Spontaneous and Widespread Electricity Generation in Natural Deep-Sea Hydrothermal Fields

Deep-sea hydrothermal vents discharge abundant reductive energy into oxidative seawater. Herein, we demonstrated that in situ measurements of redox potentials on the surfaces of active hydrothermal mineral deposits were more negative than the surrounding seawater potential, driving electrical current generation. We also demonstrated that negative potentials in the surface of minerals were widespread in the hydrothermal fields, regardless of the proximity to hydrothermal fluid discharges. Lab experiments verified that the negative potential of the mineral surface was induced by a distant electron transfer from the hydrothermal fluid through the metallic and catalytic properties of minerals. These results indicate that electric current is spontaneously and widely generated in natural mineral deposits in deep-sea hydrothermal fields. Our discovery provides important insights into the microbial communities that are supported by extracellular electron transfer and the prebiotic chemical and metabolic evolution of the ocean hydrothermal systems.     

水热条件对立方状Co3O4形貌的影响

研究了原料浓度、溶液酸度、水热反应温度和时间以及陈化方式等条件对立方状Co3O4形貌和粒度的影响,采用XRD,TEM和IR等手段跟踪反应过程,并表征产物,对水热过程中的相转变和尖晶石相Co3O4的水热形成机理进行了初步探讨     

Investigation of in Situ Surface Plasmon Resonance Spectroscopy for Environmental Monitoring in and around Deep-Sea Hydrothermal Vents

We have developed a fiber optic Surface Plasmon Resonance (SPR) sensor capable of continuous in situ and real-time monitoring of physical or chemical properties in and around deep-sea hydrothermal vents. The spectroscopic sensor system was deployed on three Alvin cruises to hydrothermal fields in the eastern Pacific: cruise AT11-20 to the East Pacific Rise (EPR) and cruises AT11-31 and AT15-09 to the Juan de Fuca Ridge. The SPR-based sensor was integrated with a thermocouple employed to measure the densities of hydrothermal vent fluid and seawater surrounding the vent. The system was battery powered and placed in a pressure vessel capable of operating six kilometers below the ocean surface in and around hydrothermal vents. Results show the potential of in situ SPR analysis for monitoring in and around hydrothermal vents, including the ability to characterize spatial gradients of the dissolved hydrocarbons and mixing of vent fluid.     

一维有序ZnO纳米棒阵列的制备和优化

以氧化铟锡透明导电膜玻璃(ITO)做载体,先在室温下采用浸渍-提拉法制备出ZnO纳米晶作为种子层,再结合低成本的水热生长法合成了一维有序的ZnO纳米棒阵列.结合X射线衍射(XRD)、扫描电子显微镜(SEM)和能量色散谱仪(EDS)表征,研究了前驱液浓度、溶胶陈化时间、种子层提拉次数、水热生长时间和次数等5种因素对ZnO纳米棒的结构及形貌的影响.研究结果表明, ZnO纳米棒阵列的长度和直径会随着前驱液的浓度和溶胶陈化时间以及水热生长时间的延长而增加.当前驱液浓度为0.5 mol·L^-1时,陈化时间为24 h,浸渍-提拉3次,水热反应3次,每次反应时间为150 min时,可得到一维有序的ZnO纳米棒阵列.     

HYDROTHERMAL ACTIVITY AND SULFIDES IN THE MARIANA TROUGH

The submarine hydrothermal activity, its occurrence, the minerals and the chemical features of the hydrothermal sulfides in the Mariana Trough are described. The mineral phases and their existing forms of the hydrothermal products formed at high temperature and intermediate-low temperature are discussed. It has been considered that the hydrothermal activity in the Mariana Trough isa small-scale one, different from those on the mid-ocean ridges and in the deep fracture zones.     

Controlled synthesis of the ZnWO4 nanostructure and effects on the photocatalytic performance

ZnWO4 photocatalysts with various morphologies were synthesized by a hydrothermal process. The effects of hydrothermal temperature and time on the crystallinity and morphology of ZnWO4 catalyst were investigated. The crystallinity was enhanced with the increase of hydrothermal temperature and hydrothermal time. The formation of ZnWO4 nanoparticles was controlled via kinetic process above 160 degrees C, and ZnWO4 nanorods with a highly [100]-preferred orientation formed via the thermodynamically control process in the temperature range of 120-140 degrees C. The morphology and crystallinity of ZnWO4 photocatalyst have a significant influence on the photocatalytic activity for aqueous Rhodamine B and gaseous formaldehyde degradation. ZnWO4 nanorod catalyst showed a much higher photocatalytic activity than the nanoparticle one. The enhanced photocatalytic activity can be attributed to the anisotropic structure of nanorod.     

