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1.
Dichloroacetic acid (DCAA) is produced during the oxidation of trichloroethylene. It is also produced in drinking water treatment as a disinfection by-product. DCAA is a problem material, because of its toxicity. The objective of this research is to find the final products and the reaction pathway of the DCAA decomposition by hydrolysis, and to increase the hydrolysis rate. The removal of both chlorine atoms in DCAA structure was achieved with hydrolysis at around 75 degrees C, and the final products were oxalic acid and glycolic acid. The reaction pathway was the production of oxalic acid and glycolic acid from two glyoxylic acid molecules by Cannizzaro reaction after the glyoxylic acid production from dechlorination of DCAA with hydrolysis. The hydrolysis rate of DCAA was increased with the use of 90% ethanol solution as solvent. The activation energy of DCAA was about 80 kJ/mol in it, while it was around 105 kJ/mol in water. 相似文献
2.
Tetsuji Yamada Misuzu Asari Takahiro Miura Tomoyuki Niijima Junya Yano Shin-ichi Sakai 《Journal of Material Cycles and Waste Management》2017,19(4):1351-1360
For 35 years, Kyoto City has conducted detailed household waste composition surveys under the guidance of Kyoto University by dividing household waste into approximately 400 categories. In addition, the city has conducted detailed composition surveys of commercial waste generated by businesses. These surveys show that food loss accounts for approximately 40% of total waste, of which leftovers and untouched food account for about 40% in both households and business facilities. Consequently, the annual generation of household and commercial food loss is estimated at about 30,000 tons. Various efforts have been made to reduce waste, including food loss, but further reduction in environmental burden is needed. Thus, Kyoto City revised the ordinance for waste reduction, and in March 2015, formulated a new municipal waste management plan. The plan not only includes the 2Rs (reduce, reuse), but also, for the first time in Japan, sets quantitative targets for reducing food loss. Kyoto City must ensure that the necessary waste reduction measures are clearly explained to the residents and business operators. To ensure that this plan is successful, it is important to clarify concrete actions that residents and business operators should implement, along with their effects. 相似文献
3.
Tetsuji Yamaguchi Yoshiaki Sakamoto Shinichi Nakayama Tjalle T. Vandergraaf 《Journal of contaminant hydrology》1997,26(1-4)
The effective diffusivity of uranium(VI) in Inada granite has been determined by through-diffusion. Experiments were performed at room temperature (20–25°C) in a 0.1 mol 1−1 KCl solution where uranium is present predominantly as the poorly sorbing UO22+. An effective diffusivity (De) of (3.6 ± 1.6) × 10−14 m2 s−1 was obtained, close to that for uranine (nonsorbing organic tracer), but one order of magnitude lower than those obtained for Sr2+ and NpO2+, and two orders of magnitude lower than that obtained for I−. According to well established theory, a proportional relationship exists between De and the diffusivity in the bulk of the solution (Dv). The effective diffusivity obtained in granite was not proportional to Dv. This agrees with results obtained for effective diffusivity in a Swedish granite. The ratio De/Dv was found to be not constant but increased with De or Dv. This result suggests a limit to the application of the theory. 相似文献
4.
Surface ozonation of polyvinyl chloride for its separation from waste plastic mixture by froth floatation 总被引:1,自引:1,他引:0
Mallampati Srinivasa Reddy Tetsuji Okuda Keisuke Kurose Tsung-Yueh Tsai Satoshi Nakai Wataru Nishijima Mitsumasa Okada 《Journal of Material Cycles and Waste Management》2010,12(4):326-331
Selective surface modification of polyvinyl chloride (PVC) by ozonation was evaluated to facilitate the separation of PVC
from other heavy plastics with almost the same density as PVC, especially polyethylene terephthalate (PET), by the froth flotation
process. The optimum froth flotation conditions were investigated, and it was found that at 40°C, 90% of PVC and PET plastics
floated. The bubble size became larger and the area covered with bubbles on the plastic surface was reduced with increasing
temperature. Optimum PVC separation was achieved with the flotation solution at 40°C and mixing at 180–200 rpm, even for sheet
samples 10 mm in size. Combined treatment by ozonation and froth flotation is a simple, effective, and inexpensive method
for PVC separation from waste plastics. 相似文献
5.
