测定活性炭对四氯化碳吸附值的新方法─—迎头色谱穿透曲线法

提出了一种快速测定活性炭对四氯化碳的吸附值新方法。详细介绍了测定的系统装置、控制条件和操作步骤；阐明了通过穿透曲线测定活性炭对四氯化碳吸附值的原理；分析了规定的四氯化碳吸附值的物理意义。该方法测定快速、操作简易，数据精度符合要求。

活性炭对VOCs的吸附性能与其特征值之间的关系

以甲苯为典型VOCs废气分子,考察了不同活性炭样品的碘值、四氯化碳吸附率(CTC值)、总比表面积和微孔比表面积与其动态甲苯平衡吸附容量的关系.结果发现,无论是低浓度还是高浓度的甲苯废气,CTC值均与活性炭的吸附容量呈现较高的线性相关性,相关系数R 2高于0.92,而碘值只在低浓度条件下与活性炭吸附容量相关性较好,这表明CTC值相比碘值是更适合表征活性炭VOCs吸附性能的特征指标.此外,以含氧类VOCs(乙酸乙酯)为吸附质,CTC值也同样显示出与吸附容量优良的相关性.除活性炭外,本文还将上述方法拓展至硅胶、分子筛、碳硅复合材料等其他多孔吸附材料,结果证明CTC值可以用来指代不同多孔吸附材料的VOCs吸附性能,相对误差在30%以内,表明CTC值作为一个吸附特征指标具有良好的普适性.

基于清炒法对白术物性及主成分含量变化的研究

目的:探究清炒法对白术物性及主成分含量变化的影响研究。方法:通过对白术生品进行炒黄、炒焦、炒炭测定物性,采用水提醇沉法提取其多糖成分,通过苯酚硫酸法测定多糖含量,利用紫外分光光度计测定,建立标准曲线,运用Excel归一化处理,通过SPSS分析炮制工艺与物性、主成分之间关系。结果:药材某些性质改变明显,氧化值:炒焦(30.47)>炒炭(21.38)>生品(11.72)>炒黄(4.94);多糖含量:炒黄(25.72)>炒焦(25.13)>生品(10.4)>炒炭(0.87)。结论:炮制改变药材大分子结构,改变药材缓和之性,多糖分子排列重新组合,挥发油成分散失,通过研究控制炮制工艺技术参数,调整中药中成分的含量及其比例,确定其适宜的工艺技术参数。

Numerical simulation on the fluidized bed gasification and CaO dechlorination of refuse derived fuel

A three-dimensional numerical model verified by previous experimental data is developed to simulate the fluidized bed gasification of refuse derived fuel （RDF）. The CaO dechlorination model obtained by the thermal gravity analysis （TGA） is coupled to investigate the process of CaO dechlorination. An Eulerian-Eulerian method is adopted to simulate the gas-solid flow and self-developed chemical reaction modules are used to simulate chemical reactions. Flow patterns, gasification results and dechlorination efficiency are obtained by numerical simulation. Meanwhile, simulations are performed to evaluate the effects of Ca/Cl molar ratio and temperature on dechlorination efficiency. The simulation results show that the presence of bubbles in the gasifier lowers the CaO dechlorination efficiency. Increasing the Ca/Cl molar ratio can enhance the dechlorination efficiency. However, with the temperature increasing, the dechlorination efficiency increases initially and then decreases. The optimal Ca/Cl molar ratio is in the range of 3. 0 to 3. 5 and the optimal temperature is 923K.

Numerical simulation of fluid dynamics in rare earth chloride solution in jet-flow pyrolysis reactor

Rare earth oxide was prepared via direct pyrolysis of rare earth chloride solution. Based on this technique, a new-type jet-flow pyrolysis reactor was designed, and then the fluid dynamics (pressure and velocity) inside the reactor was numerically simulated using a computational fluid dynamics method. The self-produced pressure (p) and the fuel inlet velocity (v) satisfied a quadratic function,p=0.06v2+0.23v?4.49. To fully utilize the combustion-generated heat in pyrolysis of rare earth chloride, an appropriate external pressure p=v2+3v?4.27 should be imposed at the feed inlet. The 1.25- and 1.5-fold increase of feed inlet diameter resulted in decline of adsorption dynamic pressure, but the intake of rare earth chloride increased by more than 30% and 60%, respectively. The fluid flow in the reactor was affected by the feeding rate; the fluid flow peaked near the throat of venturi and gradually smoothed down at the jet-flow reactor’s terminal along with the sharp decline of feeding rate.

