Facile Preparation of Hierarchically Porous Aromatic-cyclodextrin Polymers and Their Application for the Selective Adsorption of Cationic Dyes

Abstract

Porous β-cyclodextrin-containing materials have significant potential as adsorbents for the removal of pollutants from water. However, preparing these porous polymers in the aqueous phase is challenging. In this study, a kind of novel porous aromatic-cyclodextrin polymers (P-aro-CDPs) was designed and synthesized in aqueous solution under mild conditions by exploiting covalence-crosslinking reaction. P-aro-CDPs were characterized using a variety of methods, which revealed that P-aro-CDPs have a hierarchical porous structure, a highly negatively charged surface, and rich in hydroxyl groups. The prepared P-aro-CDPs showed excellent removal efficiency for methylene blue, with a maximum adsorption capacity of 194.17 mg g-1. The adsorption data are well fitted to the pseudo-second-order kinetic model and the Langmuir isotherm. The as-synthesized P-aro-CDPs material exhibited superior adsorption selection toward cationic dyes than anionic dyes whether in single or multicomponent systems. Further, the P-aro-CDPs adsorbent are reusable, and good performance over six adsorption–desorption cycles was demonstrated. Due to its off-the-beaten-path synthesis, low cost, excellent removal efficiency, and recyclability, P-aro-CDPs have great potential for use as an adsorbent in water-treatment applications.