Destruction of polychlorinated naphthalenes by a high-temperature melting treatment (GeoMelt process)

A series of treatment experiments were carried out to evaluate the applicability of a high-temperature melting treatment (GeoMelt process) to the destruction of polychlorinated naphthalene (PCN) formulation. We started with 10-kg-scale experiments in which a small melting furnace was used and then scaled up to a 1-t-scale experiment in which a melting furnace that resembled an actual treatment system was used. These runs were evaluated whether destruction efficiency (DE) of total PCNs was more than 99.999 % and whether concentrations of PCNs and polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDDs/DFs) in vitrified materials, emission gas, and scrubber water were below the target levels. Because DE values and the target levels of PCNs and PCDDs/DFs in these runs were satisfactory, then we carried out a demonstrative experiment using the actual treatment system and confirmed destruction of PCNs. Based on good results of the demonstrative experiment, stock of PCN formulation was successfully treated continuously.     

Spectroscopic analysis of NIR-dye sensitization in bulk heterojunction polymer solar cells

The photovoltaic conversion efficiency for near-infrared (NIR) sunlight is improved successfully by dye sensitization of bulk heterojunction polymer solar cells, in which the active layer was prepared by a ternary blend of poly(3-hexylthiophene), a fullerene derivative (1-(3-methoxycarbonyl)propyl-1-phenyl-[6,6]-methanofullerene), and an NIR dye, silicon phthalocyanine bis(trihexylsilyl oxide). The mechanism of the NIR-dye sensitization is studied by femtosecond transient absorption spectroscopy.     

Spectroscopic Analysis of NIR-Dye Sensitization in Bulk Heterojunction Polymer Solar Cells

The photovoltaic conversion efficiency for near-infrared (NIR) sunlight is improved successfully by dye sensitization of bulk heterojunction polymer solar cells, in which the active layer was prepared by a ternary blend of poly(3-hexylthiophene), a fullerene derivative (1-(3-methoxycarbonyl)propyl-1-phenyl-[6,6]-methanofullerene), and an NIR dye, silicon phthalocyanine bis(trihexylsilyl oxide). The mechanism of the NIR-dye sensitization is studied by femtosecond transient absorption spectroscopy.     

Sustainability of silicon feedstock for a low-carbon society

We need to ensure the sustainable management of advanced materials, such as purified silicon, that contribute to a low-carbon society. Because a drastic increase in the demand for photovoltaic (PV) systems is tightening the supply of silicon for PV cells, the sustainability of silicon feedstock needs to be explored. For this purpose, a material flow analysis of silicon in Japan from 1996 to 2006 is presented in this paper. Our analysis finds that rapid growth in demand for polycrystalline silicon (pc-silicon) and single crystalline silicon (sc-silicon) has changed the structure of the purified silicon supply. The strong demand for purified silicon for solar cells is responsible for this change. While off-grade silicon obtained as a by-product of electronic-grade silicon (EG-Si) covered the demand for solar sells before 2000, pc-silicon is currently produced independently for solar cells via an energy-intensive process. Analysis of the resource effective-use index (REI), which indicates how effectively purified silicon is used, shows progress in the effective use of pc- and sc-silicon. REI analysis indicates that the effective use of pc-silicon is reaching a maximum, while the effective use of sc-silicon is advancing, with a corresponding increase in price. To ensure a sustainable supply of silicon feedstock, this paper proposes four solutions: (1) production of solar-grade pc-silicon by a less costly and less energy-consuming method; (2) reduction in the amount of crystalline silicon per watt in solar cells; (3) acceleration of the development and deployment of other solar cell types; and (4) reuse and recycling of solar cells in the future.     

Trace metal speciation during dry and wet weather flows in the Tama River, Japan, by using diffusive gradients in thin films (DGT)

