A novel structural composite (Fe-N/FeS@C) was synthesized via a self-doping strategy by the pyrolysis of a solid mixture of lignosulfonate and ferric nitrate pretreated by mechanical activation. The ...as-synthesized composite contained 7.5 wt% of single atomic iron moieties and 16.0 wt% of encapsulated FeS nanoparticles, with a high surface area of 1095.81 m2 g–1 and plentiful micropores and mesopores (0.4–10 nm). The Fe-N/FeS@C composite was confirmed to possess outstanding catalytic activity for sulfite activation in the degradation of methylene blue, with a high reaction rate constant (0.77 g g–1 min–1) and long cycling stability (83.1% of initial activity retention after 10 recycles). Moreover, the composite exhibited satisfactory activity recovery via a simple rinsing process with ethanol and HCl, and performed well in a wide pH range of 3–11. Density functional theory calculation results further demonstrated that the reaction energy of the rate-determining step, in which SO3•− was produced from SO32– on atomic Fe moieties, was lower than that of the formation of FeSO3+ by Fe3+ and SO32–. The excellent performance of Fe-N/FeS@C was mainly attributed to the combination of the high mass loading of active sites of atomic Fe moieties anchored into carbon matrix with encapsulated FeS nanoparticles. This study provides new insight into the development of environment-friendly, stable and atomic dispersion iron composite for sulfite activation to efficiently remove organic pollutants.
Display omitted
•A composite (Fe-N/FeS@C) was developed by MA and pyrolysis technology.•Activation of sulfite using the composite exhibits a superior catalytic activity.•Both SO4•− and •OH are identified as the main reactive oxygen species.•Single atomic irons and encapsulated FeS in the catalyst are key active sites.
Supported ionic liquid membranes (SILMs) has the potential to be a new technological platform for gas/organic vapour separation because of the unique non-volatile nature and discriminating gas ...dissolution properties of room temperature ionic liquids (ILs). This work starts with an examination of gas dissolution and transport properties in bulk imidazulium cation based ionic liquids C
nmimNTf2 (n
=
2.4, 6, 8.10) from simple gas H
2, N
2, to polar CO
2, and C
2H
6, leading to a further analysis of how gas dissolution and diffusion are influenced by molecular specific gas-SILMs interactions, reflected by differences in gas dissolution enthalpy and entropy. These effects were elucidated again during gas permeation studies by examining how changes in these properties and molecular specific interactions work together to cause deviations from conventional solution–diffusion theory and their impact on some remarkably contrasting gas perm-selectivity performance. The experimental perm-selectivity for all tested gases showed varied and contrasting deviation from the solution–diffusion, depending on specific gas-IL combinations. It transpires permeation for simpler non-polar gases (H
2, N
2) is diffusion controlled, but strong molecular specific gas-ILs interactions led to a different permeation and selectivity performance for C
2H
6 and CO
2. With exothermic dissolution enthalpy and large order disruptive entropy, C
2H
6 displayed the fastest permeation rate at increased gas phase pressure in spite of its smallest diffusivity among the tested gases. The C
2H
6 gas molecules “peg” on the side alkyl chain on the imidazulium cation at low concentration, and are well dispersed in the ionic liquids phase at high concentration. On the other hand strong CO
2-ILs affinity resulted in a more prolonged “residence time” for the gas molecule, typified by reversed CO
2/N
2 selectivity and slowest CO
2 transport despite CO
2 possess the highest solubility and comparable diffusivity in the ionic liquids. The unique transport and dissolution behaviour of CO
2 are further exploited by examining the residing state of CO
2 molecules in the ionic liquid phase, which leads to a hypothesis of a condensing and holding capacity of ILs towards CO
2, which provide an explanation to slower CO
2 transport through the SILMs. The pressure related exponential increase in permeations rate is also analysed which suggests a typical concentration dependent diffusion rate at high gas concentration under increased gas feed pressure. Finally the strong influence of discriminating and molecular specific gas-ILs interactions on gas perm-selectivity performance points to future specific design of ionic liquids for targeted gas separations.
This thesis studies composite ionic liquid and polymer membranes (CILPMs} for gas separation and reactive separation membranes (RSMs) for reactive separation at elevated temperature. The aim of this ...investigation is to develop feasible CILPMs and RSM s, and optimize operating conditions to achieve high permeability and selectivity for gas separation. ClLPMs are composed of ionic liquids for facilitating gases through membranes and polymers as support. Ionic liquids: C4mimNTh, C4mim jPF6 , C4mimFAP and polymers: PMDA-ODA PI, PBI were used to fabricate CILPMs in this project. A measurement rig was designed and built to measure permeabilities and selectivities of the CILPMs for H2, N2, CO, CO2 and CH4 at various pressures and temperatures. According to the results, gas permeability and selectivity of Cl l PMs were rarely changed with the pressure but greatly affected by the temperature. Normally, permeability increased and selectivity decreased with the rising of the temperature. The presence of ionic liquid in CILPMs had positive effect on CO2 permeation through the membranes, and therefore improved CO2 separation performance. However, H2 separation performance of the membranes was reduced by ionic liquids. RSMs combine the reaction and the separation in the membrane processes. In this project, RSMs were composed of CILPMs with dissolved catalysts for gas reaction. Ruthenium complexes were chosen as the catalyst for water gas shift reaction which transfers CO into H2 . The aim of reactive separation was increasing HJCO selectivity of the membranes and reducing the CO concentration in H2 stream to a very low level. A measurement rig for testing reactive separation was designed and built. According to the results, the water gas shift reaction occurred in RSMs increased the HJCO selectivity significantly under optimized conditions. A mathematical model was developed to simulate the reactive separation process and explain the results. CILPMs and RSMs showed improvements for gas separation and more research is required for optimizing these membranes.
During a grid voltage drop, a problem is resonances in the drive-train shaft between the wind turbine and induction generator. Disadvantageous effects caused by this are noticeable vibrations and ...high mechanical stresses due to torque oscillations. The oscillations can be damped using the drive train damper, which is used to mitigate fatigue loading of drive train components, controller consisting of a nonlinear observer to estimate the torque in the rotor and computes a damping torque signal that is added to the driver's demand. The control algorithm was implemented in the existing motor control unit without any additional hardware cost. The controller was successfully tested in a test. The resonances can essentially be eliminated.
High‐dimensional inference is one of fundamental problems in modern biomedical studies. However, the existing methods do not perform satisfactorily. Based on the Markov property of graphical models ...and the likelihood ratio test, this article provides a simple justification for the Markov neighborhood regression method such that it can be applied to statistical inference for high‐dimensional generalized linear models with mixed features. The Markov neighborhood regression method is highly attractive in that it breaks the high‐dimensional inference problems into a series of low‐dimensional inference problems. The proposed method is applied to the cancer cell line encyclopedia data for identification of the genes and mutations that are sensitive to the response of anti‐cancer drugs. The numerical results favor the Markov neighborhood regression method to the existing ones.
Detection and identification of vegetable seed borne Fusarium species Liang Lizhe (Beijing Municipal Academy of Agricultural and Forestry Sciences, Beijing (China). Inst. of Vegetable Crops)
Acta Agriculturae Boreali-Sinica (China),
(Dec 1987), Volume:
2, Issue:
4
Publication
PDF
