微生物群落对多氯酚的脱氯特性及机理研究

从正在运行的流化床生物反应器中分离出对三氯酚具有高效脱氯能力的微生物群落. 在含柠檬酸钛为氧化还原缓冲剂的合成培养基中研究了该群落的生理特性. 结果表明, 该微生物菌群可以利用丙酮酸为碳源和能源, 丙酮酸发酵、硫酸盐还原和脱氯反应三个过程严格地按顺序依次进行, 并且丙酮酸浓度在最初2 d内急剧下降, 同时有代谢产物乙酸、甲酸和氢气形成. 只有当硫酸盐被还原成硫化物后, 脱氯反应才会发生. 硫酸盐和钼酸盐的存在会强烈地抑制微生物的脱氯活性. 溴乙烷磺酸酯(BES)可以完全抑制微生物的产甲烷活性. 青霉素G(10 μg/mL)对该微生物菌群的脱氯作用没有抑制. 该微生物菌群按形态特征可以分为3类, 即弧菌、链球菌和杆菌. 利用荧光标记的16S和23S rRNA寡核苷酸探针进行原位杂交试验表明, 该微生物菌群中存在Proteobacteria的r亚类和δ亚类.     

LiFePO_4表面碳包覆方法中碳源的碳化及碳源选择

LiFePO4材料表面碳包覆可以有效地提高材料的电导率,从而进一步提高材料的容量和放电性能.但碳包覆所用的碳源不同,其效果也不尽相同.结合笔者实验室工作,分析了不同碳源的碳化过程,并结合碳包覆的工艺,对LiFePO4碳包覆方法中碳源的选择及碳包覆方法作了讨论.     

不同碳源对Li_3V_2(PO_4)_3/C复合正极材料性能的影响

以甲基纤维素、壳聚糖及葡萄糖分别作为碳源,应用碳热还原法合成正极Li3V2(PO4)3/C复合材料.XRD、SEM等方法分析、表征材料的结构、形貌和电化学性能.结果表明,碳源的选择对产物的比容量、循环寿命和倍率性能等均有较大的影响.以甲基纤维素为碳源制备的单斜Li3V2(PO4)3正极材料具有较好的电化学性能,在3.0～4.5V,0.2C倍率下,其初始容量为130.6mAh·g-1,30次循环后放电比容量仍可达到108mAh·g-1.     

不同碳源对多孔球形LiFePO4/C复合材料的影响

采用喷雾干燥-碳热还原法(SDCTM),分别研究了无机和有机碳源对锂离子正极材料LiFePO4/C形貌、结构及其充放电性能的影响。结果表明:以无机碳源炭黑制备的LiFePO4/C呈不规则球形,一次颗粒粒径在800nm左右,比表面积为2m2·g-1,0.1C放电比容量为107.3mAh·g-1。而以有机碳源制备的LiFePO4/C,其形貌较为规则,呈多孔球形结构,具有较高的比表面积和放电比容量。其中,以柠檬酸为碳源制备的多孔球形LiFePO4/C复合材料,其孔径均在50nm左右,比表面积可达32m2·g-1;在室温下,0.1C和10C首次放电比容量分别为158.8和87.2mAh·g-1,具有优异的循环性能和高倍率充放电性能。     

不锈钢网阴极微生物燃料电池的产电性能研究

构建了一个以曝气池污泥为阳极接种微生物、碳毡为阳极、无任何修饰的不锈钢网为阴极的双室微生物燃料电池. 通过输出电压、功率密度以及电化学阻抗等考察了阴极面积对电池产电性能的影响,并对电池的长期运行稳定性进行评价. 研究结果表明,不锈钢网作为微生物燃料电池的阴极性能稳定. 当不锈钢网面积为2 × 2 cm²时,最大输出电压达到0.411 V,功率密度为0.303 W•m^-2,内阻841 Ω,极化内阻80 Ω. 增大阴极面积至2 × 4 cm²,最大输出电压能达到0.499 V,内阻减小至793 Ω. 不锈钢网价格便宜,具有长期运行稳定性,适宜做MFCs的阴极.     

