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Shin-ichi Nakao - One of the best experts on this subject based on the ideXlab platform.
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long term stable h 2 production from methylcyclohexane using a Membrane reactor with a dimethoxydiphenylsilane derived Silica Membrane prepared via chemical vapor deposition
Industrial & Engineering Chemistry Research, 2015Co-Authors: Kazuki Akamatsu, Masahiro Seshimo, Toshiki Tago, Shin-ichi NakaoAbstract:Continuous and stable operation of a Membrane reactor for 1054 h to dehydrogenate methylcyclohexane for the purpose of producing high-purity H2, using a dimethoxydiphenylsilane (DMDPS)-derived Silica Membrane, is successfully demonstrated. The Silica Membrane used was prepared via a chemical vapor deposition method, using DMDPS as a precursor, and Pt/Al2O3 catalysts were employed and loaded inside the tubular Membrane. During the 1054 h of continuous operation, an equilibrium shift was stably demonstrated, because of the stable extraction of the produced H2 from the reaction side to the permeate side, and, accordingly, the purity of H2 in the permeate gas was stably high. Although the DMDPS-derived Membrane showed a slight decrease in performance after 1054 h of operation, followed by regeneration under an H2 atmosphere, this first successful demonstration of the long-term stable operation of a Membrane reactor using Silica Membranes is of significance to its practical and industrial use.
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stable equilibrium shift of methane steam reforming in Membrane reactors with hydrogen selective Silica Membranes
Aiche Journal, 2011Co-Authors: Kazuki Akamatsu, Takashi Sugawara, Takuya Murakami, Ryuji Kikuchi, Shin-ichi NakaoAbstract:Equilibrium shifts of methane steam reforming in Membrane reactors consisting of either tetramethoxysilane-derived amorphous hydrogen-selective Silica Membrane and rhodium catalysts, or hexamethyldisiloxane-derived Membrane and nickel catalysts is experimentally demonstrated. The hexamethyldisiloxane-derived Silica Membrane showed stable permeance as high as 8 x 10 ―8 mol m ―2 s ―1 Pa ―1 of H 2 after exposure to 76 kPa of vapor pressure at 773 K for 60 h, which was a much better performance than that from the tetramethoxysilane-derived Silica Membrane. Furthermore, the better Silica Membrane also maintained selectivity of H 2 /N 2 as high as 10 3 under the above hydrothermal conditions. The degree of the equilibrium shifts under various feedrate and pressure conditions coincided with the order of H 2 permeance. In addition, the equilibrium shift of methane steam reforming was stable for 30 h with an S/C ratio of 2.5 at 773 K using a Membrane reactor integrated with hexamethyldisiloxane-derived Membrane and nickel catalyst.
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dehydrogenation of methylcyclohexane to produce high purity hydrogen using Membrane reactors with amorphous Silica Membranes
Industrial & Engineering Chemistry Research, 2010Co-Authors: Kazunori Oda, Takashi Sugawara, Kazuki Akamatsu, Ryuji Kikuchi, Atsushi Segawa, Shin-ichi NakaoAbstract:We developed a Membrane reactor that can produce high-purity hydrogen in one step from methylcyclohexane. This Membrane reactor combined a hydrogen-selective amorphous Silica Membrane prepared with dimethoxydiphenylsilane and oxygen and employing counter-diffusion chemical vapor deposition, and Pt/Al2O3 catalyst. The Silica Membrane showed excellent hydrogen permeance at 573 K of the order of 10−6 mol m−2 s−1 Pa−1 and high hydrogen/sulfur hexafluoride permselectivity of around 104. The Membrane reactor exhibited equilibrium shifts as expected under reaction temperatures ranging from 473 to 553 K and reaction pressures ranging from 0.1 to 0.25 MPa, and these performances were successfully predicted using a simulation model, which was also developed in this study. Finally, we demonstrated that hydrogen with purity as high as 99.95% was produced from methylcyclohexane in the Membrane reactor without using carrier gas or sweep gas.
