| 2,4-dichlorophen(2,4-DCP) is one of the chlorophenols pollutants, which is toxic,refractory and widespread in the environment. It may have a bad influence on endocrine ofplants and animals, and jeopardize human’s health for its accumulating in the body.Bioelectrochemical technology can not only use of microorganisms as a catalyst andtransform electrochemical energy into electrical energy, but also degrade pollutants orproduce some useful substances, such as the treatment of printing and dyeing wastewater,urban sewage, the production of methanol, acetic acid, etc. Low energy consumption and highefficiency can be achieved when wastewater is treated using bioelectrochemical system, aswell as no secondary pollution. And thus, bioelectrochemical technology has been widelyconcerned at home and abroad.In this study, both abiotic cathode and biocathode double-chamber BES were builtsuccessfully firstly, with sodium acetate as the anode electron donor, and2,4-DCP as thetarget pollutants. Then, the performace of the degradation of2,4-DCP in two different BESwas prepared by the research methods from electrochemistry, analytical chemistry andbiology. At last, The preliminary mechanism for biocathode enhancing the degradation of2,4-DCP by biocathode was explored. Main results in the study were as flowed:1) The microbial flora of anaerobic sludge was directional breeding using the method ofmicroorganism domesticated with different concentration gradient of2,4-DCP. And thus, themicrobial flora’s tolerance ability to2,4-DCP was enhanced, and the degradation efficiencywas also improved by90%.2) Adouble chamber BES was builted with carbon brush as electrode, sodium acetate asthe anode substrate, which tried to remove2,4-DCP. And then filling cathode chamber withsimulated wastewater contained with2,4-DCP. Under this condition, BES with the biologicalcathode can maintain stable state for a long time, and its the capacity characteristics wasmeasured: the output voltage was0.005V, current was0.05mA and internal resistance327.3Ω.3) Three different external resistors were attached to BES with biocathode/abioticcathode, and then the influence of external resistor was studied on the degradation of2,4-DCP.It turned out that: external resistance of BES with biocathode has a great influence on theremoval of2,4-DCP, and100Ω was the best.4) Treatment efficiency of2,4-DCP using the two different BESs was compared andstudied. It turned out that:2,4-DCP could be degrade in both kinds of BES, and phenol wasone of the main intermediate products. Compared with the group with the abiotic cathode,degradation rate of2,4-DCP in the group with biocathode is much higher. The introduction ofthe cathode creatures can strengthen the degradation of2,4-DCP in cathode chamber of BES.5) Cathode potential, current, the cyclic voltammetric curves and polarization curve ofboth kinds of BES were tested with steady state method, and then the preliminary mechanismfor biocathode enhancing the degradation of2,4-DCP was researched. It is found that: firstly, with the cathode microbial, electron passed from the external circuit could be quicklyconsumed. The accumulation of the electron was reduced, the cathode potential was improved,and thus the voltage and current was increased; secondly, the introduction of cathodemicroorganism reduced the energy barriers of2,4-DCP reduction reaction, and then makingthe reaction much easier; more over cathode microbes could improve the productionperformance and coulombic efficiency of BES, reduce the internal resistance and then lessenthe energy consumed, and then improve the utilization efficiency of BES cathode electron. |
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