In the pulp electrolysis, iron ions in solution play an important role, which is directly involved in the electrode reaction at the anode and oxidative leaching bismuthinite plays the role of electron transfer. Therefore, it is necessary to study the anodization process of Fe 2 + . Wang Chengyan and Qiu Dingfan measured the polarization curves of Fe 2 + on graphite anodes and clarified the rate control process of Fe 2 + anodization.
Test conditions: 333K, NH 4 Cl is 200g ∕L, H + is lg / L, stirring speed 600r ∕ min, scanning speed 1mV / s, measured FeCl 2 concentration is 0.01, 0.02, 0.03, 0.04, 0.05mol ∕L The lower anodic polarization curve takes the current density i at the same η value as the η-lgi relationship diagram, as shown in Fig. 1.
It can be seen from Fig. 5 that η is between 60 and 10 mV, and the curve shows a significant Tafel segment, indicating that in this overpotential range, the Fe 2 + anodization process is controlled by the electrochemical reaction; when η is in the 100~ Between 18mV, η is linear with {lg(i∕i 0 )+lg[i d /(i d -i)]}, as shown in Figure 2, indicating the Fe 2 + anodization process in this overpotential range. It is a mixed reaction control; when η is between 160 and 220 mV, η has a linear relationship with lg[i d /(i d -i)], as shown in Fig. 3, indicating that Fe 2 + anodizing in this overpotential range The process is controlled by diffusion.
Fig.1 η-lgi relationship diagram of different FeCl 2 concentrations
Figure 2 η-lg(i∕i 0 )+lg[i d /(id-i)]
Figure 3 η-lg[i d /(i d -i)]
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