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1.
Kazunori Yamada Tetsuya Tamura Yuya Azaki Ayumi Kashiwada Yoji Hata Katsuya Higashida Yukihiro Nakamura 《Journal of Polymers and the Environment》2009,17(2):95-102
In this study, melB tyrosinase was applied for enzymatic removal of linear and branched p-alkylphenols from aqueous solutions. First, systematic studies were carried out to estimate the effects of the process parameters such as the temperature, pH value, and enzyme dose on quinone conversion of p-cresol as a model phenol compound. A variety of p-alkylphenols were removed from aqueous solutions through the tyrosinase-catalyzed quinone conversion and subsequent nonenzymatic adsorption of quinone derivatives on chitosan beads at pH 6.0 and 30 °C under the optimum conditions determined for p-cresol. The % removal values of 98–100 were obtained for p-n-alkylphenols. Branched p-alkylphenols with a weak estrogenic activity containing 4-tert-butylphenol and 4-tert-pentylphenol, which underwent no quinone conversion by commercially available mushroom tyrosinase in the absence of H2O2, were also effectively removed by further increasing either the melB tyrosinase concentration or the amount of added chitosan beads. The present technique is much effective in the fact that a series of reactions rapidly progress under mild conditions and the chitosan beads can be readily separated from the reaction medium after the enzymatic treatment. 相似文献
2.
Katsuya Nakayama Kuchar Dalibor Keisuke Sakai Mitsuhiro Kubota Hitoki Matsuda 《Journal of Material Cycles and Waste Management》2008,10(2):102-109
The present work focuses on investigation of the effective recovery of heavy metals from molten fly ash by applying chloride-induced
volatilization. In particular, the effect of unburned carbon on the chloride-induced volatilization of lead, zinc, and copper
from model and real molten fly ashes was investigated in the temperature range 873–1173 K under a N2 atmosphere. As a result, almost 100% of lead and a significant proportion of zinc were volatilized from the real molten fly
ash samples at 1173 K. In contrast, for the model fly ash, volatilization ratios of lead and zinc at 1173 K were only 85%
and 25%, respectively. Further, the results of X-ray diffraction analysis suggested that PbO in molten fly ash was converted
either to Pb2OCl2 or Pb by respective chlorination and reduction reactions. Meanwhile ZnO and CuO in the molten fly ash were reduced to Zn
and Cu by reaction with unburned carbon. Subsequently, Pb, Zn, and Pb2OCl2 were volatilized, but Cu remained in the solid residue. Finally, the volatilization ratio of zinc increased with the addition
of carbon, and more than 98% of zinc was volatilized at 1173 K from a fly ash with a carbon content of 20%. 相似文献
3.
Jiro Moriguchi Takafumi Ezaki Teruomi Tsukahara Katsuya Furuki Yoshinari Fukui Satoru Okamoto 《毒物与环境化学》2013,95(1):119-133
The present study was initiated to examine urinary α1-microglobulin (α1-MG-U) levels among non-smoking women in the general population in Japan. A previously established database on spot urine samples from adult woman volunteers in 10 non-polluted areas all over Japan was re-examined. The data examined were on α1-MG-U, cadmium, calcium, magnesium and zinc levels in urine (Cd-U, Ca-U, Mg-U and Zn-U, respectively), urinary creatinine (CR or cr), urine specific gravity (SG or sg), smoking habits and age. Thus, 8975 never-smoking women were selected for statistical analyses. The grand geometric mean (GM) for α1-MG-U among the population was 2.1?mg/L or 2.5?mg/g?cr, depending on the correction for urine density. It was 1.1?µg/L or 1.3?µg/g?cr for GM Cd-U. The inter-area difference in α1-MG-U was <1.5?mg/g?cr or <0.7?mg/L; the area with the highest or lowest GM Cd-U was not always highest or lowest in GM α1-MG-U. The correlation coefficient (0.53) between log?Cd-U and log?α1-MG-U (both without urine density correction) became substantially smaller when the analyte levels were corrected for CR (0.25) or SG (0.26). In multiple regression analysis, the power of influence of the five independent variables (log?Cd-U, Ca-U, Mg-U, Zn-U and age) in combination was small (R 2?≦?0.13). In contrast, logistic regression analysis suggested that α1-MG-U might be elevated as a function of an increase in Cd-U, depending on the cut-off values. Discussion was made on dose (Cd-Ucr) and response (α1-MG-Ucr) relationship based on information available in literatures to show that the increment in α1-MG-Ucr per Cd-Ucr was much greater when Cd-Ucr was large, e.g., in excess of 10?µg/g?cr. 相似文献
4.
