Thio-Functionalized TMD Membranes for Stable Water Desalination
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Solution Overview
Problem
Existing semi-permeable membranes, such as graphene oxide (GO) and MXenes, suffer from instability and swelling issues, limiting their effectiveness in continuous water desalination processes, while pristine MoS2 laminates have dense channels unsuitable for mass transport.
Innovation Solution
A membrane composed of stacked layers of thio-groups functionalized single-layer transition metal dichalcogenide (TMD) nanosheets, produced by reacting TMD nanosheets with thiol-group containing compounds like cysteine, 1-propanethiol, or 3-mercaptopropane-1,2-diol, creating optimized capillary passages for water permeation and ion rejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If GO laminates are used for water permeation, then water flux is improved, but interlayer spacing swells and microstructure stability deteriorates
Solution Approach 1:
The patent changes the material parameter from GO to TMD nanosheets, which have different physical and chemical properties. TMD nanosheets maintain stable interlayer spacing in aqueous solutions while enabling water permeation, resolving the contradiction between water flux and microstructure stability
Solution Approach 2:
The patent creates a composite structure by functionalizing TMD nanosheets with thio-groups, forming a new material system that combines the advantages of TMD stability with enhanced water permeation capabilities, achieving both high productivity and structural stability
2Manufacturing precision
If MXenes membranes are used for ion sieving, then selectivity is improved, but swelling occurs due to hydrophilic functional groups
Solution Approach 1:
The patent changes the material composition from MXenes to TMD nanosheets, which have different surface chemistry properties. TMD nanosheets do not exhibit the same swelling behavior as MXenes while maintaining ion sieving selectivity, resolving the contradiction between selectivity and stability
3Stability of the object's composition
If pristine MoS2 laminates are used for separation, then structural stability is improved, but mass transport is hindered by dense channels
Solution Approach 1:
The patent functionalizes MoS2 nanosheets with thio-groups, creating controlled porosity and nanochannels within the laminate structure. This allows water and ions to transport through the otherwise dense MoS2 structure, resolving the contradiction between structural stability and mass transport
Solution Approach 2:
The patent introduces local functionalization with thio-groups at specific sites on the MoS2 nanosheets, creating localized pathways for mass transport while maintaining the overall structural stability of the MoS2 lattice
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 functionalized TMD membranes exhibit controlled swelling, enhanced water permeation, and high ion rejection, achieving up to 99.5% removal of charged solutes and maintaining stability over extended use.
Implementation Method 1
a network of water permeation capillary passages independently having a capillary width of about 4.5-5.5 Å
Implementation Method 2
Forward osmosis (FO) is a membrane process that relies on inherent osmotic pressure to induce water flow from the low concentration side (feed solution) across the semi-permeable membrane to the high concentration side (draw solution)
Data Source
AI summary
Disclosed herein is a membrane made of stacked layers of thio-groups functionalized single-layer transition metal dichalcogenide (TMD) nanosheets. The membrane is characterized by having a network of water permeation capillary passages independently having a capillary width of about 4.5-5.5 Å, a surface wettability with a contact angle of 64-90°, a degree of functionalization of 10-15%, a degree of swelling of about 0.5-4.0%; and a thickness of about 200-1,300 nm. Also disclosed herein is a method of deionizing a fluid. The method includes permeating the fluid through the present membrane via forward osmosis.