Rare Earth Separation Adsorbent with Diglycolamic Acid
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Solution Overview
Problem
Current methods for recovering rare earth elements from dilute aqueous solutions are inefficient, especially when coexisting with high concentrations of base metals, and the immobilization of extractants on substrates reduces selectivity and adsorption capacity.
Innovation Solution
A method involving an adsorbent composed of a substrate with diglycolamic acid, where the acid concentration is used to selectively desorb rare earth element ions and tetravalent ions, allowing for their separation and recovery over a long period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If extractant is immobilized on substrate to enable repeated use, then ease of operation is improved, but selectivity and adsorption capacity are reduced
Solution Approach 1:
The patent uses porous hydrophobic substrate that allows the extractant to be retained within the porous structure through hydrophobic interaction, maintaining the extractant's freedom of movement while enabling repeated use. The porous structure provides large surface area for extractant retention without requiring covalent bonding that would restrict molecular mobility.
Solution Approach 2:
The patent employs a liquid-phase system where the extractant remains in liquid form within the porous substrate, allowing it to move freely and maintain high selectivity. The liquid phase enables the extractant to dynamically interact with metal ions while being retained by the hydrophobic substrate through solubility differences.
2Productivity
If adsorbent is used to separate rare earth elements from dilute solution, then productivity is improved, but tetravalent ions concentrate in adsorbent reducing reliability over time
Solution Approach 1:
The patent selectively extracts tetravalent ions from the adsorbent using a specific eluent (hydrochloric acid or nitric acid at controlled pH), removing the harmful concentrated ions while preserving the rare earth elements. This extraction step prevents tetravalent ion accumulation that would otherwise reduce adsorbent effectiveness over time.
Solution Approach 2:
The patent changes the pH parameter of the eluent to selectively desorb tetravalent ions from the adsorbent. By controlling the acid concentration and pH, the system achieves selective removal of tetravalent ions while maintaining rare earth element retention, thereby restoring adsorbent capacity for repeated use.
3Reliability
If conventional solvent extraction is used for selective separation, then selectivity is improved, but the method is ineffective for dilute solutions with high base metal concentration
Solution Approach 1:
The patent creates a composite system combining a hydrophobic porous substrate with a liquid-phase extractant. This composite structure provides both the selectivity of solvent extraction and the ability to process dilute solutions effectively, as the porous substrate concentrates the extractant at the interface while maintaining its liquid-phase selectivity mechanisms.
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 method enables the simple and inexpensive selective adsorption and recovery of rare earth elements from dilute solutions, preventing the concentration of tetravalent ions like thorium and maintaining adsorbent effectiveness over time.
Implementation Method 1
an adsorption step of bringing a solution containing rare earth element ions and tetravalent ions of a metal element other than the rare earth element ions into contact with an adsorbent to adsorb the rare earth element ions and the tetravalent ions to the adsorbent
Implementation Method 2
a rare earth element ion desorption step in which the adsorbent after the adsorption step is brought into contact with a first acidic aqueous solution to desorb the rare earth element ions from the adsorbent
Implementation Method 3
a tetravalent ion desorption step of contacting the adsorbent after the rare earth element ion desorption step with a second acidic aqueous solution to desorb the tetravalent ions from the adsorbent
Data Source
AI summary
Provided is a method for easily and inexpensively separating a rare earth element contained in an aqueous solution.