A facile vapor-phase hydrothermal method for direct growth of titanate nanotubes on a titanium substrate via a distinctive nanosheet roll-up mechanism

We present a facile vapor-phase hydrothermal approach for direct growth of vertically aligned titanate nanotubes on a titanium foil substrate. The resultant nanotubes display external diameters of 50-80 nm and walls with an average thickness of 10 nm that consist of more than 10 titanate layers. This is in strong contrast to the titanate nanotubes obtained from alkaline liquid-phase hydrothermal methods, which are generally smaller than 12 nm in external diameter and have walls consisting of less than five titanate layers. Importantly, the investigation confirmed that under vapor-phase hydrothermal conditions, the nanotubes were formed via a distinctive nanosheet roll-up mechanism that differs remarkably from those of conventional liquid-phase hydrothermal processes. For the first time, a coaxial circular cylinder crystal structure of the resultant nanotubes was confirmed.     

有机废弃物在水热-热解耦合过程中NOx前驱物的释放机制研究

以城市污泥(SS)、中药药渣(HTW)和硅藻(DT)为对象,在水平管式反应器上对比研究了水热处理前后样品在热解过程中NO_x前驱物的生成特征,并结合热重(TGA)和X射线光电子能谱(XPS)表征分析了该耦合过程对NO_x前驱物的影响机制。结果表明,在240℃下进行水热预处理能直接或间接地影响样品燃料N在不同热解阶段时的转化路径,从而在整体层面上降低NO_x前驱物的释放量,例如当热解温度为900℃时,源于水热焦燃料N的NO_x前驱物为55.0%(SS_(240))、48.1%(HTW_(240))和51.2%(DT_(240)),比未经处理样品的NO_x前驱物释放量分别少9.5%(SS)、6.0%(HTW)和15.4%(DT),但若以原料燃料N为基准,源于水热焦的NO_x前驱物则比未经处理样品的NO_x前驱物释放量分别少90.1%(SS)、41.9%(HTW)和59.8%(DT),并且对NH_3的抑制效果高于HCN。进一步根据热失重曲线及其半焦N官能团的演变规律可以推测,水热预处理对NO_x前驱物的两条影响机制,即含N官能团的脱除(对于初次反应的NH_3释放)与含N官能团的稳定化(对于二次反应的HCN释放),可为废弃物的清洁利用提供理论参考。     

Effect of trivalent elements on the thermal and hydrothermal stability of MCM-41 mesoporous molecular materials

Effect of trivalent elements on the thermal and hydrothermal stability of MCM-41 mesoporous molecular sieve materials has been investigated. Al(III) decreases the thermal and hydrothermal stability of MCM-41 materials, whereas La(III) and Fe(III), especially Fe(III), can improve the thermal and hydrothermal stability. Benzene adsorption and IR spectra suggested that thick channel wall and the fewer structural defect sites in MCM-41 would enhance the thermal and hydrothermal stability of MCM-41.     

无机固体功能材料的水热合成化学

综述了无机固体功能材料的水热合成化学进展。重点强调强关联系固体、无机-有机杂化材料、缺陷与混合价态固体、三重价态与原子尺度p-n结以及水热生物化学。     

Fe analysis by the ferrozine method: Adaptation to FIA towards in situ analysis in hydrothermal environment

The target of this study is the adaptation of the ferrozine method to flow injection analysis (FIA) to perform iron analysis in situ using an in situ chemical analyser in hydrothermal environments. The adaptation of the method to FIA was followed by its optimisation using an experimental design screening method. The goals of the optimisation steps were to decrease the detection limit and to increase the measuring range to cope with the constraints of in situ analysis. The method allows the determination of iron in the mixing zone of hydrothermal fluid, enriched in iron, and seawater. A single manifold gives the possibility to analyse either Fe(II) or ΣFe [Fe(II) + Fe(III)] in situ, or ΣFe in the lab on hydrothermal seawater samples. The measuring range of the method was increased to up to 2000 μM, which is coherent with the study of the chemical environment of communities associated with deep-sea hydrothermal activity. Finally, the method was applied in situ using the chemical analyser Alchimist during the ATOS cruise on hydrothermal vent fields on the Mid Atlantic Ridge.     

