Gong Biyao, Yang Huachao, Wu Shenghao, Xiong Guoping, Yan Jianhua, Cen Kefa, Bo Zheng, Ostrikov Kostya
State Key Laboratory of Clean Energy Utilization, College of Energy Engineering, Zhejiang University, Hangzhou, 310027, Zhejiang, People's Republic of China.
Department of Mechanical Engineering, University of Nevada, Reno, NV, 89557, USA.
Nanomicro Lett. 2019 Jun 10;11(1):51. doi: 10.1007/s40820-019-0281-1.
Photothermal membrane distillation (MD) is a promising technology for desalination and water purification. However, solar-thermal conversion suffers from low energy efficiency (a typical solar-water efficiency of ~ 50%), while complex modifications are needed to reduce membrane fouling. Here, we demonstrate a new concept of solar vapour gap membrane distillation (SVGMD) synergistically combining self-guided water transport, localized heating, and separation of membrane from feed solution. A free-standing, multifunctional light absorber based on graphene array is custom-designed to locally heat the thin water layer transporting through graphene nanochannels. The as-generated vapour passes through a gap and condenses, while salt/contaminants are rejected before reaching the membrane. The high solar-water efficiency (73.4% at 1 sun), clean water collection ratio (82.3%), excellent anti-fouling performance, and stable permeate flux in continuous operation over 72 h are simultaneously achieved. Meanwhile, SVGMD inherits the advantage of MD in microorganism removal and water collection, enabling the solar-water efficiency 3.5 times higher compared to state-of-the-art solar vapour systems. A scaled system to treat oil/seawater mixtures under natural sunlight is developed with a purified water yield of 92.8 kg m day. Our results can be applied for diverse mixed-phase feeds, leading to the next-generation solar-driven MD technology.
光热膜蒸馏（MD）是一种很有前景的海水淡化和水净化技术。然而，太阳能热转换存在能源效率低的问题（典型的太阳能-水效率约为50%），同时需要进行复杂的改性以减少膜污染。在此，我们展示了一种太阳能蒸汽间隙膜蒸馏（SVGMD）的新概念，它将自引导水传输、局部加热以及膜与进料溶液的分离协同结合。基于石墨烯阵列定制设计了一种独立的多功能光吸收器，用于局部加热通过石墨烯纳米通道传输的薄水层。产生的蒸汽穿过间隙并冷凝，而盐/污染物在到达膜之前被截留。同时实现了高太阳能-水效率（1个太阳光照下为73.4%）、清洁水收集率（82.3%）、优异的抗污染性能以及在72小时连续运行中稳定的渗透通量。此外，SVGMD继承了MD在微生物去除和水收集方面的优势，与最先进的太阳能蒸汽系统相比，太阳能-水效率提高了3.5倍。开发了一种在自然阳光下处理油/海水混合物的规模化系统，产水率为92.8 kg m day。我们的成果可应用于多种混合相进料，引领下一代太阳能驱动的MD技术。
