Department of Physics & Astronomy, University of Western Ontario, 1151 Richmond St, London, ON N6A 3K7, Canada.
Nanoscale. 2016 May 14;8(18):9563-71. doi: 10.1039/c5nr09278g. Epub 2016 Apr 21.
A new generation of membranes for water purification based on weakly oxidized and nanoporous few-layer graphene is here introduced. These membranes dramatically decrease the high energy requirements of water purification by reverse osmosis. They combine the advantages of porous and non-oxidized single-layer graphene, offering energy-efficient water filtration at relatively low differential pressures, and highly oxidized graphene oxide, exhibiting high performance in terms of impurity adsorption. In the reported fabrication process, leaks between juxtaposed few-layer graphene flakes are sealed by thermally annealed colloidal silica, in a treatment that precedes the opening of (sub)nanometre-size pores in graphene. This process, explored for the first time in this work, results in nanoporous graphene flakes that are water-tight at the edges without occluding the (sub)nanopores. With this method, removal of impurities from water occurs through a combination of size-based pore rejection and pore-edge adsorption. Thinness of graphene flakes allows these membranes to achieve water purification from metal ions in concentrations of few parts-per-million at differential pressures as low as 30 kPa, outperforming existing graphene or graphene oxide purification systems with comparable flow rates.
这里介绍了一种基于弱氧化和纳米多孔少层石墨烯的新一代水净化膜。这些膜通过反渗透大大降低了水净化的高能耗要求。它们结合了多孔和未氧化的单层石墨烯的优点，在相对较低的压差下提供了节能的水过滤，同时还结合了高度氧化的氧化石墨烯的优点，在杂质吸附方面表现出了很高的性能。在报道的制造工艺中，通过热退火胶体二氧化硅密封相邻少层石墨烯片之间的泄漏，然后在石墨烯中打开（亚）纳米尺寸的孔之前进行处理。在这项工作中首次探索了这一过程，结果得到了纳米多孔石墨烯片，其边缘是防水的，而不会堵塞（亚）纳米孔。通过这种方法，杂质的去除是通过基于尺寸的孔排斥和孔边缘吸附的组合来实现的。石墨烯片的薄度使得这些膜能够在低至 30 kPa 的压差下从浓度为 ppm 级的金属离子中实现水的净化，性能优于具有可比流速的现有石墨烯或氧化石墨烯净化系统。