Some Limitations of BIOLOG System for Determining Soil Microbial Community

A laboratory experiment was conducted to evaluate the effect of triphenyltetrazolium chloride (TTC) on soil microorganisms and the availability of pH characterization medium in BIOLOG plates. Application of TTC decreased the color development sharply and resulted in a great biocidal effect on the growth and reproduction of soil microorganisms, indicating that TTC can affect the discrimination on soil microbial community. The microtitration plates with 21 carbon sources and two different pH levels (4.7 and 7.0) were used to determine microbial community structure of eight red soils. The average utilization (average well colour development) of the carbon sources in the plates with different pH levels generally followed the same sigmoidal pattern as that in the traditional BIOLOG plates, but the pH 4.7 plates increased the discrimination of this technique, compared with the pH 7.0 plates. Since most tested soils are acid, it seemed that it’s better to use a suitable pH characterization medium for a specific soil in the sole carbon source test.

Effect of Anions on Adsorbability and Extractability of Lead Added in Soil

The effect of accompanying anions on the adsorbability and extractability of Pb added in soils was studied by using bach equilibria and incubation-extraction mothods.Pb concentration ranged between 0.48-2.41 mM in the adsorption experiment,and Pb added to soil from 2.14 to 19.31mM Pb/kg with an incubation time of 2-16 weeks in the incubation-extraction test in which 1M NH4OAc(pH 7) was taken as an extraction agent,and the Pb compounds used are PbCl2,Pb(NO3)2 and Pb(OAc)2.The values of pH50 for Pb retention and the parameters,b and k values,of Langmuir equation were used to distinguish the difference of adsorbability and extractability of Pb affected by anions,respectively.Judging from the results of either pH50 value or b value,the influences of Cl^- and NO3^- on the adsorbability and extractability of Pb in soils were similar but quite different from those of OAc^-.The relative loading capacities of soils to Pb calculated according to the extraction rate showed that the values of Pb(OAc)2 were higher than those of PbCl2 and Pb(NO3)2.

Coagulation behavior of polyaluminum chloride: Effects of pH and coagulant dosage

Coagulation mechanisms of polyaluminum chloride(PACl) at various dosages were studied using a conventional jar test at different final and initial pH values during treating kaolin suspension. The optimal final pH and dosages for PACl were obtained based on residual turbidity and zeta potential of flocs. The coagulation zones at various PACl dosages and solution p H values were developed and compared with those of alum. It is found that the optimal mechanism under acidic condition is charge neutralization, while alkaline condition will facilitate the coagulation of PACl. Both charge neutralization coagulation and sweep coagulation can achieve high coagulation efficiency under the alkaline condition ranging from final p H 7.0 to 10.0. Stabilization, charge neutralization destabilization, restabilization and sweep zones occur successively with increasing PACl dosages with the final p H values fixed at 7.0 and 8.0, but restabilization zone disappears at final p H 10.0. When the final p H is not controlled and consequently decreases with increasing PACl dosage, no typical sweep zone can be observed and the coagulant efficiency decreases at high PACl dosage. It seems that the final pH is more meaningful than the initial p H for coagulation. Charge neutralization coagulation efficiency is dominated by zeta potential of flocs and PACl precipitates. The charge neutralization and sweep coagulation zones of PACl are broader in the ranges of coagulant dosage and p H than those of alum. The results are helpful for us to treat water and wastewater using PACl and to understand the coagulation process of PACl.

Catalytic dechlorination of chlorinated methanes by nanoscale Pd/Fe bimetallic particles

This paper examined the potential of using laboratory-synthesized nanoscale Pd/Fe bimetallic particles to dechlorinate chlorinated methanes, including dichloromethane (DCM), trichloromethane (CF) and tetrachloromethane (CT). Nanoscale Pd/Fe bimetallic particles were characterized in terms of surface area, morphology, size and structure. The parameters affecting the dechlorination efficiency were studied through batch experiments. Effects of Pd content, Pd/Fe addition, and the initial pH value of reaction system on the dechlorination efficiency of chlorinated methanes were determined systematically. Results show that nanoscale Pd/Fe bimetallic particles play a prominent role in the dechlorination of chlorinated methanes. The change of pH value and ferrous ion concentration during dechlorination reaction were also investigated in this study. It is found that the dechlorination efficiency of chlorinated methanes is in the order of CT>CF>DCM.

