Synthesis and characterization of superparamagnetic graphene oxide assembled halloysite composites for extraction of rutin

Abstract

In this work, a novel composite magnetic graphene oxide@magnetic halloysite nanotubes (MGO@magnetic Hal nanotube) was constructed to serve as an efficient solid phase adsorption tool for the separation of rutin by covalent binding of 3-aminopropyltrimethoxysilane (APTES)-functionalized magnetic graphene oxide (MGO) and magnetic halloysite (Hal) nanotubes. In particular, the amino group of APTES reacted with the epoxy bond on the basal planes of MGO instead of the edges carboxyl group, so that magnetic Hal nanotube could be inserted between the layers of MGO to prevent aggregation more effectively. In order to prove that the composite was synthesized in the ideal way, characterization tests such as FT-IR, XPS, SEM and HRTEM were made in detail. More importantly, the MGO@magnetic Hal nanotube possessed stronger super magnetism (40.82 emu g−1) than MGO and magnetic Hal nanotube by VSM characterization. In addition, further experiments show the adsorption process could be described by pseudo-second-order model and Freundlich isotherm model. Besides, the adsorption capacity of rutin by the composite was also greater than that of rutin by the single material. Some key parameters in the process of adsorption and desorption were also optimized. Finally, MGO@magnetic Hal nanotube was successfully used for the extraction of rutin from health products because of its excellent magnetism and adsorption.