微生物燃料電池陽極生物膜的保護與功率輸出的優(yōu)化研究
發(fā)布時間：2019-01-22 11:27
【摘要】：微生物燃料電池(MFC)是一種利用電活性微生物氧化降解有機小分子,將化學能轉化為電能的電化學裝置。近年來,關于MFC的理論基礎研究已取得了巨大的進展,然而其實際應用,特別是污水處理,還受到了極大的限制。一方面,當溶液中氧含量增大時,MFC陽極的厭氧電活性微生物的生物電化學活性會受到嚴重抑制甚至完全失去。因此,MFC技術難以與傳統(tǒng)的好氧污水處理技術相融合。另一方面,MFC的輸出不穩(wěn)定,單個MFC容易產生功率驟降,而且串聯(lián)MFC電池組容易發(fā)生電壓反轉,嚴重降低MFC的功率輸出。針對上述問題,本論文一方面采用物理交聯(lián)的聚乙烯醇(PVA)水凝膠對電活性微生物膜進行保護,以提高其耐氧性能;另一方面開發(fā)具有高電容的多孔碳泡沫(CF)材料作為MFC的陽極,以消除MFC的功率驟降和電壓反轉,提高MFC的功率輸出。第一部分以炭黑修飾的不銹鋼網作為陽極,在其上生長電活性微生物膜形成生物陽極;接著采用液氮冷凍/解凍物理交聯(lián)的PVA對生物陽極進行包裹固定,制備水凝膠微生物陽極。掃描電子顯微鏡(SEM)形貌表征顯示,液氮冷凍/解凍制備的PVA凝膠內部呈現(xiàn)規(guī)則的管狀結構。MFC全電池性能測試顯示,基于PVA水凝膠生物陽極的MFC可產生的最大電流密度為1.40 mA cm-2,功率密度為1200 mW m-2,與未包裹凝膠的不銹鋼網電極的產電性能相近。生物陽極的耐氧性能測試顯示,在曝純氧的條件下,水凝膠生物陽極的電活性沒有受到很大影響,以其構建的MFC的功率輸出也基本保持不變;而沒有水凝膠包裹的生物陽極,其電活性則急劇降低,這說明水凝膠生物陽極具有優(yōu)異的耐氧性能。水凝膠生物陽極的耐氧性能主要歸功于PVA水凝膠降低了氧氣擴散速率,阻礙了氧氣向電活性生物的擴散。第二部分采用高溫炭化三聚氰胺泡沫制備了柔性炭泡沫(CF)。CF具有較大的孔隙率和孔隙結構,有利于電活性微生物的生長。以900℃炭化的厚度為4 mm的碳泡沫(簡稱CF-900-4)作為陽極,可產生4.2 mA cm-2的電流密度�；贑F-900-4陽極和空氣陰極的組成的MFC,其功率密度高達3100 mW cm-2。此外,CF具有優(yōu)異的機械性能,能夠替代傳統(tǒng)剛性的炭基材料,為MFC的實際應用提供了可能。第三部分研究了電容型電極對MFC的功率驟降和其在串聯(lián)時產生的電壓反轉現(xiàn)象的影響。經過測試發(fā)現(xiàn)CF-900不僅是一種性能優(yōu)異的MFC陽極材料,還是一種出色的電容材料。充放電測試結果顯示CF-900的比電容值高達111 F g-1。將CF-900-4與空氣陰極組裝成MFC后發(fā)現(xiàn)單個電池不會發(fā)生功率驟降現(xiàn)象;MFC在串聯(lián)時也不會發(fā)生電壓反轉。因此,電容型的材料可以優(yōu)化MFC的功率輸出。
[Abstract]:Microbial fuel cell (MFC) is an electrochemical device which uses electroactive microorganisms to oxidize and degrade small organic molecules and convert chemical energy into electric energy. In recent years, great progress has been made in the theoretical research of MFC. However, its practical application, especially sewage treatment, has been greatly restricted. On the one hand, when the oxygen content in the solution increases, the bioelectrochemical activity of the anaerobic-active microorganism of MFC anode will be seriously inhibited or even completely lost. Therefore, MFC technology is difficult to integrate with the traditional aerobic wastewater treatment technology. On the other hand, the output of MFC is unstable, the power drop is easy to occur in a single MFC, and the voltage reversal is easy to occur in the series MFC battery pack, which seriously reduces the power output of MFC. To solve the above problems, on the one hand, the physical crosslinked polyvinyl alcohol (PVA) hydrogel was used to protect the electroactive microbial membrane in order to improve its oxygen resistance. On the other hand, the porous carbon foam (CF) with high capacitance is developed as the anode of MFC to eliminate the power drop and voltage reversal of MFC, and to improve the power output of MFC. In the first part, carbon black modified stainless steel mesh was used as anode, on which electroactive microbial membrane was grown to form biological anode. Then the hydrogel microbial anode was prepared by encapsulating and fixing the biological anode with liquid nitrogen freezing / thawing physical crosslinked PVA. Scanning electron microscopy (SEM) (SEM) analysis showed that the PVA gel prepared by liquid nitrogen freezing / thawing had a regular tubular structure. The maximum current density of MFC based on PVA hydrogel biological anode is 1.40 mA cm-2, power density is 1200 mW m-2, which is similar to that of uncoated stainless steel mesh electrode. The oxygen resistance test of the biological anode showed that the electroactivity of the hydrogel biological anode was not greatly affected under the condition of pure oxygen exposure, and the power output of the constructed MFC remained basically unchanged. However, the electrochemical activity of the biological anode without hydrogel encapsulation