2025 AIChE Annual Meeting

(45g) Graphene Oxide Membranes Reduced Using Superhydrophilic Zwitterionic Amine for Dye Desalination

Authors

Erda Deng, University At Buffalo
Shweta Singh, University at Buffalo, State University of New York
Chong Cheng, University at Buffalo, The State University of New York
Haiqing Lin, University of Buffalo, State University of New Yor
Graphene oxide (GO) nanosheets have emerged as an alluring membrane platform for dye desalination due to their excellent exfoliability, adjustable interlayer spacings, and rich surface chemistry. Nevertheless, they can be dispersed in aqueous solutions and need to be reduced for long-term underwater operation, which increases hydrophobicity and reduces water permeance. Herein, we developed a facile way to reduce the GO nanosheets while retaining their hydrophilicity by functionalizing them with zwitterions. Specifically, GO nanosheets were first etched with hydrogen peroxide to impart more hydrophilic groups and create in-plane nanopores and reduce tortuosity, and then they were reacted with sulfobetaine amine (SBAm) through a ring-opening mechanism. The effects of the etching time, GO layer thickness, and zwitterion content on the membrane chemistry, structure, and salt/dye separation properties are thoroughly examined. For example, GO nanosheets were etched for 4 h and reacted with SBAm before fabrication into a 25-nm membrane; it exhibited a dye-water permeance of 60 LMH/Bar and high rejection of Reactive Black (99.2%) and Methyl Blue (97.2%). More importantly, the membrane achieves Na2SO4 rejection of ~15% and a dye/salt separation factor of 110, surpassing state-of-the-art GO membranes. The membranes show minimal difference between pure water and dye water permeance, indicating negligible fouling during dye filtration. The membranes exhibit stable water permeance and >99 % dye rejection in multi-cycle tests for 70-h operation, demonstrating their potential for practical applications.