Reverse Osmosis Membrane Gelatin Support Removal
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Solution Overview
Problem
Current polyamide reverse osmosis composite membranes have high manufacturing costs and energy consumption due to the use of expensive materials like non-woven fabrics and polysulfone microporous supports, which also hinder the development of reverse osmosis membrane technology.
Innovation Solution
A preparation method involving coating a gelatin solution on a non-woven fabric layer, followed by interfacial polymerization with a salt solution and subsequent removal of the gelatin gel layer, and then conducting gas-liquid interfacial polymerization using trimesoyl chloride gas, eliminating the need for a polysulfone microporous support and enhancing the polyamide layer's cross-linking and adhesion to the non-woven fabric.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional polysulfone microporous support and non-woven fabric layer are used, then membrane structural stability is improved, but manufacturing cost increases
Solution Approach 1:
The patent removes the polysulfone microporous support layer from the traditional three-layer structure, retaining only the non-woven fabric layer as the base. This extraction of the expensive polysulfone component directly reduces manufacturing cost while the gelatin gel layer is introduced as a temporary substitute during the preparation process.
Solution Approach 2:
The gelatin gel layer serves as a temporary, disposable support structure during the interfacial polymerization process. It provides the necessary structural stability during manufacturing but is subsequently removed, replacing the expensive polysulfone support with a low-cost, biodegradable alternative that fulfills its function only temporarily.
2Strength
If non-woven fabric layer with irregular surface and higher porosity is used, then mechanical strength is improved, but polyamide functional layer formation quality deteriorates
Solution Approach 1:
The gelatin gel layer acts as an intermediary between the non-woven fabric layer and the polyamide functional layer. It provides a smooth, uniform surface that facilitates high-quality polyamide layer formation through interfacial polymerization, while the non-woven fabric layer underneath continues to provide the mechanical strength.
Solution Approach 2:
The membrane structure is segmented into distinct functional layers: the non-woven fabric layer provides mechanical strength, the gelatin gel layer provides a smooth surface for polymerization, and the polyamide functional layer provides separation performance. This segmentation allows each layer to optimize its specific function without compromising the others.
3Ease of manufacture
If gelatin gel layer is used as temporary support, then manufacturing cost is reduced, but additional processing steps are required
Solution Approach 1:
The gelatin gel layer utilizes phase transition properties, forming a gel structure during coating that provides temporary support, then undergoing dissolution/removal in the subsequent washing step. This phase transition approach allows the gelatin to fulfill its structural role during manufacturing and then be easily eliminated, adding minimal complexity to the overall process.
4Stability of the object's composition
If gas-liquid interfacial polymerization by CVD is conducted, then polyamide layer cross-linking is improved, but energy consumption increases
Solution Approach 1:
The patent replaces traditional liquid-phase interfacial polymerization with gas-liquid interfacial polymerization using chemical vapor deposition (CVD). The TMC monomer is delivered in gas phase, which enhances diffusion and reaction efficiency, improving polyamide layer cross-linking and quality while potentially reducing the energy input required compared to heating large volumes of liquid phases.
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
This method reduces the cost of membrane production, improves water flux, and increases the desalination rate by creating a more robust and cross-linked polyamide layer with enhanced nanopore structures, achieving a water flux of 84.5-85.1 LMH and a desalination rate of 99.56-99.59% under specific conditions.
Implementation Method 1
coating a gelatin solution on a non-woven fabric layer and cooling to form a gelatin gel layer
Implementation Method 2
transferring into an oil phase solution, and conducting interfacial polymerization to obtain a non-woven fabric/gel/polyamide composite membrane
Implementation Method 3
placing the non-woven fabric/gel/polyamide composite membrane in water, and heating to remove the gelatin gel layer
Implementation Method 4
introducing a trimesoyl chloride (TMC) gas from a side where the non-woven fabric layer is away from a polyamide layer, conducting gas-liquid interfacial polymerization by chemical vapor deposition (CVD)
Implementation Method 5
reverse osmosis has demonstrated its excellent performances in the fields of seawater desalination, pure water preparation, and reclaimed water reuse
Data Source
AI summary
The present disclosure provides a preparation method of a reverse osmosis composite membrane, including the following steps: coating a gelatin solution on a non-woven fabric layer and cooling to form a gelatin gel layer; coating a salt solution on a surface of the gelatin gel layer to obtain a gel/non-woven fabric composite membrane; placing the gel/non-woven fabric composite membrane in an aqueous phase solution, transferring into an oil phase solution, and conducting interfacial polymerization to obtain a non-woven fabric/gel/polyamide composite membrane; placing the non-woven fabric/gel/polyamide composite membrane in water, and heating to remove the gelatin gel layer to obtain a non-woven fabric/polyamide composite membrane; and introducing a trimesoyl chloride (TMC) gas from a side where the non-woven fabric layer is away from a polyamide layer in the non-woven fabric/polyamide composite membrane, conducting gas-liquid interfacial polymerization by chemical vapor deposition (CVD), and drying to obtain the reverse osmosis composite membrane. In the present disclosure, a reverse osmosis composite membrane prepared by the preparation method of a reverse osmosis composite membrane has a low cost, a desirable desalination rate, and a high flux.