Hydrogel Composite Draw Material for Forward Osmosis
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Solution Overview
Problem
Current draw agents for forward osmosis desalination face challenges in achieving high osmotic pressure, easy regeneration, and non-toxicity, with hydrogel powders exhibiting low flux due to water transport barriers between particles.
Innovation Solution
A hydrogel composite material comprising a porous elastic polymeric foam interpenetrated with a polymer hydrogel, which enhances water flux by providing a synergistic support structure and capillary forces for improved water transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hydrogel powder is used as draw agent, then osmotic pressure is achieved, but water flux is low due to transport barriers between particles
Solution Approach 1:
The patent combines hydrogel particles with a porous support matrix to form a composite draw agent. This merging eliminates the inter-particle transport barriers that plague loose powder systems while maintaining the high osmotic pressure capability of hydrogels. The continuous porous matrix provides unobstructed water transport pathways throughout the draw agent bed.
Solution Approach 2:
The invention utilizes a porous support matrix with controlled pore structure to host the hydrogel particles. This porous framework provides both mechanical support and continuous water transport channels, solving the flux limitation problem of powder hydrogels while maintaining their osmotic function. The pore size and distribution are optimized to facilitate water movement.
2Productivity
If amount of draw agent is increased to enhance flux, then flux increases initially, but flux remains constant due to transport barrier
Solution Approach 1:
By integrating hydrogel particles into a continuous porous matrix, the system achieves efficient water transport throughout the entire draw agent volume. This allows the full amount of draw agent to participate in water extraction, eliminating the diminishing returns observed in powder systems where only surface particles are effective.
Solution Approach 2:
The porous matrix creates continuous water transport pathways that allow water to reach all hydrogel particles uniformly. This continuity ensures that increasing the amount of draw agent linearly increases flux, as all particles remain accessible and active throughout the process.
3Productivity
If hydrogel particle size is decreased to increase contact area, then FO flux is enhanced, but water transport between particles becomes more difficult
Solution Approach 1:
The porous support matrix provides continuous water transport channels that are independent of particle size. This allows the use of fine hydrogel particles for maximum contact area with the membrane, while the matrix pores ensure water can easily reach and pass through all particles without being hindered by inter-particle spacing.
Solution Approach 2:
The combination of fine hydrogel particles with the porous matrix structure resolves the contradiction between needing small particles for contact area and needing good water transport. The matrix acts as a highway system that delivers water to all particles regardless of their size or distribution.
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 hydrogel composite material achieves a water flux of at least 3.5 L/m²h, surpassing the flux of hydrogel powders and comparable to traditional draw agents like 1.5 M NH4HCO3, while being mechanically robust and easily recyclable.
Implementation Method 1
The porous elastic polymeric foam provides a synergistic support structure for the hydrogel whist retaining the advantageous aqueous draw and swelling properties of the hydrogel. Moreover, this composite structure provides a substantial improvement over the use of hydrogel alone... the porous elastic polymeric foam element including a three-dimensional continuous network of pores interpenetrated with a polymer hydrogel
Implementation Method 2
Forward osmosis (FO) is the membrane separation process in which the osmotic pressure difference serves as the driving force for water transport, with a semi-permeable membrane acting as a separation medium. Due to the naturally driven osmotic flow, water permeates through the membrane from the feed solution to the draw agent side.
Data Source
AI summary
A hydrogel composite draw material for forward osmosis comprising: a porous elastic polymeric foam element including a three-dimensional continuous network of pores interpenetrated with a polymer hydrogel. In use, the hydrogel composite draw material draws a water flux of at least 3.5 L/m2h.