Design of EVOH nanofibers aerogel integrated with phase change materials for sustained solar-driven seawater desalination

Abstract

Solar-driven interfacial evaporation (SDIE) technology, as an environmentally friendly water treatment solution, plays a pivotal role in addressing the global freshwater crisis. However, evaporation performance significantly deteriorates under intermittent sunlight and uncontrollable weather conditions. To overcome this challenge, phase change materials (PCMs) were incorporated into the evaporator to ensure continuous desalination performance, yet PCMs leakage during prolonged operation remains a critical concern. Here, we have developed a shape-stabilized phase change composite C-EVOH-PEG based on poly(vinyl alcohol-co-ethylene) (EVOH) nanofibers aerogel and polyethylene glycol (PEG) for sustainable seawater desalination. The porous channels of the C-EVOH aerogel effectively prevent PEG leakage through the synergistic effect of capillary forces and hydrogen bonding interactions between PEG molecular segments and EVOH nanofibers, thereby achieving an ultralow leakage loss rate of 1.77 % after 20 cycling tests. Due to the stable loading of PEG within C-EVOH aerogel, the C-EVOH-PEG composite exhibits high energy storage capacity of up to 189.7 J g⁻¹. Compared to other phase change material composite evaporators, the C-EVOH-PEG composite demonstrates comparable evaporation rates of 2.08 kg m⁻² h⁻¹ under light conditions and even higher evaporation rates of 1.14 kg m⁻² h⁻¹ in dark conditions. Additionally, this composite demonstrates exceptional salt resistance in a high-salinity solution and outstanding desalination performance for seawater and other wastewater. This work offers a scalable strategy for continuous solar-driven seawater desalination with enhanced operational stability.