Influence of the hydrothermal treatment on the chromatographic properties of monolithic silica capillaries for nano-liquid chromatography or capillary electrochromatography

In the last decade, silica monolithic capillaries have focused more and more attention on miniaturized separation techniques like capillary electrochromatography (CEC), nano-liquid chromatography (nano-LC) and chip electrochromatography owing to their unique chromatographic properties and their simplified preparation compared with packed columns. They are synthesized according to a sol-gel multi-step process that includes, after a gelation step at 40 degrees C leading to the formation of the macropores network and the silica skeleton, a post-gelation step (hydrothermal treatment at 120 degrees C in basic medium) that allows to tailor the mesopores and finally a calcination or a washing step to remove remaining polymers. In order to reduce the synthesis time, the number of synthesis steps and above all the temperature synthesis, to adapt the synthesis of such silica monoliths in polymeric microsystem devices, we extensively studied the influence of the hydrothermal treatment and its duration on textural (pore size distribution) and chromatographic properties (retention, efficiency) of in situ-synthesized capillary monoliths in nano-LC and CEC. This study was performed on pure silica and octyl chains grafted silica monoliths. Untreated monoliths show small pores (<6 nm), whereas hydrothermally treated monoliths exhibit medium and large mesopores (8-17 nm). It was demonstrated that the hydrothermal treatment at 120 degrees C was not necessary for pure silica monolithic capillaries dedicated to normal phase liquid chromatography or hydrophilic interaction liquid chromatography (HILIC) and electrochromatography: the suppression of the hydrothermal treatment did not impair efficiencies in CEC and in nano-LC but contributed to increase in retention factors. Minimal plate heights of ca. 5 microm in CEC and 6 microm in nano-LC were obtained with or without hydrothermal treatment with bare silica. In the same way, the hydrothermal treatment was not necessary for grafted silica monoliths only dedicated to CEC. However, the results clearly indicate that the hydrothermal treatment becomes essential before grafting in order to preserve the efficiency of the monolithic silica capillaries dedicated to nano-LC: in this particular case, the suppression of the hydrothermal treatment leads approximately to a loss of a factor two in efficiency.     

水热处理锐钛矿TiO2纳米管阵列及其增强的光电催化活性

在含氟溶液中,通过电化学阳极氧化钛片成功制备了高度有序的TiO2纳米管阵列,先在450℃下煅烧使其晶化为锐钛矿相,再在不同温度下水热处理了这些锐钛矿阵列。用XRD、SEM和XPS表征了所制备的样品。通过在氙灯光照下光电催化降解对氯苯酚水溶液来检测样品的活性。以对苯二甲酸作为探测分子,用荧光光谱检测了在氙灯光光照下样品表面产生的羟基自由基(.OH)。通过线性伏安扫描的间隙光照实验,测定了样品的光电流响应。结果表明后水热处理对锐钛矿TiO2纳米管阵列的结晶度和形貌没有影响,但光电催化活性明显增强,而不同温度处理的样品的活性差别不大。水热处理后的TiO2纳米管阵列的光电催化活性增强的原因是,水热后TiO2纳米管阵列表面羟基含量明显增加,使得其在光电催化过程中生成的.OH增加。     

改进的水热法在无机非金属材料制备中的应用

综述了改进的水热法在无机非金属材料制备中的应用,主要包括有机溶剂-水热法、微波-水热法及有机溶剂-微波-水热法在合成纳米晶、金属氢氧化物、氧化物、晶须、水滑石及其他一些重要的无机功能材料制备中的应用。仲维卓等提出的晶体生长新理论的核心是"负离子配位多面体生长基元",模型把晶体内部结构所决定的生长规律和晶体具体的生长条件联系起来,弥补了以往晶体生长理论脱离生长具体条件的不足,开辟了水热法晶体生长理论研究的新途径。改进水热法实质上就是交叉学科技术在水热法中的应用,改进水热法虽已取得有良好的应用成果但仍存在有待解决的问题。     

先锋褐煤的热处理和水热处理改质

通过先锋褐煤热处理和水热处理,结合处理煤结构与性质表征,研究了热处理和水热处理对先锋褐煤结构、抽提和溶胀性能的影响,探讨了热处理过程水的作用。结果表明,低于热解温度下的热处理以非共价键解缔合及部分弱共价键热解为主,水与煤的水热反应能够抑制水热处理过程中煤的热解和小分子化合物释放。高温热处理以热解和脱氧为主,水热反应可以稳定煤热解活性基团,避免其二次裂解和交联,在一定程度上提高处理煤的混合溶剂抽提率,改善其溶胀性能。     

