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Concept: Hydrogen chloride


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.

Concepts: Concentration, Chemistry, Water pollution, Sodium chloride, Ion, Chlorine, Chloride, Hydrogen chloride


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.

Concepts: Crystal, Hydrogen, Ice, Phase, Chlorine, Triple point, Hydrogen chloride, Hydrochloric acid


Despite the structural, load-bearing role of cellulose in the plant kingdom, countless efforts have been devoted to degrading this recalcitrant polysaccharide, particularly in the context of biofuels and renewable nanomaterials. Herein, we show how the exposure of plant-based fibers to HCl vapor results in rapid degradation with simultaneous crystallization. Because of the unchanged sample texture and the lack of mass transfer out of the substrate in the gas/solid system, the changes in the crystallinity could be reliably monitored. Furthermore, we describe the preparation of cellulose nanocrystals in high yields and with minimal water consumption. The study serves as a starting point for the solid-state tuning of the supramolecular properties of morphologically heterogeneous biological materials.

Concepts: Water, Hydrogen, Starch, Cell wall, Chlorine, Chloride, Hydrogen chloride, Hydrochloric acid


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.

Concepts: Chernobyl disaster, Digestive system, Chlorine, Nuclear power, Hydrogen chloride, Hydrochloric acid, Fukushima Prefecture, Tōhoku region


Fourier transform microwave rotational spectroscopy is used to determine the structure of the gas-phase bimolecular complex formed between (E)-1-chloro-2-fluoroethylene and hydrogen chloride. Extensively split by nuclear quadrupole hyperfine structure and isotopic dilution, the spectrum is first identified via weak features observed using a broadband chirped pulse spectrometer in the 5.6-18.1 GHz range and studied in detail with greater sensitivity and resolution over 6.0-20.0 GHz with a Balle-Flygare, narrowband instrument. The complex has a geometry similar to that of vinyl fluoride-HCl, with HCl binding across the C═C double bond, forming a hydrogen bond to the fluorine atom of the haloethylene and bending to allow a secondary interaction to develop with the hydrogen atom in the cis position. Further consideration of structural details among the complexes of hydrogen fluoride and hydrogen chloride with (E)-1-chloro-2-fluoroethylene and vinyl fluoride suggests that the addition of a trans Cl atom in vinyl fluoride enhances the significance of the secondary interaction while deemphasizing that of the hydrogen bond.

Concepts: Oxygen, Fundamental physics concepts, Hydrogen, Atom, Chlorine, Fluorine, Hydrogen chloride, Hydrochloric acid


The efficiency of white lupine (Lupinus albus) to uptake and accumulate mercury from a soil polluted by mining activities was assessed in a pot experiment with chemically assisted phytoextraction. The mobilizing agents tested were ethylenediaminetetracetic acid (EDTA) and hydrochloric acid (HCl). Two doses of each amendment were used (0.5 and 1.0 g of amendment per kg of soil), and unamended pots were used as a control. Addition of HCl to the soil did not negatively affect plant biomass, while the use of EDTA led to a significant decrease in plant growth when compared to that found for non-treated pots, with plants visually showing symptoms of toxicity. The addition of hydrochloric acid increased root, shoot and total plant Hg uptake of white lupine by 3.7 times, 3.1 times and 3.5 times, respectively, in relation to non-amended plants. The greatest efficiency was obtained for the highest HCl dose. EDTA led to higher concentrations of total plant Hg than that found with the control, but, due to the aforementioned decrease in plant biomass, the Hg phytoextraction yield was not significantly increased. These results were attributed to the capability of both amendments to form stable Hg complexes. The concentration of Hg in the water of the soil pores after the phytoextraction experiment was very low for all treatments, showing that risks derived from metal leaching could be partially avoided by using doses and chemicals suitable to the concentration of metal in the soil and plant performance.

Concepts: Hydrogen, Chemistry, Soil, Chlorine, Lupin, Hydrogen chloride, Hydrochloric acid, Leblanc process


