Chuanhua Duan

High Permeable Graphene Oxide Membranes for Water Desalination and Purification

PROJECT DESCRIPTION
The goal of this project is to develop new graphene oxide (GO) membranes with high water permeability and high ion/contaminant rejection efficiency for water desalination and purification. GO membranes, formed by stacking micrometer-sized single GO sheets together, is a sp2 carbon based membrane that offers exciting opportunities to advance sieving membrane technology. Unlike the challenging fabrication of other carbon based membrane including CNT membranes and porous graphene membranes, GO membranes can be prepared by various scalable and cost-effective methods such as vacuum filtration, blade casting and layer-by-layer assembly. The resulting layered membrane structures consist of numerous horizontally-aligned and interconnected graphene nanochannels (GNCs). The nanoscale confinement (typical channel height below 1 nm) and surface-ion interactions of these GNCs can prevent ions from crossing the GO membrane while allowing water flow. Because of these unique advantages, GO membranes hold great promise to replace current polymer membranes for Water desalination/purification.

However, there is a serious drawback that prevents current GO membranes for practical applications. All current GO membranes have a relatively low surface porosity and high tortuosity (typical tortuosity of ~102-103 depending on the size of individual GO sheets and space between the GO sheets), which are inherent results of existing fabrication approaches and significantly limit the water permeability of this new type of membrane. To address this issue, we have been working on developing two new scalable methods to prepare new GO membranes with unit tortuosity, including template-assisted vacuum filtration and lithography-assisted patterning of existing GO membranes. The participants will use these two methods to fabricate new GO membranes and characterize their structures. They will also mount these membranes in a custom-made permeation cell and test their water permeability and ion/contaminant rejection efficiency.

LABORATORY MENTORS
Quan Xie and Siyang Xiao

RESEARCH GOALS
1. Fabricate and characterize new GO membranes with unit tortuosity.
2. Measure water permeability of the new GO membranes.
3. Measure ion rejection efficiency of the new GO memebranes

LEARNING GOALS
1. Learn vacuum filtration method to prepare GO membranes.
2. Learn basic MEMS fabrication techniques, including spin coating, lithography and oxygen plasma cleaning.
3. Learn how to test membrane permeability.
4. Learn how to test ion rejection efficiency.

PROJECT TIMELINE
Week 1-2: Read related papers; follow graduate mentors to learn basic synthesis/ fabrication techniques
Week 3-5: fabricate and characterize GO membranes with unit tortuosity
Week 6-7: Measure water permeability of new GO membranes
Week 8: poster preparation, start ion rejection measurements
Week 9: Continue measuring ion rejection efficiency of GO membranes
Week 10: Wrap-up

Learn more about Professor Duan on his faculty page.