The labile species of Ni, Cu, Zn, Cd, and Pb in the Tama River, an urban river in Tokyo, Japan, were measured using diffusive gradients in thin films (DGT) method under dry and wet weather conditions, and the results were compared with total dissolved concentrations in hourly samples collected in parallel. A total of 10 DGT deployments were made and 251 hourly samples were collected during 2 rounds of sampling, conducted between August and October, 2006. Two types of diffusive gradients in thin films (DGT) devices-DGT-RG for labile inorganic and DGT-APA for total (inorganic and organic) labile species-were applied throughout the samplings. The proportions of metals measured by DGT, compared with the dissolved metal concentrations (filtered using a membrane of 0.5 microm pore size), were 38 +/- 5% (RG) and 45 +/- 8% (APA) for Ni and 45 +/- 22% (RG) and 53 +/- 23% (APA) for Zn. No labile Cu was detected throughout the sampling; Cu was assumed to be in stable complexed forms. Labile Pb was detected in 3 out of 10 deployments only; the rest were lower than the detection limit. Dissolved and labile Cd concentrations were below the detection limits. Three rain events encountered during the sampling periods were evaluated. Rains brought considerably higher loads of metals in dissolved form, and DGT measurements indicated that labile metal loads also increased. Selected DGT measurements were compared with the WHAM 6 speciation model and found to be similar to the model-computed results.     

Behaviour of selected endocrine-disrupting chemicals in three sewage treatment plants of Beijing, China

Occurrence and fate of eight kinds of selected endocrine-disrupting compounds (EDCs) in three sewage treatment plants (STPs) of Beijing, China was investigated. These EDCs, composed of 4-octylphenol (4-OP), 4-n-nonylphenol (4-n-NP), bisphenol A (BPA), estrone (E1), 17α-estradiol (17α-E2), 17β-estradiol (E2), estriol (E3) and 17α-ethinylestradiol (EE2), in every step of STPs, were simultaneously analysed by gas chromatography/mass spectrometry after derivatisation. All the EDCs were detected in the influents of three STPs, and BPA was the most abundant compound. The concentrations of EDCs ranged from 36.6 ng/l of 17α-E2 (STP C) to 1342.3 ng/l of BPA (STP B) in the influent sewages and from below limits of detection of E2 and E3 (STP C) to 142.5 ng/l of E1 (STP B) in the effluent sewages. The STPs could not remove alkylphenols effectively from the aqueous phase with less than 40% reduction. BPA decreased over 90%, and steroid estrogens achieved considerable reductions from 64.8% of E2 to 94.9% of E3. Generally, biological treatment was more effective in removing alkylphenols, BPA and natural estrogens from the aqueous phase than primary treatment. However, the synthetic estrogen, EE2, was mostly removed by the primary treatment with about 63.5% reduction. It is the first time that the concentration of 17α-E2 in the sewage of China was reported in this paper. The compound might have a bearing with the waste effluents of dairy farms around urban area of Beijing.     

Separation, synthesis and estrogenic activity of 4-nonylphenols: two sets of new diastereomeric isomers in a commercial mixture

Two sets of new diastereomeric 4-nonylphenol (NP) isomers [4-(3,4-dimethylheptan-4-yl)phenol (344NP, NP-J, L) and 4-(3,4-dimethylheptan-3-yl)phenol (343NP, NP-K, P)] were separated from a commercial NP mixture. The mixture of these diastereomers was synthesized at the same time by a single Friedel-Crafts reaction of 3,4-dimethyl-4-heptanol and phenol, and the mixture was separated into individual NPs by HPLC equipped with Hypercarb column. For the first time, in this study the stereostructure-estrogenic activity relationship of NP diastereomers was investigated. The NP isomers (NP-L and NP-P) having the beta-methyl group over the benzene ring were found to be 2-4 times more estrogenic than their diastereomers (NP-J and NP-K). In the case of the other set of diastereomer [4-(3,5-dimethylheptan-3-yl)phenol, (353NP, NP-E, G)] containing gamma-methyl group in the molecule, the gamma-methyl proton signal (delta 0.49) in the more estrogenic isomer (NP-G) also appeared in a higher field than the corresponding methyl signal (delta 0.76) of the less estrogenic isomer (NP-E).     

Elemental composition of sediments in Lake Jinzai, Japan: Assessment of sources and pollution

Bottom sediments from Lake Jinzai in southwest Japan were analyzed to determine their chemical compositions and to assess the potential for ecological harm by comparison with sediment quality guidelines. The pollution status of lake sediments was evaluated by employing contamination factor (CF), pollution load index (PLI), and geoaccumulation index (I(geo)), focusing on a suite of elements in lakebed and core sediments. Elevated concentrations of As, Pb, Zn, Cu, TOC, N, and P were present in several layers of the upper core and other surface sediments. The elevated metal concentrations are likely related to the fine-grained nature of the sediments, reducing bottom conditions produced by abundant organic matter, and possibly minor non-point anthropogenic sources. Moreover, correlations between the concentrations of trace metals and organic carbon, nitrogen, phosphorus, and iron, suggest that these elements play a role in controlling abundances. Calculated CF, PLI, and I(geo) indicate that the sediments are strongly polluted with respect to As, moderately to strongly polluted with Zn, and moderately polluted with Pb and Cu. Metal concentrations exceed the New York State Department of Environmental Conservation (NYSDEC) lowest effect level and the Canadian Council of Ministers of the Environment (CCME) interim sediment quality guidelines that indicate moderate impact on aquatic organisms in the study area.     

