TFC RO Membranes with Beta-Diketonate Additives for Flux
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Solution Overview
Problem
Reverse osmosis membranes, particularly TFC membranes, face challenges in maintaining high flux and rejection characteristics while being prone to fouling from contaminants in brackish or seawater, with existing modifications showing limited success in enhancing flux without compromising rejection.
Innovation Solution
A process involving interfacial polymerization on a porous support membrane using a polyamine, polyfunctional acid halide, and a flux-increasing additive with a beta-diketonate formula, optionally combined with nanoparticles, to form a reverse osmosis membrane with enhanced flux and maintained salt rejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TFC membranes are used for water purification, then substantial salt rejection is achieved, but flux is reduced due to fouling from contaminants
Solution Approach 1:
The patent applies local quality by creating a thin protective layer with specific chemical composition (reactive nitrogen compounds) on the membrane surface that differs from the bulk membrane material. This surface layer provides antifouling properties while the underlying TFC structure maintains salt rejection, thus resolving the contradiction between flux and rejection.
Solution Approach 2:
The invention uses composite materials by combining the TFC membrane with a protective coating layer containing reactive nitrogen compounds. This composite structure integrates the salt rejection capability of TFC with the antifouling properties of the protective layer, simultaneously achieving both high flux and substantial rejection.
2Productivity
If materials are added to TFC membranes to increase flux, then flux enhancement is achieved, but rejection characteristics are reduced
Solution Approach 1:
The patent segments the membrane system into two functional parts: the TFC discrimination layer for salt rejection and the protective surface layer for flux enhancement. This segmentation allows each layer to optimize its specific function without compromising the other, resolving the contradiction between flux and rejection characteristics.
Solution Approach 2:
By applying the protective layer only on the surface rather than throughout the entire membrane structure, the invention maintains the rejection properties of the TFC bulk material while locally enhancing flux at the critical interface where fouling occurs.
3Reliability
If a protective layer with reactive nitrogen is applied, then chlorine damage protection is achieved, but membrane complexity increases
Solution Approach 1:
The protective layer with reactive nitrogen is applied in advance to the TFC membrane surface before the membrane encounters chlorine-containing feed streams. This preliminary action pre-establishes the chlorine resistance capability, protecting the membrane from future damage without requiring complex structural modifications.
Solution Approach 2:
The invention creates a composite membrane structure by combining TFC material with a protective coating layer, achieving chlorine damage protection through material composition rather than complex structural design, thus balancing reliability improvement with acceptable complexity.
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 a flux of at least 51.020 L·m⁻²·h⁻¹ and salt rejection of at least 99.5%, effectively purifying brackish or seawater while minimizing fouling, as demonstrated by test results under specific conditions.
Implementation Method 1
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
Implementation Method 2
reverse osmosis membranes made by interfacial polymerization... used where flux and substantial rejection characteristics are required, for example in the purification of water
Implementation Method 3
A process for preparing a reverse osmosis membrane is described that includes: (A) providing a polyamine, a polyfunctional acid halide, and a flux increasing additive having the formula Z +[0006]... Reverse osmosis membranes prepared according to this process may be capable of exhibiting a flux of at least 51.020 L·m⁻²·h⁻¹
Implementation Method 4
The polyamine, polyfunctional acid halide, and flux increasing additive may be combined with nanoparticles (e.g., zeolites or carbon nanotubes). Interfacial polymerization then yields a reverse osmosis membrane that includes (i) the porous support membrane and (ii) a discrimination layer comprising a polyamide and the nanoparticles
Data Source
Figure 1~3
AI summary
A process for preparing a reverse osmosis membrane that includes: (A) providing a polyamine, a polyfunctional acid halide, and a flux increasing additive having the formula Z+B-, where Z+ is an easily dissociable cation and B- is a beta-diketonate; (B) combining the polyamine, polyfunctional acid halide, and flux increasing additive on the surface of a porous support membrane; and (C) interfacially polymerizing the polyamine and the polyfunctional acid halide, and flux increasing additive on the surface of the porous support membrane to form a reverse osmosis membrane comprising (i) the porous support membrane and (ii) a discrimination layer comprising a polyamide. The reverse osmosis membrane is characterized by a flux that is greater than the flux of the same membrane prepared in the absence of the flux increasing additive.