铁氮掺杂碳纳米管/纤维复合物制备及其催化氧还原的效果

阴极催化剂是影响微生物燃料电池(microbial fuel cell,MFC)性能的关键因素.通过研究制备成本低廉、氧还原反应(ORR)催化活性高的阴极催化剂来替代Pt/C对于实现MFC规模化应用具有重大意义.研究采用化学气相沉淀法,以三聚氰胺作为碳氮前驱物、以黑珍珠2000或乙炔炭黑作为碳源,外加醋酸亚铁作为铁前驱物,合成了两种铁氮掺杂碳纳米管/纤维复合物(FeNCB和FeNCC),作为MFC的阴极催化剂.通过循环伏安法和旋转圆盘-环电极分析FeNCB、FeNCC和Pt/C的ORR催化活性的差异,并用MFC验证其差异.结果表明,FeNCB性能与Pt/C相当,优于FeNCC,其催化路径是通过4电子途径催化氧还原反应;MFC-FeNCB性能略优于MFC-Pt/C,显著优于MFC-FeNCB有助于MFC的扩大化,其最大功率密度为1 212.8mW·m~(-2),开路电压为0.875 V,电池稳定电压为(0.500±0.025)V.用X射线衍射、X射线光电子光谱、拉曼光谱等进一步分析显示,复合物中碳纳米管管径的大小、铁氮掺杂的类型和含量以及氧含量是引起制备的复合物催化氧还原性能差异的原因所在.     

聚噻吩改性阴极强化电极生物膜反应器去除硝酸盐机制研究

为进一步提高电极生物膜反应器的脱氮效能,采用导电聚合物聚噻吩(PTh)和电子穿梭体蒽醌-2,6-二磺酸二钠(AQDS)改性阴极材料石墨毡,系统研究了不同碳氮比(C/N)条件下,改性电极的应用对BER体系的脱氮效能、电极表面生物相和体系微生物群落结构等方面的影响.结果表明,应用PTh与AQDS协同处理石墨毡的BER体系的NO~-_3-N去除速率和效能均明显优于未处理电极体系,在HRT=4 h、C/N为2.0时NO~-_3-N的去除率达到90.0%以上.PTh/AQDS改性石墨毡电极的生物膜与电极的比重为0.26±0.04,其值为对照组的2.4倍,证明了PTh/AQDS改性后电极具有更优的生物相容性.应用PTh/AQDS改性电极的BER具有更好的微生物丰富度和多样性,AQDS促进了特定微生物Thauera_mechernichensis(24.6%)的富集和亚硝酸盐还原酶的活性,保障了BER体系的反硝化效能.     

Enzyme-electrolytic degradation of dichloromethane: Efficiency, kinetics and mechanism

Enzymatic electrolysis cell(EEC) has advantages over microbial electrolysis cell(MEC) due to the needless of microbe inoculation and high-efficiency of enzymatic reaction. In this study, an EEC was first applied to achieve the effective degradation of halogenated organic pollutants and dichloromethane(CH_2Cl_2) was utilized as a model pollutant. The results indicate that the degradation efficiency of CH_2Cl_2 after 2 hr reaction in the EEC was almost100%, which was significantly higher than that with enzyme(51.1%) or current(19.0%). The current induced the continuous regeneration of reduced glutathione(GSH), thus CH_2Cl_2 was degraded under the catalysis of GSH-dependent dehalogenase through stepwise dechlorination, and successively formed monochloromethane(CH_3Cl) and methane(CH_4). The kinetic result shows that with a current of 15 mA, the maximum specific degradation rate of CH_2Cl_2(3.77 × 10~(-3) hr~(-1)) was increased by 5.7 times. The optimum condition for CH_2Cl_2 dechlorination was also obtained with pH, current and temperature of 7.0, 15 mA and 35°C,respectively. Importantly, this study helps to understand the behavior of enzymes and the fate of halogenated organic pollutants with EEC, providing a possible treatment technology for halogenated organic pollutants.     

电极构型对空气阴极生物燃料电池发电性能的影响

在空气阴极生物燃料电池(ACMFC)中,从阴极扩散进入阳极的氧气能够被兼性微生物作为电子受体还原,进而导致电子损失严重.本研究利用葡萄糖作底物,对2种不同电极构型的空气阴极生物燃料电池ACMFC1和ACMFC2的功率输出和电子回收进行了比较研究.结果表明,ACMFC1的内阻为302.14Ω,阳极电位为-323mV,最大功率密度为3 070 mW/m³;ACMFC2的内阻为107.79Ω,阳极电位为-442mV,最大功率密度达到9 800 mW/m³.在间歇条件下,ACMFC2可以连续运行220h,电子回收率为30.1%;而ACMFC1只能运行不到50h,电子回收率为9.78%.因此,合理的设计空气阴极生物燃料电池电极构型可以减小内阻,增大电池电动势进而增大功率输出,提高电子回收率.     

