用直接数值模拟对移动颗粒层除尘的研究及实验对比

利用气固两相流数值模拟计算模型，分别采用不同粒径的移动颗粒层过滤除尘器，对不同粒径粉尘颗粒的碰撞次数进行统计，并对移动床除尘中过滤介质尺寸与粉尘粒径尺寸之间的相互选择性进行了初步研究。模拟计算了在同一风速下碰撞次数与粉尘粒径以及移动层颗粒径之间的关系。计算统计的结果与实验结果对比发现，二者存在定性上的一致。结果表明，在移动床过滤除尘器中不同粒径的过滤层对不同粒径尘粒具有明显的选择性。     

Background subtraction for fluorescence detection in thin-layer chromatography with derivative spectrometry and the adaptive Kalman filter

Background signals must be removed from analyte responses before reliable qualitative and quantitative results can be obtained. For cases in which a reliable estimate for the background response cannot be obtained, the combination of two mathematical approaches yields accurate quantitative results. First-derivative spectrometric methods, in conjunction with a curve-resolution approach based on the adaptive Kalman filter, are used to compensate for difficulties caused by background responses which are not reproducible. Derivative spectrometric techniques reduce the relative magnitude of low-frequency systematic deviations in the spectra. In this case, this has the effect of localizing model errors to restricted regions of the spectra, which in turn meets the major requirement for successful utilization of the adaptive Kalman filter. The approach is applied to fluorimetric detection for thin-layer chromatography in the quantification of polynuclear atomatic hydrocarbon compounds. Results are given which demonstrate that this combined approach yields accurate estimates for concentrations of components in overlapped chromatographic zones. A derivative spectrometric approach in conjunction with a regular Kalman-filter fit gives less accurate results, and an adaptive Kalman filter used to fit the raw spectral data fails to give any reliable quantitative information. The combined approach using derivative spectrometry anal the adaptive Kalman filter is shown to give 8-fold lower detection limits for anthracene when compared to traditional background-subtraction methods.     

色素的纳米纸色谱分离分析

采用SiO2纳米粒子结合硅烷化处理对滤纸进行改性,以罗丹明B、苏丹红Ⅰ及苏丹红Ⅳ为模型化合物,考察了改性滤纸在分离特性上的差异,对不同粒径纳米粒子、不同硅烷化试剂及不同展开剂的极性进行比较、优化后发现,在同等展开条件下,经改性纳米粒子修饰后的滤纸分离色素的效果得到明显改善,且纳米粒子越小、烷基碳链越长、硅烷化越完全,则...     

Closed-loop recirculating manifold for matrix isolation in flow injection flame atomic absorption spectrometry. Analysis of silver electrolysis solutions

Two flow injection procedures have been investigated for the determination of some elements in silver electrolysis solutions, for which the problem of the formation of silver acetylide needs to be addressed. A single line manifold was found to give acceptable results for limited time periods, but for prolonged operation it was necessary to remove the silver. This was achieved with a recirculating reactor in which the silver was precipitated as the chloride and retained on a filter of nylon fibers. Good recoveries of copper, iron, nickel and zinc from solutions containing up to 100 g/l. silver were obtained with over 95% of the silver retained on the filter. The filter was regenerated rapidly by flushing with ammonia solution.     

Choice of optimum conditions of emitter preparation for X-ray fluorescence analysis of aerosols

The nonuniformity of aerosol distribution over filter surface was studied. It was found that the distribution depends on the properties of the studied object and on the sampler type: particle concentration is often higher in the center of the filter, but in some cases, they shift to the edges; the uniform distribution of particles is observed rarely. It was shown that, if the emitter in X-ray fluorescence analysis (XRF) is a disk 3 cm in diameter cut from the center of a filter 5 cm in diameter, the systematic error of the results of analysis may be higher than 0.30. Recommendations on the choice of the conditions of sampling aerosols and emitter preparation are formulated. If these conditions are met, the results of XRF analysis of nonuniform filters are characterized by s_r = 0.05, which satisfies the admissible error.     

