Water-Insoluble Cyclodextrin-based nanocubes for highly efficient adsorption toward diverse organic and inorganic pollutants

Abstract

Cyclodextrin (CD), as a naturally green starch derivative, is a promising candidate for water treatment through adsorption. Unfortunately, the soluble nature of CD in water limits its application greatly. In this work, a water-insoluble CD-based nanocube (CL-CD@PNC) with high adsorption performance toward dissolved pollutants is first developed through a facile two-step route. The prepared CL-CD@PNC has high water stability and well-defined cubic morphology with a porous structure. Additionally, the CL-CD@PNC nanocubes present prominent adsorption performance with the maximum adsorption capacities of 2173.21, 998.54, and 966.06 mg g−1 towards methylene blue (MB), bisphenol A (BPA), and Pb(Ⅱ), respectively, which is much higher than those of many other adsorbents. The adsorption equilibrium can be achieved within 10 and 30 s for MB and Pb(Ⅱ) adsorption, respectively, indicating the ultrafast adsorption rate. These adsorption processes are ascribed to the pseudo-second-order adsorption kinetics and Langmuir isotherm model, signifying the chemical and monolayer adsorption process. Moreover, the removal efficiency of the CL-CD@PNC nanocubes towards three different pollutants remains over 85% even after 10 recycles of regeneration. The superior adsorption performance of our CL-CD@PNC is attributed to the synergetic effect of host–guest interaction, electrostatic adsorption, hydrogen bond interaction, and chelation. More importantly, the applicability of CL-CD@PNC is successfully demonstrated under real industrial wastewater conditions. This work provides a promising strategy to prepare the water-insoluble CD-based adsorbent with a regular cubic structure, which can be potentially applied in the practical applications of industrial wastewater treatment.