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1.
A poly(acrylonitrile) (PAN) nano-web was electrospun on a commercial melt-blown poly(propylene) (PP) filter medium to generate composite filter media. The performance of these media was characterized in terms of filtration efficiency and pressure drop. Quality factors calculated from these parameters were used to evaluate the overall efficacy of the filter media. Structural characterization of the composite media showed that a thin layer of nano-web could improve the overall performance by increasing filtration efficiency without significant increase of pressure drop.  相似文献   

2.
Nanofibers definitely hold great advantage and promise in filtration as they have very high specific surface area, which ensures greater probability of capturing the particles and hence, the filtration efficiency of the nanofiber filter media is high. Electrospun nanofibers are prohibitively expensive due to extremely low production rate. With recent advances in melt blowing technology, nanofibers could be produced at production rate few orders of magnitude higher than that of conventional single syringe electrospinning and hence, quite cost effective. Influence of air pressure and die to collector distance (DCD) were studied on the number average fiber diameter for the nanofibers as well as the performance properties of the nonwoven webs, each factor at three discrete levels. The nanofibers were as fine as 260 nm. A very encouraging observation of the study is very high values of quality factor observed for nanofiber nonwoven filter media. In order to compare the filtration efficiency of different nanofiber nonwoven media samples with different basis weight, a novel term of specific filtration efficiency is proposed and was found that the specific filtration efficiency with the increase in DCD or air pressure.  相似文献   

3.
Two kinds of composite filter materials were prepared by regulating the structure of melt-electrospinning polypropylene (PP) webs. The self-designed multi-nozzle melt-electrospinning device was used to produce PP webs which deposited on PP spunbonded nonwoven. Firstly, the composite filter materials with different thickness and ratios of coarse/fine fibers were prepared, and the effect of the thickness and the ratio of coarse/fine fibers on filtration properties were studied. The results showed that the filtration efficiency and pressure drop increased as thickness increased. In addition, compared with the general filters which were composed of coarse or fine fibers, the filters with coarse/fine fibers had “low pressure drop” under the similar filtration efficiency. In the case of the ratio of coarse/fine fiber about 2:2, this filter achieved optimal performance. When the thickness was 0.42 mm, its filtration efficiency for particles more than or equal to 2.0 μm could reach more than 95 %. Its pressure drop and air permeability were 18.13 Pa and 54.69 mm/s, respectively, while those of general filter were 38.67 Pa and 10.02 mm/s, respectively. After that, the composite filter materials composed of various angles of oriented webs were produced. The results showed that the filtration efficiency for particles with the size of more than or equal to 2.0 μm was higher than that of filters composed of one angle of oriented webs. In addition, the lower the orientation was, the lower the pressure drop was.  相似文献   

4.
A comparative analysis of the elasticity, microstructure and thermal stability of fibres (thickness ranging from 43.4 to 189.4 µm) isolated from pineapple leaves (PALF), coconut coir (COIR), banana leaf-stem (BAN) and oil palm empty fruit bunch (OPEFB) reported in this study. Statistical analysis of the mechanical properties derived from tensile test to rupture reveals significant differences (P<0.05) in the fibre strength (σ), stiffness (E) and extensibility (parameterized by the strain to rupture, ?). It is observed that COIR fibres yield the smallest strength, σ (=99.8±22.5 MPa), and stiffness, E (= 0.5±0.1 GPa), while PALF fibres yield the largest σ (=639.5±301.6 MPa) and E (=7.1±3.1 GPa); PALF fibres exhibit the smallest ? (=0.11±0.03) but OPEFB fibres yield the largest ? (=2.0±1.3). From scanning electron micrographs, it is observed that cellulose fibril rupture predominates in OPEFB, COIR and BAN fibres; a large proportion of the cellulose fibrils fail by pullout in PALF fibres. Thermogravimetric analysis reveals that all fibres are thermally stable up to 250 °C; the fibre residue ranges from 30 to 80 wt% after heating to 500 °C. In particular, BAN experiences the highest weight loss and PALF experiences the lowest weight loss. The findings lend to a simple approach for determining the performance of the composites by assessing the type of natural fibres for reinforcing polymeric matrices.  相似文献   

