Ultrasound enhanced electrochemical oxidation of phenol and phthalic acid on boron-doped diamond electrode

Abstract

The enhancement on degradation of two typical organic pollutants, phenol (Ph) and phthalic acid (PA) on boron-doped diamond (BDD) electrode is particularly investigated in this study. Results show that ultrasound (US) has remarkable influence on electrochemical (EC) oxidation of the two pollutants including degradation efficiency, EC oxidation energy consumption, mass transport and electrochemical reaction. With US, the enhancement on degradation efficiency and decreasing of EC oxidation energy consumption of Ph are more obvious. US can also efficiently reduce the average electrochemical oxidation energy consumption (AE), decreasing by 74 and 69% for Ph and PA, respectively. Mass transport process can be greatly accelerated by US. The mass transport coefficients of Ph and PA both reach 2.0 × 10 −5 m s −1 in ultrasound-assisted electrochemical (US-EC) process, from 5.4 × 10 −6 and 6.7 × 10 −6 m s −1 in EC, increasing by 270 and 199%, respectively. The reaction amount of Ph decreases by 79% with US, from 6.49 × 10 −10 to 1.39 × 10 −10 mol cm −2. For PA, the reaction amount decreases from 1.25 × 10 −11 to 3.11 × 10 −12 mol cm −2 with US. The oxidation peak current increases by 32% for Ph. While for PA, there is no direct oxidation happened in US-EC process.