Mallampati Srinivasa Reddy Takefumi Yamaguchi Tetsuji Okuda Tsung-Yueh Tsai Satoshi Nakai Wataru Nishijima Mitsumasa Okada 《Waste management (New York, N.Y.)》2010,30(4):597-601
This study describes the possible separation of chlorinated plastic films (PVC and PVDC) from other heavy plastic packaging waste (PPW) by selective twist formation and gravity separation. Twists formation was mechanically induced in chlorinated plastic films, whereas twist formation did not occur in PS and PET films. After twist formation, all the films had the apparent density of less than 1.0 g/cm3 and floated in water even though the true density was more than 1.0 g/cm3. However, the apparent density of the PS and the PET films increased with agitation to more than 1.0 g/cm3, whereas that of chlorinated plastic films was kept less than 1.0 g/cm3. The main reason would be the air being held inside the chlorinated plastic films which was difficult to be removed by agitation. Simple gravity separation after twist formation was applied for artificial film with 10 wt.% of the chlorinated films and real PPW films with 9 wt.% of the chlorinated films. About 76 wt.% of the artificial PPW films and 75 wt.% of real PPW films after the removal of PP and PE were recovered as settling fraction with 4.7 wt.% and 3.0 wt.% of chlorinated plastic films, respectively. These results indicate that simple gravity separation process after twist formation can be used to reduce the chlorinated plastic concentration from mixed heavy PPW films. 相似文献
6.
Yuji Sakuno Esteban R. Miño Satoshi Nakai Hidemi Mutsuda Tetsuji Okuda Wataru Nishijima Rolando Castro Amarillis García Rosanna Peña Marcos Rodríguez G. Conrado Depratt 《Environmental monitoring and assessment》2014,186(7):4181-4193
This study aims to study the distribution of contaminants in rivers that flow into the Caribbean Sea using chlorophyll-a (Chl-a) and suspended sediment (SS) as markers and ALOS AVNIR-2 satellite sensor data. The Haina River (HN) and Ozama and Isabela Rivers (OZ-IS) that flow through the city of Santo Domingo, the capital of the Dominican Republic, were chosen. First, in situ spectral reflectance/Chl-a and SS datasets obtained from these rivers were acquired in March 2011 (case A: with no rain influence) and June 2011 (case B: with rain influence), and the estimation algorithm of Chl-a and SS using AVNIR-2 data was developed from the datasets. Moreover, the developed algorithm was applied to AVNIR-2 data in November 2010 for case A and August 2010 for case B. Results revealed that for Chl-a and SS estimations under cases A and B conditions, the reflectance ratio of AVNIR-2 band 4 and band 3 (AV4/AV3) and the reflectance of AVNIR-2 band 4 (AV4) were effective. The Chl-a and SS mapping results obtained using AVNIR-2 data corresponded with the field survey results. Finally, an outline of the distribution of contaminants at the mouth of the river that flows into the Caribbean Sea was obtained for both rivers in cases A and B. 相似文献
7.
Okuda T Alcántara-Garduño ME Suzuki M Matsui C Kose T Nishijima W Okada M 《Chemosphere》2007,68(2):281-286
Techniques for enhancing the biodegradation of oil-contaminated fine soils in a slurry-phase bioreactor were investigated. Using a model system consisting of kaolin particles containing adsorbed n-dodecane as a diesel fuel surrogate, we investigated how increasing the temperature and adding a surfactant and various hydrophobic support media affected the biodegradation rate of n-dodecane. Increasing the temperature from 25 to 35 degrees C decreased the time required for complete degradation of n-dodecane by 30%, from 110h to 80h. Addition of the surfactant polyethylene glycol p-1,1,3,3-tetramethylbutylphenyl ether decreased the degradation time to less than 48h at 35 degrees C, although a high concentration of the surfactant (3000mgl(-1)) was required. We suspect that the surfactant increased the degradation rate by solubilizing the n-dodecane into the solution phase in which the microorganisms were suspended. We tested five types of organic polymers as support media for the microorganisms and found that the biodegradation time could be reduced by approximately 50% with a support medium made from polyurethane; in the presence of this medium, only 36h was required for complete decomposition at 35 degrees C. The reduction in the degradation time was probably due to transfer of the n-dodecane from the soil to the support medium, which improved contact between the n-dodecane and the microorganisms. The polyurethane support medium bearing the microorganisms was stable and could be reused. 相似文献
8.
Srinivasa Reddy Mallampati Yoshiharu Mitoma Tetsuji Okuda Shogo Sakita Mitsunori Kakeda 《Environmental Chemistry Letters》2012,10(2):201-207
This report shows that cesium can be immobilized in soils with an efficiency of 96.4% by ball milling with nano-metallic Ca/PO4. In Japan, the major concern on 137Cs deposition and soil contamination due to the emission from the Fukushima Daiichi nuclear power plant showed up after a
massive quake on March 11, 2011. The accident rated 7, the highest possible on the international nuclear event scale, released
160 petabecquerels (PBq) of iodine 131I and 15 PBq of 137Cs according to the Japanese Nuclear and Industrial Safety Agency. Both 137Cs and 131I radioactive nuclides are increasing cancer risk. Nonetheless, 137Cs, with a half-life of about 30 years compared with 8 days for 131I, is a major threat for agriculture and stock farming and, in turn, human life for decades. Therefore, in Japan, the 137Cs fixation and immobilization in contaminated soil is the most important problem, which should be solved by suitable technologies.