Parametric studies of matched filters to enhance the signal-to-noise ratios of LC-MS-MS peaks

Chromatographic parameters of reference signals employed in matched filter methods have been studied using numerical experiments to improve the signal-to-noise (S/N) ratios of small liquid chromatography (LC) peaks obtained with electrospray tandem mass spectrometers (MS-MS). These parameters include the width, shape, and S/N ratios of chromatographic peaks used as the reference signal profiles. Our results show the effect of reference peak widths on improving the S/N ratio of chromatographic peaks; the influence of reference peak shapes is negligible. To verify simulation results, various reference signals, including analyte peaks of high concentration standards, internal standard peaks, and artificial Gaussian peaks of different widths, have been employed to enhance signal peaks on real liquid chromatography-tandem mass spectrometry (LC-MS-MS) chromatograms via matched filter methods. Our experimental results demonstrate that the S/N ratio enhancement of chromatographic peaks agree with the simulation predictions. These findings, therefore, suggest that regardless of peak shape, a well-smooth peak with a width close to that of the analyte peak is an adequate reference signal, when matched filter methods are used to improve LC-MS-MS chromatograms. Nevertheless, all methods processed LC-MS-MS peaks in this study do not achieve the ideal improvement ratios estimated with simulation results. We attribute this deficiency to spike-like noise, which have considerable low frequency components riding on LC-MS-MS chromatograms. Matched filtering, which works as a low-pass filter in the frequency domain, cannot effectively eliminate low frequency flicker noise contributed by these spikes. In addition, simple median filtering does not provide adequate improvement despite being able to smooth out most spikes in the chromatograms.     

The Effect of Long-Range Fiber Space and Orientation Correlations on the Hydrodynamic Resistance and Diffusion Deposition in Fibrous Filters

On the basis of Brinkman's equation, the problem of hydrodynamic resistance is analyzed for a row of periodically arranged parallel circular fibers placed in a uniform porous medium. The results are applied to the fan model of a filter, for which an equation aimed at determination of Brinkman's constant is derived within the framework of a self-consistent theory. The resistance force acting on a unit length of each fiber is calculated as a function of the geometrical parameters of the model. The capture coefficient is found for diffusion deposition of aerosols on fibers of the model filter. The results obtained agree with the experimental data.     

Production of calibration standards for x-ray fluorescence analysis of aerosol particles precipitated on different filter materials

Calibration results are presented for a method producing filter standards of two different materials. The first filter type is a membranous filter, the second a quartz fibre filter. Multielement solutions with predetermined elemental concentrations have been produced by an aerosol generator and preciptiated onto the respective filter materials. Additionally, the particle size-distribution in the aerosol generator, depending on the salt concentration in the nebulized solution, is presented.     

Production of calibration standards for x-ray fluorescence analysis of aerosol particles precipitated on different filter materials

Calibration results are presented for a method producing filter standards of two different materials. The first filter type is a membranous filter, the second a quartz fibre filter. Multielement solutions with predetermined elemental concentrations have been produced by an aerosol generator and preciptiated onto the respective filter materials. Additionally, the particle size-distribution in the aerosol generator, depending on the salt concentration in the nebulized solution, is presented.     

两种固定化金属螯合复合亲和膜色谱介质制备

以纤维素滤纸为基质,通过碱处理、环氧活化、偶联亚氨基二乙酸二钠、固定化Ｃｕ＾２＋后制得了大孔纤维素亲和膜。另外,在活化后的膜上通过共价交联覆盖上琼脂糖,制得了具有类似“三明治”结构且性能优于的复合亲和膜,装柱后分别制得固定化金属螯合亲和膜色谱柱。对两种亲和膜进行牛血清白蛋白等温吸附测定显示,两者的最大吸附量分别为１．１７ｍｇ／ｃｍ＾２和１．３０ｍｇ／ｃｍ＾２,与传统的琼脂糖凝胶类介质吸附量相当,表     

