QUARTZ MICROBALANCE INVESTIGATION OF METAL-DEPOSITION FROM DILUTE-SOLUTIONS

A quartz microbalance was used to determine the cathodic deposition of lead (5.4 mug l-1-0.3 mg l-1) and copper (16 mug l-1-0.7 mg l-1) from dilute solutions. It was found that the removal of lead can be nearly complete when the total amount in the solution does not exceed the monolayer capacity of the electrode. Simultaneously with the formation of this monolayer, Au-Pb alloys are formed. These alloys also form when the electrode is held at a UPD (under potential deposition) potential. They were identified by electron diffraction as Au2Pb, AuPb2 and AuPb3+ The alloy formation can easily be detected from anodic stripping curves. With copper solutions, the deposition is quantitative throughout the examined range of concentrations. In contrast to the lead deposition, mainly bulk copper was formed in addition to Cu-Au alloys.