[Mechanism of enhancement on boron-doped diamond electrode electrochemical degradation efficiency by ultrasound].
Mass transport process, adsorption and desorption, and electrochemical reaction were analyzed to investigate the mechanism of enhancement on boron-doped diamond (BDD) electrode electrochemical degradation efficiency by ultrasound (US). US has considerable influences on the above steps of electrochemical oxidation. Mass transport coefficients of Ph and PA reach 2.0 x 10(-5) m/s with US, from 5.4 x 10(-6)m/s and 6.7 x 10(-6) m/s in EC process, increasing by 270% and 199%, respectively. The effect of US on adsorption and desorption has relationship with electrochemical adsorption properties of pollutants on BDD electrode surface. The adsorption amount of Ph decreases from 6.49 x 10(-10) mol/cm2 to 1.39 x 10(-10) mol/cm2, with the desorption of polymer intermediates promoted, so US makes positive effect with benefit to direct oxidation and oxidation peak current increases by 32%. For PA, the adsorption amount decreases from 1.25 x 10(-11) mol/cm2 to 3.11 x 10(-12) mol/cm2 with US, and no direct oxidation happens in US-EC process. US can improve degradation efficiency of BDD electrode and the enhancement on Ph degradation is more effective. Average electrochemical oxidation energy efficiency (AEE) of Ph increases by 287%, more than 224% of PA. This is because both direct and indirect oxidation for Ph can be enhanced by US, while for PA, direct oxidation almost disappears.
Shen
Shi-Hao
SH
Department of Chemistry, Tongji University, Shanghai 200092, China. jeffsshsh@126.com
Zhao
Guo-Hua
GH
Wu
Mei-Fen
MF
Lei
Yan-Zhu
YZ
Liu
Mei-Chuan
MC
D000327:Adsorption; D001895:Boron / Q000737:chemistry*; D018130:Diamond / Q000737:chemistry*; D004563:Electrochemistry; D004566:Electrodes; D010084:Oxidation-Reduction; D014465:Ultrasonics; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000295:instrumentation / Q000379:methods
D014874:Water Pollutants, Chemical; D018130:Diamond; D001895:Boron