Ying Yulong, Ying Wen, Guo Yi, Peng Xinsheng
School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China.
Nanotechnology. 2018 Apr 2;29(15):155602. doi: 10.1088/1361-6528/aaad50.
A graphene oxide (GO) membrane is promising for molecule separation. However, it is still a big challenge to achieve highly stable pristine GO membranes, especially in water. In this work, an ultrathin and robust GO membrane is assembled via the cross-flow method. The as-prepared 12 nm thick GO membrane (GO membrane) presents high stability with water permeance of 1505 ± 65 litres per hour per square meter per bar (LHM bar) and Evans Blue (EB) rejection of 98.7 ± 0.4%, 21-fold enhancement in water permeance compared with that of a pristine GO membrane (50-70 LHM bar) and 100 times higher than that of commercial ultrafiltration membranes (15 LHM.bar, GE2540F30, MWCO 1000, GE Co., Ltd) with similar rejection. Attributed to the surface cross-flow, the GO nanosheets will be refolded, crumpled, or wrinkled, resulting in a very strong inter-locking structure among the GO membrane, which significantly enhances the stability and facilitates their separation performance. This cross-flow assembling technique is also easily extended to assemble GO membranes onto other various backing filter supports. Based on the Donnan effect and size sieving mechanism, selective membrane separation of dyes with a similar molecular structure from their mixture (such as Rhodamine B (RhB) and Rose Bengal, and RhB and EB) are achieved with a selectivity of 133 ± 10 and 227 ± 15, respectively. Assembly of this ultrathin GO membrane with high stability and separation performance, via a simple cross-flow method, shows great potential for water purification.
氧化石墨烯（GO）膜在分子分离方面具有广阔前景。然而，制备高度稳定的原始GO膜仍然是一个巨大的挑战，尤其是在水中。在这项工作中，通过错流法组装了一种超薄且坚固的GO膜。所制备的12纳米厚的GO膜（GO膜）具有高稳定性，水通量为每小时每平方米每巴1505±65升（LHM bar），伊文思蓝（EB）截留率为98.7±0.4%，与原始GO膜（50 - 70 LHM bar）相比，水通量提高了21倍，比具有相似截留率的商业超滤膜（15 LHM.bar，GE2540F30，截留分子量1000，通用电气公司）高100倍。由于表面错流，GO纳米片会重新折叠、起皱或卷曲，从而在GO膜之间形成非常强的互锁结构，显著提高了稳定性并提升了其分离性能。这种错流组装技术也很容易扩展到将GO膜组装到其他各种支撑滤材上。基于唐南效应和尺寸筛分机制，从染料混合物（如罗丹明B（RhB）和孟加拉玫瑰红，以及RhB和EB）中选择性分离具有相似分子结构的染料，选择性分别为133±10和227±15。通过简单的错流法组装这种具有高稳定性和分离性能的超薄GO膜，在水净化方面显示出巨大潜力。
