Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences
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Enhanced methane production of Miscanthus floridulus by hydrogen peroxide pretreatment
No full textPretreatment is very important for improvement of the biogas production from biomass in anaerobic digestion (AD) process, especially for lignocellulosic substrates. Hydrogen peroxide pretreatment (HPP) was used to enhance the AD of Miscanthus floridulus. Results showed that the maximum methane yield was produced at 0.8% H2O2 concentration at neutral pH, which was 278.7 mL/g VS (volatile solid) and increased by 49% compared to untreated sample. The results of XRD (X-ray diffraction) revealed that HPP process could marginally decrease crystallinity of cellulose which could be beneficial for better substrate utilization. In addition, SEM (scanning electron microscope) analysis suggested that pretreated miscanthus had a more porous structure compared to untreated substrate. Thus HPP is an environmental friendly and economical pretreatment method for AD of miscanthus. (C) 2017 Elsevier Ltd. All rights reserved
In Situ Generation of Poly (Vinylene Carbonate) Based Solid Electrolyte with Interfacial Stability for LiCoO2 Lithium Batteries
No full textNowadays it is extremely urgent to seek high performance solid polymer electrolyte that possesses both interfacial stability toward lithium/graphitic anodes and high voltage cathodes for high energy density solid state batteries. Inspired by the positive interfacial effect of vinylene carbonate additive on solid electrolyte interface, a novel poly (vinylene carbonate) based solid polymer electrolyte is presented via a facile in situ polymerization process in this paper. It is manifested that poly (vinylene carbonate) based solid polymer electrolyte possess a superior electrochemical stability window up to 4.5 V versus Li/Li+ and considerable ionic conductivity of 9.82 x 10(-5) S cm(-1) at 50 degrees C. Moreover, it is demonstrated that high voltage LiCoO2/Libatteries using this solid polymer electrolyte display stable charge/discharge profiles, considerable rate capability, excellent cycling performance, and decent safety characteristic. It is believed that poly (vinylene carbonate) based electrolyte can be a very promising solid polymer electrolyte candidate for high energy density lithium batteries
Preparation of -SO3--coated nanopromoters for methane hydrate formation: effects of the existence pattern of -SO3- groups on the promotion efficiency
No full textSodium dodecyl sulfate (SDS) has been confirmed to be the most efficient promoter of gas hydrate formation; however, the foam generation during hydrate dissociation severely limits its application. In this study, the -SO3- group, similar to the hydrophilic group of SDS, was covalently fixed on polystyrene nanoparticles to prepare -SO3- -coated nanopromoters (-SO3-@PSNS) for methane hydrate formation. The existing form of -SO3- groups was controlled by varying the ratio of the hydrophobic and hydrophilic monomers during emulsion polymerization, which produced significant influence on the promotion efficiency. At the initial pressure of 5 MPa, when -SO3- groups existed irregularly with the macromolecules of -SO3- @PSNS in solution (-SO3- @PSNS-1), the growth rate was merely 8.02 +/- 0.95 x 10(-6) mol min(-1) mL(-1); however, when -SO3- groups were uniformly arrayed on the surface of the -SO3- @PSNS nanospheres (-SO3- @PSNS-2-3-4), the growth rate reached 18.08 +/- 3.29-40.97 +/- 2.89 x 10(-6) mol min(-1) mL(-1). When nanopromoters with regularly arrayed -SO(3)(-)groups (-SO3- @PSNS-2-3) were used at the initial pressure of 6 MPa, the entire hydrate formation process was completed within 1-2 h and the methane storage capacity reached 142 and 137 v/v, indicating much better promotion compared to other common promoters, such as SDS, nanofluids, and activated carbon. Moreover, -SO3- @PSNS-3 resulted in no foam generation during hydrate dissociation and produced excellent recycling performance in 8 cycles of methane hydrate formation. Therefore, the -SO3- -coated nanopromoters developed in this study have significant potential in the industrial application of hydrate-based natural gas storage and transportation
