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[東京], 日本化学会第87春季年会(2007)講演予稿集CD-ROM

The preconcentration method has frequently been used for the determination of ultra trace analytes in complex matrix samples by instrumental analysis. Adsorption, chromatography, coprecipitation, electrolytic deposition, evaporation, extraction, flotation, freezing, ion exchange, etc. are well known as preconcentration methods in analytical chemistry. Most of them are complicated and time-consuming. Among these methods, however, the adsorption method is simple and convenient. So far, activated carbon, porous polymers, polyurethane foam, silica gel, glass beads and tungsten wire for collecting trace elements have been reported as adsorbents. In 1973, a preconcentration method was reported in which heavy metals such as cadmium and lead were concentrated by adsorption onto a tungsten wire loop, which had been immersed for a fixed time in aqueous sample solutions. The wire loop was subsequently used as an electrically heated atomizer for atomic absorption spectrometry (AAS). Hoshino et al., have described the determination of Ag, Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn in aqueous solutions by graphite furnace atomic absorption spectrometry (GFAAS) combined with selective concentration onto a tungsten wire. These developed methods worked at the pg/mL level. Linear calibration plots can be obtained with short analysis times and no chemical pretreatment. There is, however, very little information on the application of the tantalum wire adsorption method to the determination of ultra trace metals in environmental samples. Therefore, in the present work, the determination of trace elements in waters by electrothermal atomic absorption spectrometry with preconcentration on a tantalum wire was investigated., ポスター発表梗概, Pacifichem 2005

Recently, the environmental pollution, especially marine ecosystem, by pesticides has become a serious problem. Due to their heavy use in agriculture and to their persistence, many of these compounds are present in surface and ground waters and have to be considered a potential risk for marine life as well as for drinking water quality. Various pesticides have been found as contaminants in surface and ground waters and microbial degradation is considered to be the primary mechanism for their dissipation from soil. In general, biological methods commonly require a long time for the wastewater containing pesticides at high concentration. Therefore, the rapid and simple wastewater treatment of pesticides is now required urgently. A variety of effective treatment techniques for aqueous pesticides have been proposed by ultrasonic irradiation, direct photolysis, UV irradiation in the presence of ozone or Fenton reagent and TiO₂ as a photocatalyst. Iron oxide and hydrogen peroxide are common constituents of natural and atmospheric waters. Hence, we have investigated the degradation and mineralization of pesticides in water using the goethite/H₂O₂ system. The many factors, such as pH value and initial concentrations of goethite and H₂O₂, affected on the degradation were evaluated., ポスター発表梗概, Pacifichem 2005

Halogenated organic solvents have extensively been used for several decades in industrial applications such as the manufacture of refrigerants, herbicides, plastics and solvents. Due to leaks, spills and releases from industrial sources, they inevitably contaminate environments such as soil and groundwater. Therefore, many of these halogenated aliphatics are listed as priority pollutants by the United States Environmental Protection Agency (USEPA) and known or suspected human carcinogens, mutagens or toxins. Recently, the environmental application of zero-valent iron was proposed for the removal of chlorinated compounds from water. Clearly, the use of zero-valent metals has been an active research area with efforts mostly concentrated on iron-containing water system due to the success encountered with iron-loaded subsurface permeable walls and the acceptance of zero-valent iron as being safe for the environment. In the present work, a low-cost and highly effective dehalogenation system of trihalomethanes has been developed in a continuous flow system using metallic powder under mild conditions. Many factors, such as the amount of metallic powder, kind of the powder and reaction temperature, affected on the dehalogenation were evaluated. In addition, the mechanism of the dehalogenation is discussed. This research will be able to contribute to the treatment technology of trihalomethane-contaminated ground water., ポスター発表梗概, Pacifichem 2005

In the electrochemical reduction of carbon dioxide, in water, at most metal electrodes the major reaction products were carbon monoxide and formic acid. However, only copper has proven a suitable electrode for the formation of hydrocarbons such as methane and ethylene, which can be used as fuel gases. Recently, many investigators have actively studied the electrochemical reduction of carbon dioxide using various metal electrodes in organic solvents, given that organic aprotic solvents dissolve much more carbon dioxide than water. Reduced products containing carbon monoxide, oxalic acid and formic acid were produced by the electroreduction of carbon dioxide in dimethyl sulfoxide, N,N-dimethyl formamide, propylene carbonate and acetonitrile. However, even at a copper electrode, no hydrocarbons were obtained in these organic solvents. Methanol is a better solvent of carbon dioxide than water, particularly at low temperature. The solubility of carbon dioxide in methanol is approximately five times that in water, at ambient temperature and eight to fifteen times that in water, at temperatures below 273 K. Therefore, methanol has been industrially used as a physical absorbent of carbon dioxide in the Rectisol method, at 243-263 K. Currently, over 70 large-scale plants apply the Rectisol process. In the present work, the electrochemical reduction of carbon dioxide at copper-modified nickel in water + methanol was investigated for the formation of hydrocarbons. The electrodeposition amount of copper into the nickel surface was optimized., ポスター発表梗概, Pacifichem 2005

