ZL50活性炭吸附脱除二氧化硫的吸附动力学模型(英文)

A semi-empirical adsorption kinetic model was proposed with the time compensation method to describe the chemisorption of SO2 in flue gas by carbon adsorbents for flue gas purification. The change in adsorption capacity and adsorption rate with time at different water vapor concentrations and different SO2 concentrations was studied. The model was in good agreement with experimental data. The surface reaction was probably the rate controlling step in the early stage for SO2 adsorption by ZL50 activated carbon. The parameters m and n in the nth order adsorption kinetic model were related to the magnitude of the time compensation and adsorption driving force, respectively. The change of parameter n with water vapor concentrations and sulfur dioxide concentrations was studied and some physical implications were given. The sum of square errors was less than 1.0 and the average absolute percentage deviations ranged from 0.5 to 3.2. The kinetic model was compared with other models in the literature.     

Removal of lead and cobalt using lignocellulosic fiber derived from <Emphasis Type="Italic">Citrus reticulata</Emphasis> waste biomass

The present investigation explored the use of Citrus reticulata waste biomass (CWB) for the removal of Pb(II) and Co(II) from the aqueous solutions. The Pb(II) and Co(II) biosorption was found to be dependent on pH of the solution, biosorbent dose, biosorbent particle size, temperature, shaking speed, contact time and initial concentration of metal ions. A metal uptake capacity of 41.16 and 52.64 mg/g was observed at pH 5 and 7 for Pb(II) and Co(II), respectively. The biosorption data followed the Freundlich model for both metals. The overall biosorption process was best described by pseudo-second order kinetics. The effect of several pretreatments on the biosorption efficiency of CWB was also investigated. The results demonstrated that pretreatments influenced the biosorption capacity of the biomass for the both metals significantly. Maximum biosorption capacity of 83.77 and 95.55 mg/g was observed for Pb(II) and Co(II) with sodium hydroxide treated and simply heated biomass, respectively. FTIR spectrum indicated the presence of -OH, -NH, -COOH groups in the biomass. The surface structure of CWB was analyzed by JEOL JMT 300 scanning electron microscope (SEM), and the existence of metal ions on the surface of biosorbent was determined by energy dispersive X-ray (EDX) spectroscopy.     

Biodiesel production from waste tallow

In the present investigation an attempt has been made to use waste tallow as low cost sustainable potential feed stock for biodiesel production. Effect of various process parameters such as amount of catalyst, temperature and time on biodiesel production was investigated. The optimal conditions for processing 5 g of tallow were: temperature, 50 and 60 °C; oil/methanol molar ratio 1:30 and 1:30, amount of H₂SO_4, 1.25 and 2.5 g for chicken and mutton tallow, respectively. Under optimal conditions, chicken and mutton fat methyl esters formation of 99.01 ± 0.71% and 93.21 ± 5.07%, was obtained after 24 h in the presence of acid. The evaluation of transesterification process was followed by gas chromatographic analysis of tallow fatty acid esters. A total of 98.29% and 97.25% fatty acids were identified in chicken and mutton fats, respectively. Both fats were found highly suitable to produce biodiesel with recommended fuel properties.     

Synthesis and characterization of higher fullerene (C84) in dc arc discharge using Cu as a catalyst

The synthesis of fullerenes was carried out using dc arc discharge technique. The separation and identification of higher fullerene C₈₄ was done by high performance liquid chromatography (HPLC). The raw soot collected from the high temperature region was dissolved in toluene and then toluene-extracted soot dissolved in n-hexane and kept in laboratory environment for more than one month. The peaks of C₆₀ and C₇₀ along with C₈₄ were observed. The existence of C₈₄ was confirmed by using linear regression between capacity factor log [k′] and the carbon number.     

