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Dechlorination

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https://www.readbyqxmd.com/read/28431360/contrasting-dual-c-cl-isotope-fractionation-offers-potential-to-distinguish-reductive-chloroethene-transformation-from-breakdown-by-permanganate
#1
Eylem Doğan-Subaşı, Martin Elsner, Shiran Qiu, Stefan Cretnik, Siavash Atashgahi, Orfan Shouakar-Stash, Nico Boon, Winnie Dejonghe, Leen Bastiaens
cis-1,2-Dichloroethene (cis-DCE) and trichloroethene (TCE) are persistent, toxic and mobile pollutants in groundwater systems. They are both conducive to reductive dehalogenation and to oxidation by permanganate. In this study, the potential of dual element (C, Cl) compound specific isotope analyses (CSIA) for distinguishing between chemical oxidation and anaerobic reductive dechlorination of cis-DCE and TCE was investigated. Well-controlled cis-DCE degradation batch tests gave similar carbon isotope enrichment factors εC (‰), but starkly contrasting dual element isotope slopes Δδ(13)C/Δδ(37)Cl for permanganate oxidation (εC=-26‰±6‰, Δδ(13)C/Δδ(37)Cl≈-125±47) compared to reductive dechlorination (εC=-18‰±4‰, Δδ(13)C/Δδ(37)Cl≈4...
April 18, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28431359/reconstruction-of-microbial-community-structures-as-evidences-for-soil-redox-coupled-reductive-dechlorination-of-pcp-in-a-mangrove-soil
#2
Yan Xu, Yan He, Xianjin Tang, Philip C Brookes, Jianming Xu
The aim was to investigate the influence of pentachlorophenol (PCP) on the soil microbial communities and the coupled mechanism between PCP reductive dechlorination and soil redox under anaerobic condition. Accordingly, a slurry incubation experiment was carried out in which bacterial and archaeal communities were detected by MiSeq amplicon sequencing. The original microbial community balance was gradually disrupted and new microbial structure was reconstructed subsequently through self-regulation and acclimation during PCP transformation, coupling with the changes of soil biogeochemical redox dynamics...
April 18, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28429272/electrocatalytic-dechlorination-of-2-3-5-trichlorophenol-on-palladium-carbon-nanotubes-nafion-film-titanium-mesh-electrode
#3
Zhirong Sun, Xiaoyue Ma, Xiang Hu
Palladium/carbon nanotubes-nafion film-modified titanium mesh electrode (Pd/CNTs-nafion film/Ti electrode) was prepared and used for catalytic dechlorination of 2,3,5-trichlorophenol (2,3,5-TCP). The influences of factors, such as Pd(2+) concentration, plating solution pH, and electrodeposition time and current, on the preparation of the electrode were studied by cyclic voltammetry (CV) to establish the optimal electrode preparation conditions. Additionally, the CV results highlighted that the addition of the CNTs-nafion film could enhance the electrochemical performance of the electrode...
April 21, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28427682/effects-and-mechanism-of-diclofenac-degradation-in-aqueous-solution-by-us-zn-0
#4
Ting Huang, Guangming Zhang, Shan Chong, Yucan Liu, Nan Zhang, Shunyan Fang, Jia Zhu
A system of ultrasound radiation coupled with Zn(0) was applied to degrade diclofenac. The effects of initial pH, dosage of Zn(0) and ultrasound density were investigated. To further explore the mechanism of the microcosmic reaction, the fresh and used Zn(0) powders were characterized by SEM, XRD and XPS. Radical scavengers were used to determine the oxidation performance of strong oxidizing free radicals on diclofenac, including hydroxyl radicals and superoxide radicals. The results showed that the optimum removal of diclofenac reached to over 85% at pH of 2...
July 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28424844/microbial-reductive-dehalogenation-of-trihalomethanes-by-a-dehalobacter-containing-co-culture
#5
Siyan Zhao, Matthew J Rogers, Jianzhong He
Trihalomethanes such as chloroform and bromoform, although well-known as a prominent class of disinfection by-products, are ubiquitously distributed in the environment due to widespread industrial usage in the past decades. Chloroform and bromoform are particularly concerning, of high concentrations detected and with long half-lives up to several hundred days in soils and groundwater. In this study, we report a Dehalobacter- and Desulfovibrio-containing co-culture that exhibits dehalogenation of chloroform (~0...