超疏水滤纸的制备与应用

对SiO2纳米粒子进行硅烷化改性,再将其修饰到滤纸上,制备出静态水接触角＞150°的超疏水滤纸,对制备条件进行了优化。 用热重分析及扫描电子显微镜对超疏水滤纸表征后发现,二氧化硅纳米粒子在滤纸纤维表面形成一层包裹层,即纳米级粗糙结构,这种结构对滤纸的疏水性具有关键作用。 对滤纸的油水分离性能进行了研究,发现其对非均相体系和高粘度油水混合物具有很好的分离效果。     

卡尔曼滤波分光光度法同时测定钢中钛和钼

本文采用卡尔曼滤波(KF)递推法,以苯基荧光酮-溴化十六烷基吡啶与钛,钼的显色体系同时测定钛和钼,同时以柠檬酸和抗坏血酸掩蔽干扰,并引入误差校正因子来校正加掩蔽剂后在所测波段范围内所造成的残余背景吸收,用于实际钢样分析,获得较满意的结果。     

Two-dimensional and three-dimensional fitting of enzyme kinetic data with the kalman filter

The availability of instrumentation which is capable of collecting multidimensional data has put increased demands on the data-processing methods utilized to obtain information about reaction kinetics. An enzyme-catalyzed reaction, the hydrolysis of p-nitrophenyl phosphate to p-nitrophenol, is examined so that various data-processing methods and data-collection formats can be examined and compared. The extended Kalman filter is used to obtain rate constants and values for the initial substrate concentration for three-dimensional data, and for two-dimensional kinetically perturbed data. In addition, non-linear least-squares regression with the simplex algorithm, and linear least-squares regression methods are used to analyze absorbance/time curves for this reaction. These results are compared to the results from a two-point kinetic method, and the accuracy and precision of each of the methods is evaluated. It is found that the methods based on the Kalman filter yielded results which were equivalent to or better than the results obtained from the other approaches.     

Synthesis of a copolymer with filter aid,dihydration, and scale inhibition abilities and its application to wet phosphoric acid

A new type of multifunction copolymer PAMA having filter aid, dihydration, and dynamic scale inhibition properties was synthesized using acrylamide (AM) and a homemade polyoxyethylene octylphenol ether acrylic ester (AOP) as the feedstock and persulfate as the initiator in an aqueous solution. The structure of the copolymer was characterized using FTIR and ¹H NMR spectroscopy. Scanning electron microscopy and the software Matlab 7.0 were used to investigate the influence of the copolymer on filter aid and scale inhibition. The results indicated that the copolymer consists of AM and AOP. The filtration rates of the phosphogypsum slurry increased 3.8 times compared to the blank group, and the water content of the phosphogypsum cake was reduced by 10.42% with the addition of 10 ppm of PAMA. The dynamic scale inhibition rate of sodium fluorosilicate and potassium fluorosilicate can reach up to 53.5% when the experiment runs continuously for 12 h. The experiments related to mechanism indicate that PAMA has a strong adsorbability and high bridge effect on the phosphogypsum crystals. Concurrently, PAMA can efficiently improve the microstructure of a filter cake and remove the scale layer of sodium fluorosilicate and potassium fluorosilicate adhering to the wall of a stainless steel pipe, which is beneficial for increasing the filter rate, decreasing the moisture content of the filter cake, and preventing scale layer formation on the filter.     

Surface-enhanced Raman scattering of single-walled carbon nanotubes on silver-coated and gold-coated filter paper