Nanostructured Bimetallic Iron Molybdenum Nitride as a Non-Precious Cathode Catalyst for Li-O-2 Batteries
No full textHerein we report the facile fabrication and electrocatalytic activity of nanostructured bimetallic iron molybdenum nitride (Fe3Mo3N), which was prepared by an ammonolysis process directly towards the solid state mixture of Mo precursor and Fe precursor. The prepared nanostructured Fe3Mo3N presented remarkable electrocatalytic activities towards both oxygen reduction reaction and oxygen evolution reaction in nonaqueous phase, due to the modulation of electronic configuration of catalyst by Fe element and porous structure. Then, lithium-O-2 batteries with nanostructured Fe3Mo3N as cathode catalysts were assembled, which show alleviated polarization and enhanced cyclability
Hansen Solubility Parameters of Coal Tar-Derived Typical PAHs Using Turbidimetric Titration and an Extended Hansen Approach
No full textThe advantage of selectivity for coal tar extraction can be obtained by using the solubility parameter of Hansen theory as a guide. However, most of the Hansen solubility parameters (dispersion contributions, (delta)(d); polarity contributions, (delta)(p); hydrogen bonding contributions, (delta)(hb)) of coal tar components (e.g., polycyclic aromatic hydrocarbons, PAHs) were inadequate. This study estimated the Hansen solubility parameters of naphthalene, acenaphthene, anthracene, phenanthrene, pyrene, and fluoranthene from coal tar by applying a new approach regulated by turbidimetric titration and a calculating program based on the method of exhaustion. The extended Hansen approach was used to verify the new approach and evaluate the solubility of the six PAH components in different solvents. The results show that the new method can clearly identify the differences in Hansen solubility parameters caused by various combinations of benzene rings among some isomers (e.g., anthracene and phenanthrene). Among the six PAH compounds, high relativity between their Hansen solubility parameters and solubility data was revealed, indicating an excellent reliability of the new method. An extended Hansen approach is appropriate for the estimation of solubility for the six PAHs with acceptable deviations. Moreover, the relationship between the Hansen solubility sphere and the extended Hansen approach was successfully presented by regression analysis
A novel hierarchical porous nitrogen-doped carbon derived from bamboo shoot for high performance supercapacitor
No full textPorous N-doped carbons hold good prospects for application in supercapacitor due to their low-cost, large surface area, good surface wettability, high electrical conductivity as well as extra pseudocapacitance. However, most synthetic methods required the tedious and multiple-step process with the assistance of hard/soft templates or the massive use of chemical reagents, and exogenous nitrogen sources, which made them difficult to realize industrial production and application. Here, we described a novel hierarchical porous N-doped carbons fabricated by a facile and sustainable approach via hydrothermal treatment and subsequent carbonization process by using renewable bamboo shoots as the starting material without any templates, additional chemical activation and nitrogen source. The obtained bamboo shoot-derived carbons possessed a large BET surface area (up to 972 m(2) g(-1)), hierarchically interconnected porous framework, rich and uniform nitrogen incorporation (3.0 at%). Benefiting from these unique features, the novel carbon-based electrode materials displayed a high capacitance of 412 F g(-1) in KOH electrolyte and long cycling life stability. Thus, an advanced electrode material for high-performance supercapacitor was successfully assembled by a simple and scalable synthesis route with abundant renewable resources freely available in nature
Enhanced carboxylic acids production by decreasing hydrogen partial pressure during acidogenic fermentation of glucose