5.
Solution blowing process is a new nanofiber fabricating method with high productivity. In the present study, nylon 6 nanofiber mats were solution blown and the effects of spinning conditions on nanofibers morphology were investigated. The fiber diameter ranged from 150 to 750 nm which was affected by solution concentration, gas pressure and solution feeding rate. The solution blown fibers were three-dimensional curly which made loose construction in bulk. The filtration performance of solution blown mats was evaluated. The tested solution blown nanofiber mats showed high filtration efficiency of 83.10 % to 93.45 % for 0.3 µm particles filtration and extremely low pressure drop of 15.37 to 30.35 Pa. The results indicate the solution blown nanofiber mats will find potential application of high efficiency and low resistance filter.  相似文献   

6.
In order to obtain paper respirator with dust resistance performance and antibacterial property, silk photo-catalytic respirator paper was made by loading nano-TiO2 photo-catalyst on silk based respirator paper. The pore structure, surface topography and TiO2 distribution, and the filtration performance of silk respirator paper were studied by using a pore size meter (PSM), a field emission scanning electron microscope (FESEM), and a filter tester, respectively. In addition, the antibacterial property of silk respirator paper was also investigated. The results showed that the pore structure and filtration performance of silk respirator paper could be controlled by changing the degree of beating of silk pulp and the basis weight of silk paper. Silk respirator paper of 45 g/m2 made from silk pulp having beating degree of 85 oSR had high filtration efficiency and appropriate filtration resistance. Nano-TiO2 particles were mainly attached to the surface of silk paper, and the loading of nano-TiO2 photo-catalyst resulted in a slight decrease in filtration resistance and filtration efficiency of silk respirator paper. It, however, improved the antibacterial property of silk respirator paper effectively.  相似文献   

7.
In this paper, we discussed the relationship of filter efficiency and pressure drop with the porosity, fiber diameter and filter thickness by Geodict®. We found that filter efficiency has exponential relationship with filter porosity, fiber diameter and thickness. Furthermorethe pressure drop has a linear relationship with filter thickness and exponential relationship with filter porosity and fiber diameter, respectively. The influence of electrostatic charge on the particle deposition has been investigated. Simulation results were compared with the actual test results by TSI 3160.  相似文献   

8.
Polyimide (P84) nanofibers of 200-500 nm were deposited uniformly on needle punched aramid felt with basis weight of 260-350 g/m2 by optimized electrospinning. High temperature adhesive was then electro-sprayed on the nanofiber side deliberately to bind a thin protective layer made of temperature-resistant non-wovens. The three layer structure was afterwards enforced by hot pressing to form composite filter media. The application of the adhesive was tailored not to affect the permeability of the substrate felt while exerting adhesion strength of over 1000 kPa for the media to be suitable for flue gas dust treatment under 240 ºC. When 0.3-10 μm NaCl aerosols were used as the simulated dusts, it was found that even a small amount of P84 nanofibers could obviously elevate the filtration efficiency. The composite showed 100 % removal efficiency of particles equal and greater than 2.0 μm, and 99.5 % for particles 1.0-2.0 μm in diameter.  相似文献   

9.
An efficient and reproducible protocol was established for genetic transformation in Jatropha curcas through microprojectile bombardment. Decotyledonated embryos from mature seeds were pre-cultured for 5 days and elongated embryonic axis was subjected to bombardment for the optimization of physical parameters. The frequency of transient gus expression and survival of putative transformants were taken into consideration for the assessment of physical parameters. Statistical analysis reveal that microcarrier size, helium pressure and target distance had significant influence on transformation efficiency. Among different variables evaluated, microcarrier size 1 μm, He pressure 1100 and 1350 psi with a target distance of 9 and 12 cm respectively were found optimum by co-relating microcarrier size, helium pressure and target distance on the frequency of gus expression and survival of putative transformants. Selection of putative transformants was done with increasing concentrations (5-7 mg L−1) of hygromycin. The integration of desired gene into Jatropha genome was confirmed with PCR amplification of 0.96 and 1.28 kb bands of hptII and gus gene respectively from the T0 transgenics and Southern blot analysis using PCR amplified DIG labeled hptII gene as a probe. A successful attempt of genetic transformation was made with optimized conditions using particle gene gun and establishing a stable transformation in J. curcas with 44.7% transformation efficiency. The procedure described will be very useful for the introgression of desired genes into J. curcas and the molecular analysis of gene function.  相似文献   

