水溶性有机物的电子穿梭功能研究

以源于污泥的DOM(dissolved organic matter)为供试材料,以中国希瓦氏菌(Shewanella cinica)D14T为电子转移驱动力,研究了DOM的氧化还原性能与电子穿梭功能.结果表明,污泥DOM可作为末端电子受体接受醌还原菌D14T呼吸链上的电子,从而转变为还原态DOM,而还原态DOM可将电子再次转移给Fe(Ⅲ).经D14T还原后,DOM电子供给量(e-/C)由初始2.2~14μmol.g-1增加到253~347μmol.g-1.循环伏安法与多次还原-氧化循环实验表明,DOM呈现2对明显的氧化还原峰,经3次还原-氧化循环后电子供给量可稳定维持在150~250μmol.g-1之间,说明DOM具有重复利用、反复转移电子的特性.在菌株D14T还原水铁矿的体系中,加入DOM可提高水铁矿的还原溶解速率,其原因是DOM在D14T与水铁矿之间充当了电子穿梭体的角色.这些结果反映了DOM在电子转移反应中的重要性,为DOM的环境属性提出了一个新见解.

Electron Shuttling Function of Dissolved Organic Matter

The redox reactive and electron shuttling function of dissolved organic matter (DOM) derived from sewage sludge were studied with Shewanella cinica D14~T as driving force of electron transfer. The results indicated that sludge DOM initially served as terminal electron acceptor obtaining electrons from the respiratory chain of quinone-reducing bacteria D14~T , then it translated to reduced DOM which can donate electrons to Fe(Ⅲ) again. The electron donating capacities (EDC) of DOM increased from initial capacity of 2.2-14 μmol·g~(-1) to 253-347 μmol·g~(-1) after DOM was reduced by D14~T . The cyclic voltammetry measurements and multiple reduction-oxidation cycles experiments of DOM showed that two pairs of redox peaks were clearly observed and the EDC remained at a level of 150-250 μmol·g~(-1) after three reduction-oxidation cycles, indicating that DOM can be recyclably used for electron transfer. In the system of hydrous ferric oxide (HFO) reduction by S. cinica D14~T , the reductive dissolution speed was improved with the presence of DOM, since that DOM was capable of acting as an electron shuttle between S. cinica D14~T and HFO. These results demonstrate the important role of DOM in electron transfer process, and bring out a new perspective about the functions of DOM in the environment.