| Popis: |
In this study, a method for determining the lead components in waste lead paste was proposed, using simulated and spent lead paste as research objects. To compare the effectiveness of different determining methods, we selected three methods for comparison and investigated the reasons for measurement deviation. The results indicate that the measurement deviation in the current method primarily stems from the following three factors: (1) Pb is soluble in an acetic acid solution under certain conditions; (2) Pb and PbO2 undergo redox reactions; and (3) hydrogen peroxide can undergo redox reactions with Pb. It is feasible to determine the lead content using the kinetic rules of Pb and PbO2 in the acetic acid-hydrogen peroxide system. The method of determination proposed in this paper is as follows. Firstly, lead dioxide is dissolved in hydrogen peroxide under acidic conditions. Subsequently, the concentration of lead dioxide is determined, and the quantity of hydrogen peroxide consumed is recorded. Then, a new sample is taken, and the lead oxide is dissolved in an acetic acid solution. The concentration of lead oxide is determined using the EDTA·2Na titration method. The residue of lead sulfate in the filtrate is dissolved in a sodium chloride solution, and its concentration is determined using the EDTA·2Na titration method. Based on the previously recorded volume of hydrogen peroxide, the remaining lead dioxide in the residue is dissolved in a mixture of acetic acid and hydrogen peroxide. The remaining lead dioxide is then removed from the new sample employing kinetic principles. Finally, the residual metallic lead in the sample is dissolved in a nitric acid solution, and its concentration is determined using the EDTA·2Na titration method. |