面包酵母对微量元素富集作用的研究

微量元素在维持生命的正常代谢过程中起着重要作用[1-12].但无机微量元素不但毒性较大,且以极低水平吸收,有机微量元素吸收迅速且安全,因此,利用工业微生物,尤其以酵母为载体富集微量元素,使微量元素由无机态转为有机态,以提高其生物利用度,已成为国内外研究重点.而且通过一定载体改变其化学状态,还能够确保适度含量,对医学防治具有更重要的意义.本文通过生物富集得到以氨基酸络合物等有机形式存在的微量元素,利于人体吸收利用.     

聚集诱导发光有机小分子无机纳米复合材料的研究进展

有机-无机复合荧光纳米材料制备简便,生物相容性好,成像性能优异,在化学和生物传感、生物成像、催化及能源材料等领域受到很多关注.传统的荧光有机小分子与无机材料复合时,常发生荧光猝灭,而聚集诱导发光(Aggregation-InducedEmission,AIE)有机小分子在聚集态具有高发光量子产率,为有机-无机复合荧光纳米材料的研究提供了机遇.由于AIE有机小分子功能化的无机纳米材料独特的优点,人们对其设计、合成及应用进行了较多研究.综述了AIE有机小分子和多种类型的无机纳米结构(金属纳米颗粒、钙钛矿材料、层状材料、氧化物、硫化物等)复合材料的制备和应用的新进展,特别是在化学和生物传感、生物成像、药物输运、光热治疗、催化以及能源等领域的应用,并对其发展前景进行了展望.     

活性聚苯乙烯膜诱导碳酸钙异相成核结晶

0引言生物矿物材料(如骨、牙齿、贝壳等)的优异性能[1]使得无机材料的仿生合成(又称有机模板合成)成为近年来研究的热点之一[2]。该合成技术的优点是,通过有机物分子与无机离子的相互作用,能够在温和的条件下合成出具有多级结构、特殊形貌和优异性能的有机/无机复合材料。CaCO3     

无机材料的仿生合成

生物矿化重要的特征之一是细胞分泌的有机基质调制无机矿物的成核和生长, 形成具有特殊组装方式和多级结构特点的生物矿化材料(如骨、牙和贝壳)。仿生合成就是将生物矿化的机理引入无机材料合成, 以有机物的组装体为模板, 去控制无机物的形成,制备具有独特显微结构特点的无机材料, 使材料具有优异的物理和化学性能。仿生合成已成为无机材料化学的研究前沿。本文综述了无机材料仿生合成的发展现状。     

阴极催化剂对微生物燃料电池性能的影响

以不同载量的MnO_2/rGO和Pt/C修饰阴极电极构建了生物阴极型双室微生物燃料电池(MFC),考察了不同阴极催化剂修饰MFC对其产电性能以及老龄垃圾渗滤液主要污染物去除效果的影响。结果表明,以MnO_2/rGO修饰MFC阴极电极材料,能显著提高MFC产电性能及对老龄垃圾渗滤液中污染物去除效果;输出电压为372 mV,功率密度为194 mW/m~3(是未经催化剂修饰MFC的两倍),内阻为264Ω,化学需氧量(COD)和氨氮(NH_3-N)去除率分别为58.68%和76.64%。当MnO_2/rGO载量为.0 mg/cm~2时,MFC性能与负载Pt/C的MFC性能接近,但构建成本却明显降低。     

大气颗粒物中棕色碳的化学组成、来源和生成机制

大气颗粒物中棕色碳(BrC)在近紫外波段具有强吸光性,并因其显著的气候效应被广泛关注。BrC组成、来源、演变和光学性质的不确定性是造成气候模型估算气溶胶辐射强迫不确定性的重要因素。本文综述了大气颗粒物中BrC的化学组成、来源和生成机制,聚焦分子水平上BrC组成、二次生成机制和吸光间的关联。大气颗粒物中BrC的主要类别包括有机溶剂(甲醇)提取的碳质组分、水溶性有机碳及类腐殖质; 分子水平上,硝基芳香烃和含氮杂环有机物是BrC的主要发色团。BrC的来源包括生物质等不完全燃烧一次排放和挥发性有机物氧化二次生成; 二次生成途径主要包括人为源芳香烃氧化生成硝基芳香烃等含氮组分、羰基化合物与铵/胺反应生成含氮杂环组分或低聚物。前体物和反应条件影响二次生成BrC的组成和吸光性质; BrC在大气传输过程中还会发生“光漂白”现象。在分子水平上识别和阐明BrC的发色团、二次生成机制及其演变过程是未来该领域的重点研究方向。     

