Assessment of the impact of the emission of certain organochlorine compounds on the aquatic environment

Krijgsheld, Klaas R.; Gen, A. Van Der

doi:10.1016/0045-6535(86)90052-4

Cited by 24 publications

(29 citation statements)

References 53 publications

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“…Halogenated organic compounds are often detected in the environment, either at low concentration because of natural production or at higher levels because of environmental pollution (1,2). Many synthetic halogenated compounds are more persistent in the environment than their nonhalogenated analogues, indicating that halogenation causes recalcitrance.…”

mentioning

confidence: 99%

Kinetic Mechanism and Enantioselectivity of Halohydrin Dehalogenase from Agrobacterium radiobacter

et al. 2003

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Halohydrin dehalogenase (HheC) from Agrobacterium radiobacter AD1 catalyzes the reversible intramolecular nucleophilic displacement of a halogen by a hydroxyl group in vicinal haloalcohols, producing the corresponding epoxides. The enzyme displays high enantioselectivity toward some aromatic halohydrins. To understand the kinetic mechanism and enantioselectivity of the enzyme, steady-state and pre-steady-state kinetic analysis was performed with p-nitro-2-bromo-1-phenylethanol (PNSHH) as a model substrate. Steady-state kinetic analyses indicated that the k cat of the enzyme with the (R)-enantiomer (22 s-1) is 3-fold higher than with the (S)-enantiomer and that the K m for the (R)-enantiomer (0.009 mM) is about 45-fold lower than that for the (S)-enantiomer, resulting in a high enantiopreference for the (R)-enantiomer. Product inhibition studies revealed that HheC follows an ordered Uni Bi mechanism for both enantiomers, with halide as the first product to be released. To identify the rate-limiting step in the catalytic cycle, pre-steady-state experiments were performed using stopped-flow and rapid-quench methods. The results revealed the existence of a pre-steady-state burst phase during conversion of (R)-PNSHH, whereas no such burst was observed with the (S)-enantiomer. This indicates that a product release step is rate-limiting for the (R)-enantiomer but not for the (S)-enantiomer. This was further examined by doing single-turnover experiments, which revealed that during conversion of the (R)-enantiomer the rate of bromide release is 21 s-1. Furthermore, multiple turnover analyses showed that the binding of (R)-PNSHH is a rapid equilibrium step and that the rate of formation of product ternary complex is 380 s-1. Taken together, these findings enabled the formulation of an ordered Uni Bi kinetic mechanism for the conversion of (R)-PNSHH by HheC in which all of the rate constants are obtained. The high enantiopreference for the (R)-enantiomer can be explained by weak substrate binding of the (S)-enantiomer and a lower rate of reaction at the active site.

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confidence: 99%

Kinetic Mechanism and Enantioselectivity of Halohydrin Dehalogenase from Agrobacterium radiobacter

et al. 2003

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“…The effect of pH was studied at pH 6, 7, 9 and 10. These pH values bracketed both the pKa of DCP (7.9) and the point of zero charge (pzc) of ZnO (9) (Krijgsheld and van der Gen, 1986;Kosmulski, 2006). The degradation of DCP was hampered at pH 6.…”

Section: Ph Effectsmentioning

confidence: 99%

“…As feedstock in the production of 2,4-dichlorophenoxyacetic acid, DCP may be released to the environment through uncontrolled use or improper waste management (CDC, 2000). In aquatic environment DCP would derive from biotic and abiotic degradation of higher chlorophenols and various phenoxyherbicides (Krijgsheld, 1986 and van der Gen;Brillas et al, 2000). Since chlorophenols have greater sorption potential than desorption (Krijgsheld and van der Gen, 1986) they would persist in the aquatic environment for longer periods of time.…”

