Multifunctional amphiphilic ionic liquid pathway to create water-based magnetic fluids and magnetically-driven mesoporous silica

Amphiphilic ionic liquids, 1-alkyl-3-methylimidazolium chloride (C(n)mimCl with n = 10, 12, 14, 16) were firstly used as modifiers to construct a self-assembly bilayer on the surface of iron oxide nanoparticles for generation of highly stable, water-based magnetic fluids. Subsequently, a magnet-driven mesoporous silica was synthesized by in situ self-assembly in the bilayer C(n)mimCl-stabilized magnetic fluid using the C(16)mimCl as template and tetraethylorthosilicate (TEOS) as silicon source via a hydrothermal synthesis and following calcination procedure. A systematic study was carried out addressing the influence of the alkyl chain length of C(n)mimCl in the primary and secondary layers on the stability of magnetic fluids. The characterization of TEM, XRD, VSM, electrophoresis experiments, TGA and DTA showed that stable water-based magnetic fluids can be synthesized based on the assembly of the well-defined bilayer-C(n)mimCl structure with long-chain C(16)mimCl as secondary layer on the magnetite (Fe(3)O(4)) nanoparticles. The results of small and wide-angle XRD, TEM, VSM, and N(2) absorption experiments indicated that the nano-scale magnetic Fe(3)O(4) particles were inlayed into hexagonal p6mm mesoporous silica (MCM-41 type) framework. Importantly, it was found that the obtained Fe(3)O(4)/MCM-41 was an appropriate adsorbent for the adsorption of rhodamine B and methylene blue from their aqueous solution. In addition, the adsorbent could be separated and reclaimed fleetly from the solution under external magnetic field.