PVDF Membrane Solvent Blend Balancing NMP Toxicity and Quality
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Solution Overview
Problem
There is a need for safer and less toxic solvents to replace hazardous solvents like N-Methylpyrrolidone (NMP) in the production of polyvinylidene fluoride (PVDF) membranes, which are used in water treatment applications, while maintaining membrane quality in terms of water permeability, strength, and elasticity.
Innovation Solution
A blend of triethylphosphate (TEP) and N-methylpyrrolidone (NMP) is used as a solvent system to prepare PVDF membranes, reducing the use of hazardous solvents and achieving comparable properties to membranes made with pure NMP.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If NMP solvent is used to make PVDF membranes, then membrane quality (water permeability, strength, elasticity) is maintained, but solvent toxicity and hazardousness increase
Solution Approach 1:
The patent changes the chemical composition parameter of the solvent system by replacing pure NMP with a TEP-NMP blend. Specifically, TEP is used in proportions of 10-90 wt% to displace hazardous NMP while maintaining the solvent's ability to dissolve PVDF and control membrane formation, thus reducing toxicity while preserving membrane quality
Solution Approach 2:
The patent creates a composite solvent system combining TEP and NMP in specific ratios. This composite approach leverages TEP's lower toxicity and cost advantages while retaining NMP's effective membrane-forming properties, achieving a balance between safety and performance
2Reliability
If pure NMP is used as solvent, then membrane properties are optimized, but production cost increases
Solution Approach 1:
The patent modifies the solvent composition parameter to include TEP in 10-90 wt% proportion, which reduces the quantity of expensive NMP required. This substitution maintains adequate membrane properties while lowering material costs, as TEP is a more economical solvent option
3Object-affected harmful factors
If TEP is used as sole solvent, then solvent safety and cost are improved, but membrane quality (water permeability, strength, elasticity) deteriorates
Solution Approach 1:
The patent formulates a composite TEP-NMP solvent system where NMP (10-90 wt%) complements TEP's properties. This combination ensures adequate PVDF dissolution, controlled phase inversion, and formation of membranes with acceptable water permeability, strength, and elasticity, overcoming TEP's limitations when used alone
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 TEP-NMP blend reduces the use of hazardous solvents, lowers production costs, and maintains membrane properties such as mechanical strength, elongation, and water permeability, aligning with regulatory requirements for safer industrial practices.
Implementation Method 1
dissolving PVDF polymers in a solvent
Implementation Method 2
coagulating the PVDF polymer from such solvent by the NIPS phase inversion process
Data Source
AI summary
The invention discloses a dope solution for membrane fabrication comprising a blend of TEP with NMP as a solvent system in a process to make PVDF membranes, where PVDF resin comprises a homopolymer resin, or a copolymer of VDF and at least one of hexafluoropropylene, trifluoroethylene, chlorotrifluoroethylene, or a tetrafluoropropene.