| BAI He-na,WANG Run,YANG Wan-lin,CHEN Wei-peng,DENG Ze-jun,WEI Qiu-ping,LI Jing,MA Li.Electrochemical Oxidation Performance Changes of Si/BDD Electrode under Concentrated Acidic/Basic Electrolytic Conditions[J],52(5):121-130 |
| Electrochemical Oxidation Performance Changes of Si/BDD Electrode under Concentrated Acidic/Basic Electrolytic Conditions |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.05.012 |
| KeyWord:boron doped diamond electrode electrochemical oxidation electrode stability accelerated lifetime experiments reactive blue 19 |
| Author | Institution |
| BAI He-na |
State Key Laboratory for Powder Metallurgy,Changsha , China |
| WANG Run |
School of Materials Science and Engineering, Central South University, Changsha , China |
| YANG Wan-lin |
School of Materials Science and Engineering, Central South University, Changsha , China |
| CHEN Wei-peng |
School of Materials Science and Engineering, Central South University, Changsha , China |
| DENG Ze-jun |
School of Materials Science and Engineering, Central South University, Changsha , China |
| WEI Qiu-ping |
State Key Laboratory for Powder Metallurgy,Changsha , China ;School of Materials Science and Engineering, Central South University, Changsha , China |
| LI Jing |
School of Materials Science and Engineering, Central South University, Changsha , China |
| MA Li |
State Key Laboratory for Powder Metallurgy,Changsha , China |
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| Abstract: |
| Boron doped diamond electrode (BDD) is commonly considered as an ideal anode material for electrochemical oxidation treatment of wastewater. However, the surface of BDD encounters apparent corrosion when performing in concentrated acidic or basic conditions for a considerable time up to hundreds of hours. The work aims to comparatively investigate the change characteristics of electrochemical oxidation performance of the Si/BDD electrode in concentrated acidic (1 mol/L H2SO4) or basic (1 mol/L NaOH) conditions via accelerated lifetime experiments under a constant current density of 1 A/cm2 at room temperature and expound the change and failure mechanism of electrochemical oxidation performance of BDD electrode in acidic or basic solutions. The two-electrode system was used, with a Si/BDD electrode (surface area of 4 cm2) and the stainless steel plate (with surface area equivalent to that of BDD) was adopted as the anode and cathode, respectively, and the distance between them was set as 10 mm. The cell voltage during the electrolysis process was recorded with time. The variations of cell voltage were used to assess the stability of the Si/BDD electrode. During electrochemical degradation tests, reactive blue 19 (RB-19) was chosen as the simulated dye wastewater. The fixed volume of wastewater was taken out for further characterization of the dye concentration via UV-visible spectrophotometer according to the absorbance intensity. Scanning Electron Microscope (SEM) and Raman spectroscopy were performed to characterize the morphology and composition of the Si/BDD electrode. The hydrophilicity or hydrophobicity was assessed by contact angle measurement. The electrochemical potential window for water stability after different electrolytic conditions as well as electrolytic times was determined to further assess the stability of the Si/BDD electrode. The stability of the Si/BDD electrode in 1 mol/L H2SO4 solution was different from that in 1 mol/L NaOH solution. After 195 h of electrolysis in a concentrated basic condition (i.e., 1 mol/L NaOH), an obvious corrosion phenomenon was found at the surface of the Si/BDD electrode and part of the film surface was even peeled off. As for the acidic electrolytic condition (i.e. 1 mol/L H2SO4), no peeling off was observed at the electrode surface after 600 h electrolysis. However, with the changes in the size of grain crystals and the crystal edges throughout the electrolysis, obvious corrosion occurred at the surface morphology of Si/BDD electrode, with the crystal facets forming a clear morphology to a fuzzy one. In addition, different variations of the degradation performance were observed with the Si/BDD electrode for concentrated acidic or basic conditions regarding the degradation of RB-19 dye wastewater. In concentrated basic conditions, the degradation performance firstly experienced a slight climb up to 10 h of electrolysis, followed by being unchanged with electrolysis. In terms of the concentrated acidic conditions, the degradation performance continuously increased with electrolysis. The corrosion of Si/BDD electrode in the basic solution is stronger than that in the acidic solution. Moreover, electrolysis in basic condition for 10 h is sufficient to achieve oxidation of the surface terminal from hydrogen to carboxyl, carbonyl and other oxygen-containing functional groups. These generated terminal groups are beneficial to promoting the water oxidation reaction and thus the degradation performance. However, in the acidic solution, the edges of the Si/BDD electrode are consistently electrochemically etched, forming numerous smaller sizes of crystal crystals and increasing the electroactive surface area, thus improving the degradation performance. |
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