Switchable Salt-Additive Draw Solution for Distillation-Free Desalination
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Solution Overview
Problem
Conventional solvents have fixed physical properties, leading to inefficiencies and high costs in chemical production processes due to the need for solvent removal and replacement between reaction and separation steps, and the separation of water from materials is particularly expensive and environmentally harmful.
Innovation Solution
Aqueous solvent compositions with switchable ionic strength, utilizing additives that can reversibly change their ionic strength in response to a trigger, such as carbon dioxide, allowing for non-distillative separation and concentration of solutes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional solvents are used with fixed physical properties, then the solvent can be optimized for one step (reaction or separation), but the solvent must be removed and replaced for the next step, greatly adding to economic cost and environmental impact
Solution Approach 1:
The patent applies the dynamics principle by using solvents whose physical properties can be dynamically changed through temperature, pressure, or compositional adjustments. The solvent system transitions between different states (e.g., supercritical, subcritical, liquid) to optimize performance for different process steps without requiring complete removal and replacement.
Solution Approach 2:
The patent implements parameter changes by modifying temperature, pressure, and composition parameters to transform the solvent's physical properties. For example, adjusting CO2 concentration or temperature allows the solvent to switch between high and low ionic strength states, enabling it to serve multiple functions throughout the process.
2Manufacturing precision
If distillation is used to separate water from products, then separation can be achieved, but significant energy input is required due to high heat capacity and heat of vaporization of water
Solution Approach 1:
The patent utilizes phase transitions, particularly the supercritical to subcritical transition of CO2, to achieve separation without traditional distillation. When CO2 is depressurized from supercritical to subcritical state, it selectively extracts water from the product, achieving separation through phase change rather than vaporization of water.
Solution Approach 2:
The patent replaces the thermal-mechanical distillation system with a pressure-controlled phase transition system. Instead of heating water to vaporize it for separation, the system uses pressure-adjusted CO2 phase transitions to selectively remove water, dramatically reducing energy consumption.
3Manufacturing precision
If salting out is used to separate water from hydrophobic materials, then separation can be achieved without distillation, but large amounts of salts must be used and the expense of removing salt from water afterwards is high
Solution Approach 1:
The patent changes the separation mechanism from chemical (salt addition) to physical (phase transition). By adjusting pressure and temperature parameters, CO2 undergoes phase transition to selectively extract water, eliminating the need for salt addition and subsequent salt removal operations.
Solution Approach 2:
The patent enables easy recovery and reuse of CO2 after the separation process. The CO2 that extracts water is simply depressurized and condensed back to liquid or gas form, ready for reuse, whereas salt would require energy-intensive evaporation or other removal processes.
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
Enables efficient and cost-effective solvent property adjustments without distillation, reducing energy consumption and environmental impact, and facilitating solvent reuse in chemical processes.
Implementation Method 1
the additive reversibly switches between an ionized form and a non-ionized form in response to a trigger
Implementation Method 2
the additive is a compound which can be converted, in the presence of water, from a non-ionized form to an ionized form by the action of carbonic acid
Data Source
Figure 1
Figure 2
Figure 3A~4C
AI summary
A method and system for reversibly converting water between an initial ionic strength and an increased ionic strength, using a switchable additive, is described. The disclosed method and system can be used, for example, in distillation-free removal of water from solvents, solutes, or solutions. Following extraction of a solute from a medium by dissolving it in water, the solute can then be isolated from the aqueous solution or "salted-out" by converting the water to a solution having an increased ionic strength. The solute then separates from the increased ionic strength solution as a separate phase. Once the solute is, for example, decanted off, the increased ionic strength aqueous solution can be converted back to water having its original ionic strength and reused. Switching from lower to higher ionic strength is readily achieved using low energy methods such as bubbling with CO2, CS2 or COS. Switching from higher to lower ionic strength is readily achieved using low energy methods such as bubbling with air, heating, agitating, introducing a vacuum or partial vacuum, or any combination or thereof.