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Dechlorination

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https://www.readbyqxmd.com/read/29228161/reductive-tetrachloroethene-dehalogenation-in-the-presence-of-oxygen-by-sulfurospirillum-multivorans-physiological-studies-and-proteome-analysis
#1
Jennifer Gadkari, Tobias Goris, Christian L Schiffmann, Raffael Rubick, Lorenz Adrian, Torsten Schubert, Gabriele Diekert
Reductive dehalogenation of organohalides is carried out by organohalide-respiring bacteria (OHRB) in anoxic environments. The tetrachloroethene (PCE)-respiring Epsilonproteobacterium Sulfurospirillum multivorans is one of few OHRB able to respire oxygen. Therefore, we investigated the organism's capacity to dehalogenate PCE in the presence of oxygen, which would broaden the applicability to use S. multivorans, unlike other commonly oxygen-sensitive OHRB, for bioremediation, e.g. at oxic/anoxic interphases...
December 5, 2017: FEMS Microbiology Ecology
https://www.readbyqxmd.com/read/29223901/thermally-enhanced-in-situ-bioremediation-of-groundwater-contaminated-with-chlorinated-solvents-a-field-test
#2
Jan Němeček, Jana Steinová, Roman Špánek, Tomáš Pluhař, Petr Pokorný, Petra Najmanová, Vladislav Knytl, Miroslav Černík
In situ bioremediation (ISB) using reductive dechlorination is a widely accepted but relatively slow approach compared to other technologies for the treatment of groundwater contaminated by chlorinated ethenes (CVOCs). Due to the known positive kinetic effect on microbial metabolism, thermal enhancement may be a viable means of accelerating ISB. We tested thermally enhanced ISB in aquifers situated in sandy saprolite and underlying fractured granite. The system comprised pumping, heating and subsequent injection of contaminated groundwater aiming at an aquifer temperature of 20-30°C...
December 7, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/29220813/biotransformation-and-inhibition-effects-of-hexachlorocyclohexanes-during-biogas-production-from-contaminated-biomass-characterized-by-isotope-fractionation-concepts
#3
Shujuan Lian, Marcell Nikolausz, Ivonne Nijenhuis, Athaydes Francisco Leite, Hans Hermann Richnow
Hexachlorocyclohexane (HCH) production for pesticides was banned by Stockholm Convention (2009) due to its harmful and adverse effects on the environment. Despite this measure, many areas contaminated with former HCH production-waste products still require management. As a potential solution contributing to clean-up of these sites, anaerobic digestion (AD) of pesticide-contaminated biomass to produce biogas is a promising strategy. High pesticide concentrations, however, may inhibit biogas production. Therefore, laboratory-scale batch reactors were set up to investigate biogas reactor performance in presence of HCH...
November 24, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/29216549/kinetic-research-on-dechlorinating-dichlorobenzene-in-aqueous-system-by-nano-scale-nickel-iron-loaded-with-cmc-nfc-hydrogel
#4
Xiao-Fang Wan, Congbao Guo, Yu Liu, Xin-Sheng Chai, Youming Li, Guangxue Chen
In this study, we reported on the nano-scale nickel/iron particles loaded in carboxymethyl/nanofibrillated cellulose (CMC/NFC) hydrogel for the dechlorination of o-dichlorobenzene (DCB) in aqueous solution. The biodegradable hydrogel may provide an ideal supporting material for fastening the bimetallic nano-scale particles, which was examined and characterized by TEM, SEM-EDX, FT-IR and BET. The performance of the selected bimetallic particles was evaluated by conducting the dechlorination of DCB in the solution under different reaction conditions (e...
November 23, 2017: Chemosphere
https://www.readbyqxmd.com/read/29205956/generating-hydrated-electrons-for-chemical-syntheses-with-a-green-led
#5
Robert Naumann, Florian Lehmann, Martin Goez
We present the first working system for accessing and utilizing laboratory-scale concentrations of hydrated electrons by photoredox catalysis with a green light-emitting diode (LED). Decisive are micellar compartmentalization and photon pooling in an intermediate that decays with second-order kinetics. The only consumable is the nontoxic and bioavailable vitamin C. A turnover number of 1380 shows the LED method to be on par with electron generation by high-power pulsed lasers, but at a fraction of the cost...