A new, simple, and fast method has been developed for the determination of multi-class antibiotic residues in honey (sulfonamides, tetracyclines, macrolides, lincosamides, and aminoglycosides). The separation and the determination are carried out by liquid chromatography coupled to mass spectrometry (LC-MS/MS). In the sample preparation, various parameters affecting the extraction efficiency were examined including the type of solvent, the pH, the efficiencies of cleavage of N-glycosidic linkages by hydrochloric acid, ultrasonic extraction and its duration compared to shaking, along with dispersive SPE clean-up. Experiments with fortified samples demonstrated that 10 min ultrasonic treatment with acidified methanol (HCl 2M) followed by dispersive SPE clean-up with 50 mg PSA gave an effective sample preparation method for several classes of antibiotics in honey. Anhydroerythromycin A, erythromycin A enol ether, and desmycosin were used as markers for the presence of erythromycin A and tylosin A in honey samples. The method was validated according to European Commission Decision (EC) No 2002/657. The recoveries of analytes ranged from 85 to 111%. Repeatability and intra-laboratory reproducibility were less than 20.6% and 26.8%, respectively. Decision limit (CCα) and detection capability (CCβ) ranged from 6 to 9 µg kg(-1) and from 7 to 13 µg kg(-1), respectively, except for streptomycin and neomycin which showed slightly higher CCα at 25 µg kg(-1) and CCβ at 34 µg kg(-1). Finally, the method was applied to the honey test material 02270 through a FAPAS proficiency test (PT) for the determination of tetracyclines. PT results were obtained within a Z-score range of ±2, proving that the validated method is suitable to be used in routine analysis to ensure the quality of honey.

Concepts: Hydrogen, PH, Antibiotic, Chlorine, Erythromycin, Hydrogen chloride, Macrolide, Hydrochloric acid


In this research morphological techniques were used to characterize dechlorination process of PVC when it is in the mixed waste plastics and the two important factors influencing this process, namely, the proportion of PVC in the mixed plastics and heating rate adopted in the pyrolysis process were investigated. During the pyrolysis process for the mixed plastics containing PVC, the morphologic characteristics describing PVC dechlorination behaviors were obtained with help of a high-speed infrared camera and image processing tools. At the same time emission of hydrogen chloride (HCl) was detected to find out the start and termination of HCl release. The PVC contents in the mixed plastics varied from 0% to 12% in mass and the heating rate for PVC was changed from 10 to 60°C/min. The morphologic parameters including “bubble ratio” (BR) and “pixel area” (PA) were found to have obvious features matching with PVC dechlorination process therefore can be used to characterize dechlorination of PVC alone and in the mixed plastics. It has been also found that shape of HCl emission curve is independent of PVC proportions in the mixed plastics, but shifts to right side with elevated heating rate; and all of which can be quantitatively reflected in morphologic parameters vs. temperature curves.

Concepts: Hydrogen, Plastic, Chlorine, Hydrogen chloride, Polyvinyl chloride, Hydrochloric acid, Vinyl chloride, Plastic recycling


Three organotin complexes containing furosemide as a ligand (L), Ph₃SnL, Me₂SnL₂ and Bu₂SnL₂, were synthesized and characterized. Octahedral geometry was proposed for the Me₂SnL₂ and Bu₂SnL₂, while the Ph₃SnL complex has trigonal bipyramid geometry. The synthesized organotin complexes (0.5% by weight) were used as additives to improve the photostability of poly(vinyl chloride), PVC, (40 μm thickness) upon irradiation. The changes imposed on functional groups, weight loss and viscosity average molecular weight of PVC films were monitored. The experimental results show that the rate of photodegradation was reduced in the presence of the organotin additives. The quantum yield of the chain scission was found to be low (9.8 × 10(-7)) when Ph₃SnL was used as a PVC photostabilizer compared to controlled PVC (5.18 × 10(-6)). In addition, the atomic force microscope images for the PVC films containing Ph₃SnL₂ after irradiation shows a smooth surface compared to the controlled films. The rate of PVC photostabilization was found to be highest for Ph₃SnL followed by Bu₂SnL₂ and Me₂SnL₂. It has been suggested that the organotin complexes could act as hydrogen chloride scavengers, ultraviolet absorbers, peroxide decomposers and/or radical scavengers.

Concepts: Chemical reaction, Functional group, Hydrogen, Molecule, Radical, Octahedron, Hydrogen chloride, Bipyramid


This set of experiments examined the question of when a stimulus would be most effective in overshadowing the acquisition of long-delay taste aversion learning. In Experiment 1 rats drank sucrose, the target solution, followed by a hydrochloric acid (HCl) solution before lithium injection some time later; HCl was presented either early or late in the interval. The late condition produced greater overshadowing than the early condition. The importance of the HCl-injection interval was confirmed by Experiment 2, in which the sucrose-injection interval was varied. Experiment 3 found that even placement in a different context - an event that normally produces little overshadowing of a CTA - produced one-trial overshadowing of a sucrose aversion as long as the context was novel and exposure to it occurred immediately before lithium injection. No current theoretical account of one-trial overshadowing predicts that a late event produces more overshadowing than an early event. This result can, however, be accommodated within a modified version of the Rescorla-Wagner model.

Concepts: Hydrogen, Experiment, Theory, Chlorine, Hydrogen chloride, Hydrochloric acid, Leblanc process, Vinyl chloride