. The characterization indicated that the interactions between Fe₃O₄ nanoparticles and MMT in Fe₃O₄/APTES/MMT were stronger than that of directly deposited on to MMT (Fe₃O₄-MMT) because APTES was chemically bonded to both Fe₃O₄ and MMT. Fe₃O₄/APTES/MMT had a greater Ms value (25.16 emu/g) than Fe₃O₄-MMT (23.71 emu/g). Also, ultrasonication was used to test the interactions between Fe₃O₄ and MMT. With 30 min of ultrasonication, the amount of Fe₃O₄ nanoparticles on the surface of Fe₃O₄/APTES/MMT was more than that of Fe₃O₄-MMT, and Fe₃O₄/APTES/MMT had a faster magnetic response to a magnetic field than that of Fe₃O₄-MMT because of enhanced interactions between Fe₃O₄ and MMT in Fe₃O₄/APTES/MMT. In addition, Fe₃O₄ nanoparticles were densely immobilized onto Fe₃O₄/APTES/MMT with a smaller average diameter, and the distribution of Fe₃O₄ nanoparticles on the surface of MMT was more uniform than that of Fe₃O₄-MMT. Fe₃O₄/APTES/MMT possessed stable and high magnetism, in ease of orientation and recycling in the magnetic field, and this makes it a promising candidate as anisotropic nanoparticles for use in preparing anisotropic inorganic/polymer composites and anisotropic adsorbents used in wastewater treatment. Finally, the mechanism of ATPES-modified magnetic MMT was investigated.