Semi-Permeable Membrane Water Flux via Phosphorous Co-Solvent
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Solution Overview
Problem
Existing semi-permeable membranes for water filtration, particularly in reverse osmosis and forward osmosis, face challenges in achieving high water flux while maintaining effective solute rejection, leading to energy inefficiencies and increased operational costs.
Innovation Solution
A process for preparing semi-permeable membranes involves using an aqueous phase with a polyfunctional amine monomer, an organic phase with a polyfunctional acyl halide monomer, a phosphorous containing compound, and a co-solvent, followed by interfacial polymerization to form a polyamide thin film composite layer, enhancing water flux and solute rejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tighter membrane with small pores is used to achieve higher solute rejection, then solute rejection is improved, but water flux is reduced
Solution Approach 1:
The patent changes the chemical parameters of the membrane by incorporating phosphorous containing compounds and co-solvents during interfacial polymerization. This modifies the polyamide active layer's properties to achieve both high solute rejection and high water flux simultaneously, resolving the contradiction between these two parameters.
Solution Approach 2:
The patent creates a composite membrane structure with multiple layers including a support membrane and an active layer formed by interfacial polymerization of diamine and acid chloride in the presence of phosphorous containing compounds and co-solvents. This composite structure enables the membrane to achieve both high solute rejection and high water flux by combining the functions of different materials and layers.
2Productivity
If conventional interfacial polymerization is used without additives, then manufacturing simplicity is maintained, but water flux is insufficient
Solution Approach 1:
The patent modifies the interfacial polymerization process by introducing phosphorous containing compounds and co-solvents as chemical additives. These parameter changes enhance water flux while maintaining a relatively simple process framework, balancing productivity improvement with acceptable process complexity.
3Productivity
If hydrophilic additives are added to the water phase to increase water flux, then water flux is improved, but solute rejection may be compromised
Solution Approach 1:
The patent uses phosphorous containing compounds as intermediary substances that mediate between the water phase and organic phase during interfacial polymerization. These intermediaries facilitate the formation of a polyamide active layer with enhanced water flux while maintaining effective solute rejection, avoiding the need to add hydrophilic additives to the water phase.
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 proposed method significantly increases water flux compared to membranes without the phosphorous compound and co-solvent, while maintaining acceptable solute rejection, thereby reducing energy consumption and operational costs in water filtration processes.
Implementation Method 1
allowing the polyfunctional amine monomer and the polyfunctional acyl halide monomer to perform an interfacial polymerization reaction to form a polyamide thin film composite layer
Implementation Method 2
The present disclosure relates to a membrane for water filtration, in particular a membrane form performing forward osmosis (FO), reverse osmosis (RO)
Implementation Method 3
In a forward osmosis plant a feed is typically de-watered to concentrate the feed stream
Data Source
AI summary
A process for preparing a semi-permeable membrane includes providing an aqueous phase comprising a polyfunctional amine monomer, covering a surface of a porous support membrane with the aqueous phase, applying an organic phase comprising a polyfunctional acyl halide monomer, a phosphorous containing compound and a co-solvent, and allowing the polyfunctional amine monomer and the polyfunctional acyl halide monomer to perform an interfacial polymerization reaction to form a polyamide thin film composite layer.The presence of the co-solvent together with the phosphorous compound in the organic phase potentiates the effect of the phosphorous compound so that the water flux is increased without substantially sacrificing the salt rejection.