You are right to be concerned about concentrated sulfuric acid. Avoid at all costs, especially when heated. Yes, it dissolves plastic, but also dissolves skin, clothing, and anything organic. A single drop can cause serious damage.
As for removing lead from your gold foils solution, dilute sulfuric acid is perfectly fine, even preferred. The amount of lead present is typically small, and instantly precipitates out as lead sulphate. Stay safe, and avoiding concentrated H2SO4 is a good start whenever possible.
As for removing lead from your gold foils solution, dilute sulfuric acid is perfectly fine, even preferred. The amount of lead present is typically small, and instantly precipitates out as lead sulphate. Stay safe, and avoiding concentrated H2SO4 is a good start whenever possible.