Mono-hydrolyzed TMC Polyamide RO Membranes
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Solution Overview
Problem
Reverse osmosis membranes, particularly TFC membranes, face challenges in maintaining high flux while resisting fouling and maintaining rejection characteristics during the purification of brackish or seawater, with existing methods showing limited success in improving flux without compromising rejection and being prone to fouling.
Innovation Solution
An interfacial polymerization process involving a polyamine monomer and trimesoyl chloride with a molecular additive, mono-hydrolyzed trimesoyl chloride, is used on a porous support membrane, incorporating nanoparticles that release metal ions to enhance flux and resistance to fouling, and improve membrane processing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If materials are added to TFC membranes to increase flux, then flux is improved, but rejection characteristics are reduced
Solution Approach 1:
The patent changes the chemical parameters of the membrane by incorporating mono-hydrolyzed TMC, which has different hydrolysis and polymerization characteristics than conventional TMC. This parameter change allows the membrane to achieve enhanced flux while preserving rejection characteristics, as the modified chemical structure creates optimal pore size and hydrophilicity without compromising selectivity.
Solution Approach 2:
The patent creates a composite membrane structure by combining polyamide polymer matrix with mono-hydrolyzed TMC molecules that have specific hydrolysis products. This composite approach integrates materials with complementary properties - the polyamide provides structural integrity and base selectivity, while the mono-hydrolyzed TMC adds hydrophilicity and controlled porosity, achieving both high flux and high rejection.
2Reliability
If TFC membranes are used for purification, then rejection characteristics are maintained, but fouling occurs resulting in reduced flux
Solution Approach 1:
The patent converts the typically harmful hydrophobicity of polyamide membranes into a benefit by controlled hydrolysis of TMC to form mono-hydrolyzed products. These products introduce hydrophilic carboxylic acid groups that repel organic foulants while maintaining the membrane's rejection capability. The hydrolysis process transforms the membrane surface from fouling-prone to fouling-resistant, converting a disadvantage into an advantage.
Solution Approach 2:
The patent modifies the surface chemistry parameters of the TFC membrane through controlled hydrolysis of TMC, changing the surface energy and wettability characteristics. This parameter change reduces adhesion of foulants to the membrane surface, preventing flux decline over time while preserving the dense polyamide structure necessary for high rejection of salts and contaminants.
3Ease of manufacture
If conventional TMC is used in interfacial polymerization, then membrane formation is achieved, but flux and fouling resistance are limited
Solution Approach 1:
The patent applies preliminary action by pre-hydrolyzing TMC to form mono-hydrolyzed TMC before the interfacial polymerization step. This pre-treatment modifies the reactivity and hydrolysis behavior of TMC during membrane formation, creating a polyamide layer with enhanced hydrophilicity and porosity. The preliminary hydrolysis action ensures that the resulting membrane has superior flux characteristics and fouling resistance while maintaining ease of manufacture through standard interfacial polymerization procedures.
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 process results in highly permeable RO membranes with improved flux and fouling resistance, maintaining high rejection characteristics and reducing flux decline over time, effectively addressing the limitations of existing TFC membranes in brackish and seawater purification.
Implementation Method 1
molecular additive compound is mono-hydrolyzed trimesoyl chloride
Implementation Method 2
incorporating nanoparticles that release metal ions to enhance flux and resistance to fouling
Implementation Method 3
interfacial polymerization process involving a polyamine monomer and trimesoyl chloride
Implementation Method 4
Reverse osmosis membranes, made by interfacial polymerization... are used where flux and substantial rejection characteristics are required, for example in the purification of water
Implementation Method 5
highly permeable RO membranes with improved flux
Data Source
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AI summary
Reverse osmosis membranes made by interfacial polymerization of a monomer in a nonpolar (e.g. organic) phase together with a monomer in a polar (e.g. aqueous) phase on a porous support membrane. Interfacial polymerization process is disclosed for preparing a highly permeable RO membrane, comprising: contacting on a porous support membrane, a) a first solution containing 1,3-diaminobenzene, and b) a second solution containing trimesoyl chloride, wherein at least one of solutions a) and b) contains nanoparticles when said solutions are first contacted, and recovering a highly permeable RO membrane.