Journal Article

Gradient Graphene Spiral Sponges for Efficient Solar Evaporation and Zero Liquid Discharge Desalination with Directional Salt Crystallization

Feng, Panpan, Wei, Rui, Li, Chenwei, Zhao, Demin, Ding, Meichun, Lin, Tianhao, Liu, Chen‐Yang, Yu, Jiahui, Duan, Zhenying

2024

Overview

Solar desalination is a promising strategy to utilize solar energy to purify saline water. However, the accumulation of salt on the solar evaporator surface severely reduces light absorption and evaporation performance. Herein, a simple and eco‐friendly method to fabricate a 3D gradient graphene spiral sponge (GGS sponge) is presented that enables high‐rate solar evaporation and zero liquid discharge (ZLD) desalination of high‐salinity brine. The spiral structure of the GGS sponge enhances energy recovery, while the gradient network structures facilitate radial brine transport and directional salt crystallization, which cooperate to endow the sponge with superior solar evaporation (6.5 kg m−2 h−1 for 20 wt.% brine), efficient salt collection (1.5 kg m−2 h−1 for 20 wt.% brine), ZLD desalination, and long‐term durability (continuous 144 h in 20 wt.% brine). Moreover, the GGS sponge shows an ultrahigh freshwater production rate of 3.1 kg m−2 h−1 during the outdoor desalination tests. A continuous desalination–irrigation system based on the GGS sponge for crop growth, which has the potential for self‐sustainable agriculture in remote areas is demonstrated. This work introduces a novel evaporator design and also provides insight into the structural principles for designing next‐generation solar desalination devices that are salt‐tolerant and highly efficient. A gradient graphene spiral sponge is demonstrated for solar desalination, which has a unique structure for energy recovery, radial brine transport, and directional salt crystallization. It exhibits excellent performance in solar evaporation (6.5 kg m−2 h−1), salt collection (1.5 kg m−2 h−1), freshwater production (3.1 kg m−2 h−1), durability (144 h), and zero liquid discharge desalination. This sponge can potentially enable continuous desalination–irrigation in remote areas for crop growth.

• Publisher: John Wiley & Sons, Inc,John Wiley and Sons Inc,Wiley
• Subject: Alternative energy sources / Crystallization / Desalination / directional salt crystallization / Energy consumption / Graphene / graphene sponge / Pore size / Porous materials / Salinity / Scanning electron microscopy / Seawater / solar desalination / Solar energy / solar interfacial evaporation / zero liquid discharge