Zwitterionic Polysiloxane Polyamide Membranes for Water Flow and Salt Rejection
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Solution Overview
Problem
Reverse osmosis membranes face challenges in balancing water flow and salt rejection, and are prone to contamination, with existing solutions either compromising on chlorine resistance or performance in water flow and salt rejection.
Innovation Solution
A zwitterionic polysiloxane-polyamide interpenetrating polymer network is introduced, enhancing hydrophilicity for water transfer, chlorine resistance, and anti-contamination features through electrostatic hydration and steric hindrance, integrated into the polyamide structure as an active layer in reverse osmosis membranes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional polyamide thin film composite membranes are used, then salt rejection is maintained at acceptable levels (>99%), but water flow performance is limited and membrane contamination occurs
Solution Approach 1:
The patent applies composite materials by combining polyamide with zwitterionic polysiloxane to form an interpenetrating polymer network. This composite structure integrates the salt rejection capability of polyamide with the hydrophilic and anti-contamination properties of zwitterionic polysiloxane, achieving both high water flow and maintained salt rejection performance
Solution Approach 2:
The patent changes the chemical composition parameters of the active layer by incorporating zwitterionic polysiloxane units into the polyamide network. This parameter change modifies the membrane's hydrophilicity, surface charge, and pore structure, thereby improving water flow while maintaining salt rejection through optimized molecular-level composition
2Object-affected harmful factors
If membrane surface hydrophilicity is increased to reduce contamination, then water flow increases, but chlorine resistance deteriorates due to reaction with amide nitrogens and aromatic rings
Solution Approach 1:
The patent applies local quality by introducing zwitterionic groups at specific locations within the polyamide network. These localized zwitterionic units provide hydrophilicity and anti-contamination properties without requiring modification of the entire polyamide structure, thereby preserving chlorine resistance while improving contamination resistance at critical surface regions
Solution Approach 2:
The zwitterionic polysiloxane acts as an intermediary between the polyamide matrix and the contaminating substances. It provides a protective interface that repels contaminants through electrostatic hydration and steric hindrance, preventing direct contact between harmful substances and the chlorine-sensitive polyamide groups
3Productivity
If existing methods for improving water flow are applied (different monomers, co-solvents, hydrophilic additives), then water flow increases, but salt rejection performance deteriorates or chlorine resistance is compromised
Solution Approach 1:
The patent applies preliminary action by pre-forming the zwitterionic polysiloxane-polyamide interpenetrating network during the membrane fabrication process. This preliminary structuring of the active layer ensures optimal hydrophilicity and pore configuration are established before the membrane enters service, enabling high water flow performance without subsequent performance degradation
Solution Approach 2:
The zwitterionic polysiloxane component provides multiple functions simultaneously: it enhances hydrophilicity for improved water flow, provides anti-contamination properties through electrostatic hydration, and maintains chlorine resistance by protecting the polyamide structure. This multi-functionality eliminates the need for separate modifications that would compromise overall performance
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 solution significantly increases water flow by 31% while maintaining high salt rejection and extends membrane lifetime by enhancing chlorine resistance and reducing contamination, outperforming conventional polyamide thin film composite membranes.
Implementation Method 1
enhancing hydrophilicity for water transfer, chlorine resistance, and anti-contamination features through electrostatic hydration and steric hindrance
Implementation Method 2
enhancing hydrophilicity for water transfer, chlorine resistance, and anti-contamination features through electrostatic hydration and steric hindrance
Implementation Method 3
Reverse osmosis is widely used across the world since it is the most energy-efficient desalination technology known presently
Implementation Method 4
the process of removing dissolved salt and other minerals in the sea water or salt water
Data Source
AI summary
The invention relates to polyamide polymeric films comprising zwitterionic polysiloxane. The films of the invention may be used for providing high performance in the filtration applications.