基于电化学方法研究猪粪堆肥过程溶解性有机物电子转移能力演变规律

Electron Transfer Capacities of Dissolved Organic Matter Derived from Swine Manure Based on Eletrochemical Method

堆肥水溶性有机物(Dissolved organic matter,DOM)是堆肥有机质中最活跃的部分,而具有氧化还原能力的官能团使得DOM能够作为电子穿梭体促进微生物与电子受体间的电子传递。本研究提取了8个不同阶段堆肥样品的DOM,利用电化学方法,以2,2'-联氮双(3-乙基苯并噻唑啉-6-磺胺)二铵盐(ABTS)和敌草快农药(DQ)作为介导剂,工作电压设为0.61 V/^-0.49 V,分别测定电子供给能力(Electron donating capacity,EDC)和电子接受能力(Electron accepting capacity,EAC)。同时结合三维荧光光谱、红外光谱和元素分析等方法阐明DOM结构组分变化,并探讨其变化对电子转移能力的影响。结果表明,堆肥DOM的EDC从堆肥1 d的16.850μmol e^-/(g C)增加至43 d的22.077μmol e^-/(g C),EAC从堆肥1 d的1.866μmol e^-/(g C)降至43 d的1.779μmol e^-/(g C)。三维荧光光谱分析结果表明,在堆肥过程中类腐殖质组分含量逐渐增多,类蛋白组分逐渐减少,表明堆肥过程类腐殖质组分的形成对DOM的ETC起重要的贡献作用。红外光谱显示堆肥过程中DOM含量较高的羟基和羧基变化不显著,对电子转移能力无明显贡献。元素分析结果表明,DOM中氧元素含量随着堆肥进行而增加,含硫基团是电子转移能力的贡献基团。

Dissolved organic matter(DOM)is the most active fraction of compost organic matter.The presence of the redox-active functional groups in DOM allows it to act an electron shuttle to promote the electron transfer between microorganisms and terminal electron acceptors.In this study,the electron transfer capacities(ETCs)of compost DOM samples at eight different composting stages were determined by electrochemical method.The 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS)and Diquat dibro-mide monohydrate(DQ)were used to measured electron donating capacity(EDC)and electron accepting capacity(EAC)with working voltage 0.61 V/-0.49 V,respective.The evolution characteristics of the chemical structures and components were analyzed by combining the three-dimensional fluorescence spectra,fourier transform infrared(FTIR)spectra and elemental analysis.The results showed that the electron donating capacity(EDC)of DOMincreased from 16.850μmol e-/(g C)to 22.077μmol e-/(g C),The corresponding electron accepting capacity(EAC)decreased from 1.866μmol e-/(g C)to 1.779μmol e-/(g C).The results of three-dimensional fluorescence spectroscopy show that the relative contents of humuc-likeand protein-like components gradually increased and decreased,respectively,during the composting process.The humuc-like components were the main contributor for the ETC of DOM.FTIR spectra shows that there was no significant change in the hydroxyl and carboxyl group contentsof DOM during composting,suggesting no contribution of these function groups to the ETC of DOM.The elemental analysis showed that the content of oxygen in the DOM increased during the composting process,while the sulfur-containing group may be dominated contributor forits ETC.