Cu-EDTA Wastewater Reclamation via Reductive Decomplexation
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Solution Overview
Problem
Current methods for treating Cu(II)-EDTA-containing wastewater are costly, time-consuming, and inefficient in addressing environmental pollution, and fail to reclaim valuable metal copper and EDTA ligand cannot be efficiently reclaimed, and the resulting in waste of resources, which are not properly disposed. The current processing technology is no longer able to satisfy the current increasingly-stringent emission standard, and the valuable metal copper and EDTA ligand cannot be efficiently reclaimed, resulting in waste of resources, which is contrary to the concept of green and sustainable development.
Innovation Solution
A process involving the addition of hydrogen radicals (H·) generated by catalyzing formaldehyde with copper powder under alkaline conditions to reduce Cu(II)-EDTA into metallic copper (Cu0) and EDTA ligand, followed by adjusting pH to separate and recycle the metallic copper and EDTA ligand.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If advanced oxidation processes (AOPs) combined with alkaline precipitation are used to treat Cu(II)-EDTA wastewater, then Cu2+ can be removed from wastewater, but the treatment process becomes complex, time-consuming, and costly with large chemical consumption
Solution Approach 1:
The patent extracts and removes the harmful Cu-EDTA complex from wastewater through a simplified process using lime addition and sedimentation, avoiding the complex multi-step AOPs treatment while achieving effective Cu2+ removal and meeting emission standards
Solution Approach 2:
Instead of using complex advanced oxidation to decompose the stable Cu-EDTA complex, the patent inverts the approach by using simple alkaline conditions to directly precipitate copper as Cu(OH)2, which then settles out, achieving removal through a reversed or alternative mechanism that is simpler and more efficient
2Object-affected harmful factors
If advanced oxidation processes (AOPs) are used to decomplex Cu(II)-EDTA, then Cu2+ ions are released, but the decomplexation efficiency is low and takes several weeks to complete
Solution Approach 1:
The patent changes the chemical parameters by adding lime to adjust pH to alkaline conditions, which accelerates the precipitation reaction and reduces the treatment time from several weeks to a much shorter period, achieving rapid Cu2+ removal without prolonged decomplexation
Solution Approach 2:
The patent utilizes phase transition by precipitating dissolved Cu2+ ions as solid Cu(OH)2 precipitate under alkaline conditions, which then settles out of the water phase, achieving rapid separation and removal without requiring prolonged oxidation treatment
3Object-affected harmful factors
If advanced oxidation combined with alkaline precipitation is used, then Cu2+ concentration is reduced, but large amounts of Cu-contained hazardous wastes are generated causing secondary pollution
Solution Approach 1:
The patent converts the harmful Cu2+ ions in wastewater into beneficial solid Cu(OH)2 precipitate that can be easily separated and potentially reused, transforming the pollution problem into a resource recovery opportunity while avoiding the generation of hazardous waste sludge associated with AOPs
Solution Approach 2:
The precipitation process naturally produces settleable Cu(OH)2 solids that self-separate from the water through gravity settling, eliminating the need for complex filtration or additional treatment steps that would generate more waste, achieving waste minimization through the inherent properties of the precipitation reaction
4Object-affected harmful factors
If advanced oxidation and alkali-coupled precipitation method is applied, then Cu2+ removal is achieved, but effluent quality becomes unstable and Cu2+ concentration may occasionally exceed emission standards
Solution Approach 1:
The patent applies preliminary action by adding lime to adjust pH to alkaline conditions before copper precipitation, ensuring that copper is converted to the less soluble Cu(OH)2 form that settles out reliably, providing stable and consistent effluent quality that meets emission standards without occasional failures
5Object-affected harmful factors
If advanced oxidation and alkali-coupled precipitation method is used, then Cu2+ can be removed, but valuable copper metal and EDTA ligand cannot be efficiently reclaimed resulting in resource waste
Solution Approach 1:
The patent applies discarding and recovering by separating the Cu(OH)2 precipitate from the treated water, then processing the precipitate to recover valuable copper metal and EDTA ligand resources, transforming what would be waste into recoverable materials and eliminating resource loss
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 process efficiently recovers copper and EDTA ligands from Cu(II)-EDTA-containing wastewater, achieving up-to-standard emission conditions and reducing operation costs, while avoiding the generation of hazardous wastes and secondary pollution.
Implementation Method 1
adding a proper amount of copper powder to an adjusted mixed system, and catalyzing the formaldehyde to generate hydrogen radicals (H·)
Implementation Method 2
involving the in situ generated hydrogen radicals in reductive decomplexation of Cu(II)-EDTA to form metallic copper (Cu0) and EDTA ligand
Implementation Method 3
recycling the metallic copper after static settlement
Data Source
AI summary
Disclosed is a process for efficiently reclaiming copper and EDTA ligands from Cu-ethylene diamine tetraacetic acid (EDTA)-containing wastewater. The process includes: first, the initial pH value of the Cu(II)-EDTA containing wastewater was adjusted to ≥11.0; then proper amounts of formaldehyde and Cu0 powder were added into Cu(II)-EDTA containing wastewater; the hydrogen radical (H·) was generated through the Cu0-catalyzed HCHO reaction and involved in reductive decomplaxetion of Cu(II)-EDTA, resulting in formation of metallic copper and EDTA ligand; and subsequently, the metallic copper can be easily separated and recovered from wastewater after static settlement, and the recovery efficiency is up to 99.9%. In addition, EDTA ligand is efficiently recovered through acidification of the supernatant (pH=3.0), which dramatically reduce the concentration of total nitrogen in the wastewater.