Department of Civil and Environmental Engineering, University of California , Berkeley, California 94720, United States.
Environ Sci Technol. 2017 Oct 17;51(20):11701-11709. doi: 10.1021/acs.est.7b03040. Epub 2017 Sep 27.
Water vapor generation through sunlight harvesting and heat localization by carbon-based porous thin film materials holds great promise for sustainable, energy-efficient desalination and water treatment. However, the applicability of such materials in a high-salinity environment emphasizing zero-liquid-discharge brine disposal has not been studied. This paper reports the characterization and evaporation performance of a nature-inspired synthetic leaf made of graphene oxide (GO) thin film material, which exhibited broadband light absorption and excellent stability in high-salinity water. Under 0.82-sun illumination (825 W/m), a GO leaf floating on water generated steam at a rate of 1.1 L per m per hour (LMH) with a light-to-vapor energy conversion efficiency of 54%, while a GO leaf lifted above water in a tree-like configuration generated steam at a rate of 2.0 LMH with an energy efficiency of 78%. The evaporation rate increased with increasing light intensity and decreased with increasing salinity. During a long-term evaporation experiment with a 15 wt % NaCl solution, the GO leaf demonstrated stable performance despite gradual and eventually severe accumulation of salt crystals on the leaf surface. Furthermore, the GO leaf can be easily restored to its pristine condition by simply scraping off salt crystals from its surface and rinsing with water. Therefore, the robust high performance and relatively low fabrication cost of the synthetic GO leaf could potentially unlock a new generation of desalination technology that can be entirely solar-powered and achieve zero liquid discharge.
通过基于碳的多孔薄膜材料收集阳光并局部加热来产生水蒸气，这为可持续、节能的海水淡化和水处理提供了巨大的前景。然而，此类材料在强调零液体排放盐水处理的高盐环境中的适用性尚未得到研究。本文报道了一种由氧化石墨烯（GO）薄膜材料制成的受自然启发的合成叶片的特性和蒸发性能，该材料在高盐水中表现出宽带光吸收和优异的稳定性。在 0.82 个太阳光照（825 W/m）下，漂浮在水面上的 GO 叶片以 1.1 L/m/h 的速率产生蒸汽，光到蒸汽的能量转换效率为 54%，而在树状结构中提升到水面上方的 GO 叶片以 2.0 LMH 的速率产生蒸汽，能量效率为 78%。蒸发速率随光照强度的增加而增加，随盐度的增加而降低。在 15wt%NaCl 溶液的长期蒸发实验中，尽管叶片表面逐渐并最终严重积聚盐晶体，但 GO 叶片仍表现出稳定的性能。此外，通过简单地从叶片表面刮去盐晶体并用清水冲洗，GO 叶片可以很容易地恢复到原始状态。因此，合成 GO 叶片的强大的高性能和相对较低的制造成本有可能为新一代完全太阳能驱动和实现零液体排放的海水淡化技术提供可能。
