Rare Earth Coated Membranes for Low-Pressure Contaminant Removal
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Solution Overview
Problem
Current water filtration membranes face challenges in efficiently removing contaminants like anions containing phosphorus, arsenic, and PFAS due to high pressure requirements and significant rejected water volumes, which pose safety and energy concerns, as well as disposal issues, and are limited in their ability to remove dissolved contaminants.
Innovation Solution
A membrane with a rare earth coating, specifically using cerium and lanthanum, is applied to restrict the permeability of contaminants, allowing for effective removal of anions such as phosphorus, arsenic, and PFAS, even through larger pore sizes than expected, by depositing rare earth salts on the membrane surface or embedding them within the membrane structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high pressure is applied to remove dissolved contaminants through NF and RO membranes, then contaminant removal efficiency is improved, but energy consumption and safety risks increase
Solution Approach 1:
The patent modifies the membrane's surface properties by introducing negative charge through rare earth metal oxide coatings and pH adjustment, changing the interaction mechanism from pressure-driven physical filtration to electrostatic repulsion, thereby reducing the pressure parameter needed for effective contaminant removal
Solution Approach 2:
The patent replaces the mechanical pressure-driven filtration mechanism with an electrostatic repulsion mechanism based on charge interactions, where the negatively charged membrane surface repels negatively charged contaminants, eliminating the need for high-pressure mechanical systems
2Reliability
If NF and RO membranes are used to remove dissolved content, then contaminant removal capability is improved, but rejected water volume increases
Solution Approach 1:
The patent adjusts the pH parameter to enhance the negative charge density on the membrane surface, improving electrostatic repulsion of anionic contaminants and thereby reducing the volume of rejected water while maintaining high removal capability
3Use of energy by moving object
If MF and UF membranes operate at low pressure to remove suspended particles, then energy consumption is reduced, but ability to remove dissolved contaminants is limited
Solution Approach 1:
The patent modifies the membrane's surface charge parameter through rare earth metal oxide coating and pH adjustment, enabling low-pressure membranes to achieve dissolved contaminant removal through electrostatic repulsion mechanisms rather than relying solely on pressure-driven physical filtration
Solution Approach 2:
The patent replaces the mechanical size-exclusion filtration mechanism with an electrostatic repulsion mechanism, allowing low-pressure operation while achieving effective removal of dissolved anionic contaminants through charge-based interactions
4Use of energy by moving object
If membrane pore size is increased to reduce pressure requirements, then energy consumption is reduced, but contaminant rejection efficiency decreases
Solution Approach 1:
The patent changes the interaction mechanism parameter from purely physical size-exclusion to electrostatic repulsion, allowing larger pore sizes to be used while maintaining high contaminant rejection efficiency through the negatively charged membrane surface that repels anionic contaminants regardless of pore dimensions
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 rare earth-coated membranes significantly reduce the concentration of contaminants in the permeate, achieving target concentrations or below, while reducing the need for high pressure and energy consumption, and allowing for repeated use with reapplication of the coating as needed to maintain effectiveness.
Implementation Method 1
the rare earth coating limits the permeability of contaminants that would otherwise pass through the membrane
Implementation Method 2
by depositing rare earth salts on the membrane surface or embedding them within the membrane structure
Data Source
AI summary
A rare earth coated membrane is beneficial to aid in the separation of contaminants, such as anions containing phosphorous, anions containing arsenic, PFAS, and mixtures thereof. Membranes with the rare earth coating or treatment can have larger pore sizes than would be expected to remove these contaminants. Disclosed herein are methods for treating or coating the membrane to provide the rare earth coated membrane. The coated membranes can be used to remove contaminants, such as anions containing phosphorous, anions containing arsenic, and PFAS, from liquid feeds, such as water or water-based feeds.