Electrochemical Characterization of the Interaction of Multiwalled Carbon Nanotubes with Doxorubicin

It has been suggested that multiwalled carbon nanotubes (MWCNTs) interacting with pharmaceutics may be introduced into the body as nanocarriers. To deliver the anticancer drugs, covalent or noncovalent functionalization of MWCNTs is required. In this study, the influence of oxidation on MWCNTs in the interaction with chemotherapeutic drug, doxorubicin, was characterized. The binding of doxorubicin with MWCNTs decreased rapidly with the increasing oxidation period with sulfuric acid. However, with nitric acid, the interaction increased initially and slowly decreased with time. The best results were obtained for sulfuric and nitric acid following 1 and 3?h of oxidation, respectively. The results show that sulfuric acid provided more favorable interaction for MWCNTs with doxorubicin than nitric acid.     

Adsorption of Pentafluorophenol onto Powdered,Granular, and Cloth Activated Carbons

In the present study, the adsorption of pentafluorophenol from aqueous solution onto granular activated carbon, powdered activated carbon, and activated carbon cloth has been investigated from the equilibrium and kinetic points of view. To the best of our knowledge, the removal of pentafluorophenol from aqueous solution onto activated carbon have not been reported in the literature. The experimental equilibrium data, suitably fitted by the Toth, Langmuir-Freundlich, and Redlich-Peterson isotherms, have shown that the cloth and powdered carbons exhibit the highest adsorption capacity. For all the investigated samples, the experimental kinetic data have been satisfactorily interpreted by a pseudo-second-order model. From the fitting results it has been observed that the highest rate constant and initial rate of adsorption is shown by powdered activated carbon.     

Revisiting the reactivity of different carbon bases: A theoretical study

Quantum chemical calculations are performed on different carbon bases to understand the origin of their reactivity. Both carbon(0) and carbon(II) bases may show very high values of second proton affinity as well as bond dissociation energies for gem‐dimetallation. Thus, their distinction becomes blurred when subjected to electrophilic attack. However, unlike carbon(0) bases, carbon(II) bases are ambiphilic in nature owing to the presence of a σ symmetric lone pair and a vacant π orbital concentrated on the central carbon atom. Thus, they may show different reactivity when subjected to nucleophilic attack. This reactivity difference may be considered as another distinction between these two classes of compounds. © 2013 Wiley Periodicals, Inc.     

Adsorption of lead(II) and copper(II) on activated carbon by complexation with surface functional groups

The adsorption of lead(II) and copper(II) on an activated carbon (Filtrasorb 300, Chemviron) was characterized assuming that it takes place by formation of complexes with functional groups, present in the activated carbon. Their concentration and conditional adsorption coefficients were determined for each metal by titration of the carbon in suspension in aqueous phase, at constant acidity, with the metal itself. For each titration point, the concentration of the metal in the solution phase after equilibration was determined, and the data were processed by the Ruzic linearization method, to obtain the concentration of the active sites involved in the sorption, and the conditional constant. The effect of the pH was also examined, in the range 4-6, obtaining that the adsorption increases at increasing pH. The protonation and adsorption constants were determined from the conditional adsorption coefficients obtained at the different acidities. The concentration of the active sites is 0.023 and 0.042 mmol g⁻¹, and the protonation constants are 1.0×10⁶ and 4.6×10⁴ M⁻¹ for Pb(II) and Cu(II). The corresponding adsorption constants are respectively 1.4×10⁵ and 6.3×10³ M⁻¹. All the parameters are affected by a large uncertainty, probably due to the heterogeneity of the active groups in the activated carbon. Even if so, these parameters make it possible a good prediction of the adsorption in a wide range of conditions. Other sorption mechanism can be set up at different conditions, in particular at different pH, as it has been demonstrated in the case of copper(II).     

