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Study The Electrochemical Distribution Characteristics Of Artifical Biofilms/Metals Interface Using Wire Beam Electrode Techinque

Posted on:2010-08-21Degree:MasterType:Thesis
Country:ChinaCandidate:X ZhangFull Text:PDF
GTID:2121360275985686Subject:Applied Chemistry
Abstract/Summary:PDF Full Text Request
Biofilms on metals surface in seawater is a complex electrochemical system. The heterogeneous electrochemical characteristics of biofilm/metal interface can be changed by biofilms adsorption, which has drawn increasing attentions in microbially influenced corrosion (MIC) studies. Conventional electrochemical techniques, which have been successfully used in MIC study for many years can only obtain average data on metals surface. Therefore, it is very difficult to perform them in heterogeneous electrochemical research. Local electrochemical techniques can overcome these limitations. Wire beam electrode technique can be applied in the study of heterogeneous electrochemical characteristics of biofiom/metals interface and obtain the local potential and current distributions. A novel device used for the wire beam electrode (WBE) method was developed in our lab. The system consists of standard modules (PXI 1033, PXI 2535, 4071 and 4022) and is controlled by a self-designed software (under LabVIEW environment, National Instruments Co., NI). The artificial biofilm is made by natural polysaccharide gel-calcium alginate. Hydrogen peroxide(H2O2) and glucose oxidase(GOD) are fixed in location of biofilm. In our study, this device and immobilization methods are used to investigate the potential/current distribution at artificial biofilm/matels interface for the first time. The main conclusion is as follows:(1) The simulated result shows that the potential and current distributions on stainless steel surface are heterogeneous. The heterogeneity is closely related to the H2O2 distribution in the biofilm. The presence of H2O2 can cause the potential ennoblement of stainless steel. The local ennoblement value of the stainless steel is higher than that of the whole stainless steel and the ennoblement of the whole electrode has a close relationship with the local potential ennoblement. (2) H2O2 can also cause the potential ennoblement in mild steel surface. The presence of H2O2 in location can lead to the local potential and the whole potential ennoblement. The whole potential ennoblement is determined by the local potential ennoblement. The mild steel is corrosible and the influence of H2O2 to the ennoblement of mild steel is not visible and the ennoblement disappears in a short time. Biofilms adsorption in location of mild steel can lead to the formation of anode current area.(3) GOD in biofilm can also cause the local and the whole potential ennoblement in stainless steel surface. The GOD can catalyze the oxidation of glucose to form H2O2 and gluconic acid. The production (H2O2) lead to the potential ennoblement. Ennoblement in location of stainless steel can lead to the formation of cathode current area.(4) The GOD can catalyze the oxidation of glucose to form H2O2 and gluconic acid. H2O2 lead to the ennoblement of the potential on mild steel surface. The potential peak disappear quickly. The gluconic acid production was the reason for the potential peak decrease because of the active electrochemistry of mild steel.(5)Our experiments have proved the WBE method and the device based on PXI to be a powerful tool in investigating the heterogeneous characteristics of biofilm/metals interface. This device is suitable for other heterogeneous electrochemical processes study at the micro-scale.All in all, biofilms adsorption can lead to heterogeneous electrochemical characteristics on metals surface. This indicates that the whole potential has relationship with the local potential distributions. It is concluded that that the whole potential value in metals surface is closely related to the heterogeneity and the adsorption area of biofilm. The WBE method is a potential powerful technique in MIC study.
Keywords/Search Tags:Wire beam electrode, Biofilm, Potential /Current distribution, Hydrogen peroxide, Glucose oxidase
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