10.
The biorefining of grass offers an opportunity to integrate primary production agriculture with the extraction of fibre. The study was aimed at developing protocols for processing ryegrass to determine fibre content and to generate visible and near infrared reflectance (Vis-NIR) calibrations for estimating fibre fineness with the aid of a new reference airflow method. The method for determining fineness of processed fibres has been adapted from flax fibre protocols. A Vis-NIR calibration using partial least squares (PLS) regression method was employed to generate models with a calibration set consisting of 85 samples obtained from fresh and ensiled grasses. The PLS model was successfully validated with 21 independent samples with a prediction error of 1.26 dtex. An optimised PLS model (r2 = 0.86) consisting of 106 samples has been developed. The quality assurance protocols could be used for assessing fibre content and quality of silage, hay and fresh grass.  相似文献   

11.
This paper focused on using response surface methodology (RSM) and artificial neural network (ANN) to analyze production rate of electrospun nanofibers. The three important electrospinning factors were studied including polymer concentration (wt %), applied voltage (kV) and the nozzle-collector distance (cm). The predicted production rates were in agreement with the experimental results in both ANN and RSM techniques. High regression coefficient between the variables and the response (R 2=0.975) indicates excellent evaluation of experimental data by second-order polynomial regression model. The regression coefficient was 0.988, which indicates that the ANN model was shows good fitting with experimental data. The obtained results indicate that the performance of ANN was better than RSM. It was concluded that applied voltage plays an important role (relative importance of 42.8 %) against production rate of electrospun nanofibers. The RSM model predicted the 2802.3 m/min value of the highest production rate at conditions of 15 wt % polymer concentration, 16 kV of the applied voltage, and 15 cm of nozzle-collector distance. The predicted value showed only 4.4 % difference with experimental results in which 2931.0 m/min at the same setting was observed.  相似文献   

12.
Field experiments were conducted during the rainy seasons of 2009 and 2010 for the management of the major diseases of mungbean, namely, wet root rot (Rhizoctonia solani), cercospora leaf spots (Cercospora canescens and Pseudocercospora cruenta) and yellow mosaic (Mungbean Yellow Mosaic Virus) by using different combinations of an insecticide, fungicide, and bio-formulation as seed treatment, with or without foliar sprays. A combination of seed treatment with thiamethoxam (Cruiser™) at 4 g kg−1, carboxin (Vitavax™) at 2 g kg−1 and Pusa 5SD (Trichoderma virens) at 4 g kg−1 followed by simultaneous foliar sprays of thiamethoxam (Actara™) 0.02% and carbendazim (Bavistin™) 0.05% at 21 and 35 days after sowing resulted in the highest seed germination and grain yield in mungbean with the lowest intensities of cercospora leaf spots and mungbean yellow mosaic, and moderate incidence of wet root rot. The lowest whitefly population was also observed in this treatment during all stages of the crop. The treatment combinations having Pusa 5SD as seed treatment provided the lowest wet root rot incidence. Two sprays were superior to single spray for all variables recorded, but in combination with seed treatment, single spray was found to be more cost effective as it obtained the highest return per rupee of input. Use of T. virens based bio-formulation Pusa 5SD with insecticide thiamethoxam has been effectively demonstrated for the first time along with fungicides Bavistin and Vitavax for the management of the major diseases of mungbean.  相似文献   

