Construction of Sustainable Biomass Bubble Propulsion Micromotor and Selective Recognition/Separation of Shikimic Acid with Open 3D Target Imprinting Cavity

Abstract

Self-propelled nano/micromotors that harvest external energy from the surrounding environment and transform it into the power for autonomous movement have manifested great potential in the separation field. In this work, a bubble-propelled hierarchical bifunctional monomer imprinted micromotor has been demonstrated based on natural cotton fiber (CF) biomass as a platform and MnO 2 as the catalytic medium. CF@MnO 2 is loaded with Ni(OH) 2 nanosheets by a simple hydrothermal reaction, displaying an open three-dimensional structure with a large specific surface area for the construction of an imprinted layer. The covalent functional monomer 3-aminophenylboronic acid (APBA) and noncovalent functional monomer (3-aminopropyl)triethoxysilane (APTES) were used to create imprinted cavities for the target. Such a micromotor (CF@MnO 2 @Ni(OH) 2 -MIPs) performs self-propulsion behavior powdered by the decomposition of H 2 O 2 fuel and possesses accessible recognition sites for the selective recognition and separation of shikimic acid (SA), which reinforces the adsorption kinetics process and separation specificity. The micromotor shows a maximal adsorption capacity of 127.1 mg g −1 at pH 7.5 in the presence of H 2 O 2 , which has risen by 20.9% compared with the counterpart without H 2 O 2 . In addition, the adsorption performance of the micromotor fits well with pseudo-second-order (PSO) kinetics and the Langmuir isotherm model, suggesting that chemisorption is the main rate determination step and the adsorption process is a single-layer adsorption. The adsorption quantity of SA is 4.74 times, 4.58 times, and 4.33 times higher than that of hydroquinone (HDQ), p-hydroxybenzoic acid (PHB), and Quercetin, respectively, implying the bifunctional monomer imprinted strategy enhances the affinity of CF@MnO 2 @Ni(OH) 2 -MIPs for SA. After five capture/release cycles, the adsorption capacity remains above 95%. This work provides new insight into the design of potential materials for the adsorption of SA, which may open up new avenues for fabricating advanced adsorbents for the practical separation of natural products.