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development of pore size controlled Silica Membranes for gas separation by chemical vapor deposition
Journal of Membrane Science, 2008Co-Authors: Yudai Ohta, Takashi Sugawara, Kazuki Akamatsu, Aiko Nakao, Akira Miyoshi, Shin-ichi NakaoAbstract:Abstract Silica Membranes were prepared by chemical vapor deposition using oxygen and tetramethoxysilane (TMOS), phenyltrimethoxysilane (PTMS), or dimethoxydiphenylsilane (DMDPS) as the silicon source at 873 K. The pore size was successfully controlled by changing the number of phenyl groups on the silicon precursor. The permeation test of several gases revealed that larger pores were formed upon increasing the number of phenyl groups on the source. The DMDPS-derived Membrane showed excellent hydrogen permeance at 573 K of the order of 10 −6 mol m −2 s −1 Pa −1 , and a high hydrogen/sulfur hexafluoride permselectivity of over 6800, and this excellent performance was constant for 266 h even under moist conditions containing steam at 3.4 kPa and 573 K. Characterization with XPS indicated that the DMDPS-derived Membrane was thinner than the TMOS Membrane. Additionally, the bond energies of the silicon sources were estimated based on quantum chemical calculations with the CBS-QB3 method. The results showed a strong tendency for gas-phase conversion of TMOS or PTMS to dimethoxysilanone, (MeO) 2 Si O, and DMDPS to methoxyphenylsilanone, Ph(MeO)Si O, transient intermediates that act as major precursors. It was suggested that whether the intermediate contained phenyl groups greatly influenced the enlargement of pore size of the Silica Membrane.
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relationship between the mesoporous intermediate layer structure and the gas permeation property of an amorphous Silica Membrane synthesized by counter diffusion chemical vapor deposition
Journal of the American Ceramic Society, 2007Co-Authors: Takayuki Nagano, Mikihiro Nomura, Shinji Fujisaki, Koji Sato, Koji Hataya, Yuji Iwamoto, Shin-ichi NakaoAbstract:An amorphous Silica Membrane with an excellent hydrogen/nitrogen (H2/N2) permselectivity of >10 000 and a He/H2 permselectivity of 11 was successfully synthesized on a γ-alumina (γ-Al2O3)-coated α-alumina (α-Al2O3) porous support by counter diffusion chemical vapor deposition using tetramethylorthoSilicate and oxygen at 873 K. An amorphous Silica Membrane possessed a high H2 permeance of >1.0 × 10−7 mol·(m2·s·Pa)−1 at ≥773 K. The dominant permeation mechanism for He and H2 at 373–873 K was activated diffusion. On the other hand, that for CO2, Ar, and N2 at 373–673 K was a viscous flow. At ≥673 K, that for CO2, Ar, and N2 was activated diffusion. H2 permselectivity was markedly affected by the permeation temperature, thickness, and pore size of a γ-Al2O3 mesoporous intermediate layer.
Mikihiro Nomura - One of the best experts on this subject based on the ideXlab platform.
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hydrogen production tests by hydrogen iodide decomposition Membrane reactor equipped with Silica based ceramics Membrane
International Journal of Hydrogen Energy, 2017Co-Authors: Odtsetseg Myagmarjav, Mikihiro Nomura, Nobuyuki Tanaka, Shinji KuboAbstract:Abstract The decomposition of hydrogen iodide in the thermochemical water splitting iodine–sulfur process at an intermediate temperature (400 °C) using a catalytic Membrane reactor was reported here, for the first time. The performance of a catalytic Membrane reactor based on a hexyltrimethoxysilane-derived Silica Membranes (H2 permeance of 9.4 × 10−7 mol Pa−1 m−2 s−1 and H2/N2 selectivity of over 80.0.) was evaluated at 400 °C by varying the HI flow rates of 2.6, 4.7, 6.9, 8.4, and 9.7 mL min−1. The Silica Membranes were prepared by counter-diffusion chemical vapor deposition method on γ-alumina-coated α-alumina tubes. Hydrogen was successfully extracted from the Membrane reactor using the Silica Membrane at 400 °C. A significant increase in HI conversion was achieved. The conversion achieved at an HI flow rate of 2.6 mL min−1 was approximately 0.60, which was greater than the equilibrium conversion in HI decomposition (0.22).
