Table 2. Procedure of silver recovery from dental amalgam residues using ascorbic acid as reducing agent.
| Dilution | Precipitation | Solubilization | Reduction | |||
|---|---|---|---|---|---|---|
| Sample mass (g) | Concentrated nitric acid volume at 90°C (mL) / dilution | 20% NaCl volume (mL) | Concentrated NH4OH volume (mL) | Deionized water volume (mL) | 20% NaCl volume (mL) | Amount of ascorbic acid (g) |
| A1150.0 | 150.0/1 | 300.0 | 500.0 | 1000.0 | - | 75.0 |
| A2150.0 | 150.0/1 | 300.0 | 500.0 | 1000.0 | - | 75.0 |
| B1150.0 | 500.0/5 | 750.0 | 200.0 | 2000.0 | 1000.0 | 75.0 |
| B2150.0 | 500.0/5 | 750.0 | 200.0 | 2000.0 | 1000.0 | 75.0 |
| C1200.0 | 400.0/3 | 1200.0 | 300.0 | 2000.0 | 1000.0 | 100.0 |
| C2200.0 | 400.0/3 | 1200.0 | 300.0 | 2000.0 | 1000.0 | 100.0 |
| D1200.0 | 500.0/5 | 1200.0 | 300.0 | 2000.0 | 1000.0 | 100.0 |
| D2200.0 | 500.0/5 | 1200.0 | 300.0 | 2000.0 | 1000.0 | 100.0 |
| E1200.0 | 400.0/3 | 1400.0 | 300.0 | 2000.0 | 1500.0 | 100.0 |
| E2200.0 | 400.0/3 | 1400.0 | 300.0 | 2000.0 | 1500.0 | 100.0 |
| F1200.0 | 500.0/5 | 1400.0 | 300.0 | 2000.0 | 1500.0 | 100.0 |
| F2200.0 | 500.0/5 | 1400.0 | 300.0 | 2000.0 | 1500.0 | 100.0 |