Removal of Plating Metals
from rinse waters and waste effluent of the metal plating industry
Ion exchange is a well proven technology to reduce harmful metal wastes from the metal plating industry. It is particularly suitable for the treatment of the process rinse waters and of the waste effluent. The metals of concern are chromium, cadmium, nickel, copper, lead and zinc.
Rinse water treatment and recycling
Figures 1 and 2 illustrate the two types of rinse waters that can be found in the plating industry. The treatment of these waters involves more than one ion exchange resin. A strong acid cation resin such as Amberlyst™ 16 wet is recommended for the removal of cationic metallic impurities. A weak base anion resin such as Amberlyst™ A21 can then be used for the removal of anions or cyanide metallic complexes.
In the cyanide alkaline rinse water, the strong base anion in the hydroxide form such as Amberlyst™ A26 OH follows a WBA resin to remove all weak acids, such as HCN, that leak through the WBA resin.
Figure 1: Overall Process of a Metal Finishing Plant
Figure 2: Rinse Water Recycling
Recommended Products
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Macroreticular strong acid cation exchanger with high oxidative stability |
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Macroreticular weak base anion exchanger to remove anions and cyanide metallic complexes |
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| Macroreticular strong base anion exchanger for the removal of weak acids such as HCN |
Waste effluent treatment
When the waste effluent before discharge still contains some low levels of heavy metals, about 5 to 20 ppm, a polishing unit containing a selective ion exchange resin such as Amberlite™ IRC748 is frequently included. This chelating resin installed in a merry-go-round configuration can bring the total concentration of metals below 0.1 ppm even in the presence of high concentrations of sodium or calcium salts.
1 g/L Ca2+, 1 g/L Na+, 5 ppm Zn2+, 5 ppm Ni2+, 2 ppm Cu2+, pH: 7, 20 BV
Recommended Product
| A macroreticular chelating resin with iminodiacetic functional groups which can form strong complexes with metals |
For sampling, pricing, availability or more information please contact your Rohm and Haas representative.
