Recovery of Glycine from Spent Plating Solutions

SUMMARY

Cu(II) forms barely soluble compounds with glycine in weakly acidic solutions at a molar ratio \gly\: \Cu(II)\ ≥ 2. The temperature has the most important influence on the solubility of precipitates. The rate and completeness of precipitation depends on the pH adjuster. NaHCO₃. Na₂CO₃ and NH₄OH are most suitable. With glycine Cu(II) forms two kinds of the precipitates: cis-Cu(gly)² H₂O and trans-Cu(gly)₂ 2H₂O. The participation of other organic acids such as formic, acetic, malic, phthalic and succinic retards the formation of insoluble Cu(gly)² compounds to a greater or lesser extent. In case of oxalic acid presence in Cu(II-glycine solution, a precipitate of K₂Cu(C₂0₄)i2H₂O is formed. Using the precipitation of insoluble Cu(II) glycinic compounds and electrolysis makes it possible to recover glycine from spent electroless nickel plating solutions.

Keywords:

• glycine
• copper
• recovery
• precipitation
• spent plating solutions