April 19, 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28421054/isolation-and-characterization-of-dehalobacter-sp-strain-tecb1-including-identification-of-tcba-a-novel-tetra-and-trichlorobenzene-reductive-dehalogenase
#6
Ricardo Alfán-Guzmán, Haluk Ertan, Mike Manefield, Matthew Lee
Dehalobacter sp. strain TeCB1 was isolated from groundwater near Sydney, Australia, that is polluted with a range of organochlorines. The isolated strain is able to grow by reductive dechlorination of 1,2,4,5-tetrachlorobenzene to 1,3- and 1,4-dichlorobenzene with 1,2,4-trichlorobenzene being the intermediate daughter product. Transient production of 1,2-dichlorobenzene was detected with subsequent conversion to monochlorobenzene. The dehalogenation capability of strain TeCB1 to respire 23 alternative organochlorines was examined and shown to be limited to the use of 1,2,4,5-tetrachlorobenzene and 1,2,4-trichlorobenzene...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28402894/reductive-dechlorination-of-carbon-tetrachloride-by-bioreduction-of-nontronite
#7
Sungjun Bae, Ji Bong Joo, Woojin Lee
Reductive dechlorination of carbon tetrachloride (CT) was investigated during bioreduction of iron-containing clay mineral (i.e., nontronite) by iron-reducing bacteria (Shewanella putrefaciens CN32 (CN32)). In the absence of CT, the production of Fe(II) significantly increased in nontronite suspension with CN32 in 124 d (11.1% of Fe(III) reduction), resulting in formation of new secondary Fe(II) mineral phase (i.e., vivianite (Fe(II)3(PO4)2·8H2O)). In the presence of CT, an acceleration of CT dechlorination was observed after 13 d and it reached almost 68% of removal efficiency at 32 d in nontronite suspension with CN32, which was 1...
April 1, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/28402665/kinetic-modeling-of-the-thermal-destruction-of-nitrogen-mustard-gas
#8
Juan-Carlos Lizardo-Huerta, Baptiste Sirjean, Laurent Verdier, René Fournet, Pierre-Alexandre Glaude
The destruction of stockpiles or unexploded ammunitions of nitrogen mustard (tris(2-chloroethyl)amine, HN-3) requires the development of safe processes. The thermal destruction of this kind of compound is one of the most efficient method of destruction. Because of the high-level of toxicity of this chemical, there is a considerable lack of knowledge on the chemical kinetics at high temperatures. In this study, a detailed chemical kinetic model for the pyrolysis of nitrogen mustard gas is developed based on a large number of thermokinetic parameters calculated with theoretical chemistry...
April 20, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28399481/chlorinated-phenol-treatment-and-in-situ-hydrogen-peroxide-production-in-a-sulfate-reducing-bacteria-enriched-bioelectrochemical-system
#9
Waheed Miran, Mohsin Nawaz, Jiseon Jang, Dae Sung Lee
Wastewaters are increasingly being considered as renewable resources for the sustainable production of electricity, fuels, and chemicals. In recent years, bioelectrochemical treatment has come to light as a prospective technology for the production of energy from wastewaters. In this study, a bioelectrochemical system (BES) enriched with sulfate-reducing bacteria (SRB) in the anodic chamber was proposed and evaluated for the biodegradation of recalcitrant chlorinated phenol, electricity generation (in the microbial fuel cell (MFC)), and production of hydrogen peroxide (H2O2) (in the microbial electrolysis cell (MEC)), which is a very strong oxidizing agent and often used for the degradation of complex organics...
April 5, 2017: Water Research
https://www.readbyqxmd.com/read/28399455/dioxins-degradation-and-reformation-during-mechanochemical-treatment
#10
Zhiliang Chen, Qiongjing Mao, Shengyong Lu, Alfons Buekens, Shuaixi Xu, Xu Wang, Jianhua Yan
Mechanochemical dechlorination and destruction of polychlorinated dibenzo-p-dioxins and -furans (PCDD/F) on fly ash from Municipal Solid Waste Incineration was tested with and without additives (CaO and CaO/aluminium powder). The first results disappointed because of obvious PCDD/F-reformation and a second test series was conducted after removing soluble salts (NaCl, KCl …) by thorough two-stage water washing. This second test series was successful and demonstrated good destruction results, especially with combined CaO/aluminium powder as additive...