In recent years, a separation system with a high temperature column (> 990 K), sequential metal vapor elution analysis (SMVEA) has been reported for the separation and analysis of trace metal elements. The advantages of SMVEA are (a) direct separation of metal vapors, (b) rapid analysis without a prior chemical treatment, (c) simplicity, (d) elimination of spectral and chemical interferences occurring in conventional atomic spectrometry such as atomic absorption spectrometry (AAS) and inductively coupled plasma optical emission spectrometry (ICP-OES) and (e) possibility as a powerful accessory of analytical instruments containing mass spectrometry. However, in spite of these attractions, little information on the SMVEA has been reported owing to the technical difficulty of instrumentation. Aluminium in metal contains some trace impurity metals, including zinc, which can affect its quality and numerous papers concerning the determination of zinc in aluminium metal by atomic absorption spectrometry or inductively coupled plasma optical emission spectrometry have been reported. In these methods, however, there are some problems such as poor sensitivity and optical and chemical interferences. In order to eliminate the interferences from aluminum matrix, liquid-liquid extraction, coprecipitation or an ion-exchange method to separate zinc from the matrix has been used. In the present work, the determination of zinc in aluminium metal by sequential metal vapor elution analysis with radio-frequency induction heating method was investigated. The results were in good agreement with the certified value., ポスター発表梗概, Pacifichem 2005

In order to establish the regional creation of new industrial technologies, the CREATE (Collaboration of Regional Entities for the Advancement Technological Excellence) activity program was organized by the Japan Science and Technology (JST) Agency. The program accelerates the effective joint collaborations among R&D-oriented firms, universities, public research laboratories and companies. After the end of research period of the programs selected by the JST committee, it can be expected to develop the programs into the establishment of the local Center of Excellence (COE) and its continuous management. Mie Prefecture took part in this CREATE activity program at the beginning of the year 2003 with the proposal, entitled "Environmental Restoration Project on the Enclosed Coastal Seas, Ago Bay". The dredging has been performed since 2000, so as not to worsen the sea quality in Ago Bay. Since the dredged sea bottom sediments have a horrible smell, the limitation of disposal places became a serious problem. Hence, it is necessary to develop an alternative system to treat the dredged sea bottom sediments and replace with the disposal methods. One of the alternative methods is to convert the waste of the dredged sea bottom sediments into valuable products such as an adsorbent for wastewater treatment and brick production. The development of "value-added" reused products would have particular benefits both in terms of resource recovery and protection of the environment. In the present work, the sintering preparation technology of porous materials from sea sediments was developed and the sintered porous materials were used in the purification of water., ポスター発表梗概, Pacifichem 2005

Humic and fulvic acids are natural organic polyelectrolytes that comprise the greatest proportion of naturally-occurring dissolved organic matter in aqueous systems. They are not well-defined substances, but can generally be subdivided into three fractions, namely: humin, which represents components insoluble in aqueous solutions at all pH values, humic acids, which are soluble in alkaline to weakly acidic solutions, but deposit at or below pH 2.0 and fulvic acids, which are soluble in aqueous solutions at all pH values. Humic materials may be specifically targeted for removal from potable water supplies because they can adversely affect appearance and taste and they can react with chlorine to form potentially carcinogenic chlorinated organic compounds. Therefore, the adsorption and degradation of humic substances have been widely investigated in order to optimize their removal from solution. In the present study, natural organic polyelectrolytes (humic and fulvic acids) were removed by adsorption onto minerals and degradation using advanced oxidation processes. Many factors, such as pH value, initial concentration of reagents and reaction temperature, affected on the degradation were evaluated. In addition, the mechanism of the adsorption and degradation is discussed., ポスター発表梗概, Pacifichem 2005

[東京], 日本化学会第85春季年会（2005）講演予稿集CD-ROM

[東京], 日本化学会第85春季年会（2005）講演予稿集CD-ROM