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Minimizing Non-selective Nanowrinkles of Reduced Graphene Oxide Laminar Membranes for Enhanced NaCl Rejection
Environmental Science & Technology Letters ( IF 8.9 ) Pub Date : 2020-03-20 , DOI: 10.1021/acs.estlett.0c00143
Shi Yuan 1 , Yang Li 1 , Yun Xia 1 , Yuan Kang 1 , Jindi Yang 1 , Md Hemayet Uddin 2 , Huiyuan Liu 1 , Cordelia Selomulya 1, 3 , Xiwang Zhang 1
Affiliation  

Reduced graphene oxide membranes (rGOMs) have been intensively studied for desalination and molecular sieving applications, benefiting from their selective and stable two-dimensional (2D) nanochannels. However, their performance is usually over-rated because of the limited understanding of nanowrinkles. In this study, we tuned 2D nanochannels and nanowrinkles in rGOMs to improve their performance and revealed the underlying role of nanowrinkles for water and salt separation. A good trade-off between water permeance (1.05 LMH/bar) and NaCl rejection (83%) was obtained in rGOMs thermally treated in air (Air-rGO), compared with their counterparts synthesized via thermal treatment in vacuum (Va-rGO) and HI vapor reduction (HI-rGO). Instead of the narrow and impermeable 2D nanochannels in Va-rGO and HI-rGO, 5–10 nm-sized nanowrinkles were evident to transport water and salts without selectivity, leading to the low water permeance and NaCl rejection. For Air-rGO membranes, however, the smaller and fewer nanowrinkles retarded the NaCl transfer and the slightly narrowed 2D nanochannels maintained the fast water flow, contributing to the high NaCl rejection and water permeance, respectively. This study provides new insights into the mass transport mechanism in nanowrinkles of rGOMs and advances the design of 2D membranes for desalination, molecular/ionic sieving, and other environmental applications.

中文翻译:

减少还原的氧化石墨烯层流膜的非选择性纳米皱纹,以增强NaCl的抑制作用

受益于其选择性和稳定的二维(2D)纳米通道,还原型氧化石墨烯膜(rGOM)已被广泛研究用于脱盐和分子筛应用。然而,由于对纳米皱纹的了解有限,它们的性能通常被高估。在这项研究中,我们调整了rGOM中的2D纳米通道和纳米皱纹以改善其性能,并揭示了纳米皱纹在水和盐分离中的潜在作用。与通过真空热处理(Va-rGO)合成的同类产品相比,在空气中热处理过的rGOM(Air-rGO)中获得了良好的水渗透率(1.05 LMH / bar)和NaCl截留率(83%)之间的平衡。 HI蒸气减少(HI-rGO)。代替Va-rGO和HI-rGO中狭窄且不可渗透的2D纳米通道,5–10 nm大小的纳米皱纹显然可以无选择性地输送水和盐,从而导致较低的水渗透性和NaCl截留率。然而,对于Air-rGO膜,较小和较少的纳米皱纹会延迟NaCl的转移,而略微变窄的2D纳米通道则保持了快速的水流,分别导致了较高的NaCl截留率和透水性。这项研究为rGOM的纳米皱纹中的传质机理提供了新的见解,并推进了用于脱盐,分子/离子筛分和其他环境应用的2D膜的设计。较小和较少的纳米皱纹阻碍了NaCl的转移,略微变窄的2D纳米通道保持了快速的水流,分别导致了较高的NaCl截留率和透水性。这项研究为rGOM的纳米皱纹中的传质机理提供了新的见解,并推进了用于脱盐,分子/离子筛分和其他环境应用的2D膜的设计。较小和较少的纳米皱纹阻碍了NaCl的转移,略微变窄的2D纳米通道保持了快速的水流,分别导致了较高的NaCl截留率和透水性。这项研究为rGOM的纳米皱纹中的传质机理提供了新的见解,并推进了用于脱盐,分子/离子筛分和其他环境应用的2D膜的设计。
更新日期:2020-04-23
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