Polysulfone-Acrylonitrile Blend Hollow Fiber Membrane
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Solution Overview
Problem
Existing hollow fiber ultrafiltration membranes, particularly those made from polysulfone and polyacrylonitrile, face issues with hydrophobicity leading to low flux and fouling, brittleness, and difficulties in handling and storage, while also lacking in antifouling properties and separation efficiency.
Innovation Solution
A blend membrane composed of polysulfone and poly(acrylonitrile-co-methacrylic acid) or polysulfone with a cation exchange resin (sulfonated polystyrene-divinyl benzene copolymer) is developed, enhancing flux, fouling resistance, and separation efficiency, with a bilayer sponge structure for improved mechanical strength and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polysulfone hollow fiber membranes are used, then mechanical strength is improved, but hydrophobicity increases leading to low flux and fouling
Solution Approach 1:
The patent uses a composite membrane structure combining polysulfone (PSF) as the base polymer with poly(acrylonitrile-co-methacrylic acid) (PANMA) as a hydrophilic copolymer additive (0.2-0.8% w/w). This composite approach maintains the mechanical strength of PSF while the PANMA component introduces hydrophilic groups that increase water flux and reduce fouling, achieving both strength and productivity requirements
Solution Approach 2:
The patent modifies the chemical composition parameters of the membrane by incorporating specific amounts of hydrophilic copolymer (0.2-0.8% w/w PANMA) and controlling the spinning dope composition (19-20% PSF, 2-5% PVP, 0.2-0.8% copolymer). These parameter changes transform the membrane from hydrophobic to hydrophilic, increasing flux from typical polysulfone levels to 70-250 liters/m2.h while maintaining mechanical integrity
2Productivity
If polyacrylonitrile hollow fiber membranes are used, then hydrophilicity and flux are improved, but brittleness increases leading to handling difficulties
Solution Approach 1:
The patent creates a composite system where PANMA (hydrophilic copolymer) is blended with PSF (mechanically strong polymer) in controlled ratios. The PSF matrix provides flexibility and mechanical strength to counteract the brittleness of pure PAN-based membranes, while PANMA contributes hydrophilicity and high flux, achieving both productivity and strength requirements simultaneously
Solution Approach 2:
The patent applies local quality by concentrating the hydrophilic PANMA component (0.2-0.8% w/w) in specific regions of the membrane structure formed during phase inversion, while the bulk PSF matrix (19-20% w/w) provides mechanical strength. This localized distribution allows the membrane to exhibit both high flux (from hydrophilic regions) and flexibility (from the PSF matrix)
3Productivity
If conventional ultrafiltration membranes are used, then water purification is achieved, but separation efficiency against pathogens and turbidity is insufficient
Solution Approach 1:
The patent optimizes multiple parameters including copolymer concentration (0.2-0.8% w/w), spinning dope composition (19-20% PSF, 2-5% PVP), and extrusion conditions to achieve precise pore structure control. This results in membranes with outer surface pore size 0.01-5 microns and inner surface pore size 10-220 microns, providing both high water permeability (70-250 liters/m2.h) and enhanced separation efficiency for pathogens and turbidity
Solution Approach 2:
The patent utilizes a controlled porous structure with dual-layer pore sizing: outer surface pores (0.01-5 microns) for pathogen rejection and inner surface pores (10-220 microns) for high flux. The porous architecture, combined with hydrophilic PANMA modification, achieves both high water permeability and superior separation efficiency for turbidity and microbial contamination
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 blended membrane achieves high flux rates, efficient rejection of pathogens and turbidity, and increased durability, making it suitable for point-of-use water filtration systems that produce biologically pure water without requiring electricity.
Implementation Method 1
The hollow fiber has sponge structure having 10-220 micron pore size in the inner surface and 0.01-5 microns pore size on the outer surface
Implementation Method 2
separation efficiency in removal of suspended solids, turbidity, bacteria and other pathogens from water
Implementation Method 3
blend of polysulfone (PSF) and copolymer wherein copolymer is selected from poly(acrylonitrile-co-methacrylic acid) or sulfonated polystyrene-divinyl benzene copolymer as cation exchange resin
Implementation Method 4
enhancing flux, fouling resistance, and separation efficiency
Data Source
AI summary
The present invention relates to the production of high flux hollow fiber ultrafiltration membrane prepared from poly(acrylonitrile-co-methacrylic acid), (polysulfone and poly(acrylonitrile-co-methacrylic acid)) and (polysulfone and ion exchange resin (sulfonated polystyrene-divinyl benzene copolymer)) blend and the point-of-use filtration unit there from for water purification and disinfection. The produced membrane has an active layer with pore size which effectively rejects pathogens and other bacteria from contaminated water while allowing the passage of water to produce biologically pure water for drinking. Therefore, the present invention relates to development of hollow fiber ultrafiltration membrane that delivers biologically pure water at a desirable rate, that is at a rate 25-200 liters/m2.h. The membrane performance in terms of flux and rejection efficiency is dependent on polymer material type and surface properties. The hollow fiber membrane with interpenetrated structure prepared from a blend of polysulfone and a copolymer of acrylonitrile and methacrylic acid is advantageous over the membranes made either from polysulfone or the copolymer alone in terms of durability, strength, elasticity, smoothness, flux, separation efficiency, fouling resistance properties. The surface modified blend membranes with acid groups which have smaller pore size and surface charge exhibit further improvement in the separation efficiency. Using the hollow fiber membranes a point-of-use water filtration unit which is simple, compact, inexpensive device that does not require electricity has been developed to produce 150-300 ml/min product water when attached to a tab from overhead tank of about 3 meter height.