Section: Introductionmentioning

confidence: 99%

“…In aquatic environment DCP would derive from biotic and abiotic degradation of higher chlorophenols and various phenoxyherbicides (Krijgsheld, 1986 and van der Gen;Brillas et al, 2000). Since chlorophenols have greater sorption potential than desorption (Krijgsheld and van der Gen, 1986) they would persist in the aquatic environment for longer periods of time. Unfortunately, the widespread occurrence of DCP in open waters has been reported in several countries (Abdullah and Nainggolan, 1991;Gao et al, 2008;Chiron et al, 2007;Wegman and van Den Broek, 1983).…”

Section: Introductionmentioning

confidence: 99%

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Photocatalytic Degradation of 2,4-dichlorophenol in Irradiated Aqueous ZnO Suspension

Gaya¹,

Abdullah²,

Zainal³

et al. 2010

IJC

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This paper focuses on the destruction of aqueous 2,4-dichorophenol in ZnO suspension irradiated by low wattage UV light at 299 K. The operating variables studied include initial 2,4-dichlorophenol concentration, photocatalyst doses and pH. At 1.5 g l -1 feed concentration of ZnO and 50 mg l -1 initial 2,4-dichlorophenol level, a complete degradation was achieved in 180 min. The decomposition kinetics with respect to 2,4-dichlorophenol approximates pseudo zero-order with rate constant peaking at 0.38 mg l -1 min -1 . High performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) detected benzoquinone, 2-chlorohydroquinone, 4-chlorophenol, 3,5-dichlorocatechol, hydroquinone, 4-hydroxybenzaldehyde and phenol during the ZnO-assisted photodegradation of 2,4-dichlorophenol among which some pathway products are disclosed for the first time. The reaction mechanism accounting for the degradation pathway intermediates is proposed. Inorganic anion additives such as S 2 O 8 2-, SO 4 2-, Cl -and HPO 4 2-manifested inhibition against 2,4-dichlorophenol removal.

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“…Epichlorohydrin is a common precursor for synthesizing glycerins, epoxy resins, elastomers, pesticides, textiles, membranes, paper, and pharmaceuticals (35); it harms the skin, liver, kidneys, and central nervous system and is a potential carcinogen (42). Epichlorohydrin is recognized as a water contaminant and has a concentration limit of zero in water supplies (36,37).…”

Section: Deleterious Biofilm Formation Is Reduced and Permeate Flux Ismentioning

confidence: 99%

Living biofouling-resistant membranes as a model for the beneficial use of engineered biofilms

Wood

Guha

Tang

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Membrane systems are used increasingly for water treatment, recycling water from wastewater, during food processing, and energy production. They thus are a key technology to ensure water, energy, and food sustainability. However, biofouling, the build-up of microbes and their polymeric matrix, clogs these systems and reduces their efficiency. Realizing that a microbial film is inevitable, we engineered a beneficial biofilm that prevents membrane biofouling, limiting its own thickness by sensing the number of its cells that are present via a quorum-sensing circuit. The beneficial biofilm also prevents biofilm formation by deleterious bacteria by secreting nitric oxide, a general biofilm dispersal agent, as demonstrated by both short-term dead-end filtration and long-term cross-flow filtration tests. In addition, the beneficial biofilm was engineered to produce an epoxide hydrolase so that it efficiently removes the environmental pollutant epichlorohydrin. Thus, we have created a living biofouling-resistant membrane system that simultaneously reduces biofouling and provides a platform for biodegradation of persistent organic pollutants.

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Assessment of the impact of the emission of certain organochlorine compounds on the aquatic environment

Cited by 24 publications

References 53 publications

Kinetic Mechanism and Enantioselectivity of Halohydrin Dehalogenase from Agrobacterium radiobacter

Kinetic Mechanism and Enantioselectivity of Halohydrin Dehalogenase from Agrobacterium radiobacter

Photocatalytic Degradation of 2,4-dichlorophenol in Irradiated Aqueous ZnO Suspension

Living biofouling-resistant membranes as a model for the beneficial use of engineered biofilms

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