The effect of electrode materials on the removal of red tide organisms by microelectrolysis

The oxidizing active substances produced by microelectrolysis are highly efficient algicides, and the characteristics of the anode materials are the key factors affecting the type and content of the oxidizing active substances. Currently, systematic research on the effects of the anode material type using microelectrolysis to kill red tide organisms is insufficient. In this study, Heterosigma akashiwo was selected as the experimental organism, and the microelectrolyte algal removal performances of three typical anode materials, Dimensionally Stable Anode (DSA), Platinum (Pt), and Boron-Doped Diamond (BDD) were compared under various microelectrolysis conditions, and the intrinsic mechanism of the variability in the algal removal efficiency was analyzed. Under the experimental conditions of a current density range of 0.25-0.75 A cm^-2 and an electrolysis duration of 2-4 min, the algal removal efficiency of microelectrolytes generated by three anode materials followed this descending order: DSA (Ru-Ir-Ti) > Pt > BDD. When the current density was 0.75 A cm^-2 and the electrolysis time was 4 min, the algal removal efficiency of the DSA electrolyte reached 81.7 ± 2.3 %. The values were 11.8 % and 17.3 % respectively, which were higher than those of the Pt anode and BDD anode electrolytes. The oxidizing active substance produced by microelectrolysis for all three electrode materials was predominantly hypochlorite, and the difference in its content was the fundamental reason for the variability in the algal removal efficiency. Furthermore, compared with those of the other two electrodes, the lowest chlorine evolution potential (1.76 V) and the highest chlorine production rate (Tafel slope of 148.55 mV·dec^-1) were produced using DSA as an anode material, and these conditions also resulted in the highest hypochlorite content. These results provide essential theoretical basis for the efficient application and popularization of microelectrolysis in red tide management.