Band 18, Heft 10-11

To evaluate the reactive energy release of the Al/Polytetrafluoroethylene (PTFE) mixed powder (Al and PTFE with a mass percentage of 26.5%/73.5%). Based on the traditional formula, three kinds of Al/PTFE test samples with different dosages (4, 6.5, and 9 g) were mixed. By using the self-designed airtight container, and combining with the overpressure sensor, the transient optical fiber pyrometer, and the infrared thermography. The overpressure , the visible light radiation temperature in the closed container, and the infrared light radiant temperature of the container’s outer wall have been obtained by real-time measurements during the process of cooking off, and the reaction products are analyzed by X-ray energy spectrum (EDS) and X- ray diffraction (XRD). The experimental results show that most of the solid products of Al/PTFE powder in the closed container are AlF 3 and a small number of intermediate carbon compositions. The released energy during the firing process of the active material Al/PTFE increases with the increase of the mixing amount; The bake-off energy of active material Al/PTFE mixture per unit mass in a closed container is about 10.2 kJ/g, and when the oxygen content in the closed container is sufficient, active material Al/PTFE per unit mass releases more energy.

In the present study, La 1 −  x Cr x FeO 3 ( x  = 0.0, 0.3, 0.6, 0.9, 1.0) was synthesized by micro-emulsion route and characterized by X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), Scanning electron microscope (SEM), Energy-dispersive X-ray (EDX) techniques. The dielectric, ferroelectric and photocatalytic properties were investigated and compared with un-doped material. The XRD analysis revealed orthorhombic geometry of La 1 −  x Cr x FeO 3 ( x  = 0.0, 0.3, 0.6, 0.9, 1.0), Cr was doped successfully into the lattice structure of LaFeO 3 and particles were spherical and in agglomerated form. The grain sizes were recorded to be 15, 16.9, 17.1, 17.65 and 18.3 (nm) for La 1 −  x Cr x FeO 3 ( x  = 0.0, 0.3, 0.6, 0.9, 1.0), respectively. EDX analysis confirmed the purity of LaCrFeO 3 samples. The lattice parameters, bulk density, X-ray density, crystalline size and porosity were determined were also determined of all the La 1 −  x Cr x FeO 3 samples. The dielectric constant and dielectric loss values decreased at higher frequency and Cr concentration affected the dielectric properties. The photocatalytic activity (PCA) was evaluated by degrading Congo Red (CR) dye under solar light irradiation and up to 85.43% dye degradation was achieved within 45 min of irradiation. Phyto-toxicity analysis before and after dye degradation was performed, which revealed the toxicity reduction in response of dye degradation. Results revealed that lanthanum ferrite (perovskite) doping with Cr could possibly be employed to enhance the ferroelectric, dielectric and photocatalytic properties.

In the present study, the production process of zinc sulfate from the zinc oxide ore was experimentally investigated. The effect of main operating condition such as weight ratio of sulfuric acid to zinc content of ore (H 2 SO 4 /zinc), leaching temperature (°C), stirring speed (rpm), leaching time (min), particle size (mm), solid to liquid ratio (pulp density, wt. %), additives amount (kg/m 3 ) and leaching pH on dissolution process of zinc oxide ore in H 2 SO 4 solution were evaluated. Taguchi method and Aspen Plus software were used to determine the optimum condition and simulate the production process of zinc sulfate. Also, Aspen Plus software was used to determine the efficiency of zinc sulfate production. The experimental factors and their levels were as follows: 0.937–1.875 for the weight ratio of sulfuric acid to zinc content of ore, 50–80 °C for the leaching temperature, 100–400 rpm for stirring speed, 30–120 min for leaching time, 0.01–10 mm for particle size, 10–40 wt% for pulp density, 10–50 kg/m 3 for additives amount and 1.4–2 for solution pH. The optimum condition was found to be H 2 SO 4 /Zinc ratio, 1.25; temperature, 70 °C; agitation rate, 200 rpm; leaching time, 30 min; particle size, 1 mm; pulp density, 10 wt%; additives amount, 30 kg/m 3 and pH, 1.8. The most effective factors for maximizing the dissolution of ZnO in H 2 SO 4 was the leaching pH. The predicted results by Aspen Plus simulation indicated that the total efficiency of zinc recovery at optimum condition is more than 97%.

