• Title/Summary/Keyword: gravimetric method

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Synthesis and Characterization of Reduced Graphene Oxide/Gelatin Composite Films (환원된 산화그래핀/젤라틴 복합필름의 합성과 분석)

  • Chen, Guangxin;Qiao, Congde;Xu, Jing;Yao, Jinshui
    • Polymer(Korea)
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    • v.38 no.4
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    • pp.484-490
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    • 2014
  • Reduced graphene oxide (RGO) was fabricated using gelatin as a reductant, and it could be stably dispersed in gelatin solution without aggregation. A series of RGO/gelatin composite films with various RGO contents were prepared by a solution-casting method. The structure and thermal properties of the RGO/gelatin composite films were characterized by UV-vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), differential scanning calorimeter (DSC) and thermal gravimetric analysis (TGA). The addition of RGO enhances the degree of crosslinking of gelatin films and decreases the swelling ability of the gelatin films in water, indicating that RGO/gelatin composite films have a better wet stability than gelatin films. The glass transition temperature ($T_g$) of gelatin films is also increased with the incorporation of RGO. The presence of RGO slightly increases the degradation temperature of gelatin films due to the very low content of RGO in the composite films. Since gelatin is a natural and nontoxic biomacromolecule, the RGO/gelatin composite films are expected to have potential applications in the biomedical field.

Crystal Structures and Thermal Properties of Two Binuclear Cd(II) Supramolecular Complexes Based on Quinolinecarboxylate Ligand

  • Hao, Hu-Jun;Yin, Xian-Hong;Lin, Cui-Wu;Wei, Shui-Qiang
    • Bulletin of the Korean Chemical Society
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    • v.32 no.9
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    • pp.3255-3260
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    • 2011
  • Two novel binuclear metal-organic coordination complexes $[Cd_2(L)_2(bpy)_2(H_2O)_2]{\cdot}6H_2O$ (1), $[Cd_2(L)_2(phen)_2-(H_2O)_2]{\cdot}2H_2O$ (2) (where L = 2-methylquinoline-3,4-dicarboxylate dianion, bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline) have been synthesized under hydrothermal conditions and characterized by single crystal Xray diffraction, spectral method (IR), elemental analysis and thermal gravimetric analysis (TGA). Both 1 and 2 consist of two Cd(II) atoms bridged by two monoatomic bridging carboxylate groups from two L ligands, and the second carboxylate group of each L is monodentately coordinated to Cd(II), creating a sevenmembered chelating ring. The coordination at each metal nucleus is completed by a water molecule and a chelating bidentate molecule. The 3D structures of the complexes are stabilized by ${\pi}-{\pi}$ stacking interactions and hydrogen-bonds.

Solid Phase Extraction of Celecoxib from Drug Matrix and Biological Fluids by Grafted Poly β-cyclodextrine/allyl Amine Magnetic Nano-particles

  • Kamari, Sahar;Panahi, Homayon Ahmad;Baimani, Nasim;Moniri, Elham
    • Korean Chemical Engineering Research
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    • v.55 no.3
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    • pp.287-295
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    • 2017
  • Using nanotechnology, magnetic nanoparticles of iron oxide were produced via co-precipitation method and followed modification with organic compounds. In the next step, functionalized monomer was provided via coupling ${\beta}$-cyclodextrine and allylamine onto modified magnetic nanoparticles. These nanoparticles were used to establish the adsorption rate of celecoxib. Magnetic nanoparticles are modified by (3-mercaptopropyl)trimethoxysilane. Nano-adsorbent was characterized by analytical and spectroscopic methods, such as Fourier transform infrared spectroscopy, elemental analysis, thermo-gravimetric analysis, and transmission electron microscopy (TEM). Laboratory parameters, such as the kinetics of adsorption isotherms, pH, reaction temperature and capacity were optimized. Finally, by using this nano-adsorbent in the optimized condition, extraction of celecoxib from biological samples as urine, drug matrix and blood plasma was carried out by high performance liquid chromatography with sensitivity and high accuracy.