The effects of hydrothermal aging on properties and structure of bisphenol A polycarbonate

The properties and structure of Bisphenol A polycarbonate (PC) under hydrothermal aging were investigated. The results of mechanical testing indicate that there is obvious elongation at break on the curve of PC samples before hydrothermal aging and no elongation at break after aging. After aging, the bending strength and the tensile strength of PC increase. According to scanning electron microscopy photographs of fracture surfaces, after hydrothermal aging, there are many fragments linked to the fracture surface and the length of deformation at break disappears. Differential scanning calorimetry analysis shows that the glass transition temperature (T_g) of polycarbonate increases after hydrothermal aging. Fourier transform infrared spectroscopy shows hydrolytic degradation after hydrothermal aging.     

Preparation of RGO/TiO2 photocatalyst and the mechanism of its hydrothermal process

To improve the catalytic efficiency of nanotitanium dioxide, this research investigated the phase transformation, crystal growth, and hydrogen production efficiency of nanotitanium dioxide at different temperatures and pressures. The RGO/TiO₂ photocatalyst was prepared by a hydrothermal method using graphene oxide and butyl titanate as raw materials. Different types of photocatalyst samples were prepared by adjusting the reaction temperature and time in the hydrothermal process. X‐ray diffraction and transmission electron microscope techniques were employed to investigate the nucleation and growth processes of rutile and anatase in the hydrothermal process from the perspectives of thermodynamics and kinetics. The evolution of the titanium dioxide structure with hydrothermal temperature and hydrothermal time was analyzed. Finally, photocatalytic decomposition of water data shows that the photocatalyst with the best hydrogen production effect was obtained by 12 hr of hydrothermal treatment at a hydrothermal temperature of 180°C. The total hydrogen production of this sample was 0.037 mmol/g under a xenon lamp for 3 hr.     

介孔分子筛MCM-41的水热稳定性

介孔分子筛MCM-41在催化、吸附分离以及化学组装制备先进材料等方面具有潜在的巨大应用价值,但MCM-41的低水热稳定性使其在催化研究领域中的应用受到了极大的限制。因此,提高介孔分子筛的水热稳定性具有十分重要的科研和实际应用意义。笔者对介孔分子筛MCM-41低水热稳定性的原因作了简要分析,并系统地介绍了近几年来在提高介孔分子筛水热稳定性方面的研究工作。     

Quiescent hydrothermal synthesis of reduced graphene oxide–periodic mesoporous silica sandwich nanocomposites with perpendicular mesochannel alignments

Quiescent hydrothermal conditions were applied to synthesis of the sandwich nanocomposites of reduced graphite oxide (rGO) and periodic mesoporous silica (PMS) with vertically aligned mesochannels. It was found that the formation of the PMS–rGO–PMS sandwich structure is very sensitive to the surface and synthesis conditions. Although a higher temperature hydrothermal condition promotes reduction of GO and formation of bulky mesoporous nanoparticles, quiescent hydrothermal condition can serve as an alternative approach to obtain the unusual nanocomposites and slightly promote the structural stability of PMS on the surface of rGO.     

Charge reduction in a vermiculite by acid and hydrothermal methods: a comparative study

A comparative study on acid and hydrothermal methods as ways to reduce interlamellar charge has been carried out on a vermiculite. This study showed that the application of the hydrothermal treatment as a previous step to pillaring the vermiculites, reported here for the first time, is a new route to obtain the porous material with a particular interest as heterogeneous catalysts, starting from mineral clays with a high density of charge. Modified clays have been characterized by atomic absorption, emission spectrograph, X-ray diffraction, cation-exchange capacity, total acidity, infrared spectroscopy (DRIFT), and nitrogen adsorption. The results have shown that all solids have been structurally modified. However, acid and hydrothermal methods showed different behavior. For the vermiculite, the hydrothermal treatment did not produce major differences in terms of the crystalline structure, whereas the acid method caused severe structural damage. The catalytic properties have been tested over Pt-impregnated samples (1%) using the hydroisomerization of heptane. Important catalytic activity was established for all solids with high selectivity regarding the isomer products.