Ball milling treatment is a promising treatment for the remediation of cesium-contaminated soil in dry conditions. Here, we
studied the effect, factors and mechanisms of soil Cs immobilization by ball milling with the addition of nano-metallic Ca/CaO/NaH2PO4, termed “nano-metallic Ca/PO4.” We used scanning electron microscopy combined with electron dispersive spectroscopy (SEM/EDS) and X-ray diffraction. Results
show that immobilization efficiency increases from 56.4% in the absence of treatment to 89.9, 91.5, and 97.7 when the soil
is ball-milled for 30, 60 and 120 min, respectively. The addition of nano-metallic Ca/PO4 increased the immobilization efficiency to about 96.4% and decreased the ball milling time. SEM/EDS analysis allows us to
observe that the amount of Cs decreased on soil particle surface. Use of nano-metallic Ca/PO4 over a short milling time also decreases Cs leaching. Therefore, ball milling with nano-metallic Ca/PO4 treatment may be potentially applicable for the remediation of radioactive Cs-contaminated soil in dry conditions. 相似文献
9.
Srinivasa Reddy Mallampati Yoshiharu Mitoma Tetsuji Okuda Shogo Sakita Mitsunori Kakeda 《Environmental Chemistry Letters》2013,11(2):119-125
This report shows that soil heavy metals can be totally immobilized by grinding with nano-Fe/Ca/CaO. Remediation of soils contaminated by heavy metals is a critical issue in Japan. Indeed, contaminated soils are notoriously difficult to remediate using available technologies. Major setbacks in typical immobilization techniques for heavy metals are wet conditions, forming secondary effluents and further treatment for effluents. Solidification with nano-Fe/Ca/CaO dispersion mixture is a promising treatment for the total immobilization of soil heavy metals As, Cd, Cr, Pb, and separation in dry conditions. Here, we studied the heavy metal immobilization by simple grinding with the addition of three mixtures: nano-Fe/CaO, nano-Fe/Ca/CaO, and nano-Fe/Ca/CaO/PO4. Samples were analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES) and scanning electron microscopy combined with electron dispersive spectroscopy (SEM–EDS). Results show that the addition of nano-Fe/Ca/CaO immobilized 95–99 % of heavy metals, versus 65–80 % by simple grinding. After treatment, 36–45 wt% of magnetic and 64–55 wt% of nonmagnetic fractions of soil were separated. Their condensed heavy metal concentration was 85–95 % and 10–20 %, respectively. Nano-Fe/Ca/CaO treatment reduced the concentration of leachates heavy metals to values lower than the Japan soil elution standard regulatory threshold of 0.01 mg/l for As, Cd, and Pb; and 0.05 mg/l for Cr. This technology can therefore immobilize totally soil heavy metals and reduce heavy metal by separation. 相似文献
10.
Kim HJ Han B Kim YJ Hwang KD Oh WS Yoo SY Oda T 《Journal of the Air & Waste Management Association (1995)》2011,61(12):1334-1343
A novel two-stage wet electrostatic precipitator (ESP) has been developed using a carbon brush pre-charger and collection plates with a thin water film. The electrical and particle collection performance was evaluated for submicrometer particles smaller than 0.01- 0.5 micrometer in diameter by varying the voltages applied to the pre-charger and collection plates as well as the polarity of the voltage. The collection efficiency was compared with that calculated by the theoretical models. The long-term performances of the ESP with and without water films were also compared in tests using Japanese Industrial Standards dust. The experimental results show that the carbon brush pre-charger of the two-stage wet ESP had approximately 10% particle capture, while producing ozone concentrations of less than 30 ppb. The produced amounts of ozone are significantly lower than the current limits set by international agencies. The ESP also achieved a high collection rate performance, averaging 90% for ultrafine particles, as based on the particle number concentration at an average velocity of 1 m/sec corresponding to a residence time of 0.17 sec. Higher particle collection efficiency for the ESP can be achieved by increasing the voltages applied to the pre-charger and the collection plates. The decreased collection efficiency that occurred during dust loading without water films was completely avoided by forming a thin water film on the collection plates at a water flow rate of 6.5 L/min/m(2). 相似文献