Depositional Characteristics of Atmospheric PCBs in Several Media Used Passive Air Samplers (대기 중 PCBs의 PAS에 이용되는 여러 매체의 PCBs 침착 특성)

  • Chun, Man-Young
    • Journal of Environmental Health Sciences
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    • v.39 no.2
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    • pp.151-158
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    • 2013
  • Objective: This study was carried out to determine the depositional characteristics of pine needles, pine tree bark, moss, and soil, which are used as a passive air sampler (PAS) of atmospheric polychlorinated biphenyls (PCBs). Methods: All four media were sampled from the same site. PCB concentrations were analyzed by GC/MSD, and the lipid contents were measured using the gravimetric method. Results: The total PCB concentration (IUPAC No. 28, 52, 101, 138, 153, 180) was the highest in soil (227.97 pg/g dry), followed by pine needles (71.36 pg/g dry), pine tree bark (44.58 pg/g dry), then moss (21.91 pg/g dry). Pine needles contained the highest lipid contents (21.31 mg/g dry), whereas soil (10.01 mg/g dry), pine tree bark (4.85 mg/g dry), and moss (1.92 mg/g dry) contained less. The concentration of lower-chlorinated PCBs was relatively high in pine needles, pine tree bark and moss, but not in soil. The PCB concentrations were proportional to their lipid contents in pine needles, pine tree bark and moss, but a different trend was revealed in soil. Conclusions: The PCBs concentrations in the media were affected by various factors including atmospheric PCB concentrations, lipid contents, and depositional pathways. However, each of these factors had a varying influence depending on the type of medium.

SBA-15 Supported Fe, Ni, Fe-Ni Bimetallic Catalysts for Wet Oxidation of Bisphenol-A

  • Mayani, Suranjana V.;Mayani, Vishal J.;Kim, Sang Wook
    • Bulletin of the Korean Chemical Society
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    • v.35 no.12
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    • pp.3535-3541
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    • 2014
  • Bisphenol A is considered as pollutant, because it is toxic and hazardous to living organisms even at very low concentrations. Biological oxidation used for removing this organic from waste water is not suitable and consequently application of catalytic wet oxidation has been considered as one of the best options for treating bisphenol A. We have developed Fe/SBA-15, Ni/SBA-15 and Fe-Ni/SBA-15 as heterogeneous catalysts using the advanced impregnation method for oxidation of bisphenol A in water. The catalysts were characterized with physico-chemical characterization methods such as, powder X-ray diffraction (PXRD), FT-IR measurements, N2 adsorption-desorption isotherm, thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis. This work illustrates activity of the catalysts for heterogeneous catalytic degradation reaction revealed with excellent conversion and recyclability. The degradation products identified were not persistent pollutants. GC-MS analysis identified the products: 2,4-hexadienedioic acid, 2,4-pentadienic acid and isopropanol or acetic acid. The leachability study indicated that the catalysts release very little metals to water. Therefore, the possibility of water contamination through metal leaching was almost negligible.

Characteristics of Nano-Particles Exhausted from Diesel Passenger Vehicle with DPF

  • Park, Yong-Hee;Shin, Dae-Yewn
    • Journal of Environmental Health Sciences
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    • v.32 no.6
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    • pp.533-538
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    • 2006
  • The nano-particles are known to influence the environmental protection and human health. The relationships between transient vehicle operation and nano-particle emissions are not well-known, especially for diesel passenger vehicles with DPF(Diesel Particulate Filter). In this study, two diesel passenger vehicles were measured on a chassis dynamometer test bench. The particulate matter (PM) emission of these vehicles was investigated by number and mass measurement. The mass of the total PM was evaluated using the standard gravimetric measurement method, and the total number concentrations were measured on a ECE15+EUDC driving cycle using Condensation Particle Counter (CPC). According to the investigation results, total number concentration was $1.14{\times}10^{11}$M and mass concentration was 0.71mg/km. About 99% of total number concentration was emitted during the $0{\sim}400s$ because of engine cold condition. In high temperature and high speed duration, the particulate matter was increased but particle concentration was emitted not yet except initial engine cold condition According to DPF performance deterioration, the particulate matter was emitted 2 times and particle concentration was emitted 32 times. Thus DPF performance deterioration affects particle concentration more than PM.

