Oleophobic Composite Membranes via Atomic Layer Deposition
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Solution Overview
Problem
Current oil-resistant membranes used in oily wastewater treatment experience severe fouling by crude oil, leading to a dramatic decline in performance and lifetime, as they are not effective in resisting the adhesion of crude oil due to flexible polymer chains and soft surface morphology.
Innovation Solution
The development of oleophobic membranes using atomic layer deposition (ALD) to create a conformal oxide coating with a strong hydration state on the surface, incorporating hydrophilic moieties and specific oxide materials like TiO2 and SnO2, which reduce crude oil adhesion by minimizing contact area through a tightly bound hydration layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polymer membranes are used for oily wastewater filtration, then membrane fabrication is simple and cost-effective, but the membranes experience severe fouling by crude oil leading to dramatic performance decline
Solution Approach 1:
The patent combines polymer membrane substrate with inorganic oxide coatings (TiO2, SnO2, Al2O3, SiO2, ZnO) to create a composite membrane structure. The inorganic coating layer provides rigid roughness and stable hydrophilic moieties that resist crude oil adhesion, while the polymer substrate provides mechanical support and porosity for filtration
Solution Approach 2:
The patent modifies surface properties by controlling oxide coating thickness (1-20 nm), hydroxyl group density, and surface energy characteristics. These parameter changes transform the surface from oleophilic to oleophobic while maintaining hydrophilicity, preventing crude oil adhesion under filtration pressure
2Reliability
If polymer membranes with hydrophilic moieties are used, then water affinity is improved, but flexible polymer chains allow oil to penetrate and adhere to the surface
Solution Approach 1:
The patent creates a surface layer with distinct properties from the bulk membrane. The oxide-coated surface possesses rigid roughness and stable hydrophilic groups that repel oil, while the underlying polymer bulk maintains flexibility and porosity for water transport
Solution Approach 2:
The patent utilizes surface roughness at micro- and nano-scales created by the oxide coating. This hierarchical roughness structure reduces the actual contact area between oil and solid surface, with water trapped in the roughness features serving as a physical barrier
3Reliability
If inorganic coatings are applied to enhance anti-oil performance, then crude oil repellence is improved, but coating thickness control and uniformity become challenging
Solution Approach 1:
The patent employs atomic layer deposition (ALD) to replace conventional coating methods. ALD provides precise nanometer-scale thickness control (1-20 nm), uniform conformal coverage on porous surfaces, and excellent adhesion through controlled chemical reactions
Solution Approach 2:
The patent controls coating properties by adjusting ALD process parameters including deposition temperature, precursor dosage, and cycle number. These parameter changes enable precise control of coating thickness, composition, and crystalline structure to optimize anti-oil performance
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 ALD-coated membranes exhibit superior crude oil repellence, maintaining performance and stability under filtration pressure, with TiO2 and SnO2 coatings showing extraordinary low adhesion and prolonged anti-oil performance, significantly improving membrane lifetime and fouling resistance.
Implementation Method 1
an ideal anti-oil surface would be hierarchically structured and fully hydrated. Water trapped in micro- and nano-structures reduces the contact area between oil and solid, and the water on the solid surface serves as a physical barrier to prevent direct oil adhesion
Implementation Method 2
depositing an oxide coating on the surface of the first side of the membrane by atomic layer deposition
Implementation Method 3
an ideal anti-oil surface would be hierarchically structured and fully hydrated. Water trapped in micro- and nano-structures reduces the contact area between oil and solid
Implementation Method 4
Water trapped in micro- and nano-structures reduces the contact area between oil and solid
Data Source
AI summary
Atomic layer deposition is utilized to deposit a coating on a membrane. The coated membrane exhibits a tightly bound hydration layer upon exposure to water. The resultant coated membrane is oleophobic.