Biomimetic porous cellular foam with space thermal domains for efficient uranium extraction from seawater

Abstract

Designing materials with efficient capabilities for extracting uranium (U) from natural seawater and anti-biofouling remains a challenge. Herein, inspired by a thermal insulation honeycomb, a bionic thermal insulation foam with the property of spatial thermal confinement was designed using polyacrylonitrile (PAN) cross-linked dense amine foam (CN). The “space thermal domain” is formed by the semi-closed bionic insulation foam to raise the temperature around the macro-environmental area, resulting in a great enhancement of the thermal effect of the kinetic process of the adsorption reaction. In addition, the movement rate of molecules in the CPAO/CN is greatly accelerated by the photothermal effect from the “space thermal domain”, thereby improving the ability to extract U(VI) from natural seawater. Based on generating biologically toxic free radical active oxygen and keeping the internal high temperature, CPAO/CN has high anti-biological pollution activity. Due to the temperature gradient generated by the CPAO/CN in the liquid-phase environment, the Seebeck effect is induced, and the migration and aggregation of high-energy photogenerated electrons are accelerated to achieve efficient capture of U(VI) species in extreme environments. By combining molecular dynamics (MD) simulations with experiments, CPAO/CN indeed maintains the high U(VI) adsorption capacity at high temperatures as well as in a slightly alkaline (pH = 8.2 for seawater) environment. After 30 days of extraction in a natural marine environment, the light-induced U(VI) extraction capacity of CPAO/CN from seawater reaches 5.9 mg g⁻¹, which is 8.5 times that of CN. Our work provides a general approach for designing bionic insulation materials to enhance the capacity of U(VI) extraction from seawater.