Assessing the Adequacy of Wright's Model Reconstructed Stream-Flow Data for Reservoir Storage-Yield-Reliability Analysis

As a method of reconstructing long stream-flow data records for consistent yield analysis, the Environment Agency in England and Wales has adopted the catchment model of Wright. However, to date none of the calibrated models has been verified using criteria directly linked to the intended purpose of the reconstructed data. This paper reports the findings of a simulation study carried out to assess the adequacy of Wright's model reconstructed stream-flow data for reservoir storage-vield-reliability analysis.     

Clostridium difficile colitis associated with treatment of Helicobacter pylori infection

Helicobacter pylori infection of the stomach is being detected and treated more often now than ever before. This is likely to result in an increase in complications such as antibiotic-associated diarrhea. However, there is no literature on the incidence of such diarrhea, particularly Clostridium difficile colitis, in patients treated for Helicobacter pylori infection. We report the case of a patient who developed Clostridium difficile colitis after treatment for Helicobacter pylori infection with metronidazole, amoxicillin, H2 blockers, and bismuth subsalicylate. This patient presented with severe diarrhea that responded to a course of metronidazole with rapid disappearance of symptoms. The incidence of Clostridium difficile colitis in patients treated for Helicobacter pylori infection has not been studied. This unique association, although not unexpected, has not yet been reported in the literature. The increasing number of patients being diagnosed and treated for this infection requires a heightened awareness on the part of physicians, to assure early diagnosis and treatment of this treatable, yet potentially dangerous, complication.     

MHD flow control for plasma technology applications

MHD effects arising in plasma sources, such as short-pulsed magnetoplasmadynamic generators and inductively heated plasma generators, are analyzed with both algebraic models and measured data. Functional principles of the sources based on their MHD behavior are explained. Moreover, Stewart numbers in the order of magnitude of at least 10⁻¹ are calculated for the systems and qualified as an identifier for the magnetic influence on plasmas. Here, the considered plasma systems that are a priori known as MHD systems were used to determine typical values of the Stewart number. Based on this experience the concept of a plasma probe to magnetically influence or control weakly ionized free stream plasma flows is presented.     

Intergranular Nanostructure Effects on Strength and Toughness of Si3N4

Strength, toughness, microstructure, and atomic adsorption arrangement in silicon nitrides with MgO and RE₂O₃ additions (RE = La, Gd, Y, Lu) were examined. Mechanical properties were high for La, Gd, and equal La–Lu additions, but surprisingly were progressively lower for Y‐ and Lu‐doped samples. The lower strength and toughness were associated with fewer visible crack deflections and grain bridges. Detailed microstructural analysis of the Lu‐doped material revealed a complex intergranular nanostructure with variable Lu content and Si₃N₄ nanocrystals. Furthermore, the Lu‐rich areas showed an extra Lu‐adsorption site on the Si₃N₄ prismatic planes not previously observed in other studies. This inhomogeneous structure was attributed to grain growth impingement and higher viscosity of the Lu‐doped oxynitride glass that slows homogenization. The Y‐doped material with nearly identical glass viscosity demonstrates intermediate behavior. Finally, substituting half of the Lu₂O₃ with La₂O₃ resulted in a homogenous intergranular structure, attributed to a lower viscosity of the oxynitride glass phase, and high mechanical properties. Overall, care must be taken when adapting Si₃N₄ processing parameters for the smaller ionic radius rare earth dopants such as Lu and Y.     

SAW sensor read range limitations and perspectives

Wireless monitoring systems with passive surface acoustic wave (SAW) sensors offer novel and prodigious perspectives for remote monitoring and control in harsh environments. This paper reviews the working principle of such passive sensors and their state-of-the-art behavior. All major fields of the SAW sensor require operation over a longer reading range, which is the current limitation, hindering the massive implementation of these passive devices. This foremost limitation of the SAW based sensor system occurs when the reply signal strength at the reader becomes too weak for reliable recognition and identification. SAW sensor network read range limitations and advanced techniques for its enhancement are deliberated. Deployment design to maintain the communication reliability and connectivity of the sensor/interrogators network is also discussed.