Application of the powder of porous titanium carbide ceramics to a reusable adsorbent for environmental pollutants

The aim of this study is to investigate the utilization of the powder of porous titanium carbide (TiC) ceramics as a novel adsorbent or a material for solid-phase extraction (SPE). The adsorption and elution of inorganic and organic pollutants, Pb(II), 2,4,6-trichlorophenol (TCP), perfluorooctane sulfonate (PFOS), and perfluorooctanoic acid (PFOA), to the material were evaluated. The cartridge packed with TiC ceramics powder was used for the extraction test of pollutants. The solution containing pollutants at 1.0 mu g mL(-1) was passed through the TiC cartridge, and the substances were almost quantitatively removed. Furthermore, the pollutants retained in the cartridge were eluted with 3 N HCl for Pb(II) and with methanol for organic pollutants. The recoveries of pollutants were over 80%. In addition, we used the TiC cartridge for the solid-phase extraction of water samples (500 mL each of the distilled water and the river water) by adding pollutants at determined concentrations. Every pollutant was adsorbed almost quantitatively, and eluted by 3 N HCl or methanol. From these results, we concluded that the powder of porous TiC ceramics is a useful reusable adsorbent for the water cleanup and solid-phase extraction.ArticleJOURNAL OF HAZARDOUS MATERIALS. 185(2-3):725-731 (2011)journal articl

Effects of Extraction Solvents on the Extraction Efficiencies of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans, and Polychlorinated Biphenyls in Reference Materials

This study investigated the extraction efficiency of a couple of different extraction solvents for Certified Reference Materials of soil and sediment that include Polychlorinated Dibenzo-p-dioxins and Dibenzofurans and Coplanar Polychlorinated Biphenyls using Soxhlet and Pressurized Liquid extraction (PLE). n-Hexane, toluene, acetone, acetone/n-hexane and acetone/toluene (1:1, v/v) as solvents were examined. Unsatisfactory results for Soxhlet extraction were obtained using n-hexane alone. For PLE, satisfactory results were obtained using all solvents used for this study. The obtained results for PLE were the same or even higher than those for Soxhlet extraction. We also examined relationship between solubilityof 2, 3, 7, 8-TetraCDD/CDF in the solvent (Xdxn) and the estimated solubility (Xs). The results indicated that a linear relation was found between Xdnx and Xs for Soxhlet extraction, but no linear relation was found in those for PLE. The result suggests that choice of extraction solvent for PLE requires consideration for the analyte solubilityin extraction solvent at the temperature and pressure above boiling points of solvents

Loss of Polychlorinated Dibenzo-p-dioxins, Polychlorinated Dibenzofurans and Coplanar Polychlorinated Biphenyls during Vacuum Concentration for Ultra-trace Analysis

We investigated the effectof kinds of organic solvent on the losses of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/DFs), coplanar polychlorinated biphenyls (Co-PCBs), and their 13C12-labeled compounds during vacuum concentration. n-Hexane and toluene solutions containing the standards of those compounds were tested for the purpose. The kind of organic solvent has remarkable effect on the loss of 13C12-Co-PCBs from the standard solutions, while it has littleor no effect on the losses of Co-PCBs, PCDD/DFs, and 13C12-PCDD/DFs from the standard solutions. The losses of lower chlorinated "Co12-C0-PCBs with w-hexane solution were greater than theloss of the compounds with toluene solution. The relative PCBs with w-hexane solution were greater than theloss of the compounds with toluene solution.The relative amounts of 13C１2-Co-PCBs in the condensate solvent produced during the vacuum concentration show that those of the compounds with toluene solution were less than that of n-hexane solution. These results demonstrate that the minimization of loss of the compounds with n-hexane solution may be achieved by adding toluene before the vacuum concentration. We also examined the relationship between the relative amounts of Co-PCBs and 13C12-Co-PCBs in the condensate solvents and vapor pressures of those compounds. amounts of Co-PCBs and 13C12-Co-PCBs in the condensate solvents and vapor pressures of those compounds. amounts of Co-PCBs and 13C12-Co-PCBs in the condensate solvents and vapor pressures of those compounds. There was the difference in the regression line slopes of the relativeamounts vs. in the vapor pressures between the n-hexane solution and toluene solution. This fact could be useful for the optimization of the vacuum concentration conditions in the convenient analytical methods

Effects of the Tibetan High and the North Pacific High on the Occurrence of Hot or Cool Summers in Japan

In this study, we investigated the effects of the Tibetan High near the tropopause and the North Pacific High in the troposphere on occurrences of hot or cool summers in Japan. We first classified Japan into six regions and identified hot and cool summer years in these regions from a 38-year sample (1980–2017) based on the monthly air temperature. To investigate the features of circulation fields over Asia during hot and cool summers in Japan, we calculated the composite differences (hot summer years minus cool summer years) of several variables such as geopotential height, which indicated significant high-pressure anomalies in the troposphere and lower stratosphere. These results suggest that both the North Pacific and the Tibetan Highs tend to extend to Japan during hot summer years, while cool summers seem to be associated with the weakening of these highs. We found that extension of the Tibetan High to the Japanese mainland can lead to hot summers in Northern, Eastern, and Western Japan. On the other hand, hot summers in the Southwestern Islands may be due to extension of the Tibetan High to the south. Similarly, the latitudinal direction of extension of the North Pacific High is profoundly connected with the summer climate in respective regions

Effects of the Tibetan High and the North Pacific High on the Occurrence of Hot or Cool Summers in Japan

In this study, we investigated the effects of the Tibetan High near the tropopause and the North Pacific High in the troposphere on occurrences of hot or cool summers in Japan. We first classified Japan into six regions and identified hot and cool summer years in these regions from a 38-year sample (1980–2017) based on the monthly air temperature. To investigate the features of circulation fields over Asia during hot and cool summers in Japan, we calculated the composite differences (hot summer years minus cool summer years) of several variables such as geopotential height, which indicated significant high-pressure anomalies in the troposphere and lower stratosphere. These results suggest that both the North Pacific and the Tibetan Highs tend to extend to Japan during hot summer years, while cool summers seem to be associated with the weakening of these highs. We found that extension of the Tibetan High to the Japanese mainland can lead to hot summers in Northern, Eastern, and Western Japan. On the other hand, hot summers in the Southwestern Islands may be due to extension of the Tibetan High to the south. Similarly, the latitudinal direction of extension of the North Pacific High is profoundly connected with the summer climate in respective regions