Scalable fabrication of deoxygenated graphene oxide nanofiltration membrane by continuous slot-die coating

• Published in: Journal of membrane science Vol. 612; p. 118454
• Main Authors: Kim, Ji Hoon, Choi, Yunkyu, Kang, Junhyeok, Choi, Eunji, Choi, Seung Eun, Kwon, Ohchan, Kim, Dae Woo
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.10.2020
• Subjects: aqueous solutions; artificial membranes; coatings; Continuous coating; dyes; Graphene oxide; Nanofiltration; Scale-up; sieving; Slot-die coater; sodium hydroxide; Nanofiltration; Graphene oxide; Continuous coating; Slot-die coater; Scale-up
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/j.memsci.2020.118454

Graphene oxide (GO) has been widely used for the fabrication of nanofiltration membranes because precise molecular sieving can be achieved through the narrow interlayer spacing between stacked GO sheets. Herein, the scalable and continuous fabrication of a GO membrane is demonstrated by using a slot-die coater at a coating speed of 6 mm s−1. The thickness of the GO membrane can be controlled in 100-nm scale depending on the concentration of the GO solution and substrate morphology. Moreover, the coating layer and d-spacing (6.5–7.5 Å) of the GO membrane is preserved, even in aqueous solution, as GO is partially reduced by NaOH treatment (so-called deoxygenated GO, dGO). A membrane performance test reveals that the dGO membrane is effective for filtering sub-nanometer-size dye molecules with a rejection rate of up to 99% (brilliant blue G) and a pure water permeance of 30 LMH bar−1. The dGO membrane operates stably under cross-flow and high pressure up to 12 bar. Scale-up of the GO membrane fabrication using the slot-die coating technique is feasible because the coating process is continuous. [Display omitted] •Continuous and scalable fabrication of graphene oxide membrane was demonstrated using slot-die coating method.•NaOH treatment was effective to enhance membrane stability in an aqueous solvent under cross-flow filtration.•The membrane can filter sub-nanometer-size molecules up to 99% rejection with pure water permeance of 30 LMH/bar.•This coating method can be applied to other two-dimensional materials beyond graphene oxide.