High‐Affinity Adsorbent with Honeycomb Structure for Efficient Acteoside Separation

Abstract

In this study, a series of adsorbents with honeycomb structure that hyperbranched polyethyleneimine (PEI) functionalized carboxymethyl chitosan (CMC/PEI) are successfully designed for acteoside (ACT) separation. The microstructures of adsorbents are adjusted to optimum by changing the molecular weight and addition amount of PEI. The scanning electron microscope (SEM) and N 2 adsorption-desorption experiment results show that CMC/PEI-70000-4.5g presents the honeycomb structure with the highest specific surface area and the largest pore volume. The honeycomb structure has the multiple internal cavities, which provide sufficient space for accommodating and adsorbing ACT molecules, improving the adsorption capacity. Furthermore, this work introduces PEI on the inner and outer surface of pores and forms an amino layer, which has high-affinity for ACT molecules and realizes the excellent selectivity. Therefore, CMC/PEI-70000-4.5g shows the highest adsorption capacity of 125.67 mg g −1 and selectivity of 5.38. The adsorption process of ACT can be fitted by pseudo-second-order kinetics, intraparticle diffusion, and Langmuir isotherm models. High-affinity (hydrogen bond, hydrophilic attraction, and Van der Waals force) is proposed as the main driving forces for adsorption between CMC/PEI-70000-4.5g and ACT. This work provides a strategy to synthesize the adsorbents with honeycomb structure for bioactive components separation from natural products.