Surface-enhanced Raman scattering (SERS) spectra of single-walled carbon nanotubes (SWCNTs) on metal-coated filter paper are reported for the first time. Experimental results show that the metal-coated filter paper is very effective and active. The SERS spectrum not only shows that all Raman bands of SWCNTs in normal Raman scattering have been generally enhanced, but also shows many new bands, which characterize the structure of SWCNTs and the interaction between SWCNTs and silver/gold nanoparticles, arising from symmetry lowering and selection rule relaxing of SWCNTs induced by the silver/gold surface. In our case, it is difficult to separate the contributions of the electromagnetic and chemical mechanisms to the great enhancement of the Raman signal. The analysis shows that the SERS spectra of SWCNTs on the metal-coated filter paper provide convenience for probing the sample molecules with fine structures related to defects of SWCNTs, the diameter of SWCNTs, and the SERS mechanism of SWCNTs deposited on metal-coated filter paper. Moreover, this can be used as a probe technique for monitoring the synthesis quality of SWCNTs with significant higher sensitivity than other methods, which has promise of being a new technique for monitoring synthesis quality of SWCNTs.     

Physical and chemical forms of radionuclides of 38S, 38Cl, 39Cl, and 82Br, produced at a high-energy proton accelerator facility

High-energy protons and neutrons produce various radionuclides in the air, mainly through the nuclear spallation of atmospheric elements. Air samples were collected from the EP-2 tunnel of the KEK 12 GeV proton synchrotron facility with a filter pack, which consisted of a membrane filter for aerosols, a Na₂CO₃-impregnated filter for acidic gases, and an activated carbon fiber filter for non-acidic gases. Sulfur-38 was found on the membrane and Na₂CO₃-impregnated filters, ³⁸Cl and ³⁹Cl were on the membrane, Na₂CO₃-impregnated, and ACF filters, and ⁸²Br was only on the ACF filter. The results on the relative abundances of aerosol and gaseous acidic components have indicated that ³⁸Cl produced by thermal neutron capture, which is the main reaction for ³⁸Cl production in the EP-2 tunnel air, are likely not to be present as aerosol or acidic gas. This was similar to the case of ⁸²Br produced by thermal neutron capture.     

Determination of trace nitrite ion in water by spectrophotometric method after preconcentration on an organic solvent-soluble membrane filter

A simple and rapid preconcentration technique, based on collecting trace nitrite on a membrane filter and dissolving the membrane filter in an organic solvent, has been applied to its spectrophotometric determination in water. At pH 2.0, nitrous acid diazotizes with p-aminoacetophenone. which is then coupled with N-(1-naphthyl)ethylenediamine, at the same pH. The azo dye formed is collected on a 0.45 urn nitrocellulose filter at pH 4.7 as its ion associate with dodecyl sulfate. The ion associate and filter are dissolved in a small volume of 2-methoxyethanol (methylcellosolve), and acidized with 0.05 ml of 2 M hydrochloric acid and the absorbance of the resulting solution is measured at 555 nm against a reagent blank. Detection limits better than O.1 mug/dm(-3) as NO(2)(-) can be achieved. The ions normally present in water do not interfere when sodium metaphosphate is added as a masking agent. The proposed method has been applied to the analysis of water samples from several sources, the recoveries of the nitrite added to the samples are quantitative, and results found are satisfactory.     

Phosphorescence characteristics of acetophenone, benzophenone, p-aminobenzophenone and Michler's ketone in various environments

The phosphorescence characteristics (excitation and emission spectra and lifetimes) of acetophenone (AP), benzophenone (BP), p-aminobenzophenone (PABP) and Michler's ketone (MK) adsorbed on Whatman No. 1 filter paper were measured at various temperatures, and compared with the phosphorescence characteristics in different solvent glasses at 77 K. Both AP and BP phosphoresce on filter paper only at low temperature (208 K). The phosphorescence lifetimes of AP and BP are < 1 msec, indicating a (3)(n,pi(*)) lower triplet level for paper substrates. With PABP, the low lying triplet state in polar solvents is (3)(CT) and in non-polar solvents is (3)(n, pi(*)); PABP on filter paper results in spectral characteristics similar to those of PABP in polar solvents at 77 K. The lifetime of PABP is longer than that of BP, indicating a (3)(CT) low-lying triplet state. MK, like PABP, has strongly environment-dependent photophysical properties. MK, when adsorbed on filter paper, has an intense long-lived luminescence at room temperature, resulting in a limit of detection of 3 ng ml or 3 pg, and a linear dynamic range of over 3 orders of magnitude. MK appears to be strongly hydrogen-bonded to the filter paper. In studies in ethanol and other solvents, MK adsorbed on filter paper shows a dramatic change in its phosphorescence spectrum when the temperature is lowered from 298 K to 208 K; the phosphorescence peak moves to longer wavelengths and the intensity decreases. The temperature effect could arise from the presence of several conformers of MK or be due to different environmental sites or E-type delayed fluorescence. The low-lying triplet state of MK on filter paper is most likely a (3)(CT) state. Lowering the temperature appears to increase the phosphorescence intensity for ketones which phosphoresce in the (3)(n,pi(*)) triplet state, but affects it only slightly for analytes which phosphoresce in the (3)(pi,pi(*)) triplet state. Room-temperature phosphorescence seems to arise for aromatic ketones and aldehydes with low-lying (3)(pi, pi(*)) or (3)(CT) triplet states.     

