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ABSTRACT: Sewage sludge acquired from Giheung Respia treatment facility was characterized and converted into gas, bio-oil and char by
pyrolysis. The rate of conversion as a function of temperature was obtained from differential thermogravimetric analysis (DTG)
for different heating rates. The activation energy calculated from data selected conversions shows that the activation energy
decreased with increasing conversion up to 10%, steadily increased from 10 to 70%, and substantially increased from 70 to
90%. Depending on the level of conversion, the values of activation energies varied between 181 and 659 kJ/mol. The gas product
obtained in the experiment at 450 °C, 20 min mainly included CO2 (30%), CO (23%) and CH4 (17%). The product yields of gas, oil and char were systematically studied by changing the pyrolysis temperature and residence
time.
Key wordsBiomass-Pyrolysis-Sewage Sludge-TGA-Conversion
Korean Journal of Chemical Engineering 05/2012; 27(1):163-167. · 0.99 Impact Factor
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ABSTRACT: Pine trees comprise over 35% of the forests in Korea, since 1989, pine wilt disease introduced via the Japanese pine sawyer has been infecting many of these trees. As a renewable resource, pine can be converted to bio-oil, gas, and char through pyrolysis. In this study, the pyrolysis characteristics of pine trees were investigated using thermogravimetric analyzer, with most of the materials decomposing between 330 and 370 degrees C at heating rates of 5-20 degrees C/min. The apparent activation energy increased from 145 to 302 kJ mol(-1) with increasing pyrolysis conversion. The kinetics of pine tree pyrolysis were experimentally and mathematically evaluated. The kinetic parameters were determined using nonlinear least-squares regression of the experimental data assuming first-order kinetics. It was found from the kinetic rate constants that the predominant reaction pathway was A (pine) to gas (C(1)-C(4)) rather than A to bio-oil at temperatures of 330-370 degrees C.
Bioresource technology 12/2010; 101(24):9797-802. · 4.25 Impact Factor
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ABSTRACT: Hyaluronic acid (HA) was extracted in a relatively large scale from rooster comb using a method similar to that reported previously. The extraction method was modified to simplify and to reduce time and cost in order to accommodate a large-scale extraction. Five hundred grams of frozen rooster combs yielded about 500 mg of dried HA. Extracted HA was characterized using asymmetrical flow field-flow fractionation (AsFlFFF) coupled online to a multiangle light scattering detector and a refractive index detector to determine the molecular size, molecular weight (MW) distribution, and molecular conformation of HA. For characterization of HA, AsFlFFF was operated by a simplified two-step procedure, instead of the conventional three-step procedure, where the first two steps (sample loading and focusing) were combined into one to avoid the adsorption of viscous HA onto the channel membrane. The simplified two-step AsFlFFF yielded reasonably good separations of HA molecules based on their MWs. The weight average MW (M(w) ) and the average root-mean-square (RMS) radius of HA extracted from rooster comb were 1.20×10(6) and 94.7 nm, respectively. When the sample solution was filtered through a 0.45 μm disposable syringe filter, they were reduced down to 3.8×10(5) and 50.1 nm, respectively.
Journal of Separation Science 09/2010; 33(22):3530-6. · 2.73 Impact Factor
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ABSTRACT: The aim of this study was to test the utility of our computed tomography (CT) grading system, compared with endoscopy, for association with the development of esophageal stricture in patients with caustic ingestion.
This retrospective case series involved 49 patients with caustic ingestion from 1998 to 2009. The degree of esophageal damage was graded using a scoring system based on the extent of esophageal wall edema and the damage in adjacent tissue as seen on thoracoabdominal CT scans. The presence of esophageal stricture was established by esophagography. Diagnostic performance was compared using receiver operating characteristic (ROC) analysis. Sensitivity and specificity were calculated for the grading system.
The CT grading score results showed that grade III was the most common injury (20 cases, 40.8%), followed by grade IV (14 cases, 28.6%), grade II (9 cases, 18.4%), and grade I (6 cases, 12.2%). In addition, damage to the esophagus was significantly correlated with esophageal stricture when the extent of damage approached grades III and IV (p < 0.001). The CT grading system for esophageal stricture resulted in a slightly larger area under the receiver operating characteristic curve (0.90) compared with endoscopic grading system (0.79). The sensitivity and specificity of CT grading system were moderately higher than those of endoscopic grading system.
