Experimental and FEM failure analysis and optimization of a centrifugal-pump volute casing

Material and geometry are two key factors in ideal mechanical performance of centrifugal-pump casings engaged in high pressures.This paper presents the model generation, static structural analysis, and geometrical modifications performed for a failed volute casing of a real centrifugal-pump. Failure would be examined under hydrostatic test conditions. Finite Element Method is employed in stage of theoretical problem investigation.To control failure phenomenon, necessary geometrical modifications are applied to the model. Geometrical modifications must have the least effect on hydraulic performance and avoid excessive manufacturing costs.Finally, some test volute casings with new geometry would be built to experimentally validate the analytical results and inspect the hydraulic performance.     

Optimization of solid-phase extraction using developed modern sorbent for trace determination of ametryn in environmental matrices

In recent years, there has been a significant increase in molecularly imprinted solid-phase extraction (MISPE) technique for the purification and clean-up of environmental samples. In this study, solid-phase extraction using the imprinted polymer has been optimized with the experimental design approach for a triazine herbicide, named ametryn with regard to the critical factors such as sample pH, sample concentration, sample flow-rate, sample volume, elution solvent, washing solvent and sorbent mass. These factors were evaluated statistically and also validated with spiked drinking water samples and showed a good reproducibility over six consecutive days as well as six within-day experiments. Also, in order to the evaluate efficiency of the optimized MISPE protocols, enrichment capacity, reusability and cross-reactivity of cartridges have been studied. Finally, a selective MISPE was successfully demonstrated for ametryn with a recovery of above 90% for spiked drinking water samples. It was concluded that the central composite design could prove beneficial for aiding the MIP and MISPE development.     

Superhydrophobic–superoleophilic electrospun nanofibrous membrane modified by the chemical vapor deposition of dimethyl dichlorosilane for efficient oil–water separation

Superhydrophobic and superoleophilic functionalized electrospun poly(vinylidene fluoride) (PVDF) membranes with water repellence, breathability, and oil-sorption and oil–water separation properties were achieved with a combination of an electrospinning technique and the chemical vapor deposition of dichlorodimethyl silane. The samples were laterally characterized by scanning electron microscopy, atomic force microscopy, water contact angle measurement, and Fourier transform infrared spectroscopy. The maximum water contact angle value was 152.0 ± 2.5° for the PVDF nanofibrous membranes with 500 μL of deposited silane (PMS2) obtained under certain conditions. The PMS2 membranes showed 100.0, 93.7, 23.3, 35.0, and 100.0% separation efficiencies for n-hexane, kerosene, crude oil, frying oil, and toluene, respectively. The understudy membrane exhibited reasonable waterproofness and remarkable breathability (water vapor transition rate = 215.21 g/m².h). Moreover, the superhydrophobic and superoleophilic nanofibrous membranes also showed good reusability, stability, moderate water-repellent properties, breathability, antifouling properties, and oil–water separation ability after several cycles. These properties confirmed potential in feasible applications, including protective cloths and in the purification of oil-polluted water. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47621.     

生物活性泡沫乳液反应器处理被苯、甲苯、二甲苯污染的空气

A novel bioactive foam emulsion bioreactor for benzene, toluene and xylene (BTX) contaminated air streams treatment has been developed. The gas-liquid interfacial area by biocompatible foam and driving force for mass transfer by a water immiscible organic phase were increased in this reactor. The effect of several parameters such as gas residence time, oxygen content, and organic phase concentration on bioreactor performance was studied. Experimental results showed an average elimination capacity (EC) of 220 g&;#8226;m－3&;#8226;h－1 with removal efficiency (RE) of 89.59% for BTX inlet concentration of 1 g&;#8226;m－3 at 15 s gas residence time in the bioreactor. The statistical developed model predicted that the maximum elimination capacity of the reactor for BTX could be reached to 423.45 g&;#8226;m－3&;#8226;h－1. Continues operation of the bioreactor with high EC and RE was demonstrated by optimizing the operational parameters of the bioreactor. Overall the results suggest that the bioreactor developed can be very effective systems to treat BTX vapors.     

Static magnetic properties of Co and Ru substituted Ba-Sr ferrite

M-type hexagonal ferrite powders, Ba_0.5Sr_0.5Co_xRu_xFe_(12−2x)O₁₉ (x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2) have been synthesized by conventional ceramic method. Magnetic properties have been investigated as a function of substitution of Co and Ru ions at applied external field of 10 kOe. XRD and SEM revealed hexagonal structure for these ferrites. The Co and Ru ions substitution cause increase in saturation magnetization and rapid decrease in magnetocrystalline anisotropy at lower substitution. The magnetic parameters variation has been explained by taking into account preferential site occupancy of sublattice sites by substituted ions. Curie temperature decreases with substitution due to weakening of superexchange interaction. The obtained hysteresis parameters suggest that the proposed materials cannot be used for recording applications.