Calculation of environmental concentration and comparison of output for existing chemicals using regional multimedia modeling 总被引:1,自引:0,他引:1
The environmental fate of 40 existing chemicals is discussed using the EUSES multimedia distribution and risk assessment model with site-specific parameter setting in an urban area of Japan including a highly industrial region. There has been a strong need to assess the environmental fate of a huge number of existing chemicals. Data on the emission amounts of chemicals are essential for such prediction, and PRTR surveys may yield this data. The study delivered the following results: (1) Volatile compounds with large amounts of emission showed higher predicted concentrations in air, and the concentrations of several compounds agreed well with averaged monitoring data within an order of magnitude. (2) A close relationship was found between the concentration of water and that of sediment, suggesting that the fate of chemicals in sediment essentially depended on the water environment. (3) A group of volatile solvents had high mass distribution ratio to air. Some compounds having high solubility in water were also included in that group due to the high ratio of air emission. Highly hydrophobic compounds with logK(OW) larger than 6.0 showed a high distribution ratio to soil and sediment. (4) Volatile compounds were mostly taken through air. The exposure through fish is a dominant pathway for highly hydrophobic compounds. (5) Exposure ratio could be gathered from physicochemical properties. The exposure from fish intake was roughly estimated by logK(OW), whereas exposure from air and water intake was difficult to estimate simply by vapor pressure and solubility in water, respectively. 相似文献
5.
Kawamoto K Arey JS Gschwend PM 《Journal of the Air & Waste Management Association (1995)》2003,53(12):1426-1435
Expected urban air concentrations of the gasoline additive methyl tertiary butyl ether (MTBE) were calculated using volatile emissions estimates and screening transport models, and these predictions were compared with Boston, MA, area urban air measurements. The total volatile flux of MTBE into the Boston primary metropolitan statistical area (PMSA) airshed was calculated based on estimated automobile nontailpipe emissions and the Universal Quasi-Chemical Functional-Group Activity Coefficient computed abundance of MTBE in gasoline vapor. The fate of MTBE in the Boston PMSA was assessed using both the European Union System for the Evaluation of Substances, which is a steady-state multimedia box model, and a simple airshed box model. Both models were parameterized based on the meteorological conditions observed during air sampling in the Boston area. Measured average urban air concentrations of 0.1 and 1 microg/m3 MTBE during February and September of 2000, respectively, were comparable to corresponding model predictions of 0.3 and 1 microg/m3 and could be essentially explained from estimated temperature-dependent volatile emissions rates, observed average wind speed (the airshed flushing rate), and reaction with ambient tropospheric hydroxyl radical (*OH), within model uncertainty. These findings support the proposition that one can estimate gasoline component source fluxes and use simple multimedia models to screen the potential impact of future proposed gasoline additives on urban airsheds. 相似文献
6.
PCDDs/DF and Co-PCB (dioxin) formations were studied with ash from a newly developed gasification and melting process for
municipal solid waste. Ash samples were heated in a laboratory-scale fixed-bed reactor. Emphasis was placed on the effects
of the type and composition of ash, temperatures, gas residence time, and gaseous organic precursors. Investigations using
macroscopic and homologue distribution analyses led to the following conclusion. The ash from the gasification–melting process
had the ability to generate dioxins in flue gas. A possible carbon source is unburned carbon in the ash samples, although
this was very low (less than 0.01%). An experimental result that the level of dioxins generated from preheated fly ash obtained
from a conventional incinerator was much lower than that from nonheated fly ash supported this conclusion. Dioxin concentrations
obviously showed temperature dependence and peaked at 350°C. Dioxins formed in a gasification–melting process ash were readily
desorbed from the surface, probably because of the low carbon content of the ash. There was no experimental evidence that
gaseous organic precursors fed to the reactor generated dioxins. Therefore, an organic precursor was not essential for the
formation of dioxins. A good linear relationship obtained between PCDDs/DFs and gas residence time also supported the assumption.