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preparation of an h2 permselective Silica Membrane for the separation of h2 from the hydrogen iodide decomposition reaction in the iodine sulfur process
International Journal of Hydrogen Energy, 2017Co-Authors: Odtsetseg Myagmarjav, Nobuyuki Tanaka, Shinji Kubo, Ayumi Ikeda, Mikihiro NomuraAbstract:Abstract A high-performance, H2-permselective Silica Membrane derived from hexyltrimethoxysilane (HTMOS) was developed for application in the thermochemical water-splitting iodine–sulfur process. Silica Membranes, referred to here as HTMOS Membranes, were prepared via counter-diffusion chemical vapor deposition on γ-alumina-coated α-alumina support tubes with outer diameters of 10 mm. Special attention was devoted to obtain high H2/HI selectivity, high H2 permeance, and good stability in the presence of corrosive HI gas. The effects of the deposition conditions, temperature, and period were investigated. The HTMOS Membrane prepared at 450 °C for 5 min exhibited high H2/HI selectivity (>175) with H2 permeance on the order of 10−7 mol Pa−1 m−2 s−1. On the basis of stability experiments, it was found that the HTMOS Membrane was stable upon HI exposure at a temperature of 400 °C for 11 h.
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relationship between the mesoporous intermediate layer structure and the gas permeation property of an amorphous Silica Membrane synthesized by counter diffusion chemical vapor deposition
Journal of the American Ceramic Society, 2007Co-Authors: Takayuki Nagano, Mikihiro Nomura, Shinji Fujisaki, Koji Sato, Koji Hataya, Yuji Iwamoto, Shin-ichi NakaoAbstract:An amorphous Silica Membrane with an excellent hydrogen/nitrogen (H2/N2) permselectivity of >10 000 and a He/H2 permselectivity of 11 was successfully synthesized on a γ-alumina (γ-Al2O3)-coated α-alumina (α-Al2O3) porous support by counter diffusion chemical vapor deposition using tetramethylorthoSilicate and oxygen at 873 K. An amorphous Silica Membrane possessed a high H2 permeance of >1.0 × 10−7 mol·(m2·s·Pa)−1 at ≥773 K. The dominant permeation mechanism for He and H2 at 373–873 K was activated diffusion. On the other hand, that for CO2, Ar, and N2 at 373–673 K was a viscous flow. At ≥673 K, that for CO2, Ar, and N2 was activated diffusion. H2 permselectivity was markedly affected by the permeation temperature, thickness, and pore size of a γ-Al2O3 mesoporous intermediate layer.
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preparation of a catalyst composite Silica Membrane reactor for steam reforming reaction by using a counterdiffusion cvd method
Industrial & Engineering Chemistry Research, 2006Co-Authors: Mikihiro Nomura, Masahiro Seshimo, Hitoshi Aida, Katsuya Nakatani, Suraj Gopalakrishnan, Tom Ishikawa, Mitsutaka Kawamura, Takashi Sugawara, Shin-ichi NakaoAbstract:A Silica Membrane prepared by a counterdiffusion CVD method using tetramethyl orthoSilicate and O2 was applied to a steam reforming reaction of methane. This Silica Membrane showed hydrothermal stability for more than 80 h at 773 K under H2O/N2 = 3. The H2/H2O permeance ratio was about 290 after the hydrothermal stability test. Rh or Ni catalyst was dipped on a porous alumina substrate before chemical vapor deposition (CVD). As a result, a composite catalytic Membrane of a hydrogen permselective Silica layer and a catalyst layer was obtained. This catalyst composite Membrane reactor was applied to steam reforming reaction to extract hydrogen. Rh catalyst showed better stability than that for Ni catalyst. Methane conversion was increased to 64.5% from the equilibrium value (31.4%) at 773 K under S/C = 2 by the Rh-dipped Membrane reactor. High conversion of methane was due to high selectivity of H2/H2O that was confirmed by the simulation evaluation.
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Preparation of a stable Silica Membrane by a counter diffusion chemical vapor deposition method
Journal of Membrane Science, 2005Co-Authors: Mikihiro Nomura, Suraj Gopalakrishnan, Takashi Sugawara, Shin-ichi NakaoAbstract:Abstract A stable Silica Membrane having excellent H2/N2 permeance ratio (over 1000) was prepared by the counter diffusion chemical vapor deposition method using tetramethyl orthoSilicate (TMOS) and O2 as reactants at 873 K. TMOS and O2 were provided in the opposing geometry of the substrates, and Silica layer was deposited in the substrate pores. Apparent activation energies through the Silica Membranes increased with increasing deposition temperatures. The activation energy of H2 was ca. 20 kJ mol−1 through the Membrane. H2 permeance at 873 K permeation test was 1.5 ×10−7 mol m−2 s−1 Pa−1. H2/N2 permeance ratio was kept for 21 h under the typical steam-reforming conditions of methane for a Membrane reactor (76 kPa of steam at 773 K).