Effect of Various Levels of Dietary Fat on Cell Proliferation of Rat Colon (식이지방의 양적 변화가 대장 상피세포 증식에 미치는 영향)

  • 이중희
    • Journal of Nutrition and Health
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    • v.32 no.4
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    • pp.394-400
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    • 1999
  • Since it has generally been considered that high-hat diets promote carcinogenesis, fat intake of less than 30% of total calories has been recommended to reduce the risk of cancer. Specific dietary guidelines for fat intake to reduce the risk of colon cancer have not yet been established. In order to determine the level of dietary fat needed the risk of colon cancer, rats were fed one of four experimental fat diets, very low(7% of total calories from corn oil, VLC), low(15% LC), medium (30%, MC), and high fat(45%, HC). Cell proliferation as an intermediate biomarker of color carcinogenesis was measured by the in vivo incorporation of bromodeoxyuridine into DNA. Fecal lipid excretion was measured by gravimetric method. As fat levels in the diet increased, fecal lipid concentrations also increased (VLC

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Synergistic Effects of Mo-V Based Mixed Oxide Catalysts for Acrolein Oxidation(I) (아크로레인 산화용 Mo-V 계 혼합산화물 촉매의 상승효과(I))

  • Na, Suk-Eun;Kim, Kyung-Hoon;Chung, Jong-Shik;Park, Dae-Won
    • Applied Chemistry for Engineering
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    • v.3 no.4
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    • pp.717-721
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    • 1992
  • Mechanical mixtures of vanadium molybdate and copper molybdate catalysts prepared by coprecipitation method, and those of $MoO_3$ and $V_2O_5$ were used to study the synergistic effects between each metal oxide for the selective oxidation of acrolein. The catalytic activity results revealed that the conversion of acrolein and yield of acrylic acid were increased with the mixture catalysts and it could be explained by a remote control mechanism. Thermal gravimetric analysis confirmed the evolution of lattice oxygen in the mixture catalysts.

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Development of the Geoid Model in Korean Peninsula referred to Bessel Ellipsoid (베셀타원체상에서의 한반도 지오이드 모델의 개발)

  • 이석배
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.16 no.2
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    • pp.213-223
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    • 1998
  • This paper deals with the geoid modelling in and around Korean peninsula referred to Bessel ellipsoid. Several useful data were used to compute precise geoidal heights referred to GRS80 by remove and restore technique and FFT technique was used to evaluate Stokes' integral. All grid point elevations extracted from GTOPO 30 and Bessel coordinates of all grid point were computed through coordinates transformation by applying three transformation parameters. Finally, geoidal heights referred to Bessel ellipsoid were calculated by geometric method. As the results of this study, a precise gravimetric geoid model referred to GRS80 (KOGGDM33) and geoid model referred to Bessel ellipsoid(KOBGDM33) in and around Korean peninsula were developed. KOBGDM33 shows the gradual distribution of geoidal heights from -91.8 m in Yongampo to -39.0 m in the straits of Korea.

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Experimental Measurement and Correlation of two α-Amino Acids Solubility in Aqueous Salts Solutions from 298.15 to 323.15 K

  • Abualreish, Mustafa Jaipallah;Noubigh, Adel
    • Korean Chemical Engineering Research
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    • v.58 no.1
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    • pp.98-105
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    • 2020
  • By the gravimetric method at atmospheric pressure, the solubility of two α-amino acids was resolved over temperatures from (293.15 to 323.15) K. The α-amino acids studied were L-arginine and L-histidine. Results showed a salting-out effect on the solubility of the tested amino compounds. It is obvious that there was an increase in the solubility, in aqueous chloride solutions, with the increasing temperature. Results were translated regarding the salt hydration shells and the ability of the solute to form hydrogen-bond with water. The solubility data was precisely associated with a semi-empirical equation. The standard molar Gibbs free energies of transfer of selected α-amino compounds (ΔtrGo) from pure water to aqueous solutions of the chloride salts have been calculated from the solubility data. The decrease in solubility is correlated to the positive (ΔtrGo) value which is most part of the enthalpic origin.