摘要:
Fenton反应中,由于各种介质价态及形态的改变,氧化还原电位(ORP)也随之发生变化.在滴加H2O2过程中,H2O2/[Fe2+]0的摩尔比小于0.75时,ORP的升高是一个快速过程;大于0.75后,ORP的变化趋于缓慢.当体系中没有加入有机物时,随着过量H2O2的加入,Fe2+以微量且较稳定的浓度存在,体系的ORP也保持较稳定的状态;当加入石油烃后,伴随着H2O2浓度降至微量,少量Fe3+能被有机自由基还原成Fe2+,相对应的ORP也出现下降.不同H2O2浓度对应不同的ORP曲线,H2O2浓度愈高,ORP最大值出现得也愈迟.通过研究ORP的变化规律,进一步揭示了Fenton反应的机理.
Abstract:
Transformations of both chemical valence and species of reagents brought about variation of redox potential(ORP)in Fention's reaction.When H2O2 is titrated into an Fe2+ bearing solution,ORP increased rapidly with increasing H2O2 at a molar ratio of H2O2/[Fe2+] 0 below 0.75.Above the ratio,however,the increasing rate of ORP evidently slowed down.In the absence of organic substrate,the ORP remained as a constant value for a longtime following a fast increase with addition of H2O2.When hydrocarbon is added into the solution,however,there exists the maximum ORP,and increase of Fe2+ was observed after it arrived at the minimum point.Different H2O2 do ses corresponded to different ORP curves.Longer time was needed to reach the maximum point of ORP for a higher concentration of H2O2.