Design of palygorskite-based aerogels for organic dye waste-water treatment

It is a challenge to develop high-efficiency, easy-recyclable adsorbents for the removal of dyes from environmental waters. Herein, we report the construction of two types of palygorskite (Pal)-polymer aerogels with distinctive hierarchically meso − microporous structure, which different polymer species-sodium alginate (SA) and chitosan (CS) through the sol-gel method, cross-linking, and freeze-drying, for the removal of dye pollutants from water. A hierarchical porous structure of aerogel accelerates the diffusion of dye water. Notably, this developed strategy enables selective dye adsorption by tuning the polymer and component contents in the Pal-polymer aerogel. Indeed, the maximum adsorption capacity of the Pal-SA composite aerogel for malachite green (cationic) dye reached 2008 mg/g and that of the Pal-CS(Fe³⁺) composite aerogel for sunset yellow (anionic) reached 976 mg/g. In addition, the composite aerogels can be regenerated many times without significant loss of effectiveness. This work provides a new concept and strategy for dye waste-water treatment.