December 5, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/29195092/dechlorinating-performance-of-dehalococcoides-spp-mixed-culture-enhanced-by-tourmaline
#6
Wei Wang, Xingyu Liu, Kerui Li, Tielong Li
Dehalococcoides spp. were extensively studied and applied to in-situ trichloroethylene (TCE) remediation since it is the only genus that can reduce TCE to harmless ethene completely. However, this technology was hindered because of the requirement of electron donor (i.e. hydrogen or fermentable organic substrate). Considering the spontaneous electric field and in-situ hydrogen production capacity of tourmaline, this mineral was used as an environmental-friendly bio-promoter for dechlorinating mixed culture containing Dehalococcoides spp...
November 20, 2017: Chemosphere
https://www.readbyqxmd.com/read/29191611/activation-of-peroxymonosulfate-using-drinking-water-treatment-residuals-for-the-degradation-of-atrazine
#7
Huijuan Zhang, Xitao Liu, Jun Ma, Chunye Lin, Chengdu Qi, Xiaowan Li, Zhou Zhou, Guoxuan Fan
Drinking water treatment residuals (WTRs) are safe byproducts of water treatment plants containing iron. This work studies the degradation of atrazine (ATZ) by WTR-catalyzed peroxymonosulfate (PMS) in aqueous solutions. Factors that affect the catalytic performance (the PMS concentration, catalyst dose, initial solution pH, reaction temperature and water matrix species) were investigated. The results show that the catalytic degradation efficiency of ATZ increases with the increase in PMS concentration and temperature, whereas a higher content of WTRs results in lower removal efficiency because of the quenching effect and negative effect of high pH...
November 22, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/29178800/natural-attenuation-and-anaerobic-benzene-detoxification-processes-at-a-chlorobenzene-contaminated-industrial-site-inferred-from-field-investigations-and-microcosm-studies
#8
Wenjing Qiao, Fei Luo, Line Lomheim, Elizabeth Erin Mack, Shujun Ye, Jichun Wu, Elizabeth A Edwards
A five-year site investigation was conducted at a former chemical plant in Nanjing, China. The main contaminants were 1,2,4-trichlorobenzene (TCB) reaching concentrations up to 7300 µg/L, dichlorobenzene (DCB) isomers, monochlorobenzene (MCB) and benzene. Over time, these contaminants naturally attenuated to below regulatory levels under anaerobic conditions. To confirm the transformation processes and to explore the mechanisms, a corresponding laboratory microcosm study was completed demonstrating that 1,2,4-TCB was dechlorinated to 1,2-DCB, 1,3-DCB and 1,4-DCB in approximately 2%/10%/88% molar proportions...
November 27, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/29175687/biouptake-toxicity-and-biotransformation-of-triclosan-in-diatom-cymbella-sp-and-the-influence-of-humic-acid
#9
Tengda Ding, Kunde Lin, Lianjun Bao, Mengting Yang, Juying Li, Bo Yang, Jay Gan
Triclosan is one of the most frequently detected emerging contaminants in aquatic environment. In this study, we investigated the biouptake, toxicity and biotransformation of triclosan in freshwater algae Cymbella sp. The influence of humic acid, as a representative of dissolved organic matter, was also explored. Results from this study showed that triclosan was toxic to Cymbella sp. with 72 h EC50 of 324.9 μg L-1. Humic acid significantly reduced the toxicity and accumulation of triclosan in Cymbella sp...
November 23, 2017: Environmental Pollution
https://www.readbyqxmd.com/read/29175406/evaluation-of-carbon-isotope-fractionation-during-anaerobic-reductive-dehalogenation-of-chlorinated-and-brominated-benzenes
#10
Seo Yean Sohn, Kevin Kuntze, Ivonne Nijenhuis, Max M Häggblom
Compound specific stable isotope analysis (CSIA) has been established as a useful tool to evaluate in situ biodegradation. Here, CSIA was used to determine microbial dehalogenation of chloro- and bromobenzenes in microcosms derived from Hackensack River sediments. Gas chromatography-isotope ratio mass spectrometry (GC-IRMS) was used to measure carbon isotope fractionation during reductive dehalogenation of hexachlorobenzene (HCB), pentachlorobenzene (PeCB), 1,2,3,5-tetrachlorobenzene (TeCB), 1,2,3,5-tetrabromobenzene (TeBB), and 1,3,5-tribromobenzene (TriBB)...