No full textIn this study, the effect of reduced hydrogen partial pressure (P-H2) on the generation of carboxylic acids from acidogenic fermentation of glucose was investigated. Three strategies were applied to reduce P-H2: headspace removal (T1), CO2 sparging (T2) and H-2:CO2 (80:20) sparging (T3). Results showed that the production of carboxylic acids in T1-T3 were 10.21, 11.64 and 12.71 g/L, respectively, which were 1.04, 1.19 and 1.30-fold of that in the control (T4). The composition of carboxylic acids changed significantly in T3 with enhancement of homoacetogenesis, as more acetate and butyrate were produced comparing to the control. In addition, decreasing P-H2 led to more carbon flow to carboxylic acids. Species of Clostridium became dominant in treatment T3, resulting in the shift of metabolic pathways. This study demonstrated that decreasing P-H2 could increase the production of carboxylic acids, especially under the strategy of enhancing homoacetogenesis
Surface-enhanced Raman scattering of dipolar molecules by the graphene Fermi surface modulation with different dipole moments
No full textWe report the modulation of Raman scattering spectrum of chromophore/graphene hybrids by tunning the molecular polarization with different terminal groups (methyl, methoxy, nitrile, and two nitros). Based on the density functional theory, the specific dipole moment values of the chromophore molecules are calculated. An obvious surface-enhanced Raman scattering (SERS) was observed and the scattering intensity of molecule increases with enlarged dipole moment. According to the analysis of G band Raman shifts of graphene, the enhancement of the Raman signal can be attributed to strong electronic coupling between graphene and chromophore, which is closely related with the modulation of graphene Fermi surface by changing the dipole moment of the molecule. Besides, the optimization of the ground state geometry and the binding energy of the hybrids were also calculated with the Density Functional Based Tight Bonding (DFTB) method, which confirms that the enhanced Raman scattering of molecules on graphene arises from the improved energy level matching between graphene Fermi surface and molecular band, further providing a new way to design novel SERS devices. (C) 2017 Elsevier B.V. All rights reserved
Design of photobioreactors for mass cultivation of photosynthetic organisms
No full text光合微生物是生产环境友好的目标产品的重要生物资源,光生物反应器是实现这些过程的重要工具。目前,用于光催化的光生物反应器的设计具有挑战性,大多数光反应器仍然采用半经验的方法进行设计和放大。即使对于高效的光生物反应器,由于缺乏对光的传播、流体动力学、传质、细胞生长之间耦合作用的深刻了解,依靠半经验方法设计的反应器具有投资和运行成本高、使用寿命短的缺点,因此迄今为止尚没有一款合适的光生物反应器可用于光合微生物的大规模培养。首先,本文概述了影响光生物反应器性能的关键参数包括光、混合、传质、温度、p H值、投资和运行成本等,强调了在商业化培养中光生物反应器的寿命、清洁成本和温度控制的重要性。然后,推荐了四种(即管式光生物反应器、塑料袋式光生物反应器、柱状气升环流式光生物反应器和平板气升环流式光反应器)可进行光合微生物大规模培养的光生物反应器。最后,阐述了采用计算流体力学这一有力工具进行光生物反应器建模从而实现光生物反应器的理性设计,并分析了当今数学建模的难点,展示了基于机理模型设计光生物反应器的发展前景。 Photosynthetic microorganisms are important bioresources for producing desirable and environmentally benign products, and photobioreactors (PBRs) play important roles in these processes. Designing PBRs for photocatalysis is still challenging at present, and most reactors are designed and scaled up using semiempirical approaches. No appropriate types of PBRs are available for mass cultivation due to the reactors' high capital and operating costs and short lifespan, which are mainly due to a current lack of deep understanding of the coupling of light, hydrodynamics, mass transfer, and cell growth in efficient reactor design. This review provides a critical overview of the key parameters that influence the performance of the PBRs, including light, mixing, mass transfer, temperature, pH, and capital and operating costs. The lifespan and the costs of cleaning and temperature control are also emphasized for commercial exploitation. Four types of PBRs-tubular, plastic bag, column airlift, and flat-panel airlift reactors are recommended for large-scale operations. In addition, this paper elaborates the modeling of PBRs using the tools of computational fluid dynamics for rational design. It also analyzes the difficulties in the numerical simulation, and presents the prospect for mechanism-based models. (C) 2017 THE AUTHORS. Published by Elsevier LTD on behalf of the Chinese Academy of Engineering and Higher Education Press Limited Company