Geochemical evaluation of present-day Tuul River sediments, Ulaanbaatar basin, Mongolia

The Tuul River flows through the Ulaanbaatar basin of Mongolia and is the main source of water for the capital city, Ulaanbaatar. The Tuul catchment can be divided into three parts around Ulaanbaatar (upper, middle, and lower), according to the extent of urbanization. Sixteen surface water and groundwater samples were collected to evaluate present-day water quality and 34 stream sediment samples taken to examine their geochemical composition in relation to provenance and to assess the impact of urban activity on heavy metal accumulation. Groundwater quality in the upper and central water sources was adequate, but high concentrations of NO ₃ ^? were found in the lower water source. Heavy metal concentrations in the sediments are evaluated by comparison with average upper continental crust (UCC) values, coupled with ecological risk assessment by reference to sediment quality guidelines (SQG). The results show average abundances of potentially toxic metals such as As, Pb, Zn, Cu, Ni, Cr, and V are higher in the middle part (within the city) than in the upper and lower parts. However, all three parts show depletion in some chalcophile and high field strength elements (Cu, Ni, Cr, Sr, Nb, Zr, Th, Sc) relative to UCC, indicating that the river sediments were derived from a highly felsic crustal source. The assessment using SQG shows As and Cr are present in levels that cause adverse aquatic biological effects. Although concentrations of Pb, Zn, Cu, and Ni are generally below their respective threshold effect levels, in the middle reaches, values increase and border on the probable effect level. This suggests significant anthropogenic contamination in the urban areas, increasing values above a naturally low regional background.     

Estrogen equivalent concentration of 13 branched para-nonylphenols in three technical mixtures by isomer-specific determination using their synthetic standards in SIM mode with GC-MS and two new diasteromeric isomers

Thirteen isomers of branched para-nonylphenols (para-NP) in three technical mixtures were isomer-specifically determined using their synthesized standards by SIM of structurally specific ions, m/z 135, 149 or 163 with GC–MS. Of the 13 isomers, four isomers, 4-(2,4-dimethylheptan-4-yl)phenol, 4-(4-methyloctan-4-yl)phenol, 4-(3-ethyl-2-methylhexan-2-yl)phenol (3E22NP) and 4-(2,3-dimethylheptan-2-yl)phenol synthesized for their determinations were first used as standard substances. The 13 isomers in the technical mixtures individually occurred at mass percent portion of more than 2%. The total mass percent portions in the mixtures from Tokyo Chemical Industry (TCI), Aldrich, and Fluka covered with 89 ± 2%, 75 ± 4% and 77 ± 2%, respectively. The abundance of 4-(3,6-dimethylheptan-3-yl)phenol in the three mixtures was the largest with 11.1 ± 2% to 9.9 ± 0.3%, while that of 4-(2-methyloctan-2-yl)phenol was the smallest with 2.9 ± 0.3% to 3.0 ± 0.2%. Additionally, structures of four new isomers of more than 1% portion present in a technical mixture were elucidated as two pairs of diastereomeric isomers: two types of 4-(3,4-dimethylheptan-4-yl)phenol (344NP) and those of 4-(3,4-dimethylheptan-3-yl)phenol (343NP). By estrogenic assay of 13 isomers with yeast estrogen screen system, the activity of 3E22NP was the highest, while that of 4-(3-methyloctan-3-yl)phenol was the least. Their relative activities to that of 3E22NP were individually calculated. Estrogenic equivalent concentrations of the three technical mixtures were predictively evaluated. The ratio of the EEC to the conventional concentration, total mass percent portions of the 13 isomers in technical mixtures were 0.208 for TCI, 0.206 for Aldrich and 0.205 for Fluka. The predicted estrogenic activity of measured concentration of para-NP in technical mixtures was approximately 5-fold greater than the measured estrogen agonist activity.