类气相ClO2脱除燃煤烟气中氮氧化物实验研究

燃煤电厂排放的烟气中含有大量的氮氧化物,不仅对生态环境造成了巨大的危害,也是产生雾霾的主要原因之一。氮氧化物中的主要成分为NO,NO不溶于水的特性使其难以在传统脱硫塔中进行脱除。为经济有效的脱除燃煤烟气中的氮氧化物,采用氧化吸收法进行脱硝研究。通过对比不同氧化剂的氧化性能,选取ClO2为氧化剂,将其在140℃的条件下进行气化,转变为类气相氧化剂。将烟气中NO预氧化成易溶于水的NO2,再结合饱和氢氧化钙溶液吸收氧化产物进行燃煤烟气脱硝研究。通过电子顺磁共振检测(ESR)以及·OH抑制剂添加实验说明类气相ClO2在氧化过程中产生了·OH等强氧化性自由基,极大地促进了对NO的氧化。实验结果表明,脱硝效率随物质的量比(ClO2/NO)的增加而增加,当物质的量比(ClO2/NO)大于0.84后,脱除效率增加缓慢;在110~170℃内,温度对类气相ClO2脱除NO的影响较小;酸性条件有利于NO的脱除效率的增加,但总体影响较小,当烟气中SO2与NO共同存在时,类气相ClO2优先氧化烟气中的NO。最佳反应条件为:物质的量比(ClO2/NO)=0.84,反应温度为140℃,溶液pH=3左右,此时NO的氧化脱除效率可以达到92.5%。采用离子色谱对氧化产物分析,指出NO的主要氧化产物为NO-3并提出类气相ClO2对烟气中NO的氧化脱除机理,表明类气相ClO2结合碱液氧化吸收具有良好的工业应用前景。

蒙脱土改性气相缓蚀剂的制备及性能研究

采用蒙脱土对吗啉类气相缓蚀剂进行改性,通过气相防锈甄别试验和气相缓蚀能力试验,对改性气相缓蚀剂进行了防锈性能评定,结果表明,蒙脱土的引入增强了气相缓蚀剂的缓蚀能力。密闭空间挥发减重试验表明,改性气相缓蚀剂的挥发能力有所提高。模拟大气腐蚀水的电化学极化曲线表明,蒙脱土的引入进一步增大了对阳极和阴极电化学过程的抑制作用。

Determination of phthalate esters in fat-containing foods by packed nanofiber solid-phase extraction column and gas chromatography

A new method for simultaneous determination of four phthalate esters （ PAEs） in commercial fat-containing foods was developed by the combination of a packed nanofibers column based on solid-phase extraction with gas chromatography-flame ionization detector （ GC-FID ）. Conditions for obtaining optimum extraction efficiency such as extraction solvents, morphologies of adsorbent, ion strength and pH were investigated and optimized in detail. Under the optimized conditions, the limits of detection （LODs） found for dibutyl phthalate （DBP） , butyl benzyl phthalate （BBP）, diethyl hexyl phthalate （DEHP） and di-n-octyl phthalate （DNOP） were 50, 25, 50 and 25 ng/g, respectively. Good linearity of four PAEs was achieved in the range of 50 to 4 000 ng/g. The proposed method was applied for analyzing different kinds of fat-containing samples. PAEs in commercial fat-containing samples can be highly extracted by a packed solid-phase extraction column of 5 mg polystyrene （ PS） nanofibers. The satisfactory average recoveries were obtained in the range of 96. 7% to 102. 3% , and the relative standard deviations （RSDs） below 5% were achieved. The proposed method reduces the organic solvent consumption, the complex and tedious procedures for sample pretreatment, and achieves high sensitivity and reproducibility for the investigated PAEs.

Microwave Extraction Followed by Solid-phase Extraction for the Determination of Phthalate Esters in Fish Samples by Gas Chromatography

A new analytical procedure based on solid-phase extraction method coupled to GC-FID has been developed and validated for the determination of five phthalate esters （PAEs） （dimethyl-（DMP）, diethyl-（DEP）, di-n-butyl-（DBP）, di-2-ethylhexyl- （DEHP）, di-n-octyl-（DOP）） in fish samples. There was a good linear relationship in the range of 0.05-10μg with the detection limits of 0.09-0.16ng .The recoveries obtained for PAEs ranged from 88.6% to 96.4%with RSD of 4.2%-10.2%.The applicability of the developed method was demonstrated for real fish samples.