decreased sharply, which indicated that the hydrogel biological anode had excellent oxygen resistance. The oxygen resistance of hydrogel biological anode is mainly attributed to the decrease of oxygen diffusion rate by PVA hydrogel, which hinders the oxygen diffusion to electroactive organisms. In the second part, the flexible carbon foam (CF). CF) was prepared by high temperature carbonized melamine foam, which has large porosity and pore structure, which is beneficial to the growth of electrically active microorganisms. The current density of 4 mm carbon foam (CF-900-4), which was carbonized at 900 鈩，
本文編號：2413170
[Abstract]:Microbial fuel cell (MFC) is an electrochemical device which uses electroactive microorganisms to oxidize and degrade small organic molecules and convert chemical energy into electric energy. In recent years, great progress has been made in the theoretical research of MFC. However, its practical application, especially sewage treatment, has been greatly restricted. On the one hand, when the oxygen content in the solution increases, the bioelectrochemical activity of the anaerobic-active microorganism of MFC anode will be seriously inhibited or even completely lost. Therefore, MFC technology is difficult to integrate with the traditional aerobic wastewater treatment technology. On the other hand, the output of MFC is unstable, the power drop is easy to occur in a single MFC, and the voltage reversal is easy to occur in the series MFC battery pack, which seriously reduces the power output of MFC. To solve the above problems, on the one hand, the physical crosslinked polyvinyl alcohol (PVA) hydrogel was used to protect the electroactive microbial membrane in order to improve its oxygen resistance. On the other hand, the porous carbon foam (CF) with high capacitance is developed as the anode of MFC to eliminate the power drop and voltage reversal of MFC, and to improve the power output of MFC. In the first part, carbon black modified stainless steel mesh was used as anode, on which electroactive microbial membrane was grown to form biological anode. Then the hydrogel microbial anode was prepared by encapsulating and fixing the biological anode with liquid nitrogen freezing / thawing physical crosslinked PVA. Scanning electron microscopy (SEM) (SEM) analysis showed that the PVA gel prepared by liquid nitrogen freezing / thawing had a regular tubular structure. The maximum current density of MFC based on PVA hydrogel biological anode is 1.40 mA cm-2, power density is 1200 mW m-2, which is similar to that of uncoated stainless steel mesh electrode. The oxygen resistance test of the biological anode showed that the electroactivity of the hydrogel biological anode was not greatly affected under the condition of pure oxygen exposure, and the power output of the constructed MFC remained basically unchanged. However, the electrochemical activity of the biological anode without hydrogel encapsulation decreased sharply, which indicated that the hydrogel biological anode had excellent oxygen resistance. The oxygen resistance of hydrogel biological anode is mainly attributed to the decrease of oxygen diffusion rate by PVA hydrogel, which hinders the oxygen diffusion to electroactive organisms. In the second part, the flexible carbon foam (CF). CF) was prepared by high temperature carbonized melamine foam, which has large porosity and pore structure, which is beneficial to the growth of electrically active microorganisms. The current density of 4 mm carbon foam (CF-900-4), which was carbonized at 900 鈩，
本文編號：2413170
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