Studies on degradation of traditional Chinese medicine wastewater by a novel doped Ti/PbO2 electrode

In this study, we prepared a novel lead dioxide electrodes doped with Bi and Cu on Ti substrate by electro-deposition, and applied this electrode in electro-catalytic tests to treat traditional Chinese medicine wastewater. The electrode was characterized by using the Scanning Electron Microscope (SEM), Energy Dispersive X-ray Detector (EDX), and X-ray Diffraction (XRD). The results showed that this novel electrode got good surface characteristics. Electro-catalytic experiments were conducted at 3800 mg·L^-1 initial COD and 15 g·L^-1 initial chloride ions. By means of orthogonal test, we got the best conditions, the pH value, plate spacing, current density and electrolysis time were 9, 1 cm, 30 mA·cm^-2 and 240 min, respectively. Among these four factors, the most important was pH, then the current density and distance between plates, and the minimal influence factor was time of electrolysis. Under these conditions, the removal efficiency of COD and chloride ion by electro-catalytic reached to 63% and 42%, respectively. Although the effluent still met the requirements of biological treatment, excessive influent concentration (raw wastewater) had an adverse effect on COD and chloride ion removal. The novel electrode we have prepared could effectively remove COD and chloride ions from the traditional Chinese medicine wastewater and significantly improve the wastewater biodegradability, so this method had a practical value.