Vapor-Assisted Electrostatic Spray for Polyamide Membranes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing polyamide composite membranes for nano-filtration and reverse osmosis suffer from wide pore size distribution, leading to inadequate selective separation performance between solutes of similar sizes, such as salt ions and organic substances.
Innovation Solution
A vapor-assisted electrostatic spray method is employed to prepare polyamide composite membranes, where the relative humidity is adjusted to 80-90% to improve the dispersibility of amine monomers and control the reaction degree, resulting in a membrane with a narrow pore size distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If classical interfacial polymerization is used to prepare polyamide composite membranes, then the membrane can be manufactured with relatively simple process, but the pore size distribution becomes wide leading to poor selective separation performance
Solution Approach 1:
The patent changes the physical state parameter of the aqueous phase from liquid to vapor by adjusting relative humidity to 80-90%, which fundamentally alters the interfacial polymerization process. This parameter change enables precise control of monomer diffusion and reaction, resulting in narrow pore size distribution (0.5-2.0 nm) while maintaining manufacturing feasibility
Solution Approach 2:
The patent introduces water vapor as an intermediary substance that mediates between the aqueous monomer solution and the organic phase. The water vapor facilitates controlled mass transfer and reaction at the interface, enabling precise pore size control without requiring complex intermediate layers or additional processing steps
2Quantity of substance
If the viscosity of aqueous reaction solution is increased to control monomer diffusion rate, then some control over diffusion is achieved, but the selective separation performance between solutes of similar sizes remains insufficient
Solution Approach 1:
Instead of changing the viscosity parameter of the aqueous solution, the patent changes the physical state to vapor phase by controlling relative humidity. This fundamental parameter change provides superior control over monomer diffusion and reaction kinetics, achieving both diffusion control and high selective separation performance (separation accuracy of 1 Å between solutes)
3Manufacturing precision
If surfactant-assisted interfacial polymerization is used to prepare polyamide separation layer with narrow subnano pore size distribution, then separation accuracy reaches 1 Å, but the operation requirements become strict making scale production unfavorable
Solution Approach 1:
The patent uses water vapor as a natural intermediary that simplifies the interfacial polymerization process without requiring surfactants. The water vapor automatically provides the necessary control over monomer diffusion and reaction, achieving narrow pore size distribution (0.5-2.0 nm) and high separation accuracy while maintaining loose operational requirements suitable for scale production
Solution Approach 2:
The patent changes the physical state parameter from liquid to vapor phase, which fundamentally simplifies the process compared to surfactant-assisted liquid-phase polymerization. This parameter change eliminates the need for strict operational controls and surfactant additives, making the process suitable for industrial scale production while maintaining high separation accuracy
4Ease of manufacture
If classical interfacial polymerization is used, then the process is simple, but a large amount of oily and aqueous waste liquids are produced with low monomer utilization rate
Solution Approach 1:
The patent utilizes phase transition of water from liquid to vapor to drive the interfacial polymerization process. The water vapor condenses and facilitates controlled reaction at the interface, enabling complete monomer utilization without producing waste liquids. This phase transition approach maintains process simplicity while eliminating waste and improving monomer utilization rate to nearly 100%
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 method significantly enhances the selective separation performance of the polyamide composite membrane, achieving high selectivity for monovalent/multivalent ions and organic substances of similar sizes, while also improving the membrane's anti-fouling performance and reducing solvent usage.
Implementation Method 1
a polyamide composite membrane prepared by vapor-assisted electrostatic spray
Implementation Method 2
adjusting a relative humidity of a surrounding environment of an electrostatic spray equipment to 80% to 90%
Implementation Method 3
vapor-assisted electrostatic spray interfacial polymerization method
Implementation Method 4
placing the composite polymer membrane in an environment of 50 to 80° C. for heat treatment of 5 to 20 minutes
Data Source
AI summary
A method of preparing a polyamide composite membrane using a vapor-assisted electrostatic spray is provided which relates to the field of preparation of polyamide composite membranes and comprises: step S1, adjusting a relative humidity of a surrounding environment of an electrostatic spray equipment to 80% to 90%; step S2, taking an amine monomer solution and an acyl chloride monomer solution as raw materials and placing the two raw materials in a spray system of the electrostatic spray equipment; step S3, wrapping a polymer ultrafiltration membrane on a receiving roller of the electrostatic spray equipment and setting electrostatic spray process parameters for electrostatic spraying; step S4, taking down an electrostatically-sprayed composite polymer membrane and placing the composite polymer membrane in an environment of 50 to 80° C. for heat treatment of 5 to 20 minutes, to prepare a finished polyamide composite membrane.