April 4, 2017: Chemosphere
https://www.readbyqxmd.com/read/28397501/layer-by-layer-assembled-laccase-enzyme-on-stimuli-responsive-membranes-for-chloro-organics-degradation
#11
Rupam Sarma, Md Saiful Islam, Anne-Frances Miller, Dibakar Bhattacharyya
Functionalized membranes provide versatile platforms for the incorporation of biocatalysts and nanostructured materials for efficient and benign environmental remediation. The existing techniques for remediating chloro-organics in water consist of both physical and chemical means mostly using metal oxide-based catalysts, despite associated environmental concerns. To offer bioinspired remediation as an alternative, we herein demonstrate a layer-by-layer approach to immobilize laccase enzyme onto pH-responsive functionalized membranes for the degradation of chloro-organics in water...
April 21, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28394198/dechlorination-of-pvc-wastes-by-co-hydrothermal-treatment-with-alkaline-additives
#12
Peitao Zhao, Tian Li, Weijie Yan, Longji Yuan
Some chemicals were usually utilized in the hydrothermal dechlorination (HTD) of chlorine-containing wastes without revealing their roles. This work intends to investigate the role of chemical additives in the HTD of PVC (polyvinyl chloride). Several chemicals, including Na2CO3, KOH, NaOH, NH3·H2O, CaO and NaHCO3, were added into the PVC HTD process, which was conducted in subcritical Ni(2+)-containing water at 220 °C for 30 min. The results show the alkalinity of additives had notable effects on the dechlorination efficiency (DE) of PVC due to the neutralization between HCl and additives...
April 10, 2017: Environmental Technology
https://www.readbyqxmd.com/read/28378313/microbial-degradation-of-chloroethenes-a-review
#13
Iva Dolinová, Martina Štrojsová, Miroslav Černík, Jan Němeček, Jiřina Macháčková, Alena Ševců
Contamination by chloroethenes has a severe negative effect on both the environment and human health. This has prompted intensive remediation activity in recent years, along with research into the efficacy of natural microbial communities for degrading toxic chloroethenes into less harmful compounds. Microbial degradation of chloroethenes can take place either through anaerobic organohalide respiration, where chloroethenes serve as electron acceptors; anaerobic and aerobic metabolic degradation, where chloroethenes are used as electron donors; or anaerobic and aerobic co-metabolic degradation, with chloroethene degradation occurring as a by-product during microbial metabolism of other growth substrates, without energy or carbon benefit...
April 5, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28373866/the-nife-hydrogenases-of-the-tetrachloroethene-respiring-epsilonproteobacterium-sulfurospirillum-multivorans-biochemical-studies-and-transcription-analysis
#14
Stefan Kruse, Tobias Goris, Maria Wolf, Xi Wei, Gabriele Diekert
The organohalide-respiring Epsilonproteobacterium Sulfurospirillum multivorans is able to grow with hydrogen as electron donor and with tetrachloroethene (PCE) as electron acceptor; PCE is reductively dechlorinated to cis-1,2-dichloroethene. Recently, a genomic survey revealed the presence of four gene clusters encoding NiFe hydrogenases in its genome, one of which is presumably periplasmic and membrane-bound (MBH), whereas the remaining three are cytoplasmic. To explore the role and regulation of the four hydrogenases, quantitative real-time PCR and biochemical studies were performed with S...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28370367/assessing-the-toxicity-of-the-inert-safener-benoxacor-toward-chironomus-riparius-effects-of-agrochemical-mixtures
#15
Kasey Bolyard, Susan E Gresens, Allison N Ricko, John D Sivey, Christopher J Salice
The environmental effects of safeners, agrochemicals that protect crops from herbicide toxicity, are largely unknown, perhaps because they are classified as inert ingredients. We assessed the toxicity of 1) the dichloroacetamide safener benoxacor, 2) its degradation product, monochloro-benoxacor, 3) the herbicide with which benoxacor is paired, S-metolachlor and 4) a mixture of S-metolachlor + benoxacor, to larvae of Chironomus riparius. Under iron-reducing conditions, benoxacor can undergo reductive dechlorination producing monochloro-benoxacor...