Reconstructing bubble profiles from gas-liquid two-phase flow data using agglomerative hierarchical clustering method

The knowledge of bubble profiles in gas-liquid two-phase flows is crucial for analyzing the kinetic processes such as heat and mass transfer, and this knowledge is contained in field data obtained by surface-resolved computational fluid dynamics (CFD) simulations. To obtain this information, an efficient bubble profile reconstruction method based on an improved agglomerative hierarchical clustering (AHC) algorithm is proposed in this paper. The reconstruction method is featured by the implementations of a binary space division preprocessing, which aims to reduce the computational complexity, an adaptive linkage criterion, which guarantees the applicability of the AHC algorithm when dealing with datasets involving either non-uniform or distorted grids, and a stepwise execution strategy, which enables the separation of attached bubbles. To illustrate and verify this method, it was applied to dealing with 3 datasets, 2 of them with pre-specified spherical bubbles and the other obtained by a surface-resolved CFD simulation. Application results indicate that the proposed method is effective even when the data include some non-uniform and distortion.

Assessment of Triazine Herbicides in Soil by Microwave-assisted Extraction Followed by Gas Chromatography Coupled to Mass Spectrometry Detection

An alternative and fast method for the analysis of a mixture of nine triazines herbicides in soil is presented. The method is based on MAE （microwave-assisted extraction） of herbicides using ethyl acetate as extractant. The economy in the use of solvents coupled with the decrease in extraction time and lower power consumption make MAE a technique that meets the principles of green chemistry. MAE operational parameters, extraction time, mass of the sample and extraction temperature, were optimized by RSM （response surface methodology）. Determination of analytes was completed using gas chromatograph coupled to mass spectrometry detection. The selected triazines could be efficiently extracted by the solvent at 80 ℃ for 10 min, with 80% output of maximum power. When the optimized method was applied to analysis samples, the recoveries of analytes ranged from 81.8 to 106.0% and relative standard deviations were lower than 8.41%. The method is stable and reasonable, which can be used for the determination of ninetriazine herbicides residues in soil.

Organic composition of gasoline and its potential effects on air pollution in North China

When gasoline is burned to power an automotive engine, a portion of the fuel remains unburned or is partially burned and leaves the engine as hydrocarbon and oxygenated compounds. In addition, a small portion of the fuel can escape the vehicle through evaporation. Changes in alkanes, olefins and aromatics each affect emissions differently, which could complicate control strategies for air pollution. In this study, we collected 31 gasoline samples over five provinces and cities(Beijing, Tianjin, Hebei, Shandong, and Shaanxi) in North China between 2012 and 2013. The organic composition of the gasoline samples was analyzed using the gas chromatography-mass spectrometry(GC-MS) method, and the aniline compounds were analyzed by solvent extraction and the GC-MS method. The ratios of alkanes, aromatics, olefins and other organic compounds in gasoline were 40.6%, 38.1%, 12.9% and 8.4%, respectively. The aromatic and benzene exceedances were 15 and 8 based on the China's gasoline standards(III), and they accounted for 48.4% and 25.8% of all the gasoline samples, respectively. Strong carcinogen aniline compounds were detected in all 31 samples, and the content of aniline compounds in 3 samples exceeded 1%. The high proportion of aromatics and olefins in the gasoline increased the emissions of carbon monoxide(CO) and toxics, as well as the atmospheric photochemical reactivity of exhaust emissions, which could hasten the formation of secondary pollutants. Our results are helpful for redefining government strategies to control air pollution in North China and relevant for developing new refining technology throughout China.

Relative contribution of the anthropogenic forcing and natural variability to the interdecadal shift of climate during the late 1970s and 1990s

Global warming accelerated after the late1970 s and slowed down after the late 1990 s, accompanying the significant interdecadal changes in the regional climate.We hypothesized that the interdecadal changes linearly consisted of two independent components, anthropogenic forcing and natural decadal variability, which can be represented simply by the radiative forcing effect of carbon dioxide (RFCO_2) and the Pacific Decadal Oscillation(PDO), respectively. The combined effect of the RFCO_2 and PDO could explain the majority of the surface temperature changes during the late 1970 s and 1990 s, but the magnitudes of the relative contribution of the RFCO_2 and the PDO are inconsistent in different regions. For both the surface temperature and geopotential height, the RFCO_2 could induce significantly positive anomalies over almost the entire globe for these two shifts, exhibiting a larger magnitude in the mid–high latitudes and in the late 1990 s shift.The PDO could induce opposite anomalies for the two interdecadal shifts due to its phase transitions(negativepositive–negative). Furthermore, for the shift in the late 1970s, both the RFCO2(53.7 %–66.7 %) and the PDO(33.3 %–46.3 %) were important in regulating the tropical geopotential height, whereas the RFCO_2 dominated the changes in the mid-latitudes. For the western Pacific subtropical high, the RFCO2(PDO) could explain 52.3 %–62.1 %(37.9 %–47.7 %) of the change. The negative effect of the PDO counteracted most of the RFCO_2 effects for the late 1990 s shift.