Polyamide Membrane for Water Treatment with Covalent Biguanidine
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Solution Overview
Problem
Existing water treatment membranes face challenges in achieving improved filtration performance, particularly in terms of salt rejection and flux characteristics, which are essential for efficient water treatment processes.
Innovation Solution
A water treatment membrane with a polyamide active layer that incorporates biguanidine compounds covalently bonded within the layer, utilizing specific chemical structures represented by Chemical Formulae 1 and 2, enhancing salt rejection and flux characteristics through increased free volume and stable integration of the biguanidine compound.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional polyamide-based composite membranes are used for water treatment, then the membrane provides basic filtration function, but the salt rejection and flux characteristics are insufficient to meet tightened environmental regulations
Solution Approach 1:
The patent introduces biguanidine compounds with specific chemical structures (Chemical Formulae 1 and 2) containing divalent aliphatic/alicyclic/aromatic groups and specific nitrogen-containing moieties (Formulae 5-7) to modify the polyamide active layer. This chemical parameter change creates covalent bonds that enhance salt rejection while maintaining flux characteristics, resolving the contradiction between reliability and productivity.
Solution Approach 2:
The patent creates a composite polyamide active layer by combining traditional polyamide with biguanidine compounds through covalent bonding. This composite structure integrates the filtration capabilities of polyamide with the salt rejection enhancement of biguanidine, achieving both high salt rejection and acceptable flux simultaneously.
2Reliability
If biguanidine compounds are added to enhance salt rejection, then the membrane structure becomes more complex, but the manufacturing process and structural integration remain challenging
Solution Approach 1:
The biguanidine compounds are pre-synthesized with specific chemical structures (Formulae 1 and 2) containing predetermined functional groups that enable covalent bonding with polyamide. This preliminary preparation of the chemical structure ensures that the compounds can be effectively integrated into the membrane during the interfacial polymerization process, reducing manufacturing complexity.
Solution Approach 2:
The biguanidine compounds act as intermediary molecules that bridge the polyamide matrix and the salt rejection function. Their specific chemical structure serves as a mediator that facilitates covalent bonding while maintaining the membrane's overall structure, thus enhancing salt rejection without excessive structural complexity.
3Reliability
If the polyamide active layer is formed by interfacial polymerization with biguanidine compounds, then salt rejection is improved, but the manufacturing process requires precise control of multiple parameters
Solution Approach 1:
The patent specifies precise chemical parameters for the biguanidine compounds (Chemical Formulae 1 and 2 with specific groups U1, A1-A5, V1-V3) and their incorporation into the aqueous or organic solution phase during interfacial polymerization. These parameter specifications enable consistent salt rejection enhancement while providing clear manufacturing guidance to control the polymerization process.
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 membrane exhibits enhanced salt rejection and flux characteristics, maintaining high performance even after exposure to acids or bases, with salt rejection rates of 97% or more and flux rates of 8.50 l/m²/h (5 gfd) or more, surpassing traditional methods.
Implementation Method 1
a biguanidine compound is present as a covalent bond in the polyamide active layer
Implementation Method 2
performing an interfacial polymerization to form a polyamide active layer
Implementation Method 3
a semi-permeable membrane which permeates water, but shows impermeability to salts
Implementation Method 4
a porous support
Implementation Method 5
enhancing salt rejection and flux characteristics through increased free volume
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The present specification relates to a water treatment membrane including: a porous support; and a polyamide active layer provided on the porous support, in which the polyamide active layer includes one or more selected from among a unit represented by Chemical Formula 1, a unit represented by Chemical Formula 2, a unit represented by Chemical Formula 3, and a unit represented by Chemical Formula 4, and a manufacturing method thereof.