Joao Diniz C Da Costa - One of the best experts on this subject based on the ideXlab platform.
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adsorption and transport of gases in a supported microporous Silica Membrane
Journal of Membrane Science, 2014Co-Authors: Xuechao Gao, Joao Diniz C Da Costa, Suresh K BhatiaAbstract:We investigate gas adsorption and transport in a disordered microporous Silica Membrane having mean pore diameter 1.5 nm, coated on a porous tubular asymmetric support. The adsorption isotherms are found to be Langmuirian, with equilibrium constants that are accurately predicted for nonpolar gases, considering Lennard–Jones (LJ) interactions with a single layer of oxygen atoms on the pore surface. For the polar gas, CO2, the hydroxyls groups on the pore walls strongly increase the affinity with the pore walls, and a superposition of the LJ potential and an empirically represented electrostatic interaction is found to be adequate in correlating the Langmuirian equilibrium constant. The gas transport in the microporous Silica layer is investigated using effective medium theory, with single pore transport represented by combination of pore mouth and internal pore diffusion resistances. Good agreement is observed for all the gases using different coordination numbers, indicating that the essential features of the transport in the Silica micropores are captured in the approach. It is found that the overall transport resistance is dominated by the pore mouth barrier; however, the internal diffusion resistance in the relatively smaller pores is significant, especially for weakly adsorbed gases at higher temperature. In addition, the dependence of the pore mouth barrier coefficient on temperature and diffusing species are in good agreement with predictions of transition-state theory, with larger more strongly adsorbed molecules having higher activation energy. The proposed methodology is validated against experiment by comparison of the predicted flux for different gases in the supported Membrane at various feed pressures in the low pressure range of 200–400 kPa, using the parameters obtained at 200 kPa.
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long term performance cobalt oxide Silica Membrane module for high temperature h2 separation
Energy and Environmental Science, 2012Co-Authors: Christelle Yacou, Simo Sma, Joao Diniz C Da CostaAbstract:Here we show the long term performance at high temperatures of a multi-tube module containing 8 Membranes in 4 parallel lines with a total of 545 cm2 area. The Membranes were prepared via thin film dip coating of cobalt oxide Silica (CoOxSi) sol–gel on tubular alumina supports. A preliminary study found that the sol–gel containing 20 mol% cobalt oxide formed the best microporous structure with the highest surface area and pore volume. All resulting Membranes delivered permeances of ∼1 × 10−7 mol m−2 s−1Pa−1 at 500 °C, indicating a high repeatability for the Membrane fabrication process. The permselectivities of helium (He) and hydrogen (H2) over carbon dioxide (CO2) and nitrogen (N2) increased from 10–20 at 100 °C to values close to 1000 at 500 °C. Additionally, the apparent energies of activation (Eact) for the smaller kinetic diameter gases He and H2 at 12.2 and 19.5 kJ mol−1 were high and contrary to the negative values for larger gases N2 and CO2 at −1.8 and −7.4 kJ mol−1. These remarkable results were attributed to the molecular sieving mechanism of the microporous Silica which was enhanced by the embedding of cobalt oxide into the matrix, delivering structural control with an average pore size of 3 A. The Eact for H2 permeance was higher than that of He, indicating that the cobalt oxide played an important role in H2transport. Two Membrane lines performed exceptionally well for binary gas mixture processing with H2 purity reaching values close to 100% in the permeate stream for argon (Ar) concentrations of up to 80% in the retentate stream. A major finding here is that the binary gas selectivity was independent of temperature, contrary to the permselectivity observed for single gas permeance. Further, the H2 flow rate was greatly affected by the concentration of Ar in the mixture, while the temperature dependency played only a marginal role. In particular, competitive adsorption in the percolative pathways containing pore constrictions or bottlenecks of the anisotropic CoOxSi matrix allowed Ar to impede H2 diffusion. Finally, the CoOxSi Membranes proved thermally stable and robust for 2000 h of testing for various thermal cycles up to 500 °C.
