Concept: Hydrogen chloride
Simultaneous removal of nitrate and pentachlorophenol from simulated groundwater using a biodenitrification reactor packed with corncob
- Environmental science and pollution research international
- Published about 5 years ago
Both nitrate and pentachlorophenol (PCP) are familiar pollutants in aqueous environment. This research is focused on the simultaneous removal of nitrate and PCP from simulated contaminated groundwater using a laboratory-scale denitrification reactor packed with corncob as both carbon source and biofilm support. The reactor could be started up readily, and the removal efficiencies of nitrate and PCP reached up to approximately 98 % and 40-45 % when their initial concentrations were 50 mg N/L and 5 mg/L, respectively, after 15-day continuous operation at 10 h of hydraulic retention time (HRT) and 25 °C. Approximately 91 % of PCP removal efficiency was achieved, with 2.47 mg/L of chloride ion release at 24 h of HRT. Eighty-two percent of chlorine in PCP removed was ionized. The productions of 3-chlorophenol and phenol and chloride ion release indicate that the reductive dechlorination reaction is a major degradation pathway of PCP under the experimental conditions.
Bioaccessibility of Fukushima-Accident-Derived Cs in Soils and the Contribution of Soil Ingestion to Radiation Doses in Children
- Risk analysis : an official publication of the Society for Risk Analysis
- Published 11 months ago
Ingestion of contaminated soil is one potential internal exposure pathway in areas contaminated by the Fukushima Daiichi Nuclear Power Plant accident. Doses from this pathway can be overestimated if the availability of radioactive nuclides in soils for the gastrointestinal tract is not considered. The concept of bioaccessibility has been adopted to evaluate this availability based on in vitro tests. This study evaluated the bioaccessibility of radioactive cesium from soils via the physiologically-based extraction test (PBET) and the extractability of those via an extraction test with 1 mol/L of hydrochloric acid (HCl). The bioaccessibility obtained in the PBET was 5.3% ± 1%, and the extractability in the tests with HCl was 16% ± 3%. The bioaccessibility was strongly correlated with the extractability. This result indicates the possibility that the extractability in HCl can be used as a good predictor of the bioaccessibility with PBET. In addition, we assessed the doses to children from the ingestion of soil via hand-to-mouth activity based on our PBET results using a probabilistic approach considering the spatial distribution of radioactive cesium in Date City in Fukushima Prefecture and the interindividual differences in the surveyed amounts of soil ingestion in Japan. The results of this assessment indicate that even if children were to routinely ingest a large amount of soil with relatively high contamination, the radiation doses from this pathway are negligible compared with doses from external exposure owing to deposited radionuclides in Fukushima Prefecture.
The pressure-temperature phase diagram of ice displays a perplexing variety of structurally distinct phases. In the century-long history of scientific research on ice, the proton-ordered ice phases numbered XIII through XV were discovered only recently. Despite considerable effort, none of the transitions leading from the low-temperature ordered ices VIII, IX, XI, XIII, XIV and XV to their high-temperature disordered counterparts were experimentally found to display the full Pauling entropy. Here we report calorimetric measurements on suitably high-pressure-treated, hydrogen chloride-doped ice XIV that demonstrate just this at the transition to ice XII. Dielectric spectroscopy on undoped and on variously doped ice XII crystals reveals that addition of hydrogen chloride, the agent triggering complete proton order in ice XIV, enhances the precursor dynamics strongest. These discoveries provide new insights into the puzzling observation that different dopants trigger the formation of different proton-ordered ice phases.
HBr and DMPU form a room temperature-stable complex DMPU-HBr providing a mild, effective and selective hydrobrominating reagent toward alkynes, alkenes and allenes. HBr-DMPU could also replace other halogenating reagents in the halo-Prins reaction, ether cleavage and deoxy-bromination reactions.
The ν2 and ν5 fundamental bands of thionyl chloride (SOCl2) were measured in the 420 cm(-1)-550 cm(-1) region using the FT-far-IR spectrometer exploiting synchrotron radiation on the AILES beamline at SOLEIL. A straightforward line-by-line analysis is complicated by the high congestion of the spectrum due to both the high density of SOCl2 rovibrational bands and the presence of the ν2 fundamental band of sulfur dioxide produced by hydrolysis of SOCl2 with residual water. To overcome this difficulty, our assignment procedure for the main isotopologues (32)S(16)O(35)Cl2 and (32)S(16)O(35)Cl(37)Cl alternates between a direct fit of the spectrum, via a global optimization technique, and a traditional line-by-line analysis. The global optimization, based on an evolutionary algorithm, produces rotational constants and band centers that serve as useful starting values for the subsequent spectroscopic analysis. This work helped to identify the pure rotational submillimeter spectrum of (32)S(16)O(35)Cl2 in the v2=1 and v5=1 vibrational states of Martin-Drumel et al. [J. Chem. Phys. 144, 084305 (2016)]. As a by-product, the rotational transitions of the v4=1 far-IR inactive state were identified in the submillimeter spectrum. A global fit gathering all the microwave, submillimeter, and far-IR data of thionyl chloride has been performed, showing that no major perturbation of rovibrational energy levels occurs for the main isotopologue of the molecule.
