| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 212483 | Hydrometallurgy | 2012 | 7 Pages |
Present work is focused on the selective leaching of lead from the soldering material present on the outer layer i.e. epoxy resin of waste PCBs, liberated through a novel pre-treatment technique of organic swelling using n-methyl-2-pyrrolidone. Nitric acid was found as a suitable leachant to dissolve lead. Initially, the effect of temperature, S:L ratio, leaching time and acid concentration on leaching of lead was investigated using fresh solder material containing 47.36% lead and remaining tin. With 0.2 M HNO3 at S:L ratio 1:100 (g/mL) and temperature 90 °C, 99.99% lead was leached in 120 min. Leaching kinetics followed 1 − (1 − X)1/3 = Kct i.e. chemically controlled reaction model with activation energy 26.94 kJ/mol. Validation of lead leaching from solder of liberated epoxy resin of swelled PCBs indicates that 99.99% of lead could be leached out at 90 °C with 0.2 M HNO3 in 45 min. Tin left in the residue of the liberated resin was further leached with 3.5 M HCl at 90 °C for 120 min at S:L ratio 1:20 (g/mL), which dissolve almost 98.74% tin. Then, metal free epoxy resin was washed with water to utilize it or dispose-of safely without affecting the environment.
►Lead recovery from waste PCBs using novel pre-treatment was followed by leaching. ►Studies were made for lead dissolution from solder and epoxy resin of PCBs using HNO3. ►99.99% lead was leached from waste using 0.2 M HNO3, pulp density 10 g/L at 90 °C. ►Studies showed chemical controlled lead leaching with 26.94 kJ/mol Ea. ►Tin could be leached out from HCl and epoxy resin can be utilized safely.
