Composite Membrane Plasticizer Additives Pressure Compaction
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Solution Overview
Problem
Conventional composite membranes used for fluid purification, such as seawater desalination, face challenges in maintaining high selectivity, flux, and chemical tolerance while being efficient and economical, with issues like pressure-induced compaction leading to lower porosity and reduced membrane performance over time.
Innovation Solution
A composite membrane is developed with a porous base membrane coated with a polyamide layer containing a C3-C8 cyclic carbonyl compound and a C1-C8 amide compound, which enhances performance through interfacial polymerization, using specific additives like cyclohexanone and acetamide, to improve selectivity and resistance to solutes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pressure is applied to force water through the membrane, then water flux is improved, but the polyamide film becomes compacted leading to lower porosity and loss of membrane performance
Solution Approach 1:
The patent introduces plasticizers (C3-C8 cyclic carbonyl compounds and C1-C8 amide compounds) to change the physical and chemical parameters of the polyamide layer, making it more resistant to pressure-induced compaction while maintaining high water flux and selectivity
Solution Approach 2:
The patent creates a composite polyamide layer by incorporating plasticizer additives into the interfacial polymerization reaction, resulting in a multi-component material that combines the selectivity of polyamide with the flexibility and pressure resistance of plasticizer molecules
2Productivity
If the polyamide layer is made thinner to improve water flux, then productivity is improved, but selectivity and chemical tolerance deteriorate
Solution Approach 1:
The patent modifies the polyamide layer properties by incorporating plasticizers that maintain layer integrity and selectivity even at reduced thickness, allowing high flux while preserving rejection capabilities
Solution Approach 2:
The patent optimizes the porous structure of the polyamide layer through plasticizer incorporation, maintaining appropriate porosity for high flux while preserving the dense enough structure for selectivity
3Ease of manufacture
If conventional interfacial polymerization is used to create the polyamide layer, then manufacturing is simple, but the membrane lacks sufficient chemical tolerance and performance under varying conditions
Solution Approach 1:
The patent modifies the interfacial polymerization process by adding plasticizer compounds to the reaction mixture, changing the chemical composition and properties of the resulting polyamide layer to enhance chemical tolerance while maintaining manufacturing simplicity
Solution Approach 2:
The plasticizer compounds act as intermediaries in the polyamide layer, providing chemical tolerance and performance stability under varying conditions while allowing the membrane to maintain its structural integrity
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 enhanced composite membrane exhibits improved permeability and salt rejection, maintaining performance under varying conditions and chemical exposure, with a synergistic effect observed when both additives are used together, avoiding damage to the membrane even at higher concentrations.
Implementation Method 1
contacting under interfacial polymerization conditions an organic solution comprising a polyacid halide with an aqueous solution comprising a polyamine, said contacting being carried out on a surface of a porous base membrane
Data Source
AI summary
The present invention provides a composite membrane comprising a porous base membrane and a polyamide coating disposed on said porous base membrane, said polyamide coating comprising a C3-C8 cyclic carbonyl compound and a C1-C8 amide compound, said amide compound comprising at least one N—H moiety. In addition the present invention provides a method of preparing a composite membrane comprising contacting under interfacial polymerization conditions an organic solution comprising a polyacid halide with an aqueous solution comprising a polyamine, said contacting being carried out on a surface of a porous base membrane, said organic solution further comprising a C3-C8 cyclic carbonyl compound, said aqueous solution comprising a C1-C8 amide compound, said amide compound comprising at least one N—H moiety.