氧化还原沉淀法制备Mn-Ce-Co-Ox/PPS滤料及其低温SCR活性

先用十二烷基硫酸钠（SDS）对聚苯硫醚（PPS）滤料进行表面改性,随后通过氧化还原沉淀法制得不同质量比的Mn-Ce-Co-O_x/PPS复合滤料。考察了复合滤料在低温选择性催化还原（SCR）反应过程中的催化活性,并通过XRD、FESEM、TEM和XPS等表征手段对复合滤料的结构及性能进行表征分析。结果表明,Mn-Ce-Co-O_x/PPS复合滤料在120-160 ℃时的脱硝效率达到86%-100%,明显优于超声法制备的Mn-Ce-Co-O_x/PPS-UM复合滤料的低温SCR活性,且1.2Mn-Ce-Co-O_x/PPS复合滤料的活性最优。1.2Mn-Ce-Co-O_x/PPS复合滤料中MnO₂、Ce₂O₃、CeO₂、CoO、Co₃O₄以蜂窝状形式均匀分散在PPS纤维表面,且呈弱结晶性结构;其较高的Ce³⁺/（Ce³⁺+Ce⁴⁺）比值和Co元素浓度是该1.2Mn-Ce-Co-O_x/PPS复合滤料具有优异低温SCR活性的主要原因。此外,与Mn-Ce-Co-O_x/PPS-UM复合滤料相比,1.2Mn-Ce-Co-O_x/PPS复合滤料也具有良好的抗H₂O和抗SO₂性能。     

Improvement of water vapor adsorption ability of natural mesoporous material by impregnating with chloride salts for development of a new desiccant filter

The aim of this study is the development of a new adsorbent for the desiccant material which can be regenerated by the domestic exhaust heat by using natural mesoporous material, Wakkanai siliceous shale. To improve this shale’s performance to adsorb/desorb the water vapor, lithium chloride, calcium chloride or sodium chloride was supported into the mesopores by impregnating with each chloride solution. Especially sodium chloride was effective to increase the water vapor adsorption amount 5–7 times of that of natural shale in the relative humidity range from 50 to 70%. Moreover, the appropriate impregnating concentrations were determined as 5wt% from the relationship between the maximum water vapor adsorption amount and the mesopore volume. Based on these results, a new desiccant filter has been developed by impregnated original paper with lithium chloride and sodium chloride. This paper contained shale powder in the synthetic fibers. The dehumidification performance of this filter was evaluated under the simulated summer condition in Tokyo. From the cyclic adsorption/regeneration test, this shale and chlorides filter could adsorb and desorb 60 g/h water vapor repeatedly at the regeneration temperature of 40°C. On the other hand, a silica gel filter and a zeolite filter adsorbed and desorbed only 10 g/h and 25 g/h, respectively. These results suggested that the shale impregnated with the chlorides has the best dehumidification ability as a new desiccant material. Further, the desiccant filter made from the shale will achieve the effective use of the low temperature exhaust heat.