Band 18, Heft 2 -

The effect of lanthanum addition on the activity of a series of Ni/γ-Al 2 O 3 catalysts for anisole hydrodeoxygenation (HDO) was evaluated. Catalyst characterization using hydrogen temperature-programmed reduction (H 2 -TPR) and UV-visible spectroscopy suggests that lanthanum incorporation results in the formation of larger metallic Ni domains in the catalyst surface, which in turn favour the direct anisole hydrogenation pathway to methoxycyclohexane. Despite the improvements to reducibility that resulted from the incorporation of La, the catalysts displayed lower selectivity towards cyclohexane, independent of total nickel loading. The catalytic activity results were rationalized in terms of a proposed reaction pathway where anisole is initially hydrogenated followed by sequential deoxygenation steps.

The melts dissolution characteristics and reaction process during the preparation of Fe-Si alloys by the melts electrochemical method were studied. The thermodynamic calculations and experimental results showed that the solubility of SiO 2 in KCl-NaCl-NaF melts was 0.24 mas% at 1073 K. The cyclic voltammetry data showed that the reduction of SiO 2 on a Pt electrode was a one-step electron process; when SiO 2 accounted for 0.24 mas% of the NaCl-KCl-NaF melts, the Fe-Si alloy was prepared by electrodeposition at 1073 K. When the deposition time was 30 min, Fe 3 Si was formed.

Fe/ZSM-5 catalysts were prepared by three kinds of ion exchange methods: aqueous ion-exchange (AI), hydrothermal ion-exchange (HI) and solid-state ion-exchange (SI). Their catalytic activities were tested for NOx reduction by CO in a separated NOx adsorption-desorption process. In this paper, performances of adsorption, reduction and dynamic adsorption-reduction were all investigated. All three catalysts exhibited good reduction activity at above 300 °C. Fe/ZSM-5(SI) exhibited excellent NOx removal efficiency in the dynamic adsorption-reduction experiments. However, in the dynamic process the adsorption efficiency of Fe/ZSM-5(AI) and the reduction efficiency of Fe/ZSM-5(HI) is not very good. The catalysts were further characterized by SEM, BET, XRD, XRF, XPS and TPD. It was found that the Fe content of the Fe/ZSM-5(SI) was the highest. Further, Fe is supported in the form of Fe 2 O 3 particles. Bronsted acid sites were also playing a major role in the high catalytic activity. TPD and in situ DRIFT experiments show that more Fe loading in α acid sites could result in a higher NOx removal efficiency.

Heat transfer and flow characteristics under air-water Taylor flow in a square microchannel with T-junction were investigated in this work. Different hydraulic diameters of models were discussed numerically by VOF method. Flow patterns such as bubbly flow, slug flow, annular flow and churn flow were identified by both numerical simulation and experimental methods. Simulation results including bubble formation process, bubble length, bubble velocity, void fraction and heat transfer fit well with literature data. The pressure differential of two sides in gas phase played an important role in bubble development. The gas and liquid superficial velocities were found to have a significant impact on bubble behavior. And the higher liquid viscosity would promote higher bubble velocity, also enhance heat transfer, but weaken the void fraction. The results showed a tiny but not ignorable effect of geometric dimensioning on bubble and liquid slug lengths. An appropriate correlation was proposed to estimate bubble length, and the deviation was −10 ~ + 15 %. By using moving frame of reference technique, the internal circulations inside the moving slugs were displayed more clearly.

Foam formation is a widespread phenomenon and often a serious problem in fermentation processes. Inverted cones used as mechanical foam breakers are rotating devices that pump the fluid up and pulverize it at the edge. The shearing and centrifugal actions of such geometries can help to control foaming. In this study, a model was developed using Computational Fluid Dynamics (CFD), based on the non-Newtonian properties of foam, to describe and explain the action of inverted cones as foam breakers.

This paper is mainly to study the mixing efficiency and pressure drop of the Minkowski fractal obstacle micromixers. The mixing efficiency of primary Minkowski fractal obstacle (PMFO) micromixer and secondary Minkowski fractal obstacle (SMFO) micromixer are compared at five kinds of Reynolds numbers. With the increase of obstacle height and the decrease of distance, the chaotic convection in the microchannel is enhanced. Especially at obstacle height (h) = 0.2 mm, obstacle distance (D) = 0.15 mm, and Re = 100, the vortex caused by the Minkowski fractal obstacle structure is more obvious. In addition, vortex phenomenon increases the contact area of two fluids and enhances chaotic convection. It shows that the flow direction of the fluid in the microchannel varies significantly.

