Nano-Micro Letters

Graphene Array based Anti-fouling Solar Vapour Gap Membrane Distillation with High Energy Efficiency

Biyao Gong1, Huachao Yang1, Shenghao Wu1, Guoping Xiong2, Jianhua Yan1, Kefa Cen1, Zheng Bo1, *, Kostya (Ken) Ostrikov3, 4

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Nano-Micro Lett. (2019) 11: 51

First Online: 10 June 2019 (Article)

DOI:10.1007/s40820-019-0281-1

*Corresponding author. E-mail: bozh@zju.edu.cn (Bo Zheng)

 

Abstract

 


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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, multi-functional 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-2 day-1. Our results can be applied for diverse mixed-phase feeds, leading to the next-generation solar-driven MD technology.


 

Keywords

Solar energy; Plasma-made nanostructures; Photothermal conversion; Water purification

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