March 30, 2017: Environmental Toxicology and Chemistry
https://www.readbyqxmd.com/read/28358500/molecular-mechanism-of-dioxin-formation-from-chlorophenol-based-on-electron-paramagnetic-resonance-spectroscopy
#16
Li Li Yang, Guorui Liu, Minghui Zheng, Yuyang Zhao, Rong Jin, Xiaolin Wu, Yang Xu
Few studies have investigated the free radical intermediates involved in the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from chlorophenol. This study clarified the reaction pathways during thermochemical formation of PCDDs from 2,3,6-trichlorophenol (TCP) over a Cu(II)O/silica matrix, which was used to simulate fly ash, at 298-523 K. The reaction was studied using electron paramagnetic resonance (EPR) spectroscopy and theoretical calculations. In situ EPR indicated the TCP radical (TCPR) formed by hydrogen abstraction of TCP...
March 30, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28357551/changes-in-the-microbial-community-during-repeated-anaerobic-microbial-dechlorination-of-pentachlorophenol
#17
Hui Tong, Manjia Chen, Fangbai Li, Chengshuai Liu, Changzhong Liao
Pentachlorophenol (PCP) has been widely used as a pesticide in paddy fields and has imposed negative ecological effect on agricultural soil systems, which are in typically anaerobic conditions. In this study, we investigated the effect of repeated additions of PCP to paddy soil on the microbial communities under anoxic conditions. Acetate was added as the carbon source to induce and accelerate cycles of the PCP degradation. A maximum degradation rate occurred at the 11th cycle, which completely transformed 32...
March 29, 2017: Biodegradation
https://www.readbyqxmd.com/read/28350169/simple-direct-routes-to-polymer-brush-traps-and-nanostructures-for-studies-of-diffusional-transport-in-supported-lipid-bilayers
#18
Alexander Johnson, Peng Bao, Claire R Hurley, Michaël Cartron, Stephen D Evans, C Neil Hunter, Graham J Leggett
Patterned poly(oligo ethylene glycol) methyl ether methacrylate (POEGMEMA) brush structures may be formed by using a combination of atom-transfer radical polymerization (ATRP) and UV photopatterning. UV photolysis is used to selectively dechlorinate films of 4-(chloromethyl)phenyltrichlorosilane (CMPTS) adsorbed on silica surfaces, by exposure either through a mask or using a two-beam interferometer. Exposure through a mask yields patterns of carboxylic acid-terminated adsorbates. POEGMEMA may be grown from intact Cl initiators that were masked during exposure...
April 5, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28342422/synergistic-desalination-of-potash-brine-impacted-groundwater-using-a-dual-adsorbent
#19
Nick P Gibb, James J Dynes, Wonjae Chang
The impact of saline mining effluent has been a significant environmental concern. Natural and modified clay-mineral adsorbents have been receiving increasing attention for salinity reduction of brine-impacted water, especially for natural resource extraction sites and surrounding environments. In this study, a dual-adsorbent treatment based on the sequential application of calcined layered double hydroxide (CLDH) and acid-treated zeolite was developed, evaluated and characterized for the desalination of potash brine-impacted groundwater...
March 22, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28342352/mechanochemical-mechanism-of-rapid-dechlorination-of-hexachlorobenzene
#20
Shanshan Deng, Shaoguo Kang, Nannan Feng, Jianxin Zhu, Bo Yu, Xiaofeng Xie, Jing Chen
Recent researches indicate that mechanochemical treatment (MCT) is a promising method to degrade the environmental hazards, especially in the area of persistent organic pollutants (POPs) disposal. However, the mechanochemical dechlorination mechanism of POPs still needs to be further verified. In this mechanochemical process, hexachlorobenzene (HCB) was chosen as a model pollutant with aluminum and alumina (Al+Al2O3) powders as the co-milling regents. Both of the intermediate analysis and quantum chemical calculations were adopted to elucidate the free radical dechlorination mechanism of HCB...
March 12, 2017: Journal of Hazardous Materials
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