Composite Aerogel with Hierarchical Hydrophilic Networks for Solar Evaporation and Salt-Resistant Brine Concentration

Solar-driven interfacial evaporation (SDIE) offers a sustainable route for treating high-salinity wastewater; however, reconciling ultra-high evaporation rates with long-term salt resistance remains a critical bottleneck. Herein, a structurally robust, sponge-templated composite aerogel (PCPG) is developed by confining a polyvinyl alcohol (PVA)-based semi-interpenetrating network (semi-IPN) within a polyurethane (PU) sponge skeleton. In this architecture, Carbon Black (CB) and PEDOT:PSS are synergistically integrated to ensure broadband solar absorption (>90%) and reinforce the gel matrix. The abundant hydrophilic groups within the polymer chains regulate the water state, effectively reducing the evaporation enthalpy to 831.5 J g⁻¹. Crucially, the composite features a hierarchical porous structure: the gel's micropores facilitate rapid capillary water supply, while the sponge's macropores enable efficient back-diffusion of salt ions. Leveraging these synergistic effects, PCPG achieves an exceptional pure water evaporation rate of 6.13 kg m⁻² h⁻¹ with 123.08% efficiency under 1 sun irradiation. Remarkably, it sustains a stable rate of 5.21 kg m⁻² h⁻¹ in 20 wt% NaCl brine without salt accumulation.Validated by both experiments and numerical simulations, this work presents a scalable, salt-resistant solution for zero-liquid discharge (ZLD) desalination and industrial brine management.