November 20, 2017: Chemosphere
https://www.readbyqxmd.com/read/29172040/effect-of-long-term-fertilization-on-humic-redox-mediators-in-multiple-microbial-redox-reactions
#11
Peng Guo, Chunfang Zhang, Yi Wang, Xinwei Yu, Zhichao Zhang, Dongdong Zhang
This study investigated the effects of different long-term fertilizations on humic substances (HSs), humic acids (HAs) and humins, functioning as redox mediators for various microbial redox biotransformations, including 2,2',4,4',5,5'- hexachlorobiphenyl (PCB153) dechlorination, dissimilatory iron reduction, and nitrate reduction, and their electron-mediating natures. The redox activity of HSs for various microbial redox metabolisms was substantially enhanced by long-term application of organic fertilizer (pig manure)...
November 21, 2017: Environmental Pollution
https://www.readbyqxmd.com/read/29169109/mechanism-and-efficiency-of-contaminant-reduction-by-hydrated-electron-in-the-sulfite-iodide-uv-process
#12
Keer Yu, Xuchun Li, Liwei Chen, Jingyun Fang, Huali Chen, Qiangbiao Li, Nianping Chi, Jun Ma
Advanced reduction by the extremely strong reducing species, hydrated electron (eaq(-)), is a promising and viable approach to eliminate a wide variety of persistent and toxic contaminants. In this study, we proposed a sulfite/iodide/UV process, which offered efficient production of eaq(-) for contaminant reduction. Using monochloroacetic acid (MCAA) as a simple eaq(-) probe, the availability of eaq(-) was assessed, and the mechanism involving the roles of S(IV) and iodide in the process was elucidated. A pronounced synergistic effect of S(IV) and iodide was observed in MCAA reductive dechlorination...
November 15, 2017: Water Research
https://www.readbyqxmd.com/read/29163905/laboratory-scale-photoredox-catalysis-using-hydrated-electrons-sustainably-generated-with-a-single-green-laser
#13
Robert Naumann, Christoph Kerzig, Martin Goez
The ruthenium-tris-bipyridyl dication as catalyst combined with the ascorbate dianion as bioavailable sacrificial donor provides the first regenerative source of hydrated electrons for chemical syntheses on millimolar scales. This electron generator is operated simply by illumination with a frequency-doubled Nd:YAG laser (532 nm) running at its normal repetition rate. Much more detailed information than by product studies alone was obtained by photokinetical characterization from submicroseconds (time-resolved laser flash photolysis) up to one hour (preparative photolysis)...
November 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/29154092/anoxic-biodegradation-of-triclosan-and-the-removal-of-its-antimicrobial-effect-in-microbial-fuel-cells
#14
Lu Wang, Yulei Liu, Chao Wang, Xiaodan Zhao, Gurumurthy Dummi Mahadeva, Yicheng Wu, Jun Ma, Feng Zhao
Triclosan (TCS) is an emerging organic contaminant in the environment. Here, the anoxic bio-degradation of TCS in microbial fuel cells (MFCs) was explored. It was found that anoxic biodegradation of TCS could be achieved in MFC, and the removal rate of TCS was accelerated after reactor acclimation. After 7 months of operation, 10mg/L TCS could be removed within 8days in MFCs. Fluorescence microscopy results revealed that the microbe cells in the reactors were intact, and the microbes were in active state. Flow cytometry test showed that the proliferation of inoculated microbe was higher in MFC effluent than that in TCS solution...
October 13, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/29130464/boronic-acid-recognition-of-non-interacting-carbohydrates-for-biomedical-applications-increasing-fluorescence-signals-of-minimally-interacting-aldoses-and-sucralose
#15
Angel Resendez, Md Abdul Halim, Jasmeet Singh, Dominic-Luc Webb, Bakthan Singaram
To address carbohydrates that are commonly used in biomedical applications with low binding affinities for boronic acid based detection systems, two chemical modification methods were utilized to increase sensitivity. Modified carbohydrates were analyzed using a two component fluorescent probe based on boronic acid-appended viologen-HPTS (4,4'-o-BBV). Carbohydrates normally giving poor signals (fucose, l-rhamnose, xylose) were subjected to sodium borohydride (NaBH4) reduction in ambient conditions for 1 h yielding the corresponding sugar alcohols from fucose, l-rhamnose and xylose in essentially quantitative yields...