Copper complexation by tannic acid in aqueous solution

The speciation of titrated copper in a dissolved tannic acid (TA) solution with an initial concentration of 4 mmol organic carbon (OC)/l was investigated in a nine-step titration experiment (Cu/OC molar ratio = 0.0030–0.0567). We differentiated between soluble and insoluble Cu species by 0.45 μm filtration. Measurements with a copper ion selective electrode (ISE) and diffusive gradients in thin films (DGT) were conducted to quantify unbound Cu(II) cations (‘free’ Cu) and labile soluble Cu complexes. For the DGT measurements, we used an APA hydrogel and a Chelex 100 chelating resin (Na form). Insoluble organic Cu complexes (>0.45 μm) was the dominant Cu species for Cu/OC = 0.0030–0.0567 with a maximum fraction of 0.96 of total Cu. At Cu/OC > 0.0100, Cu-catalysed degradation of aggregate structures resulted in a strong increase of free Cu and (labile) soluble Cu complexes with a maximum fraction of 0.28 and 0.32 of total Cu, respectively. Labile (i.e. DGT-detectable) soluble Cu complexes had a relatively high averaged diffusion coefficient (D) in the APA hydrogel (3.50 × 10⁻⁶– 5.58 × 10⁻⁶ cm² s⁻¹).     

PVA-SbQ固定叶绿体及其生物传感器在检测除草剂中的应用

聚乙烯－苯乙烯吡啶（PVA－SbQ）是一种新的光敏聚合物，在紫外光诱导下形成大分子网状结构，电镜照片显示PVA－SbQ固定的新鲜菠菜叶绿体－20℃贮存6mo后，内，外膜结构完整，类囊体膜排列整齐，还原DPIP的能力保留50％，将叶绿体膜固定在铂电极上，制成生物传感器，在含0．035H2O2的50mmol L^-1,pH7.4Tris-HCl缓冲液中，25℃条件下用示差脉冲伏安法检测除草剂，在0－1.0 μg/L浓度范围，百草枯，敌草隆，扑草净和阿特闰津具有较好的线性关系。图6参29     

Pt/Mg-Ce-O catalyst for NO/H<Subscript>2</Subscript>/O<Subscript>2</Subscript> lean de-No<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> reaction

The NO/H₂/O₂ reaction was studied under oxidizing conditions in the 100-400 °C range over 0.1 wt% Pt supported on various metal oxides such as MgO, CeO₂, SiO₂, La₂O₃, CaO, Y₂O₃ and TiO₂. The Pt/MgO and Pt/CeO₂ catalysts showed good catalytic behaviours. Here, we find that the Pt/Mg-Ce-O catalyst, prepared from MgO and CeO₂ by the sol-gel method, is a very active and selective catalyst towards N₂ formation in the whole 100–400 °C range. This catalyst appears to be the most active, selective and stable one ever reported in the literature for the NO/H₂/O₂ reaction, even in the presence of 5%v H₂O or 20 ppmv of SO₂ in the feed stream.Selected article from the Regional Symposium on Chemistry and Environment, Krusevac, Serbia, June 2003, organised by Dr. Branimir Jovancicevic.     

高浓度苯酚在石墨电极上电解特性的研究

研制了数据在线采集记录系统对高浓度苯酚在石墨电极上电解过程的循环伏安行为进行了研究。采用连续循环伏安法考察了体系电解的特点,并考察了支持电解质、扫描速率、苯酚的浓度对反应体系的影响。结果表明:峰电流密度与扫描速率的平方根及苯酚浓度呈线性递增关系,支持电解质的添加量在苯酚电解过程存在最佳值,多次扫描过程中峰电流密度有下降趋势。实验推断电解效率下降是由于电极表面被聚合物污染导致,这一现象对电解处理有机物种的系统控制过程具有重要意义。     

气体扩散电极制备及其对苯酚降解效果的研究

以质量比9∶1的活性炭和乙炔黑制备气体扩散电极,着重研究电流密度、pH值、曝气量等因素对H2O2产生量的影响.结果表明:pH值在较大范围内均适用;电流密度控制在50～75 mA/cm2,曝气量确定为5 L/min时,反应产生H2O2较多.另外,利用该气体扩散电极做阴极,石墨电极做阳极,以Na2SO4为电解质,研究了电解时间、电流密度、pH值、初始苯酚浓度、曝气量等因素对苯酚降解效果的影响.结果表明:在电流密度为75 mA/cm2、曝气量为5 L/min、初始pH=3的条件下,当苯酚的初始浓度为80 mg/L时,1 h后其去除率达77%.     

三维电极方法降解模拟废水COD机理研究

采用细胞色素C法和Ti(Ⅳ ) 5 Br PADAP法证实了三维电极降解废水COD过程中有活性物质H2 O2 及·OH自由基的存在 ;采用红外光谱对废水处理前后的有机物结构进行了研究。并对三维电极方法降解废水COD的机理进行了探讨