Cognitive and emotional disorders have been reported in veterans intoxicated with sulfur mustard (SM) a chemical weapon belonging to the category of vesicating agents. However, the intense stress associated with the SM intoxication may render difficult determining the exact role played by SM intoxication itself on the emergence and maintaining of cognitive disorders. Animal’s model would allow overcoming this issue. So far, we presently investigated the cognitive and emotional impact of an acute cutaneous intoxication with CEES (2-chloroethyl ethyl sulfide), a SM analog in C57/Bl6 mice. Our study evidenced that up to 5days after a single acute neat CEES skin exposure, compared to controls, mice exhibited i) a significant increase in anxiety-like reactivity in an elevated plus-maze and in an open-field tasks and ii) an alteration of working memory in a sequential alternation task. In contrast, mice submitted to intoxication with a diluted CEES solution or hydrochloric acid (HCl) did not show any memory or emotional impairments. Given that, Our data shows that a single local cutaneous intoxication with neat CEES induced long-lasting cognitive and emotional pejorative effects, in accordance with the epidemiological observations in veterans. Thus, the single acute neat CEES cutaneous intoxication in mice could allow studying the sulfur mustard-induced cognitive and emotional disorders and their further counter-measures.
Trichloroethylene (TCE) is a widespread environmental pollutant common in groundwater plumes associated with industrial manufacturing areas. We had previously isolated and characterized a natural bacterial endophyte, Enterobacter sp. strain PDN3, of poplar trees, that rapidly metabolizes TCE, releasing chloride ion. We now report findings from a successful three-year field trial of endophyte-assisted phytoremediation on the Middlefield-Ellis-Whisman Superfund Study Area TCE plume in the Silicon Valley of California. The inoculated poplar trees exhibited increased growth and reduced TCE phytotoxic effects with a 32% increase in trunk diameter compared to mock-inoculated control poplar trees. The inoculated trees excreted 50% more chloride ion into the rhizosphere, indicative of increased TCE metabolism in planta. Data from tree core analysis of the tree tissues provided further supporting evidence of the enhanced rate of degradation of the chlorinated solvents in the inoculated trees. Test well groundwater analyses demonstrated a marked decrease in concentration of TCE and its derivatives from the tree-associated groundwater plume. The concentration of TCE decreased from 300 µg/L upstream of the planted area to less than 5 µg/L downstream of the planted area. TCE derivatives were similarly removed with cis-1,2-dichloroethene decreasing from 160 µg/L to less than 5 µg/L and trans-1,2-dichloroethene decreasing from 3.1 µg/L to less than 0.5 µg/L downstream of the planted trees. 1,1-dichloroethene and vinyl chloride both decreased from 6.8 and 0.77 µg/L, respectively, to below the reporting limit of 0.5 µg/L providing strong evidence of the ability of the endophytic inoculated trees to effectively remove TCE from affected groundwater. The combination of native pollutant-degrading endophytic bacteria and fast-growing poplar tree systems offers a readily deployable, cost-effective approach for the degradation of TCE, and may help mitigate potential transfer up the food chain, volatilization to the atmosphere, as well as direct phytotoxic impacts to plants used in this type of phytoremediation.
As a naturally abundant biopolymer, chitosan is considered to be a suitable adsorbent for stannate (SnO3(2-)) in tin plating wastewater. However, mass transfer of the adsorbent and its recycling remain challenging problems. Though flexible poly(vinyl chloride) (PVC) is highly flammable due to the addition of plasticizers, the traditional flame retardant, antimony trioxide (Sb2O3), is potentially harmful. In this study, chitosan was anchored onto the surface of PVC resin to adsorb SnO3(2-) from wastewater. Thereafter, tin-doped chitosan-coated PVC resin was readily recycled and processed into a flexible PVC composite (modified fPVC). The limiting oxygen index value of the modified fPVC increased to 33.1%, and the peak heat release rate decreased to 161kW/m(2). In addition to reducing fire hazards, this approach also decreased the content of harmful hydrogen chloride gas released during the combustion of modified fPVC. Meanwhile, the tensile properties of modified fPVC were enhanced compared with those of the Sb2O3-treated sample. These results indicated the synthesis of an eco-friendly Sb2O3-free flexible PVC composite that poses a low fire hazard.
A novel three-component reaction of pyridine N-oxides, acyl chlorides, and cyclic ethers is described. Treatment of an electron-deficient pyridine N-oxide with an acyl chloride in the presence of a cyclic ether at 25-50 °C leads to a substituted pyridine as a single regioisomer in up to 58% isolated yield. Isotopic-labeling experiments and substrate scope support the reaction proceeding through a carbene intermediate.
Chlorine (Cl2) and hydrogen chloride (HCl) are heavily utilized industrial chemicals that present significant respiratory health risks. The metal-organic framework UiO-66-NH2 has shown an unprecedented ability in powder form to remove chlorine gas. Here, we engineered UiO-66-NH2 into 20×40 mesh granules and evaluated their ability to remove chlorine and hydrogen chloride gas challenges. The exposed materials were characterized with nitrogen isotherms, powder X-ray diffraction, and attenuated total reflectance - Fourier transform infrared spectroscopy. Breakthrough results revealed that UiO-66-NH2 sorption of chlorine and hydrogen chloride met or exceeded sorption of state-of-the-art metal-impregnated activated carbon materials on a mass and volume basis in engineered form.