November 22, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/29128723/copper-mediated-reductive-dechlorination-by-green-rust-intercalated-with-dodecanoate
#16
Li-Zhi Huang, Zhou Yin, Nicola G A Cooper, Weizhao Yin, Emil Tveden Bjerglund, Bjarne W Strobel, Hans Christian B Hansen
A layered Fe(II)-Fe(III) hydroxide (green rust, GR) was intercalated with dodecanoate (known as GRC12) and then amended with Cu(II) (GRC12(Cu)) before reaction with chloroform (CF), carbon tetrachloride (CT), trichloroethylene (TCE) or tetrachloroethylene (PCE). Reduction of CT by GRC12(Cu) was 37 times faster than with GRC12 alone before the active Cu species was consumed. The Cu mediated reaction followed the dichloroelimination pathway as observed for GRC12 alone, with carbon monoxide (82.5%) and formate (26...
November 6, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/29127932/the-effects-of-different-types-of-crop-straw-on-the-transformation-of-pentachlorophenol-in-flooded-paddy-soil
#17
Jiajiang Lin, Jun Meng, Yan He, Jianming Xu, Zuliang Chen, Philip C Brookes
The incorporation of various types of crop straw to agricultural soils has long been practiced to improve soil fertility. However, the effects of crop straw on the fate of organo-chlorine pesticides in flooded paddy soils are not well understood. The dechlorination of pentachlorophenol (PCP) in four vertical profiles (0-10, 10-20, 20-30, 30-50 mm depth) of two flooded paddy soils, a Plinthudult (Soil 1) and a Tropudult (Soil 2) was investigated following the application of four crop straws (rice, wheat, rape and Chinese milk vetch) to them...
November 8, 2017: Environmental Pollution
https://www.readbyqxmd.com/read/29127825/surfactant-structural-effects-on-mediated-electrocatalytic-dechlorination-links-between-the-micellar-enhancement-of-dechlorination-reactions-and-micellar-properties
#18
K Chandrasekara Pillai, G Muthuraman, Il-Shik Moon
Electrocatalytic dechlorination mediated by micelle-solubilized electrocatalysts has attracted considerable current interest for pollutant degradation. Aggregation in micellar assemblies and their interactions with the additives in solution are affected by the surfactant structure. By choosing appropriate surfactant molecules, the system properties may be altered to achieve enhanced dechlorination efficiency. Cetyltrimethylammonium bromide-based surfactants with different hydrocarbon lengths and headgroup structures were studied for their structural effects on [Co(I)(bipyridine)3](+)-mediated dechlorination reactions...
October 31, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/29125288/uptake-translocation-and-biotransformation-of-organophosphorus-esters-in-wheat-triticum-aestivum-l
#19
Weining Wan, Honglin Huang, Jitao Lv, Ruixia Han, Shuzhen Zhang
The uptake, translocation and biotransformation of organophosphate esters (OPEs) by wheat (Triticum aestivum L.) were investigated by a hydroponic experiment. The results demonstrated that OPEs with higher hydrophobicity were more easily taken up by roots, and OPEs with lower hydrophobicity were more liable to be translocated acropetally. A total of 43 metabolites including dealkylated, oxidatively dechlorinated, hydroxylated, methoxylated, and glutathione- and glucuronide- conjugated products were detected derived from eight OPEs, with di-esters formed by direct dealkylation from the parent tri-esters as the major products, followed with hydroxylated tri-esters...
November 10, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/29119491/the-mechanism-of-2-chlorobiphenyl-oxidative-degradation-by-nanoscale-zero-valent-iron-in-the-presence-of-dissolved-oxygen
#20
Yu Wang, Linhao Liu, Guodong Fang, Lei Wang, Fredrick Orori Kengara, Changyin Zhu
It has recently been demonstrated that the addition of nanoscale zero-valent iron (nZVI) to oxygen-containing water or soil aquifers results in the oxidation of organic compounds. However, there has been little insight about the generation of the reactive oxygen species (ROS) that play a vital role in the transformation of contaminants in the presence of nZVI. This study investigated (i) the degradation of 2-chlorobiphenyl (2-CB) by nZVI; (ii) the generation and role of ROS in this process. Under anaerobic and aerobic conditions, the removal efficiency of 2-CB was 65...
November 8, 2017: Environmental Science and Pollution Research International
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