Bilayer Electrospun Membrane for Fracking Wastewater
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Solution Overview
Problem
Current membrane technologies, such as reverse osmosis and nanofiltration, are not practical for treating highly impaired fracking wastewater due to high total dissolved solids and the presence of organic compounds and surfactants, which lead to significant fouling and high treatment costs.
Innovation Solution
Development of a bilayer electrospun membrane with an omniphobic permeate-facing surface and an oleophobic feedstock-facing surface, utilizing zwitterionic polymers and fluorine-coated silica nanoparticles to prevent fouling and scale formation, enhancing antifouling and antiwetting properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional hydrophobic membranes are used for membrane distillation, then water vapor can pass through the membrane pores, but organic compounds and surfactants adsorb onto the membrane surface causing fouling
Solution Approach 1:
The membrane surface is modified with omniphobic coatings that create low-surface-energy regions, making the surface locally different from the bulk hydrophobic membrane material. This local modification prevents adsorption of organic compounds and surfactants while maintaining the bulk hydrophobicity needed for vapor transport
Solution Approach 2:
The membrane combines hydrophobic base material (for vapor phase separation) with omniphobic surface coating (for fouling prevention). This composite structure integrates two functional materials: the hydrophobic matrix provides the driving force for membrane distillation while the omniphobic surface layer prevents fouling by both polar and non-polar contaminants
2Manufacturing precision
If membrane treatment is used for highly impaired fracking wastewater, then water purification is achieved, but significant pretreatment is required due to high TDS and organic compounds
Solution Approach 1:
The membrane distillation process exploits phase transition of water from liquid to vapor phase. The hydrophobic membrane allows only vapor phase water molecules to pass through while blocking liquid phase contaminants, high TDS, and organic compounds. This phase-based separation mechanism enables direct treatment of highly impaired wastewater without complex pretreatment steps
3Object-affected harmful factors
If omniphobic surfaces with nanoparticles are used, then low surface energy compound wicking is prevented, but the membrane remains susceptible to fouling by surfactants
Solution Approach 1:
The omniphobic surface coating is applied in advance to create a protective barrier that preemptively prevents surfactant and organic compound adsorption. The low-surface-energy fluorinated surface creates an energy barrier that repels contaminants before they can adhere to the membrane, preventing fouling rather than treating it after occurrence
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 bilayer membrane significantly reduces fouling, increases membrane lifespan, and improves the efficiency of wastewater treatment by maintaining high flux and salt rejection, even in the presence of low-surface tension compounds and crude oil, while preventing adsorption of foulants and scale formation.
Implementation Method 1
an omniphobic, permeate-facing surface configured to suppress scale formation and low-surface tension compounds from wicking and fouling the membrane
Implementation Method 2
an oleophobic, feedstock-facing surface configured to prevent foulants from depositing on and adsorbing to the membrane
Implementation Method 3
The driving force for MD is the vapor pressure difference between the feedstock and permeate sides
Implementation Method 4
allow water vapor to pass through the membrane pores and condense on the permeate side
Data Source
AI summary
A bilayer electrospun membranes for treating hydraulic fracking wastewater via membrane distillation, and more particularly to bilayer electrospun membranes having an omniphobic layer to prevent low-surface tension solution wicking and an oleophobic antifouling surface to prevent foulant depositing on the membrane. Nanoparticles are decorated on the omniphobic surface through electrochemical interaction, which is coated with a fluorine monomer on the nanoparticles. A zwitterionic co-polymer is grafted using self-assembly between hydroxy groups on the antifouling surface generated by alkaline treatment and anchor segment epoxy groups on zwitterionic co-polymer.