Contaminant-Sequestering Coatings for Selective PFAS Water Filtration
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Solution Overview
Problem
Current methods for removing per- and polyfluoroalkyl substances (PFAS) from water sources, such as PFOS and PFOA, are non-selective and expensive, limiting their application for large-scale filtration.
Innovation Solution
A contaminant-sequestering coating comprising a network of hydrolyzed silane compounds with fluorinated functionalities and thiol functional groups is applied to substrates, forming a network with a hydrophilic polar head region, fluorine-containing region, and anchor region to sequester PFAS and heavy metals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adsorption on granular and powdered activated carbon is used for PFAS removal, then PFAS can be removed from water, but the method is non-selective and expensive, limiting its application for large-scale filtration
Solution Approach 1:
The patent applies local quality by creating a coating with specific local functional groups (thiol and fluorinated functionalities) at the surface of the filtration medium. This localized functionalization allows selective PFAS removal at the surface level while using inexpensive bulk materials, resolving the contradiction between removal effectiveness and cost scalability
Solution Approach 2:
The patent uses composite materials by combining inexpensive filtration media (such as sand or activated carbon) with a thin coating of silane compounds containing thiol and fluorinated functionalities. This composite structure provides selective PFAS removal capability while maintaining low cost and scalability for large-scale filtration applications
2Reliability
If highly porous-activated carbon is used for PFAS adsorption, then PFAS removal is achieved, but the approach is non-selective for PFAS with different chain lengths and expensive to implement
Solution Approach 1:
The coating incorporates thiol functional groups that provide specific local interaction sites for PFAS molecules. These thiol groups create a chemically selective environment that can differentiate between PFAS with different chain lengths and structures, enabling selective removal while using inexpensive bulk materials
Solution Approach 2:
The patent changes the chemical parameters of the filtration surface by introducing thiol and fluorinated functionalities through silane coating. This parameter change transforms the surface chemistry to be more selective for PFAS molecules, allowing differentiation based on molecular structure and chain length
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 coating effectively sequesters up to 100% of PFAS and heavy metals from water, reducing their concentration to below 80 parts-per-trillion, as recommended by the EPA, and can be applied to various substrates including filtration media and ion-exchange resins.
Implementation Method 1
a contaminant-sequestering coating (e.g., in a dry and/or solid state) that comprises a network of hydrolyzed silane compounds
Implementation Method 2
the plurality of hydrolyzed silane compounds to condense (e.g., condensation reaction between the plurality of hydrolyzed silane compounds) with each other and or with a substrate to form a contaminant-sequestering coating
Implementation Method 3
adsorption on granular and powdered activated carbon... this approach is both nonselective for PFAS with known limitations
Data Source
AI summary
Contaminant-sequestering coatings include a network of hydrolyzed silane compounds including (i) a plurality of fluorinated functionalities, and (ii) a plurality of thiol functional groups are provided. The network of hydrolyzed silane compounds includes a fluorinated silane including (a) a hydrophilic polar head region. The polar head region includes one or multiple units of ethylene glycol (EG) functionality, (b) a fluorine-containing region, and (c) an anchor region including a silicon atom. The contaminant-sequestering coatings may sequester one or more per- and polyfluoroalkyl substances (PFAS), heavy metals, biological species, or any combination thereof.