Filtration media and systems for reduction of micropollutants in liquids
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Solution Overview
Problem
Conventional washing machines are ineffective in removing microfibers and microparticles from water, particularly microplastics, which contaminate water supplies during laundry cycles, due to limitations in filtration technologies.
Innovation Solution
The integration of a filtration system within the washing machine that utilizes a combination of preformed polymer mesh and porous membranes, including graphene-based membranes, to capture microfibers and microparticles, with specific pore sizes and materials such as Hydrophilic Polycarbonate, Hydrophobic Cellulose Acetate, Polytetrafluoroethylene, and Graphene Oxide-based carbon nanotubes, to enhance filtration efficiency and water flux.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional filtration technologies are used in washing machines, then the device complexity remains low, but the removal efficiency of microplastics and microparticles is insufficient
Solution Approach 1:
The filtration system is divided into multiple stages with different filter elements having progressively smaller pore sizes. The first filter element captures larger particles while subsequent elements capture smaller microplastics, allowing each component to be optimized independently for its specific size range
Solution Approach 2:
The patent employs filter elements with specifically engineered porous structures having controlled pore sizes (e.g., 10-50 μm, 1-10 μm, 0.1-1 μm). These porous materials are selected and arranged to create effective barriers against microplastics of different dimensions while maintaining water flow
2Reliability
If filter elements with smaller pore sizes are used to capture smaller microparticles, then the removal efficiency increases, but the water flux decreases
Solution Approach 1:
The filtration train is segmented into multiple elements with progressively smaller pore sizes. Larger particles are captured by elements with larger pores that maintain high water flux, while smaller microparticles are captured by downstream elements with smaller pores, distributing the filtration burden across multiple components
Solution Approach 2:
The system uses a series of filter elements where each element performs partial filtration for its size range. The cumulative effect of multiple partial filtration stages achieves high overall removal efficiency without requiring any single element to have excessively small pores that would severely restrict water flow
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 filtration system achieves high efficiency in removing microplastics and microparticles, with the graphene-based membranes demonstrating at least 95% mass removal efficiency for microplastics, while maintaining a high water flux density, thereby improving water quality and reducing contamination.
Implementation Method 1
The porous membrane may have a pore size of about 10 microns to about 100 microns, and more preferably about 30 microns to about 50 microns, to capture microfibers and/or microparticles
Implementation Method 2
Hydrophobic Graphene Oxide based carbon nanotube (GOx-CNT) having a static water angle of about 90-155 degrees or about 90-125 degrees, whereby the porous membrane removes polymer microparticles
Implementation Method 3
Hydrophobic Cellulose Acetate (CA) having a static water angle of about 90-125 degrees; Hydrophobic Polytetrafluoroethylene (PTFE) having a static water angle of about 90-110 degrees
Data Source
AI summary
A washing machine includes a filter that is operably connected to a water circulation system to filter water. The filter may include a mesh filter element and a porous membrane whereby water passes through the mesh element and then through the porous membrane prior to exiting the washing machine. The porous membrane may include a plurality of openings of about 5 microns to about 100 microns to capture microparticles.