13.
In this study, the effect of processing parameters such as temperature, pressure, time of compaction process and areal density on high-velocity impact behaviour of high performance polyethylene fibre cross-ply composites were investigated by Taguchi method. Samples were made through high temperature and pressure compacting process and morphology and interlayer adhesive of samples were investigated by scanning electron microscopy “SEM and T-peel test, repectively. Taguchi method was used to plan a minimum number of experiments. Statistical analysis, analysis of variance (ANOVA), was also employed to determine the relationship between experimental conditions and yield levels. ANOVA was applied to calculate sum of square, variance, ratio of factors variance to error variance and contribution percentage of each factors on response. A hemispherical tip type projectile was used for high velocity impact tests and the depth of trauma as the response factor was measured after impacting test. Results showed that when the temperature, pressure, and time of compacting process were 125 °C, 3 MPa, and 30 min for the composite sample with 7.4 kg/m2 areal density, the trauma depth was decreased to its lowest value.  相似文献   

14.
In this study, central composite design (CCD) based on response surface methodology (RSM) was employed to optimize parameters of melt-spinning process of poly(ethylene terephthalate) partially oriented multifilament yarn (POMFY). On the basis of a four-variable CCD, RSM was used to determine the effects of spinning temperature, spinning pressure, take-up velocity and quenching air velocity on the levels of the elongation of POMFY as the response. The POMFY samples were also characterized by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis. By applying a quadratic regression analysis, an equation indicating the effect of each variables on the response was developed. The predicted values of the parameters showed excellent agreement with the experimental values (R 2=0.9565, Adjusted-R 2=0.916). Moreover, the results confirmed that the CCD mathematical model was a suitable method to optimize the melt-spinning parameters of POMFY in an industrial scale.  相似文献   

15.
Carboxymethyl cellulose (CMC)-polyvinyl alcohol (PVA) and chitosan (CS)-polyvinyl alcohol were cross-linked by Fe3+ and glutaraldehyde respectively to prepare the cation exchange membrane layer and the anion exchange membrane layer, polyvinyl alcohol-sodium alginate (SA)-copper phthalocyanine tetrasulfonic acid (CuTsPc, or copper tetracarboxy phthalocyanine: CuTcPc) cation exchange nanofibers or polyvinyl alcohol-chitosan-copper tetraaminophthalocyanine (CuTAPc) anion exchange nanofibers prepared by electrospinning technique were introduced into the interlayer to obtain the modified bipolar membrane (BPM). The experimental results showed that in comparison with the BPM without the cation/anion exchange nanofibers interlayer, the water splitting efficiency of the modified BPM was obviously increased, and its membrane impedance decreased. When the concentration of CuTsPc in the PVA-SA-CuTsPc nanofibers was 3.0 %, the transmembrane voltage drop (IR drop) of the CMC-PVA/PVA-SA-CuTsPc/CS-PVA BPM was as low as 0.5 V at a high current density of 90 mA·cm?2.  相似文献   

16.
Accurate modeling of fibrous filter pressure drop and particle capture/loading behavior includes many phenomena, including partial-to-full slip flow at fiber boundaries, random fiber location and orientation, particle/fiber and particle/particle adhesion and bouncing. Filter media fibers are usually joined together by binders which form significant percentages of the solid material in the media. Complete simulation of media geometry would be three-dimensional (3-D). However, complex 3-D geometries in computational fluid dynamics (CFD) demand powerful computing resources, and hence have been limited to a few fibers. Studies using 2-Dimensional (2D) models were effective in predicting media airflow resistance and particle capture for simple geometries. More realistic 2-D simulations reflecting the random diameter distribution and positioning of fibers with appropriate local boundary conditions should allow still better predictions. To this end we measured the geometric properties of three glass fiber media. 2-D models of fibers with binder links were developed. Statistical fiber diameter distributions were evaluated to determine which provided closer agreement with the measured fiber diameter distributions under the geometric constraints present. For the high standard deviations of fiber diameters present in these media, the number of fibers needed for valid statistics is rather large, which means that complete 3-D simulations are probably not practical.  相似文献   

