Salt-resistant carbon aerogel with hierarchical interconnected channels for continuous and efficient solar evaporation of hypersaline water

Solar-driven water evaporation is a sustainable solution for hypersaline water treatment, but salt accumulation on the evaporator surface seriously threatens the evaporation system longevity. Despite previous great efforts, critical challenges remain in preventing salt accumulation while maintaining a high evaporation rate. Herein, a salt-resistant three-dimensional carbon nanofiber/graphene oxide composite aerogel (CNF/GOA) with a high evaporation rate was designed. The introduction of GO dramatically enhanced the mechanical property of CNF/GOA and constructed abundant hierarchical interconnected channels for rapid water replenishment and salt diffusion. By suppressing heat conduction loss to bulk water and decreasing water evaporation enthalpy based on regulating the immersion depth and pore structure of CNF/GOA, an evaporation rate of 3.47 kg m−2 h−1 (3.5 wt% NaCl solution) was achieved under 1 sun irradiation (1 kW m−2). More importantly, hypersaline water evaporation (24.0 wt% NaCl brine and industrial hypersaline wastewater) without salt crystallization was achieved. The results of 24-h continuous testing and 10 cycles of 8-h testing proved that CNF/GOA possessed outstanding long-term stability. The outdoor evaporation experiment of the concentrated desulfurization wastewater exhibited a high evaporation rate (23.26 kg m−2 d−1, 7:00–17:00), indicating CNF/GOA had great practical application prospect. This work may offer a fascinating avenue towards practical hypersaline wastewater treatment.