Nowadays, the presence of antibiotics in the environment has been identified as an important concern for the various life cycle. Thus, this study was conducted to evaluate ciprofloxacin (CIP) adsorption efficiency onto the multi-walled carbon nanotube (MWCNTs) and magnetic multi-walled carbon nanotube (MMWCNTs). In this experimental study, the characteristics of the studied adsorbents were determined using SEM, FTIR and XRD methods. The effects of operational parameters including contact time (10–120 min), initial concentration of CIP (10–100 mg/L), adsorbent dosage (0.1–1 g/L) and pH (3–9) were evaluated. The isotherm and kinetics studies of the CIP adsorption onto the studied adsorbents were also carried out. The adsorption efficiency increases by increasing the contact time and adsorbent dosage, while it increased by increasing the CIP initial concentration. The results showed that higher CIP adsorption efficiency was observed at pH = 7, adsorbent dosage of 0.5 g/L, CIP concentration of 30 mg/L and contact time of 120 min. The isotherm and kinetics studies revealed that the CIP adsorption data were better described by the Langmuir isotherm model and pseudo-second-order kinetics equation model. It can be concluded that both of these adsorbents have suitable potential to remove the CIP from aqueous solution but this ability is greater in MMWCNTs.

In this study, photo-catalytic degradation of methyl orange (MO) azo dye was examined by undoped and Ce 2 O 3 / CuO/ N doped ZnO nanoparticles stabilized on γAl 2 O 3 . Highest photo-catalytic activity was observed for the N-doped 10 wt. % ZnO-γAl 2 O 3 sample. One of the optimal points with the complete MO decomposition was determined at an initial concentration of 8.25 ppm, pH 3.25, catalyst loading of 0.36 g/L and 12.56 W UV-light irradiation after 120 min. Physical and chemical properties of materials were investigated by X-ray diffraction analysis (XRD), Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) and UV–visible diffuse reflectance spectroscopy (DRS) method. The experimental data were best fitted by a Langmuir-Hinshelwood approach photo-catalysis developed kinetic reaction rate in the form of −r=0.2797I0.5[Cat.]0.5[Dye] /1+0.1079[Dye]0+0.4086I0.5[Cat.]0.5$- r = 0.2797\, {I^{0.5}}\, {[Cat.]^{0.5}}\, \, [Dye]{\text{ }}/\, \, \, 1 + 0.1079\, {[Dye]_0}\, + \, 0.4086\, {I^{0.5}}\, {[Cat.]^{0.5}}$.

The Heterogeneous photocatalysis, increasingly used in effluent purification, is attracting more and more attention by the development of new photocatalytic materials based on semiconductors deposited on various supports. In this work, TiO 2 supported on cellulosic fiber was prepared and characterized by different analytical techniques such as X-ray Photoelectron Spectrometry and Brunauer-Emmett-Teller surface area. Its photocatalytic activity was investigated for the degradation of Solophenyl Scarlet BNLE (SS), an organic pollutant present in textile effluents. Several conditions were investigated such as adsorption under UV and visible irradiation, catalyst recyclability, the simulated effluent pH and the presence of H 2 O 2 as an oxidant agent. Results showed that under UV light, the removal of SS decreased significantly with increasing initial dye concentration. For an initial concentration of 5 mg/L, SS degradation was reached more than 95 % after 2 hours of treatment (neutral pH, T = 20 °C). The supported TiO 2 on cellulose remains effective over four cycles of dye treatment. In the presence of H 2 O 2 , the degradation process was inhibited with increasing the molar ratio [H 2 O 2 ]/[SS] 0 from 5 to 30. The kinetic modeling showed that the removal of this pollutant followed a pseudo-first-order model (Langmuir-Hinshelwood) with a regression coefficient (R 2 ) value of 0.984.

This study focuses on the synthesis of iron molybdate [Fe 2 (MoO 4 ) 3 ] nanoparticles (NPs) using simple co-precipitation process. The catalyst synthesized was characterized by advanced instrumental techniques such as XRD, SEM, EDX, TGA and FTIR, which confirmed the successful synthesis of NPs. Organic compound Rhodamine B (Rh. B) dye was selected for photo-degradation due to its complex structure and carcinogenic nature. Results exhibited that at neutral pH, the synthesized catalyst is highly effective for the degradation of Rh. B. For 20 mg/L initial concentration with an initial pH of 6.7, the degradation efficiency of Rh. B reaches 98  % within 180 min. Furthermore, the solution pH (1 to 11) affects the catalytic activity. This indicates that at neutral and/or alkaline pH, the usage of iron molybdate overwhelms the efficiency of Fenton-like reaction. It has been observed that Fe 2 (MoO 4 ) 3 showed excellent stability as after recycling it for 9 times its performance remained effective. Based on these data, the synthesized catalyst could be conveniently employed for degradation of toxic pollutants.