Electron Shuttling Function of Dissolved Organic Matter
水溶性有机物的电子穿梭功能研究

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.