Ultrathin Graphene Oxide Membranes for High-Flux Gas Separation
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Solution Overview
Problem
Current microporous membranes are thick and face challenges in reducing thickness below 20 nm without introducing non-selective defects, limiting their flux and separation selectivity, while graphene-based membranes are impermeable to small gas molecules, lacking practical separation membranes for gas mixtures.
Innovation Solution
The development of ultrathin graphene oxide (GO) membranes with thicknesses ranging from 1.8 nm to 180 nm, formed through a method involving dispersing single-layered graphene oxide in water, centrifugation, and dilution, followed by filtration on a substrate, enabling high flux and selectivity for gas mixtures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If membrane thickness is reduced to sub-20 nm range, then flux is improved, but non-selective defects are introduced
Solution Approach 1:
The patent employs graphene oxide membranes with controlled porous structures that allow molecular sieving at ultra-thin thickness. The porous nature of GO enables selective permeation based on molecular size and shape, achieving high flux while maintaining separation selectivity through the inherent pore structure rather than relying on thicker membrane layers.
Solution Approach 2:
The patent uses composite graphene oxide membranes that combine the high surface area and porous structure of GO with controlled defect distributions. This composite approach allows optimization of both flux and selectivity by leveraging the unique properties of graphene oxide and managing the impact of defects through controlled preparation methods.
2Productivity
If graphene-based materials are used, then membrane thickness is reduced to maximize flux, but impermeability to small gas molecules occurs
Solution Approach 1:
The patent modifies the physical and chemical parameters of graphene by oxidizing it to form graphene oxide, which introduces pores and functional groups that enhance gas permeation. This parameter change transforms graphene from being impermeable to being selectively permeable, allowing small gas molecules to pass through while maintaining the ultra-thin structure for high flux.
Solution Approach 2:
Graphene oxide is inherently porous with a controlled pore structure that enables gas permeation. The porous nature allows small gas molecules to diffuse through the membrane while the thin structure maintains high flux, resolving the contradiction between impermeability and gas transport.
3Reliability
If current microporous membranes are made thicker, then separation selectivity is maintained, but flux is limited
Solution Approach 1:
The patent utilizes the porous structure of graphene oxide to achieve molecular sieving at ultra-thin thickness. The porous nature allows selective permeation based on molecular size, enabling high separation selectivity without requiring thick membrane layers, thus maintaining high flux while achieving effective separation.
Solution Approach 2:
The patent replaces the mechanical approach of using thick membranes to achieve separation with a molecular-level mechanism. By utilizing the inherent porous structure and molecular sieving capability of graphene oxide, the membrane achieves separation at the molecular level rather than relying on physical thickness, thereby maintaining high flux while achieving effective separation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The ultrathin GO membranes exhibit superior separation performance for H2 mixtures, achieving high selectivities and permeances, surpassing previous membrane technologies, with potential applications in H2 separations, gas sensors, and seawater desalination.
Implementation Method 1
Ultrathin, molecular-sieving graphene oxide membranes for separations
Implementation Method 2
the transport rates of H2 and CO2 were 3 to 4 orders of magnitude higher than N2 and CH4 through porous graphene flakes
Data Source
AI summary
Methods for forming an ultrathin GO membrane are provided. The method can include: dispersing a single-layered graphene oxide powder in deionized water to form a single-layered graphene oxide dispersion; centrifuging the graphene oxide dispersion to remove aggregated graphene oxide material from the single-layered graphene oxide dispersion; thereafter, diluting the single-layered graphene oxide dispersion by about ten times or more through addition of deionized water to the graphene oxide dispersion; and thereafter, passing the single-layered graphene oxide dispersion through a substrate such that a graphene oxide membrane is formed on the substrate. Filtration membranes are also provided and can include: a graphene oxide membrane having a thickness of about 1.8 nm to about 180 nm, with the graphene oxide membrane comprises about 3 to about 30 layers of graphene oxide flakes.