Desalination Membrane With Grafted Solid Salt
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Solution Overview
Problem
Conventional desalination methods, such as reverse osmosis, require high pressure and energy-intensive heating processes to extract fresh water from seawater, and alternative methods like forward osmosis with ammonium carbonate solutions are cumbersome and inefficient.
Innovation Solution
A desalination treatment membrane is developed with a desalting membrane and a base material where solid salt is graft-polymerized, allowing for osmotic pressure-induced water permeation without the need for high pressure or heating, using a solid salt that swells with water but remains stable on the base material surface, enhancing water flow rates and reducing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If reverse osmosis method is used to desalinate seawater, then fresh water can be extracted from seawater, but high pressure (about 55 atmospheres) is required which increases energy consumption
Solution Approach 1:
The patent replaces the mechanical pressure application system of reverse osmosis with a chemical osmotic pressure system. Instead of applying 55 atmospheres of external pressure mechanically, the invention uses the natural osmotic pressure generated by the ammonium carbonate solution on the permeate side to drive water permeation, thereby eliminating the need for high-pressure pumps and reducing energy consumption.
Solution Approach 2:
The patent utilizes the phase transition of ammonium carbonate solution upon heating. The ammonium carbonate solution on the permeate side is heated to decompose it into ammonia and carbon dioxide gases, which are then removed. This phase transition allows for the regeneration of the draw solution and enables continuous operation of the forward osmosis process.
2Quantity of substance
If forward osmosis with ammonium carbonate solution is used, then heating is required to decompose the solution which increases energy consumption and process complexity
Solution Approach 1:
The patent changes the concentration parameter of the ammonium carbonate solution over time. The solution concentration increases as water permeates through the membrane, and then is regenerated by heating and gas removal. This dynamic parameter change allows the process to maintain effectiveness while simplifying the overall system design compared to continuous high-pressure systems.
3Productivity
If polymer electrolyte membrane with direct graft-polymerization is used, then transmembrane flow rate is increased, but membrane stability may be compromised
Solution Approach 1:
The patent uses a composite membrane structure combining a hydrophobic polymer base membrane with grafted polymer electrolyte chains. This composite structure maintains the mechanical stability and selectivity of the hydrophobic base while adding the hydrophilic channels and ionic groups of the grafted electrolyte to enhance water permeation and flow rate.
Solution Approach 2:
The patent applies local quality modification by grafting polymer electrolyte chains only on the surface or specific regions of the hydrophobic membrane. This localized modification enhances water permeation and flow rate in the critical transport regions while preserving the overall structural integrity and stability of the base membrane.
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 membrane achieves higher fresh water flow rates at lower pressures compared to conventional methods, reducing energy expenditure and eliminating the need for heating, while maintaining stability and preventing clogging, thus efficiently desalinating seawater.
Implementation Method 1
a base material (4) disposed on the fresh water side in close contact with the desalting membrane (2), wherein solid salt (3) is fixed to the base material (4) by graft-polymerization... the solid salt (3), which has a function of inducing an osmotic pressure necessary for permeation of water in seawater through the desalting membrane (2)
Implementation Method 2
The solid salt (3) swells with water which has permeated the desalting membrane (2)
Data Source
AI summary
According to one embodiment, a desalination treatment membrane includes a desalting membrane and a base material which is disposed in close contact with the desalting membrane, wherein a solid salt is fixed to the base material by a graft-polymerization.