Effect of Boundary Layers on Polycrystalline Silicon Chemical Vapor Deposition in a Trichlorosilane and Hydrogen System

This paper presents the numerical investigation of the effects of momentum, thermal and species boundary layers on the characteristics of polycrystalline silicon deposition by comparing the deposition rates in three chemical vapor deposition （CVD） reactors. A two-dimensional model for the gas flow, heat transfer, and mass transfer was coupled to the gas-phase reaction and surface reaction mechanism for the deposition of polycrystalline silicon from trichlorosilane （TCS）-hydrogen system. The model was verified by comparing the simulated growth rate with the experimental and numerical data in the open literature. Computed results in the reactors indicate that the deposition characteristics are closely related to the momentum, thermal and mass boundary layer thickness. To yield higher deposition rate, there should be higher concentration of TCS gas on the substrate, and there should also be thinner boundary layer of HCl gas so that HCl gas could be pushed away from the surface of the substrate immediately.

Effect of various Na/K ratios in low-salinity well water on growth performance and physiological response of Pacific white shrimp Litopenaeus vannamei

To investigate the influence of sodium to potassium （Na/IO ratios on the growth performance and physiological response of the Pacific white shrimp （Litopenaeus vananmei）, various concentrations of KC1 were added to low-salinity well water （salinity 4） in an 8-week culture trial. Six treatments with NWK ratios of 60：1, 42：1, 33：1, 23：1, 17：1, and 14：1 were replicated in triplicate. The highest weight-gain rate （3 506±48）% and survival rate （89.38±0.88）% was observed in well water with Na/K ratios of 23：1 and 42：1, respectively, while the feed conversion ratio （1.02～0.01）, oxygen consumption, and ammonia-N excretion rate was the lowest in the medium with a Na/K ratio of 23：1. Gill Na＋-K＋-ATPase activity, as an indicator of osmoregulation, peaked in the treatment where the Na/K ratio was 17：1. The total hemocyte count, respiratory burst, and immune-related enzyme activities （ALP, LSZ, PO, and SOD） ofL. vananmei were affected significantly by Na/K ratios （P〈0.05）. After challenged with Vibrio harveyi, the cumulative mortality of shrimp reared in a Na/K ratio of 23：1 （30±14.14）% was significantly lower than the control （75～7.07）%. In conclusion, the addition of K＋ to low-salinity well water in L. vannamei cultures is feasible. Na/K ratios ranging from 23：1 to 33：1 might improve survival and growth. Immunity and disease resistance are also closely related to the Na/K ratio of the low-salinity well water. The findings may contribute to the development of more efficient K^＋ remediation strategies for L. vananmei culture in low-salinity well water.

Numerical Study of the Mixing of Density-Stratified Fluid with a Jet

Density stratification of LNG （liquefied natural gas） is produced in a storage tank when one LNG is loaded on top of another LNG in the same tank. Mixing LNG by a jet issued from a nozzle on the tank wall is considered to a promising technique to prevent and eliminate stratification in LNG storage tanks. This study is concerned with the numerical simulation of a jet flow issued into a two-layer density-stratified fluid in a tank and the resultant mixing phenomena. The jet behavior was investigated with the laboratory-based experiment of the authors＇ previous study. A numerical method proposed by the authors is employed for the simulation. The upper and lower fluids are water and a NaCl-water solution, respectively, and the lower fluid is issued vertically upward from a nozzle on the bottom of the tank. The Reynolds number （Re） defined by the jet velocity and the nozzle diameter ranges from 95 to 2,378, and the mass concentration of the NaCl-water solution Co is set at 0.02 and 0.04. The simulation highlights the jet-induced mixing between the upper and lower fluids. It also clarifies the effects of Re and C0 on the height and horizontal spread of the jet.

Reacting Flow of Hydrogen Chloride and Ammonia in Experimental and Numerical Modelling

The experimental and numerical investigations of the flow with reaction of two gases: hydrogen chloride HC1 and ammonia NH3 were performed. The article contains description of the visualisation method of the formation and flow of particles of ammonia chloride NH4Cl. Analyses of mean concentration and variance of concentration fluctuations of dispersed phase were performed for different outputs of gases. Numerical calculations were performed for analysed phenomenon. Both numerical and visualisation results were matched and compared.