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Ion Exchange
Description
- How it works
- Contaminated solution passes over an ionic resin
- A similarly charged benign ion replaces the contaminate ion in the water. The contaminate ion attaches to the resin
- The benign ions go into the wastewater, while the contaminates remain trapped on the resin
- When all the benign ions on the resin have gone into solution, the resin is 'spent'. Passing a concetrated solution containing these ions (acid or base) can regenerate the resin.
- Removes impurities from:
- Incoming water supply
- Drag-in
- Corrosion
- Reduced or decomposed bath chemicals
- Other sources too...
Advantages / Limitations
- May not be practical for cyanide solutions (except gold cyanide)
For Incoming Water
- Can reduce water use and wastewater generation by removing initial contaminates
- Cleaner rinse may result in better quality of products
For Chemical Baths
- Can reduce water use and wastewater generation
- Increase plating rates
- Decrease energy use
For Rinse Water
- Can reduce water use and wastewater generation by keeping the water cleaner, longer
- Cleaner rinse may result in better quality of products
Implementation Process
- Determine operating conditions
- For Incoming Water: Measure the quality of the incoming water supply and relate that to process cleanliness standards
- For Chemical Baths: Identify the optimal process bath operating parameters (i.e. pH, ion concentration, etc.)
- For Rinse Water: Determine optimal operating parameters
- Investigate necessary equipment
- Determine if the contaminates are cations, anions, or a combination of both
- Determine cost effectiveness, including
- chemical savings
- disposal cost reduction
- capital investment
- energy cost
- labor cost
- resin replacement
- Purchase and install equipment
- Train and monitor employees – give incentives for superior performance
Resources
- Cushnie, George C. Jr. Pollution Prevention and Control Technology for Plating Operations. National Center for Manufacturing Sciences, Ann Arbor, MI, 1994.
Vendors
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