Ammoniacal etching solutions treatment

Treatment of ammoniacal etching solutions by SLM-based technique... 

Ammoniacal etching solutions are widely used in the electronic industry to etch a thin copper layer on printed circuit boards. During this process a spent etching solution with Cu(II) content up to 160 mg L is formed. Traditionally this solution is submitted to neutralization in order to achieve copper precipitation. After this treatment, the generated ammoniacal wastewater still contains several mg of copper and must be appropriately managed. In particular, copper concentration in this wastewater must be reduced to less than 5 mg L in order to be reused or safely discharged. The predominant form of copper (II) ions in this wastewater is [Cu(NH3)4] ". ... 

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