Multi-Stage Osmotic Separation for Multivalent Ion Enrichment
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Solution Overview
Problem
Current methods for producing multivalent-ion-rich streams are inefficient in separating multivalent ions from monovalent ions, often requiring high-pressure membranes that are costly and difficult to manufacture, and do not effectively utilize multi-stage osmotic separation to enhance separation processes.
Innovation Solution
The method involves a multi-stage osmotic separation process using ion-selective membrane separators and osmotic membrane separators, where an aqueous feed stream containing both monovalent and multivalent ions is processed to produce a multivalent-ion-rich stream and a monovalent-ion-rich stream through multiple osmotic separation steps, with hydraulic pressures applied to facilitate water transport across membranes, reducing the need for high-pressure membranes and enhancing separation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-pressure membranes are used to separate multivalent ions from monovalent ions, then separation efficiency is improved, but equipment cost and manufacturing difficulty increase
Solution Approach 1:
The separation process is divided into multiple stages with different functions: a first stage uses an ion-selective membrane to separate monovalent ions from multivalent ions, and a second stage uses an osmotic membrane to remove water from the monovalent ion stream. This segmentation allows each membrane to be optimized for its specific function rather than requiring a single high-pressure membrane to perform both separations, reducing equipment cost and manufacturing complexity.
Solution Approach 2:
The invention changes the operating parameters from high-pressure single-stage separation to low-pressure multi-stage separation. By using osmotic pressure gradients instead of high hydraulic pressure and operating at lower pressures across multiple stages, the system achieves comparable or superior separation efficiency while using less expensive, easier-to-manufacture membrane components.
2Manufacturing precision
If multi-stage osmotic separation is implemented, then separation efficiency and ion purity are improved, but process complexity increases
Solution Approach 1:
The process is segmented into distinct functional stages: (1) ion-selective membrane separation to divide monovalent and multivalent ions, and (2) osmotic membrane dehydration of the monovalent ion stream. Each stage produces a specific intermediate stream that feeds into the next stage, creating a modular process that improves ion purity while keeping complexity manageable through clear functional separation.
Solution Approach 2:
The invention introduces intermediate streams that facilitate the multi-stage process. The first permeate stream (monovalent ions) and first retentate stream (multivalent ions) serve as intermediaries between the ion-selective membrane stage and the osmotic membrane stage. These intermediaries allow the system to achieve high ion purity by enabling selective water removal from the monovalent ion stream without requiring direct contact between all process components.
3Productivity
If high transmembrane osmotic pressure gradients are used, then water transport rate is improved, but energy requirements increase
Solution Approach 1:
The osmotic separation process uses periodic or staged draw solution replacement to maintain effective osmotic pressure gradients. By cycling through multiple draw solutions with progressively lower osmotic pressures across two osmotic membrane stages, the system sustains adequate water transport rates without requiring excessively high pressure gradients, thereby reducing energy consumption compared to single-stage high-pressure systems.
Solution Approach 2:
Draw solutions act as intermediaries that mediate water transport across the osmotic membranes. The first draw solution removes water from the first permeate stream, and the second draw solution removes water from the second permeate stream. This intermediary mechanism allows water transport to occur through osmotic pressure gradients rather than direct high hydraulic pressure, reducing energy requirements while maintaining productive water flux.
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 approach effectively separates multivalent ions from monovalent ions, achieving high purity and concentration of multivalent ions in the product stream while reducing energy requirements and equipment costs by using lower transmembrane osmotic pressure gradients and multiple osmotic membrane steps.
Implementation Method 1
transporting an aqueous feed stream containing solubilized multivalent ions and solubilized monovalent ions into an ion-selective membrane separator comprising an ion-selective membrane to produce a first permeate stream containing at least about 75% of the solubilized monovalent ions from the aqueous feed stream and a first retentate stream containing at least about 75% of the solubilized multivalent ions from the aqueous feed stream
Implementation Method 2
applying a hydraulic pressure to the first side of the first osmotic membrane such that water is transported from the first permeate stream through the first osmotic membrane to the first draw inlet stream to produce a first draw product stream having a lower osmotic pressure than the first draw inlet stream
Data Source
AI summary
Disclosed herein are systems and methods in which ion-selective separation and multi-stage osmotic separation is used to produce multivalent-ion-rich process streams. According to certain embodiments, multiple separations may be used to process an aqueous feed stream containing solubilized monovalent ions and solubilized multivalent ions to produce a stream enriched in the multivalent ions. The separations may be arranged, according to certain embodiments, to enhance the overall separation process such that the product stream contains—relative to the initial aqueous feed stream—a high amount of multivalent ions, a high amount of water from the aqueous feed stream, and/or a high ratio of multivalent ions to monovalent ions.