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hydrogen gas mixture separation by cvd Silica Membrane
Journal of Membrane Science, 2008Co-Authors: Joao Diniz C Da CostaAbstract:In this work we investigate the performance of high flux chemical vapour deposition (CVD) Silica Membranes for the separation of gas mixtures containing H-2 and CO2 at various temperatures. The Membranes were prepared by a counter diffusion CVD method where tetraethyl orthoSilicate (TEOS) and (O-2 were used as reactants. Single gas permeation resulted in activated transport for the smaller kinetic diameter gases (H-2 and He) whilst the larger kinetic diameter gases (CO2 and N-2) showed negative activation energy. The single gas permeation of H-2 increased from 5.1 x 10(-7) to 7.0 x 10(-7) Mol m(-2) s(-1) Pa-1 in the temperature range 100-400 degrees C. and H-2/CO2 and H-2/N-2 selectivities reached 36 and 57 at 400 degrees C, respectively. The H-2 purity in the permeate stream also increased with temperature for H-2:CO2 binary gas mixture, thus being beneficial for H-2 diffusion. H-2 competitively permeated through the Membrane at a several range of gas mixtures. and a saturation level was achieved at H-2:CO2 60:40 feed concentration, where the diffusion of CO2 molecules became negligible delivering similar to 99% H-2 purity in the permeate stream. These results substantiate that the counter diffusion CVD method produced thin Silica film Membranes with a very precise pore size control, in particular suggesting a narrow pore distribution with average pore radius of about 3.1 angstrom.
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performance of hydrophobic and hydrophilic Silica Membrane reactors for the water gas shift reaction
Separation and Purification Technology, 2003Co-Authors: S Giessler, Luke Jordan, Joao Diniz C Da CostaAbstract:In this study, a novel molecular sieve Silica (MSS) Membrane packed bed reactor (PBR) using a Cu/ZnO/Al2O3 catalyst was applied to the low-temperature water gas shift reaction (WGS). Best permeation results were H-2 permeances of 1.5 x 10(-6) mol(.)s(-1) m(-2) Pa-1, H-2/CO2 selectivities of 8 and H-2/N-2 selectivities of 18. It was shown that an operation with a sweep gas flow of 80 cm 3 min(-1), a feed flow rate of 50 cm(3) min(-1) and a H2O/CO molar ratio of one at 280 degreesC reached a 99% CO conversion. This is well above the thermodynamic equilibrium and achievable PBR conversion. Hydrophilic Membranes underwent pore widening during the reaction while hydrophobic Membranes indicated no such behaviour and also showed increased H-2 permeation with temperature, a characteristic of activated transport. (C) 2003 Elsevier Science B.V. All rights reserved.
Hashem Sharghi - One of the best experts on this subject based on the ideXlab platform.
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solid phase extraction and pre concentration of sub ppb level of copper in aqueous samples on octadecyl Silica Membrane disks modified with a new anthraquinone derivative and its determination by atomic absorption spectrometry
Separation Science and Technology, 2005Co-Authors: Mojtaba Shamsipur, Armen Avanes, Hashem SharghiAbstract:Abstract A simple and reliable method for rapid and selective separation and preconcentration of trace amounts of Cu2+ ions from different aqueous samples for the measurement by atomic absorption spectrometry is presented. By the passage of aqueous samples through an octadecyl‐bonded Silica Membrane disk modified by 1‐hydroxy‐2‐(prop‐2′‐enyl)‐4‐(prop‐2′‐enyoxyl)‐9,10‐anthraquinone, the Cu2+ ions adsorb quantitatively and almost all matrix elements will pass through the disk to drain. The retained copper ions are then stripped from the disk by a minimal amount of nitric acid as eluent. The proposed method permitted large enrichment factors of 400 and higher. The limit of detection of the method is 100 ng Cu2+ per 1000 mL. The effects of various cationic interferences on the recovery of copper in binary mixtures were studied. The method was successfully applied to the determination of copper in SRM bovine liver, tea leaves, and a synthetic seawater sample.
