Malonamide Extractant Palladium Separation Nitric Acid
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Solution Overview
Problem
Current methods fail to effectively extract palladium from aqueous nitric solutions with high efficiency, selectivity, and stability, especially in the context of recycling waste electrical and electronic equipment, as existing extractants either have slow kinetics, deteriorate in nitric environments, or require complexing agents.
Innovation Solution
A liquid-liquid extraction process using an organic phase with a malonamide free of sulfur atoms, adjusting the nitric acid content in the aqueous phase to less than 2.5 mol/L, allows for the selective separation and recovery of palladium from a mixture with other metallic elements, excluding the use of sulfur diamides and complexing agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional extractants (sulfides, sulfoxides, phosphorus derivatives) are used to extract palladium from nitric aqueous phase, then extraction efficiency is improved, but the extractants deteriorate in nitric environment or present slow kinetics
Solution Approach 1:
The patent changes the chemical parameters of the extractant by using malonamide compounds with specific molecular structures (containing oxygen and nitrogen atoms in specific configurations) that are chemically stable in nitric acid environments while maintaining high extraction efficiency for palladium from nitric aqueous phases
Solution Approach 2:
The patent employs composite extractant systems combining malonamide compounds with specific diluents in organic phases, creating a synergistic system that achieves both high extraction efficiency and stability in nitric medium, overcoming the limitations of single-component extractants
2Manufacturing precision
If sulfur diamides are used to extract palladium, then selectivity is improved, but the process complexity increases and additional complexing agents are required
Solution Approach 1:
The patent extracts and removes sulfur atoms from the extractant molecule, using malonamide compounds without sulfur content to achieve palladium separation, thereby simplifying the process by eliminating the need for sulfur diamides and associated complexing agents while maintaining high selectivity
Solution Approach 2:
The patent employs malonamide compounds as simple, effective extractants that do not require complex supporting chemical systems, using straightforward organic-phase extraction chemistry that avoids the need for multiple complexing agents and simplifies process operation
3Productivity
If nitric acid concentration is increased to improve extraction, then extraction rate is improved, but the stability of existing extractants deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the extractant to malonamide compounds with specific molecular structures that are chemically compatible with high nitric acid concentrations, allowing the system to operate effectively at elevated acidities without extractant degradation
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 process achieves significant palladium extraction rates (>75%) with a selectivity factor of at least 10, maintaining stability and flexibility in various diluents, even at high nitric acid concentrations, and avoids the need for additional complexing agents.
Implementation Method 1
a process for separating palladium from other metallic elements contained in an aqueous nitric phase via a liquid-liquid extraction using an organic phase containing, as extractant, a malonamide free of sulfur atom
Data Source
Figure 1~2
AI summary
The present invention relates to a process for separating palladium from the other metal elements contained in a nitric aqueous phase consisting in bringing a nitric aqueous phase containing, in addition to the palladium, at least one other metal cation, the valency of which is greater than or equal to 2, into contact with a water-immiscible organic phase, then in separating the nitric aqueous phase and the organic phase into which palladium has been extracted, said organic phase containing at least one malonamide as extractant and said nitric aqueous phase containing at most 2.5 mol.L-1 of nitric acid.