Recycling of waste electroplating solution

Electroplating a platinum group metal surface layer on other metal substrates instead of the overall metal parts of platinum group metals can greatly save the amount of use. Among them, Pt plating, Pd plating and Rh plating are more widely used. Platinum electroplating was mostly used in jewelry, tableware, medical equipment, and scientific instruments in the early days. Now it is widely used in platinum-coated titanium anodes in chemical industry and cathodic protection, electronic appliances, aerospace and other fields. Palladium plating is mainly used for decoration of electrical contacts, jewelry, watches and eyeglass frames. Rhodium plating is mainly used in scientific instruments, microscopes, searchlight reflectors and electrical contact devices.

The composition and properties of the electroplating solution: Preparing the electroplating solution and electroplating are knowledge contents of electrochemistry and electrical engineering. This section only briefly introduces the chemical properties and application common sense of platinum group metals.

1. Platinum plating solutions include:

1. Chloroplatinic acid plating solution: containing H2PtCl6 15-25g/L, [HCl]>1 mol/L;

2. Alkaline electroplating solution: contains Na2Pt(OH)6 about 18g/L, Na2SO4 about 30g/L, NaOH about 5g/L, and sodium oxalate Na2C2O4 about 5g/L;

2. Palladium plating solutions include:

1. Acidic palladium plating solution: containing Pd (PdCl2) about 50g/L, NH4Cl about 50g/L, pH 0.1-0.5;

2. Weakly alkaline palladium plating solution: containing Pd10-40g/L [added in the form of Pd(NH3)2Cl2 salt], NH4Cl about 10g/L, (NH4)2SO4 about 25g/L, pH8.5-9;

3. Ruthenium plating solutions include:

1. Ruthenium chloride plating solution: contains Ru about 2g/L (added in the form of ruthenium nitrosyl chloride RuNOCl3 compound), H2SO4 2 mol/L;

2. Ammonium sulfamate plating solution: contains Ru about 10g/L [added in the form of (NH4)3N (Ru2Cl4H2O) 2 compound)], amine sulfamate 10g/L, pH 1.3;

4. Cyanide molten salt electroplating solution: In the molten salt of NaCN+KCN mixture (550-600℃), Pt 3g/L or Ir 5-6g/L are electrolytically dissolved under argon protection as a solution for electroplating platinum and iridium. plating solution.