Assessment of the degree of esophageal damage using CT, a noninvasive modality, in patients who visit the emergency department following caustic ingestion should be useful in estimating the occurrence of complications including esophageal stricture.
Clinical Toxicology 02/2010; 48(2):137-42. · 2.22 Impact Factor
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ABSTRACT: In this work, pyrolysis characteristics were investigated using thermogravimetric analysis (TGA) at heating rates of 5-20 degrees C/min. Most of the materials were decomposed between 330 degrees C and 370 degrees C at each heating rate. The average activation energy was 236.2 kJ/mol when the pyrolytic conversion increased from 5% to 70%. The pyrolysis kinetics of oak trees was also investigated experimentally and mathematically. The experiments were carried out in a tubing reactor at a temperature range of 330-370 degrees C with a reaction time of 2-8 min. A lump model of combined series and parallel reactions for bio-oil and gas formation was proposed. The kinetic parameters were determined by nonlinear least-squares regression from the experimental data. It was found from the reaction kinetic constants that the predominant reaction pathway from the oak trees was to bio-oil formation rather than to gas formation at the investigated temperature range.
Bioresource technology 09/2008; 100(1):400-5. · 4.25 Impact Factor
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ABSTRACT: An improved HPLC procedure for separating ciprofloxacin and its four metabolites, M1, M2, M3, M4 in urine, was developed. The procedure used is reversed phase chromatography, the stationary phase being the C18-column, followed by quantification using a UV detector. The mobile phase is a mixture of isopropanol, acetonitrile, tetrabutylammonium bromide (TBABr), heptanesulfonic acid (HSA), and 0.05% triethylamine, (adjusted to pH=3.0 with phosphoric acid.) In the process of determining the optimum separation condition, the effect of each ion-pairing reagent on the retention of all analytes was investigated and explained as well. This method involves an off-line solid phase extraction, using C18 Sep-Pak cartridges for ciprofloxacin and its metabolites in urine. The desorption condition is investigated by using different kinds of organic solvents, or a mixture of organic solvents and phosphate buffer, adjusted to different values of pH. At the optimum desorption condition, all analytes show a recovery rate over 90%. Based on this optimum condition, this method was applied to pharmacokinetic study of solutes in urine sample.
Journal of Liquid Chromatography & Related Technologies 02/2007; 23(7)(1069–1081 (2000)):1069-1081. · 0.71 Impact Factor
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ABSTRACT: Carbon black is one of the most useful particulate materials in the industrial field. Among the various physical properties of carbon black, size and size distribution are the most important properties to affect the quality of a final product. However, it is difficult to measure the exact particle size of carbon black since it suffers unavoidable interference from flocculation. In this study, the effects of various factors on the dispersion of industrial carbon blacks were investigated for the determination of size and size distribution of carbon black particles. Sedimentation and flow field-flow fractionations (FIFFF) were used to determine the size of carbon black, and their optimum analytical conditions were tested by changing surfactant, pH, ionic strength, and method of dispersion. The results showed that surfactant structure and its concentration played significant roles in dispersion stability. Carbon black was dispersed well with a nonionic surfactant with a pH of around 8 and an ionic strength of 0.003 M. The mean diameters measured from two types of FFF and photon correlation spectroscopy are in good agreement. This study demonstrates the potential of sedimentation and flow FFF for analyzing highly adsorptive industrial particles and guides for sample preparation.
Analytical and Bioanalytical Chemistry 03/2003; 375(4):489-95. · 3.78 Impact Factor
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Journal of Liquid Chromatography & Related Technologies 09/1997; 20(16-17):2741-2756. · 0.71 Impact Factor
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Journal of Liquid Chromatography & Related Technologies 09/1997; 20(16-17):2599-2614. · 0.71 Impact Factor
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Instrumentation Science & Technology 05/1997; 25(2):133-145. · 0.43 Impact Factor