The micromixer geometry presented consists of T-type micromixer with premixing chamber, hexagonal shaped chambers and obstacles. In order to observe influences of obstacle shape, aspect ratio and position, simulations are carried out for two types of obstacle shapes viz. rectangular and triangular for the Reynold number in the range from 0.1 to 75. Flow and mixing dynamics are studied to investigate the effect of geometric modifications for identifying the mixing mechanisms. The effect of obstacle shape, aspect ratio and position is investigated using the performance characteristics viz. mixing index and pressure drop quantitatively. Both the micromixers demonstrate different mixing mechanisms, including transverse flow, vortices and chaotic advection due to split and recombination action. The mixing performance is diffusion dominated below Re < 5 and it is advection dominated beyond Re > 5. At Re ≥ 20, the mixing index observed is 0.80 in all the micromixer design configurations.

Computational fluid dynamics (CFD) was used to investigate the influence of complex rheological properties for Bingham-pseudoplastic fluids on hydrodynamics and heat transfer performance in an industrial polymerization coiled agitated reactor. The fluid rheology was described by the Herschel–Bulkley rheological model. The power consumption obtained by CFD simulation was in good agreement with the plant data. The relationship between the Metzner–Otto constant and power-law index for dual axial flow impellers was investigated. The hydrodynamics strongly depends on the rheological parameters and rotational speed. The flow domain is composed of two parts: the cavern around the impellers, and the stagnant zone adjacent to helical coils and tank wall which resulting in poor mixing and heat transfer performance. With the increase of rotational speed, the stagnant zone could be effectively eliminated, while the heat transfer performance could be significantly improved.

The present investigation is focused on the preparation, characterization, and photocatalytic activity evaluation of TiO 2 /zeolite, WO 3 /zeolite, WO 3 /TiO 2 /zeolite, and WO 3 /TiO 2 composites. Zeolite fujasite (FAU) was synthesized by the hydrothermal method, while the semiconductor/zeolite composites by a straightforward physical mixture and calcination treatment. The photocatalytic activity of the materials was evaluated through the methyl orange (MO) degradation under near-UV irradiation (365 nm). The photocatalysts were characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), Energy-dispersive X-ray Spectroscopy (EDX), UV–vis diffuse reflectance spectroscopy and nitrogen physisorption. Results indicated that TiO 2 , WO 3 , and Zeolite Y kept their crystalline phases after the preparation method. TiO 2 and WO 3 particles were distributed on zeolite surface. Also, no significant changes in the band gap energies of the photocatalysts were found. The surface area of zeolite FAU decreased with the addition of TiO 2 and WO 3 . The best MO degradation under near-UV irradiation was obtained with WO 3 /TiO 2 heterojunction and TiO 2 P25, no synergistic effect was found between semiconductors and zeolite FAU. Additionally, the kinetic data of the photocatalytic elimination of MO with all photocatalysts under near-UV radiation was investigated with several models: Zero-order, First-Order, Second Order, Modified Freundlich and Parabolic Diffusion, they were consistent with Modified Freundlich model. The effect of initial pH and photocatalyst weight was explored for TiO 2 /Zeolite composite and it was found that the best MO degradation was obtained at natural pH of 10.3 and 0.2 g of composite was the optimal amount of photocatalyst. Finally, the positive hole formation in all photocatalysts was detected by UV–vis spectroscopy and it was discovered that the highest density of positive holes was obtained with TiO 2 /zeolite composite.

