Department of Civil & Environmental Engineering, University of Utah, Salt Lake City, UT 84112, USA.
J Hazard Mater. 2010 Sep 15;181(1-3):521-5. doi: 10.1016/j.jhazmat.2010.05.045. Epub 2010 May 16.
The role of hydroxyl radical is investigated in electrochemical oxidation of organic contaminants with naphthalene as a model compound. The strategy employed was competitive kinetic for hydroxyl radical between naphthalene and other hydroxyl scavengers if the hydroxyl radical is produced in situ at the anode by the electrolysis of water. Methanol, d3-methanol, acetone and d6-acetone were used as competitors for hydroxyl radical and their molar concentrations were calculated based on their reaction constants with hydroxyl radical. The hydroxyl radical was not responsible for naphthalene loss in these experiments. The first order reaction rate constants in the batch experiments containing only naphthalene, 2 mM of each of acetone and d6-acetone were 0.093, 0.094 and 0.118 h(-1), respectively. Higher concentrations (4 mM) acetone and d6-acetone did not affect naphthalene degradation. Rate constants using methanol and d6-methanol as competitors for hydroxyl radical in batch degradations test were 0.128 and 0.099 h(-1), respectively. Based on the naphthalene degradation trends and reaction rate constants, it was concluded that, under the given set of conditions, hydroxyl radical was not responsible for naphthalene degradation during electrolytic degradation tests. This research suggests that the role of hydroxyl radical should be considered very carefully in modeling such indirect electrolytic oxidation processes.
研究了羟基自由基在电化学氧化有机污染物中的作用，以萘作为模型化合物。如果羟基自由基是通过水的电解在阳极原位产生的，则采用竞争动力学方法来研究羟基自由基与其他羟基清除剂之间的竞争动力学。甲醇、d3-甲醇、丙酮和 d6-丙酮被用作羟基自由基的竞争物，根据它们与羟基自由基的反应常数计算出它们的摩尔浓度。在这些实验中，羟基自由基不是导致萘损失的原因。仅含有萘、2 mM 每种丙酮和 d6-丙酮的间歇实验中的一级反应速率常数分别为 0.093、0.094 和 0.118 h(-1)。较高浓度（4 mM）的丙酮和 d6-丙酮对萘的降解没有影响。使用甲醇和 d6-甲醇作为竞争物的批处理降解试验中的速率常数分别为 0.128 和 0.099 h(-1)。根据萘的降解趋势和反应速率常数，可以得出结论，在给定的条件下，羟基自由基不是电解降解试验中萘降解的原因。这项研究表明，在模拟这种间接电解氧化过程时，应非常小心地考虑羟基自由基的作用。
