High-performance 3D Hydrogels-based evaporator with multidirectional hierarchical pore structure for efficient salt-resistance in continuous water desalination

Abstract

The emerging hydrogel-based solar-driven interfacial evaporation system shows great potential for energy-efficient sea water desalination. However, achieving optimal performance in three-dimensional hydrogel solar evaporators during long-term operation remains a significant challenge due to the trade-off between salt resistance and evaporation efficiency. Here, a hydrogel with multidirectional hierarchical pore structure was developed, demonstrating high evaporation performance and salt resistance by homogeneously mixing multi-walled carbon nanotubes, sodium alginate and cellulose (CSC). Coupled with COMSOL simulations, the evaporation kinetics involving the competitive relationship between water transport and heat transfer are further elucidated to guide the evaporator design. The results suggest that the average evaporation rate of CSC hydrogel evaporator is up to 3.0 kg·m⁻²·h⁻¹ after continuous evaporation in 20 wt% brine for 10 h under one sun illumination. The CSC hydrogel evaporator demonstrates substantial purification of common organic compounds. This innovative design of the CSC hydrogel evaporator shows a great potential for desalination applications.