电吸附技术的应用与研究

本文综述了活性炭、活性炭纤维、炭气凝胶及活性氧化铝等材料的电吸附/脱附技术的研究进展。主要介绍了其在去除水中无机和有机污染物方面的应用，并对今后的研究方向提出了建议。     

聚苯乙炔/碳纳米管复合材料的导电性能研究

本文以无水A lC l3作催化剂合成聚苯乙炔(PPA),用H2SO4对其进行磺化改性,采用其混法制得了PPA/碳纳米管(CNTs)及磺化PPA/CNTs复合材料,对二者的常温电导率及变温电导率进行了测试。结果表明:磺化PPA的电导率较PPA的提高了3个数量级;随着CMTs含量增加,复合材料的电导率升高;PPA/CNTs导电的阈值是3%,达极限电导率(0.04S/m)所需CNTs含量为25%,而磺化PPA/CNTs导电的阈值是2%,达极限电导率所需CNTs(0.14 s/m)含量为25%。并分析了温度变化对复合材料电阻变化的影响因素。     

EMI shielding and dynamic mechanical analysis of graphene oxide-carbon nanotube-acrylonitrile butadiene styrene hybrid composites

Carbon nanomaterials such as carbon nanotubes (CNTs), graphene and their hybrid have been studied extensively. Despite having excellent properties of CNTs and graphene have not yet been fully realized in the polymer composites. During fabrication agglomeration of CNTs and restacking of graphene is a serious concern that results in the degradation of properties of nanomaterials into the final composites. To improve the dispersion of CNTs and restacking graphene, in the present research work, we focused on the hybridization of graphene oxide and CNTs. Multiwalled carbon nanotubes (MWCNTs), functionalized carbon nanotubes (FCNTs), and graphene oxide-carbon nanotubes (GCNTs) reinforced acrylonitrile butadiene styrene (ABS) composites were prepared separately by vacuum filtration followed by hot compression molding. Further, dynamic mechanical analysis (DMA), and electromagnetic interference (EMI) shielding properties of ABS composites reinforced carbon nanofillers were investigated. The dynamic mechanical properties of polymers strongly depend on the adhesion of fillers and polymer, entanglement density of polymer chains in the presence of carbon fillers. The dynamic mechanical characteristics such as storage, loss modulus, and damping factor of prepared composites were significantly affected by the incorporation of MWCNTs, FCNTs, and GCNTs. Maximum EMI shielding effectiveness of −49.6 dB was achieved for GCNT-ABS composites which were highest compared to MWCNTs-ABS composites (−38.6 dB) and FCNTs-ABS composites (−36.7 dB) in the Ku band (12.4–18 GHz). These results depict the great potential of GCNTs-ABS composites to be used in various applications of efficient heat dissipative EMI shielding materials for electronic devices.     

Directional pyrolytic growth of microscale carbon fibers on electrochemically pretreated polyacrylonitrile-based carbon microfibers

Vapor-grown carbon microfibers were synthesized pyrolytically on electrochemically pretreated polyacrylonitrile-based carbon microfibers (PAN-CFs) without introducing any catalyst. Cyclohexane was used as the carbon source for the growth of fibers in a thermal chemical vapor deposition process (CVD). Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used for the characterization of the fibers. Microscale carbon fibers with about 1 to 2 μm in diameter were formed at 1123 K, while carbon microfibers of about 0.3 μm in diameter were synthesized at 1048 K. A pretreatment at negative potential or sequentially at both positive and negative potentials was found to be a prerequisite for the growth of carbon microfibers in the CVD process. Without electrochemical pretreatment or when only a positive potential was applied, the growth of microscale carbon fibers did not occur. Correspondence: Michael Bron, Analytische Chemie – Elektroanalytik und Sensorik, Ruhr-Universit?t Bochum, Universit?tsstr. 150, 44780 Bochum, Germany