Received: February 14, 2000 / Accepted: June 30, 2000 相似文献
7.
Nobuhisa Watanabe Shusuke Takemine Katsuya Yamamoto Yuki Haga Mitsuyasu Takata 《Journal of Material Cycles and Waste Management》2016,18(4):625-630
Perfluorooctanoic acid (PFOA), perfluorohexanoic acid (PFHxA) and perfluorooctane sulfonate (PFOS) adsorbed onto granular activated carbon (GAC) were thermally treated in N2 gas stream. The purpose was to assess the fate of perfluoroalkyl and polyfluoroalkyl substances (PFASs) during thermal regeneration of GAC, which had been used for water treatment. Mineralized F, residual PFASs including short-chained species, and volatile organic fluorine (VOF) were determined. In a temperature condition of 700 °C, VOF were 13.2, 4.8, and 5.9 % as for PFOA, PFHxA, and PFOS. However, the VOF decreased to 0.1 %, if the GAC and off-gas were kept at 1000 °C. No PFASs remained in GAC at 700–1000 °C; at the same time, short-chained PFASs were slightly detected in the aqueous trapping of off-gas at 800 and 900 °C conditions. The destruction of PFASs on GAC could be perfect if the temperature is higher than 700 °C; however, the process is competitive against volatile escape from GAC. Destruction in gaseous phase needs a temperature as high as 1000 °C. Destruction of PFASs on the surface of GAC, volatile escape from the site, and thermolysis in gas phase should be considered, as to thermal regeneration of GAC. 相似文献
8.
Thermal gasification and reforming technologies applicable over a wide temperature range were investigated for high efficiency
and for the calorific value of the gas evolved from organic waste such as woody debris. The durability of the reforming catalyst
and the availability of catalyst regeneration were investigated using laboratory-scale catalytic reformers and a gasifier.
Commercial Ni-based catalyst and calcined limestone (CaO) were applied to the reforming reaction. The results of woody waste
gasification and reforming revealed the hydrogen concentration produced to be sustained at a high catalyst temperature of
1123 K, which prevented the catalyst from deactivating. The results also indicated that catalyst regeneration by air oxidation
at the same temperature would be effective for enhancing catalytic activity. 相似文献
9.
A. Samad Nur Syafiqah Abdul-Rahim Abdul Samad Mohd Yusof Mohd Johari Tanaka Katsuya 《Environmental science and pollution research international》2020,27(10):10367-10390
Environmental Science and Pollution Research - This study assessed the economic value of public urban green spaces (UGSs) in Kuala Lumpur (KL) city by using the hedonic price method (HPM). It... 相似文献
10.
Here, we present the evolution profile of tar in the product gas during cedar biomass gasification. We also discuss the evolution of other contaminants (H2S, COS, NH3, HCN, and HCl). The cedar wood was gasified under various operating conditions in a bench-scale externally heated updraft gasifier; this was followed by thermal reforming.Tar levels in the product gas were significantly affected by the operating conditions used. At a gasification temperature of 923 K, there was no clear relation between the evolution of phenolic tar in the product gas as a function of residence time. The evolution of PAH tar at a low gasification temperature was lower than the evolution of phenolic tar. With increasing temperature, the proportion of PAH tar content became significant. At a gasification temperature of 1223 K, increasing the residence time reduced the content of PAH tar owing to a catalytic effect associated with ash generation at high temperatures. Increasing the steam-to-carbon (S/C) ratio under thermal conditions had a slight effect on PAH conversion. However, increasing the equivalence ratio (ER) effectively reduced the tar levels.The conversion of fuel-sulfur and fuel-nitrogen to volatile-sulfur and volatile-nitrogen, respectively, increased with increasing S/C ratio and ER. The evolutions of COS and HCN gases were much smaller than the evolution of H2S and NH3. The evolution of HCl in the product gas decreased slightly with increasing ER. Increasing the S/C ratio decreased the HCl levels in the product gas. The effect of temperature on contaminant levels could not be fully understood due to limited availability of experimental data at various temperatures. We also compare our findings with data in the literature. 相似文献