17.
Mozzarella stretching water (MSW) is a dairy effluent generated from mozzarella cheese production that does not have a real use and is destined to disposal, causing environmental problems and representing a high disposal cost for dairy producers. Spent brewery yeast (SBY) is another promising food waste produced after brewery manufacturing that could be recycled in new biotechnological processes. Aurantiochytrium mangrovei is an aquatic protist known as producer of bioactive lipids such as omega 3 long chain polyunsaturated fatty acids (ω3 LC-PUFA), in particular docosahexaenoic acid (DHA). In this work MSW and SBY have been used to formulate new sustainable growth media for A. mangrovei cultivation and production of DHA in an attempt to valorize these effluents. MSW required an enzymatic hydrolysis to enhance the biomass production. The new media obtained from hydrolysed MSW was also optimized using response surface methodologies, obtaining 10.14 g L−1 of biomass in optimized medium, with a DHA content of 1.21 g L−1.  相似文献   

18.
Strain BC79, isolated from primeval forest soil in Qinling, Mountains, China, was identified as Bacillus methylotrophicus based on morphological, biochemical, physiological and chemotaxonomic analyses as well as phylogenetic 16S rDNA sequencing data. This strain was able to suppress mycelial growth and conidial germination of numerous plant pathogenic fungi in dual cultures on solid media. For exploring potential biocontrol activity, we assessed fermentation conditions for studying B. meth1ylotrophicus BC79. The active substance of BC79, phenaminomethylacetic acid, was extracted by TLC and HPLC, and identified as the strongest inhibitory substance described in B. methylotrophicus. Experiments in a greenhouse showed that application of BC79 culture filtrates 24 h before inoculation of Magnaporthe oryzae, the causal agent of rice blast, had 89.87% biocontrol efficiency. B. methylotrophicus BC79 colonized rice plant tissues and at 10 days after filtrate application, its population in leaves (1.65 × 108 CFU/g) was much larger than in stems (6.78 × 107 CFU/g) or roots (3.56 × 107 CFU/g). Field trials indicated that BC79 culture filtrate (4000 g/667 m2) showed the highest efficiency for M. oryzae, with 84.8% biocontrol effect, followed by of 15% phenaminomethylacetic acid extract (75.5%) and 20% tricyclazole (76.1%). Seedling and post-transplant stages were the best periods to apply BC79 for control of rice blast. The B. methylotrophicus BC79 strain hence has enormous potential as an agricultural agent for biocontrol of rice blast.  相似文献   

19.
Understanding the mode of transport of water vapor through the film is important for improving the moisture barrier properties of wheat gluten (WG) films. Effective permeability (Peff), solubility (Seff), and diffusion (Deff) coefficients of a hydrophilic cast WG film were determined at 25°C within the relative humidity (RH) range of 0–84% (with a 9–13% RH gradient between upstream and downstream water vapor flux). Peff, Seff, and Deff increased substantially as the RH gradient moved upwards in the RH spectrum. Peff increased by four orders of magnitude from the lowest RH condition of 0–11% (3.8×10−11 g·m/m2·s·Pa) to the highest RH condition of 75–84% (4.1×10−7 g·m/m2·s·Pa). A moisture sorption isotherm of the film at 25°C was constructed. Both the Guggenheim–Anderson–DeBoer (GAB) and the Kuhn moisture sorption isotherm models showed a good fit to the experimental adsorption data. Testing of WG films at the expected conditions of actual use is necessary to quantify the water vapor permeation through the films.  相似文献   

20.
Polypropylene/polystyrene blends with different viscosity ratios, p, ranging from 1.6×10?2 to 10.8, were prepared by using textile-grade isotactic polypropylene (iPP) and five kinds of atactic polystyrene (aPS), named PS1, PS2, PS3, PS31 and PS46 with different molecular weight, and then melt-spun into composite fibers with matrix-fibril morphology at different take-up velocities, v L , ranging from 125 to 1000 m/min. The effects of p on the diameters and quantities of dispersed droplets in extrudate fibers, and the effects of p and v L on the size and quantities of fibrils in take-up fibers were discussed, respectively. Based on a quantitatively characterization for the coalescence and deformation of droplets during melt spinning, a theoretical analysis based on Newtonian fluids simplification and the deformation theory was presented to predict the deformation and breakup of droplets during melt spinning. It is found that there is a good fit between theoretical and observed experimental results at most discussed take-up velocities. Furthermore, the uncertainties of Newtonian fluids simplification and a hypothesis of local energy dissipation from migration and coalescence were noted to explain the deviations between predicted and experimental data.  相似文献   

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