Directional Solvent Extraction for Low-Energy Water Desalination
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Solution Overview
Problem
Current water desalination methods are energy-intensive and inefficient, particularly for producing fresh water from seawater, and existing electrochemical methods are less efficient and costly, posing significant challenges in addressing global water shortages and environmental sustainability.
Innovation Solution
The use of directional solvents like edible oils and fatty acids, which selectively dissolve water while leaving salts behind, allowing for temperature-controlled desalination processes that separate water from saline solutions using low-quality heat sources, reducing energy consumption and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If reverse osmosis is used for desalination, then fresh water can be produced from seawater, but high energy consumption is required due to large pressures needed to drive water through membranes
Solution Approach 1:
The patent changes the fundamental parameter of the desalination process from pressure-driven (reverse osmosis) to temperature-driven (directional solvent extraction). By using temperature to control the solubility and phase behavior of the solvent system, the process achieves water separation without requiring high pressures, thereby reducing energy consumption while maintaining fresh water production capability
Solution Approach 2:
The patent introduces a directional solvent as an intermediary substance that selectively extracts water from saline solution. This solvent acts as a mediator between the saline feed and the fresh water product, enabling separation through selective dissolution and phase separation rather than direct pressure-driven membrane filtration, thus reducing the energy barrier
2Quantity of substance
If multi-stage flash distillation is used for desalination, then fresh water can be produced from seawater, but the process becomes capital intensive and energy demanding
Solution Approach 1:
The patent extracts the water separation function from complex multi-stage thermal processes and implements it through a single-stage directional solvent extraction process. The solvent selectively extracts water from the saline solution in one step, eliminating the need for multiple flash chambers, heat exchangers, and complex temperature staging required in MSF distillation, thereby reducing device complexity while maintaining production efficiency
Solution Approach 2:
The patent changes the operating parameters from high-temperature multi-stage thermal processing to moderate-temperature single-stage solvent extraction. By using temperature to control solvent solubility and phase separation rather than relying on multiple flash evaporation stages, the process achieves water production with simpler equipment and lower capital requirements
3Quantity of substance
If electrochemical methods are used for desalination, then salt can be removed to achieve potable water, but the process becomes more efficient only for brackish water and remains costly
Solution Approach 1:
The patent replaces electrochemical membranes and electrical fields with a chemical intermediary (directional solvent) that selectively interacts with water molecules. This solvent mediates the separation process through selective dissolution and phase separation, eliminating the need for expensive electrochemical equipment, electricity consumption, and complex control systems, thereby reducing process cost while achieving effective salt removal for both seawater and brackish water
4Quantity of substance
If conventional desalination methods are used, then fresh water can be produced, but transport of water is expensive and energy-intensive due to its heavy weight
Solution Approach 1:
The patent uses a directional solvent as an intermediary carrier that dissolves water in an organic phase. This allows water to be transported in a less dense, energy-efficient form. The solvent-water mixture can be transported more easily than pure water, and upon reaching the destination, the water is recovered through phase separation, reducing the energy required for water transport while ensuring fresh water supply
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 achieves high-purity water production with significant energy and economic savings, offering a more efficient and environmentally friendly solution for water desalination, suitable for industrial and agricultural use, and meeting drinking water standards.
Implementation Method 1
Certain solvents, such as edible oils (e.g., soybean oil) and some fatty acids, possess an unusual characteristic of being able to directionally dissolve water while not dissolving other water-soluble salts, such as sodium chloride
Implementation Method 2
The saline solution and solvent are heated before or after contact to enhance the directional dissolution of water into the solvent and to thereby produce distinct phases
Implementation Method 3
After extraction, the first phase is cooled to precipitate the water from the solvent; and the precipitated water is then removed from the solvent
Data Source
AI summary
Substantially pure water is produced via desalination using a directional solvent that directionally dissolves water but does not dissolve salt. The directional solvent is heated to dissolve water from the salt solution into the directional solvent. The remaining highly concentrated salt water is removed, and the solution of directional solvent and water is cooled to precipitate substantially pure water out of the solution.