2003 Progress Report: Electrolysis and Ion Exchange for the In Process Recycling of Copper from Semi-Conductor Processing SolutionsEPA Grant Number: R829627
Title: Electrolysis and Ion Exchange for the In Process Recycling of Copper from Semi-Conductor Processing Solutions
Investigators: Doyle, Fiona M. , Evans, James W.
Institution: University of California - Berkeley
EPA Project Officer: Carleton, James N
Project Period: January 1, 2002 through December 31, 2004 (Extended to April 30, 2007)
Project Period Covered by this Report: January 1, 2003 through December 31, 2004
Project Amount: $325,000
RFA: Technology for a Sustainable Environment (2001) RFA Text | Recipients Lists
Research Category: Sustainability , Pollution Prevention/Sustainable Development
The objective of this research project isto develop an understanding of the electrodeposition of copper onto extended-area electrodes, and of the adsorption/desorption of copper onto ion exchange resins with a high affinity for copper. The principles elucidated in this work will pave the way for subsequent development of commercial-scale electrolysis/ion exchange processes for recovering copper throughout semiconductor fabrication plants.
- We used a rotating disk electrode (RDE) to demonstrate that aminoacetaldehyde dimethylacetal inhibits copper deposition whereas ethanolamine has little effect. These species model the intermediate and final reduction products of glycine, respectively. Glycine was previously shown to inhibit copper deposition.
- We also used RDE to demonstrate that alanine inhibits copper deposition, regardless of the presence of air. This contrasts the behavior of glycine, which only inhibits deposition in de-aerated solutions.
- We used an electrochemical quartz crystal microbalance to measure adsorption directly and demonstrated that adsorption of glycine onto copper increases markedly with increasingly cathodic potentials, forming layers several tens of monolayers thick.
- We demonstrated that copper will deposit throughout porous carbon electrodes if inhibiting agents are present, but only on the exterior in the absence of inhibitors. This is potentially problematic for treating effluents of different compositions.
- We developed a novel fluidized bed electrode for copper deposition wherein the cathodic “current collector” and anode are kept a fixed distance apart to maintain a constant cell voltage as the copper deposit builds up.
- We demonstrated that dilute aqueous ethylenediaminetetraacetic acid (EDTA) solutions elute copper from Dowex M4195 (with a bispicolylamine functional group) as effectively as the more concentrated ammonia solutions. However, neither eluted all the copper.
- We demonstrated that elution efficacy of aqueous bispicolylamine was similar to that of EDTA.
- We observed progressive decrease in uptake capacity of Dowex M4195 with repeated uptake/elution/regeneration cycles.
- We explored the potential of separating different metallic contaminants using selective elution from Dowex M4195.
- We started work on a sulfonic acid ion exchange resin, because of difficulties encountered with the chelating resin Dowex M4195.
We will improve and document the performance of novel fluidized bed electrodes for copper recovery. We also will generate kinetic data and uptake-elution isotherms for a sulfonic acid resin for different concentrations of copper and pH. We will analyze uptake and elution isotherms to provide the basis for models for uptake and selectivity of metals onto resins to guide the commercial development of effective ion exchange units.