3D interconnected periodic carbon-tube membrane enabled self-cleaning solar brine treatment and autonomous salt production

Abstract Interfacial solar vapor generation, an emerging solar technology, shows great potential for efficient and sustainable water treatment. With the solar-thermal energy localized in the interfacial water layer, this approach significantly enhances the evaporation rate. However, as the interfacial water layer typically exists in the evaporator (IWIE), precipitated salts tend to adhere to the evaporator during evaporation. This not only brings unavoidable performance degradation due to the block of incident sunlight and vapor escaping channels, but also causes the waste of salt resources. Herein, we propose a concept of interfacial water layer on the evaporator (IWOE), featuring self-cleaning solar brine treatment and autonomous salt production. Further, we experimentally demonstrate this concept using a rationally tailored three-dimensional carbon-tube (3D-CT) membrane, which reaches an elegant equilibrium of surface tension, gravity, and buoyancy under water. During the solar treatment of saturated brine, salt crystals precipitate and grow within this interfacial water layer, leading to autonomous tilt of the membrane and glide of the salt crystals. Thus, the 3D-CT membrane with IWOE enables autonomous self-cleaning solar brine treatment and salt production out of high-concentration brine, showing promising implications in various fields such as wastewater treatment, water-salt separation, and sea resource production.