Effect of catechins and tannins on hydroxyl radical formation in depleted uranium-hydrogen peroxide systems
Effect of catechins and tannins on hydroxyl radical formation in depleted uranium-hydrogen peroxide systems
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DOI：
10.1007/s10967-009-0133-4
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发表时间：
2010
影响因子：
1.6
通讯作者：
A. Nakajima;Emiko Matsuda;Y. Ueda
中科院分区：
文献类型：
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作者：
A. Nakajima;Emiko Matsuda;Y. Ueda
用自旋捕集法研究了儿茶素和单宁对铀酰离子（UO_（22+））-过氧化氢（H_2 O_2）体系的影响。表没食子儿茶素（EGC）清除·OH能力较低，但能显著增强和加速UO 22 +-H2 O2溶液中·OH的生成。表没食子儿茶素没食子酸酯（EGCG）具有较强的·OH-清除能力，在UO_（22+）-H_2 O_2溶液中能显著增强和加速·OH的生成。这些结果表明，EGC和EGCG对UO 22+还原为UO 2+的作用增强和加速了·OH的生成。单宁对UO_（22+）-H_2 O_2溶液中·OH生成的影响因单宁的不同而异。含羞草单宁（MMT）和白坚木单宁（QBT）对·OH的生成有促进作用，板栗单宁（CNT）、紫穗槐单宁（MBT）和没食子单宁（CGT）对·OH的生成有抑制作用;柿子单宁（PST）和甘比尔单宁（GBT）对·OH的生成有抑制作用，但这种抑制作用应与UO 22+离子的强耦合作用相结合。在紫外光照射的H_2O_2溶液中，MBT对·OH的吸收能力最强，MMT最弱。综上所述，MMT和QBT被归类为缩合单宁，具有非常高的还原UO 22+为UO 2+的能力，类似于儿茶素如EGC和EGCG，而MBT，一种可水解单宁，具有更高的还原·OH的能力。
The effects of catechins and tannins on the uranyl ion (UO22+)-hydrogen peroxide (H2O2) system were examined using the spin-trapping method. Epigallocatechin (EGC), having low•OH-scavenging ability, significantly enhanced and accelerated the hydroxyl radical (•OH) formation in the UO22+–H2O2solution. Epigallocatechin gallate (EGCG), having high•OH-scavenging ability, fairly enhanced and accelerated hydroxyl radical (•OH) formation in the UO22+–H2O2solution. These results indicate that the enhancement and acceleration of•OH formation are caused by the reduction of UO22+to UO2+by EGC and EGCG. The effects of tannins on•OH formation in the UO22+–H2O2solution varied with tannins. Mimosa (MMT) and quebracho (QBT) tannins enhanced and accelerated•OH formation, while chestnut (CNT), mylobaran (MBT) and Chinese gallo- (CGT) tannins heavily depressed it. In the solution containing persimmon (PST) and gambir (GBT) tannins, the depression of•OH formation caused by the strong coupling with UO22+ion should be added to the enhancement caused by the reduction of UO22+to UO2+. MBT indicated the highest ability to scavenge•OH in the UV-irradiated H2O2solution, and MMT, the lowest. In summary, MMT and QBT, classified as condensed tannins, have very high abilities to reduce UO22+to UO2+, similarly to catechins such as EGC and EGCG, while MBT, a hydrolysable tannin, has higher abilities to scavenge•OH.