The existence of certain filamentous organisms may indicate one or more operation and control problems in activated sludge reactors. Microscopic evaluation of these filamentous organisms needs staining methods that can be achieved after some steps. This study is the first to show that textile dyes such as Astrazon Blue FGGL (BB41) and Astrazon Red FBL (BR46) can be used to identify filamentous organisms. Both dyes were used as a new, effective, and easy method for detecting the presence of filamentous bacteria. When contacted with BB41 and BR46, the filamentous bacteria and their characteristics were easily observed under the microscope. According to sources, textile dyes used in this study have not been used to diagnose filamentous bacteria before. According to the findings of this study, important morphological properties of filamentous bacteria were easily observed using BB41 and BR46. “Attached growth, branching, septa, and granules of various nutrients” were clearly seen by the stains (BB41 and BR46) with the help of this method. This method may allow the examiners to examine the specimens of filamentous bacteria in the activated sludge reactors. Detailed information has been presented in this paper.

To reveal the catalytic potential of abandoned naturally occurring material, we synthesized titania-termite hill composite (Ti-THC) via an incipient wetness impregnation route, characterized by various techniques and tested as a catalyst for transesterification of waste frying oil (WFO). The reusability of the prepared catalyst was also studied to evaluate its stability. The effects of reaction process parameters, such as temperature, time, catalyst loading and methanol/WFO molar ratio on fatty acid methyl ester (FAME) yield, were investigated using a central composite design approach. SEM result revealed pores formation on the catalyst surface, while XRD and EDX analyses confirmed successful insertion of titania into the aluminosilicate layer of the termite hill. The maximum FAME yield of 90.78% was obtained at optimum experimental conditions of 71.16 °C reaction temperature, 2.12 h reaction time, 1.03 wt.% catalyst loading and 9.96:1 methanol/WFO molar ratio. The catalyst still maintained its better stability after being reused for three reaction cycles.

Presence of nitrate and phosphate ions is difficult to remove from the lakes, as they are highly soluble in water. A way of chemical method adopted to remove these ions from the drinking water using the simple method use of naturally abundant chitosan with charcoal. Adsorption of nitrate and phosphate anions from aqueous solution (water/waste water) on both the chitosan and activated charcoal was investigated. In batch mode adsorption study leads to developing efficient low-cost removal method is important to protect the aquatic environment from the high concentration of nitrate and phosphate anions intake as well as adverse effects on human health. The modified chitosan microspheres had a laudable performance for nitrate and phosphate adsorption Use of this material as an adsorbent is a cheaper and biocompatible method. A systematic study of the adsorption of nitrate and phosphate anions on chitosan and activated charcoal was performed by varying the pH, the initial concentration, contact time, and adsorbent dosage. The results demonstrate that the adsorption process was followed adsorption kinetics of both first and second order kinetics when we use of the chitosan and activated charcoal and chitosan is promising for treating water that is contaminated with nitrate and phosphate anions.

Nanocomposites plays a very significant role in the catalysis and photocatalysis. Our aim is to synthesize multiphase nanocomposite material with advanced catalytic properties that are useful in the energy and environmental applications. Nano silver (Ag 0 ) decorated Zinc-Cobalt/Titania composite (Ag decorated Zn-Co/TiO 2, AZCT) with nonporous in nature as well as single grain size of 10–15 nm with beautiful morphological in nature. The material has multiphase crystalline in nature predicted from the powdered X-ray diffraction studies (PXRD) and FT-IR analysis, which illustrate the multiphase crystalline powder with high surface area of nanoporous in nature. The synthesized nanocomposite material is labelled as AZCT.

The work relates to development and presentation a two-parameter continuation method for determining catastrophic sets of stationary states of a tubular chemical reactor with mass recycle. The catastrophic set is a set of extreme points occurring in the bifurcation diagrams of the reactor. There are many large IT systems that use the parametric continuation method. The most popular is AUTO’97. However, its use is sometimes not convenient. The method developed in this work allows to eliminate the necessity to use huge IT systems from the calculations. Unlike these systems, it can be inserted into the program as a short subroutine. In addition, this method eliminates time-consuming iterations from the calculations.