Post-Synthetically Modified COFs for Recyclable Rare-Earth Capture

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Solution Overview

Problem

Existing materials for rare-earth element (REE) capture and recycling lack efficiency and recyclability, and covalent organic frameworks (COFs) are underutilized due to limited molecular diversity and chemical lability in aqueous and low-pH conditions, hindering their application in REE extraction.

Innovation Solution

A general strategy using the Ugi multicomponent reaction to post-synthetically modify imine-based COFs, introducing functional handles like diglycolic acid moieties for efficient REE capture, enhancing chemical stability and recyclability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If liquid-liquid extraction with soluble ligands is used for REE binding, then extraction efficiency is improved, but chemical waste increases and ligand recyclability decreases

Engineering Contradiction:

Improveextraction efficiencyVSAvoidchemical waste

Core Design Contradiction:

ProductivityVSLoss of substance

Solution Approach 1:

The patent employs covalent organic frameworks (COFs), which are porous crystalline materials with high surface area and tunable pore structures. These frameworks provide abundant active sites for REE binding while maintaining structural integrity for reuse, thus achieving high extraction efficiency without generating chemical waste.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The invention creates composite materials by integrating REE-binding ligands into COF structures. This composite approach combines the high efficiency of soluble ligands with the recyclability and environmental friendliness of solid materials, eliminating chemical waste while maintaining productivity.

Inventive Principle:

Principle #40Composite materials

2Productivity

If homogeneous ligands are used for REE binding, then extraction efficiency is improved, but recyclability decreases and extraction costs increase

Engineering Contradiction:

Improveextraction efficiencyVSAvoidrecyclability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The COF materials provide a solid porous framework that immobilizes the binding ligands, allowing the material to be filtered and reused multiple times. The porous structure ensures high accessibility of REE ions to binding sites, maintaining extraction efficiency across multiple cycles.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The patent enables easy recovery of the solid COF adsorbent from the liquid phase through filtration. The recovered material can be regenerated and reused, dramatically improving recyclability and reducing extraction costs compared to homogeneous ligands that are difficult to recover.

Inventive Principle:

Principle #34Discarding and recovering

3Reliability

If solid adsorbents are used for REE capture, then recyclability is improved and organic solvent use is reduced, but extraction efficiency decreases

Engineering Contradiction:

ImproverecyclabilityVSAvoidextraction efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The COF materials feature well-defined porous structures with high surface area and controlled pore sizes. This porous architecture provides abundant accessible binding sites for REE ions, enabling high extraction efficiency while maintaining the recyclability advantages of solid adsorbents.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The invention optimizes key parameters including pore size, surface area, and functional group density of the COF materials. By tuning these parameters, the material achieves both high extraction efficiency and excellent recyclability, overcoming the traditional trade-off between these two properties.

Inventive Principle:

Principle #35Parameter changes

4Reliability

If COFs are used for REE extraction, then recyclability is improved, but molecular diversity and chemical stability in aqueous/low-pH conditions are limited

Engineering Contradiction:

ImproverecyclabilityVSAvoidmolecular diversity

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent systematically varies structural parameters of COFs including pore size, surface area, and functional group types to optimize performance. This parameter optimization enables the COFs to maintain high chemical stability in aqueous and low-pH conditions while achieving excellent REE extraction efficiency and recyclability.

Inventive Principle:

Principle #35Parameter changes

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 modified COFs demonstrate significantly higher adsorption capacity and recyclability for REE ions, outperforming previous materials by more than 40 times for adsorption capacity and ensuring fast, efficient capture and release.

Implementation Method 1

solid adsorbent is utilized to capture REE ions from the solution

Methodology Applied

Scientific EffectAdsorption: Adsorption

Data Source

PatentUS20250282713A1Efficient capture and release of the rare-earth elements using covalent organic frameworks

Publication Date: 2025.09.11 IOWA STATE UNIV RES FOUND INC

AI summary

The present disclosure is directed to a covalent organic framework comprising repeating units of a moiety comprising Formula (I):wherein X, Y, R, R′, n1, and n2 are as described herein. The present disclosure is also directed to a method of making the covalent organic frameworks and a method of separating rare-earth elements using the covalent organic frameworks.