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solid phase extraction and determination of lead in soil and water samples using octadecyl Silica Membrane disks modified by bis 1 hydroxy 9 10 anthraquinone 2 methyl sulfide and flame atomic absorption spectrometry
Talanta, 2000Co-Authors: Mojtaba Shamsipur, Farhad Raoufi, Hashem SharghiAbstract:Abstract A simple, reliable and relatively fast method has been developed to selectively separate and concentrate trace amounts of lead from aqueous samples for the measurement by flame atomic absorption spectrometry. By the passage of aqueous samples through an octadecyl-bonded Silica Membrane disk modified by a recently synthesized bis(anthraquinone)sulfide, Pb2+ ions adsorb quantitatively and almost all matrix elements will pass through the disk to drain. The retained lead ions are then stripped from the disk by minimal amount of acetic acid as eluent. The proposed method permitted large enrichment factors of about 300 and higher. The limit of detection of the proposed method is 50 ng Pb2+ per 1000 ml. The effects of various cationic interferences on the recovery of lead in binary mixtures were studied. The method was successfully applied to the determination of lead in soil and water samples.
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solid phase extraction of ultra trace copper ii using octadecyl Silica Membrane disks modified by a naphthol derivative schiff s base
Analytica Chimica Acta, 2000Co-Authors: Mojtaba Shamsipur, Hashem Sharghi, Alireza Ghiasvand, Hossein NaeimiAbstract:Abstract A simple and reliable method for the rapid extraction and determination of ultra trace amounts of copper(II) ions using octadecyl-bonded Silica Membrane disks modified by a recently synthesized Schiff’s base (2,2′-[1,2-ethanediyl bis(nitriloethylidyne)] bis(1-naphthalene)) and atomic absorption spectrometry is presented. Extraction efficiency and the influence pH, nature and amount of counter anion, flow rates and type of stripping acid were evaluated. The capacity of the Membrane disks modified by 5 mg of the ligand was found to be 396 μg of copper. The limit of detection of the proposed method is 4 ng per 1000 ml. The method was applied to the extraction and recovery of copper in different water samples.
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solid phase extraction and determination of trace amounts of lead ii using octadecyl Silica Membrane disks modified with a recently synthesized anthraquinone derivative and atomic absorption spectrometry
Microchemical Journal, 1999Co-Authors: Farhad Raoufi, Yadollah Yamini, Hashem SharghiAbstract:Abstract A simple and fast method for extraction and determination of trace amounts of lead(II) ions using octadecyl-bonded Silica Membrane disks modified with 1,8-dihydroxy-2,7-bis(prop-1′-enyl)-9,10-anthraquinone and atomic absorption spectrometry (AAS) is introduced. Extraction efficiency and the influence of flow rates, pH, and type and smallest amount of stripping acid were investigated. Maximum capacity of the Membrane disks modified with 2 mg of the anthraquinone derivative used was found to be 255 μg Pb 2+ . The limit of detection of the proposed method is 5 ng/ml. The method is applied to the recovery of Pb 2+ from different synthetic samples and a spring water sample.
Mojtaba Shamsipur - One of the best experts on this subject based on the ideXlab platform.
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solid phase extraction of ultra traces silver i using octadecyl Silica Membrane disks modified by 1 3 bis 2 cyanobenzene triazene cbt ligand prior to determination by flame atomic absorption
Journal of Hazardous Materials, 2009Co-Authors: Mohammad Kazem Rofouei, Mojtaba Shamsipur, Mahmood Payehghadr, Asieh AhmadalinezhadAbstract:Abstract A simple, reliable and rapid method for preconcentration and determination of the ultra trace amount of silver using octadecyl Silica Membrane disk modified by a recently synthesized triazene ligand, 1,3-bis(2-cyanobenzene)triazene (CBT), and flame atomic absorption spectrometry is presented. Various parameters including pH of aqueous solution, flow rates, the amount of ligand and the type of stripping solvents were optimized. The breakthrough volume was greater than 1800 ml with an enrichment factor of more than 360 and 6.0 ng l −1 detection limit. The capacity of the Membrane disks modified by 5 mg of the ligand was found to be 1070 μg of silver. The effects of various cationic interferences on the percent recovery of silver ion were studied. The method was successfully applied to the determination of silver ion in different samples, especially determination of ultra trace amount of silver in the presence of large amount of lead.
