Alicyclic Polyamide Nanofiltration Membrane Uniformity
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Solution Overview
Problem
Existing nanofiltration membranes face issues with inconsistent membrane structure and morphology, low flux, poor selectivity, and poor anti-fouling properties due to uncontrollable interfacial polymerization processes, leading to inadequate separation performance for monovalent and divalent salts.
Innovation Solution
Alicyclic polyamide nanofiltration membranes are prepared using a spin-coating method with alternating layers of alicyclic acid chloride and amine solutions, allowing for controlled distribution and reaction of monomers to achieve uniform thickness, low roughness, and high selectivity, enhancing both monovalent and divalent salt rejection rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional interfacial polymerization is used to prepare nanofiltration membranes, then membrane formation is achieved, but the membrane structure and morphology are inconsistent and roughness is high
Solution Approach 1:
The patent applies preliminary action by pre-coating the porous support with a uniform layer of aqueous amine solution before introducing the organic acid chloride solution. This preliminary coating ensures that the polymerization reaction occurs on a predetermined, uniform surface rather than allowing uncontrolled interfacial polymerization, thereby achieving consistent membrane structure and low roughness while maintaining ease of manufacture
Solution Approach 2:
The patent uses the porous support membrane as an intermediary substrate that provides a controlled surface for monomer coating and reaction. The support membrane acts as a mediator between the aqueous and organic phases, enabling uniform distribution of the aqueous amine solution before the organic acid chloride is introduced, thus achieving consistent active layer formation without requiring complex process control
2Productivity
If traditional nanofiltration membranes are used, then salt separation is achieved, but water flux is low
Solution Approach 1:
The patent applies parameter changes by systematically optimizing the concentration ratios of aqueous to organic monomers (specifically using a 2:1 to 4:1 ratio of amine to acid chloride), coating speeds, and reaction temperatures. These parameter optimizations enable the formation of a thinner, more uniform active layer with controlled pore structure, achieving high water flux while maintaining excellent salt rejection selectivity through precise control of membrane morphology
3Manufacturing precision
If conventional coating methods are used, then membrane coverage is achieved, but thickness uniformity is poor and roughness is high
Solution Approach 1:
The patent replaces complex mechanical coating control systems with a simplified method of controlling coating speed and monomer concentration ratios. By using a controlled coating process where the aqueous amine solution is applied at a specific speed followed by the organic acid chloride solution, the method achieves uniform thickness and low roughness without requiring complex mechanical control systems, thus reducing device complexity while improving manufacturing precision
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 resulting membranes exhibit high flux and selective permeability, with rejection rates exceeding 99% for certain salts and improved flux compared to traditional methods, demonstrating enhanced performance in water softening and salt separation applications.
Implementation Method 1
Alternately and uniformly coating at least an alicyclic acid chloride solution and at least an alicyclic amine solution on a porous support membrane using a spin coating method or a soaking method for interfacial polymerization
Implementation Method 2
nanofiltration membrane could remove most of Ca, Mg and other divalent ions, and simultaneously permeate monovalent ion such as sodium potassium chloride
Implementation Method 3
nanofiltration membrane could substantially retain sodium sulfate and allow sodium chloride to permeate
Implementation Method 4
Alternately and uniformly coating at least an alicyclic acid chloride solution and at least an alicyclic amine solution on a porous support membrane using a spin coating method
Data Source
AI summary
The present invention discloses a highly selective alicyclic polyamide nanofiltration membrane and a making method thereof. The method comprises the following steps: alternately and uniformly coating at least an alicyclic acid chloride solution and at least an alicyclic amine solution on a porous support membrane, using a spin coating method or a soaking method, to form at least one layer of the alicyclic polyamide nanofiltration membrane. Preferred embodiments exhibit improved ion selectivity, e.g. increased water flux, enhanced divalent/monovalent rejection selectivity, reduced fouling and improved divalent rejection rate (Ca2+, Mg2+) compared to the traditional aromatic-alicyclic mixed-structure polyamide nanofiltration membrane and/or the whole aromatic polyamide nanofiltration membrane. Therefore, the alicyclic polyamide nanofiltration membranes made in the present invention has great application prospect in the fields of zero-liquid discharge of industrial wastewater, water softening, and produce water treatment, etc.