Title: Leaching of lead from solder material of waste printed circuit boards (PCBs)
Abstract: 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.
Publication Year: 2012
Publication Date: 2012-04-24
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 120
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