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solid phase extraction and pre concentration of sub ppb level of copper in aqueous samples on octadecyl Silica Membrane disks modified with a new anthraquinone derivative and its determination by atomic absorption spectrometry
Separation Science and Technology, 2005Co-Authors: Mojtaba Shamsipur, Armen Avanes, Hashem SharghiAbstract:Abstract A simple and reliable method for rapid and selective separation and preconcentration of trace amounts of Cu2+ ions from different aqueous samples for the measurement by atomic absorption spectrometry is presented. By the passage of aqueous samples through an octadecyl‐bonded Silica Membrane disk modified by 1‐hydroxy‐2‐(prop‐2′‐enyl)‐4‐(prop‐2′‐enyoxyl)‐9,10‐anthraquinone, the Cu2+ ions adsorb quantitatively and almost all matrix elements will pass through the disk to drain. The retained copper ions are then stripped from the disk by a minimal amount of nitric acid as eluent. The proposed method permitted large enrichment factors of 400 and higher. The limit of detection of the method is 100 ng Cu2+ per 1000 mL. The effects of various cationic interferences on the recovery of copper in binary mixtures were studied. The method was successfully applied to the determination of copper in SRM bovine liver, tea leaves, and a synthetic seawater sample.
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separation and pre concentration of trace amounts of cerium iii on octadecyl Silica Membrane discs modified with 1 3 5 trithiacyclohexane and its spectrophotometric determination by arsenazo iii
Separation Science and Technology, 2002Co-Authors: Mojtaba Shamsipur, Mohammad Yousefi, Zahra Ghasemi, Leila Hagiaghababaei, Mohammad Reza GanjaliAbstract:A simple and reliable method for rapid and selective separation and determination of trace amounts of Ce3+ ions from aqueous samples using octadecyl-bonded Silica Membrane discs modified with 1,3,5-trithiacyclohexane (TTCH) and spectrophotometry with arsenazo(III) is presented. Extraction efficiency and the influence of sample matrix, pH of sample solution, type and minimum amount of stripping acid, and flow-rates were investigated. The maximal capacity of the Membrane discs modified with 15 mg of TTCH was found to be 547 μg of cerium. The limit of detection of the proposed method is 2 ng/mL. The effects of various cationic interferences on the percent recovery of cerium in binary mixtures were studied. The method was applied to the recovery of Ce3+ ions from synthetic samples.
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solid phase extraction and determination of lead in soil and water samples using octadecyl Silica Membrane disks modified by bis 1 hydroxy 9 10 anthraquinone 2 methyl sulfide and flame atomic absorption spectrometry
Talanta, 2000Co-Authors: Mojtaba Shamsipur, Farhad Raoufi, Hashem SharghiAbstract:Abstract A simple, reliable and relatively fast method has been developed to selectively separate and concentrate trace amounts of lead from aqueous samples for the measurement by flame atomic absorption spectrometry. By the passage of aqueous samples through an octadecyl-bonded Silica Membrane disk modified by a recently synthesized bis(anthraquinone)sulfide, Pb2+ ions adsorb quantitatively and almost all matrix elements will pass through the disk to drain. The retained lead ions are then stripped from the disk by minimal amount of acetic acid as eluent. The proposed method permitted large enrichment factors of about 300 and higher. The limit of detection of the proposed method is 50 ng Pb2+ per 1000 ml. The effects of various cationic interferences on the recovery of lead in binary mixtures were studied. The method was successfully applied to the determination of lead in soil and water samples.
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solid phase extraction of ultra trace copper ii using octadecyl Silica Membrane disks modified by a naphthol derivative schiff s base
Analytica Chimica Acta, 2000Co-Authors: Mojtaba Shamsipur, Hashem Sharghi, Alireza Ghiasvand, Hossein NaeimiAbstract:Abstract A simple and reliable method for the rapid extraction and determination of ultra trace amounts of copper(II) ions using octadecyl-bonded Silica Membrane disks modified by a recently synthesized Schiff’s base (2,2′-[1,2-ethanediyl bis(nitriloethylidyne)] bis(1-naphthalene)) and atomic absorption spectrometry is presented. Extraction efficiency and the influence pH, nature and amount of counter anion, flow rates and type of stripping acid were evaluated. The capacity of the Membrane disks modified by 5 mg of the ligand was found to be 396 μg of copper. The limit of detection of the proposed method is 4 ng per 1000 ml. The method was applied to the extraction and recovery of copper in different water samples.