Construction of carboxylated chitosan/unsaturated polyester resin aerogels with layered porous structures for efficient adsorption of dyes and heavy metals and rapid separation of o/w emulsions

Abstract

With the acceleration of global industrialization, a large amount of polluted wastewater is discharged indiscriminately, which both pollutes the environment and threatens human health. In this study, by constructing a binary system of unsaturated polyester resin/carboxychitosan, and improving the inherent defects of carboxychitosan aerogel, we successfully prepared aerogels with high porosity, low density, and laminar porous structure for water remediation by using a combination of the sol-gel method and directional freezing technology. Thanks to the synergistic effect of surface wettability and special pore structure, the aerogel not only adsorbs and separates MB and Pb(II) efficiently with a separation efficiency of more than 99 %, but also has a separation efficiency of 99.7 % for the o/w emulsions, which can be reused. The adsorption process is consistent with Pseudo-second-order kinetics and Langmuir isotherm, and is mainly influenced by electrostatic interactions and hydrogen bonding. Compared with other water body remediation materials, the chemical durability and structural stability of this aerogel are more excellent, and it maintains the efficient purification ability for multiple pollutants under special treatments such as prolonged UV aging and mechanical agitation, and is expected to be an ideal material for the synergistic treatment of multiple pollutants in complex environments.

Keywords: Carboxychitosan; Directional freezing; Unsaturated polyester resin; Wastewater remediation; o/w emulsion separation.