超声辅助电催化氧化降解苯酚影响因素的研究

为探讨水体中苯酚的超声辅助电催化氧化降解,考察了超声的频率和声强、溶液的pH值、温度、支持电解质的浓度,电流密度以及苯酚的浓度等因素的影响。在超声声强分别为21.1W/cm2和27.1W/cm2下电催化氧化降解40min,COD去除率分别为59.3%和64.4%,明显高于无超声作用下41.6%的COD去除率;在中性和弱碱性介质中(pH0值在7￣11之间)苯酚的降解效果较好,pH0=10时,苯酚降解的准一级反应速率常数最大;体系的初始pH值超过11,苯酚的降解速率下降很快,这主要是因为体系的碱性太强导致许多副反应的发生,降低了电流效率,反而不利于污染物的氧化降解;溶液中的支持电解质Na2SO4的浓度(CNa2SO4)为10g/L时,苯酚降解的准一级反应速率常数和电催化氧化降解反应时的槽电压均达到最优;在电催化氧化降解过程中,随着电流密度的增加,污染物的氧化降解速率和效率也随之增大。综合考虑降解效率和电流效率两方面因素,电流密度在10￣30mA/cm2范围内较为适宜。

Influence Factors of Ultrasonic-assistant Electrocatalytic Oxidation of Phenol

ID: 1003-6504(2006)10-0007-03-EAAbstract: Factors including ultrasonic frequency and intensity, pH, temperature and electrolyte concentration were investigated during the process of ultrasonic-assistant electrocatalytic oxidation of phenol. COD removal efficiency was 59.3% and 64.4% respectively under ultrasonic intensity of 21.1 and 27.1 W.cm-2 in 40min electrolysis, which was significantly higher than that of 41.6% without ultrasonic. The efficiency of phenol degradation was better in neutral and weak basic medium with pH range of 7~11. Quasi-first order constant and applied voltage can be optimized in Na2SO4 concentration of 10g.L-1. The rate and efficiency of degradation rise with increase of current intensity during the process, with appropriate current intensity range from 10 to 30 mA.cm-2.