Highly-controllable imprinted polymer nanoshell at the surface of magnetic halloysite nanotubes for selective recognition and rapid adsorption of tetracycline

Here, a general and effective method for preparing molecularly a imprinted polymer nanoshell on magnetic halloysite nanotubes (MHNTs) to make highly-controllable core–shell nanorods (MMINs) is described for the first time, and the as-obtained nanomaterials were then used for selective recognition and rapid adsorption of tetracycline (TC) from aqueous solution. Magnetic nanoparticles were uniformly loaded into the lumen of halloysite nanotubes (cheap, abundantly available and durable) using the impregnation and pyrolysis method. Vinyl groups were then anchored at the surface of MHNTs, subsequently directing the highly selective occurrence of imprinted polymerization at the surface, and the uniformly core–shell imprinted nanorods were easily produced via in situ precipitation polymerization, with tunable nanoshell thickness, by controlling the total amounts of monomers. The MMINs with a shell thickness of 35 nm exhibited the largest saturation adsorption capacity to TC, and the equilibrium data was well-described using the Langmuir isotherm model. The kinetic experiment showed the adsorption process reached equilibrium in about 10 min, and a pseudo-second-order kinetic model was used to fit the data well. The nanocomposites displayed selective recognition for TC and could be rapidly separated from solution by a magnet, with good stability and regeneration property, which provided practical applications for wastewater treatment, biological molecule purification and drug extraction.