Bilayer solar crystallizer by a directional liquid transport fabric for stable brine treatment and ion recycling

Abstract

Directional and asymmetric liquid transport (DALT) materials are promising for human moisture management and atmospheric water harvesting, but they are less known for their benefits in brine transportation and salt crystallization. Here, it is discovered a unique salt crystallization behavior of the DALT fabric which the salt with porous structure prefers to crystallize on the surface rather than in the inner space of the DALT fabric. Based on that, a bilayer solar crystallizer has been engineered by integrating this DALT fabric as an external crystalline interface with an inner adsorbent loaded wicking layer for simultaneous brine treatment and resource recovery. This bilayer structure separated the brine wicking channel from the crystallization interface, thereby reducing the efficiency losses by salt scaling to maintain the stable evaporation rate (>1.6 L/m2/h) during the brine treatment. Furthermore, the adsorbent in the inner layer (Li4Ti5O12 (LTO)) can recover Li+ by the adsorption (alkaline)-desorption (acid) cycle, and the successful LiCl recovery from the brine with high efficiency (>81%) and purity (94.8%) is demonstrated by this bilayer solar crystallizer. This work fills in the understanding of brine transportation and salt crystallization in DALT materials, demonstrating the great potential for its application in wastewater treatment and resource recovery.