Primary and secondary kinetic hydrogen isotope effects in the solution and gas phase decomposition of t-alkoxides

D/H fractionation factors between MeOH and Ph2PH in dilute solutions of tetrachloroethylene, benzene, tetrahydrofuran, pyridine, and acetonitrile and T/H fractionation factors between MeOH and Me2PH vapors were measured. The experimental results agree very well with values calculated from the statistical theory of isotope effects formulated by Bigeleisen and Mayer. There are correlations between observed fractionation factors and solvent polarity, and the interaction energy of methanol with the given solvent. Another correlation has been found between enthalpy of the exchange reactions and the interaction energy between methanol and the given solvent. Key words: isotope effects, fractionation factor, diphenylphosphine, methanol.

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Secondary hydrogen isotope effects on simple cleavage reactions in the gas phase. The .alpha.-cleavage of tertiary amine cation radicals

Journal of the American Chemical Society ◽

10.1021/ja00220a024 ◽

1988 ◽

Vol 110 (12) ◽

pp. 3869-3873 ◽

Cited By ~ 24

Author(s):

Steen. Ingemann ◽

Steen. Hammerum ◽

Peter J. Derrick

Keyword(s):

Gas Phase ◽

Tertiary Amine ◽

Hydrogen Isotope ◽

Isotope Effects ◽

Cation Radicals ◽

Cleavage Reactions

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Dynamics of the weak hydrogen bond in a gas phase. Three-dimensional model and isotope effects of the bond length

Journal de Chimie Physique ◽

10.1051/jcp/1993901631 ◽

1993 ◽

Vol 90 ◽

pp. 1631-1641 ◽

Cited By ~ 1

Author(s):

ND Sokolov ◽

VA Savel'ev

Keyword(s):

Hydrogen Bond ◽

Bond Length ◽

Gas Phase ◽

Isotope Effects ◽

Three Dimensional ◽

Weak Hydrogen Bond ◽

Dimensional Model ◽

Three Dimensional Model

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Unravelling the process of petroleum hydrocarbon biodegradation in different filter materials of constructed wetlands by stable isotope fractionation and labelling studies

Biodegradation ◽

10.1007/s10532-021-09942-1 ◽

2021 ◽

Author(s):

Andrea Watzinger ◽

Melanie Hager ◽

Thomas Reichenauer ◽

Gerhard Soja ◽

Paul Kinner

Keyword(s):

Stable Isotope ◽

Constructed Wetlands ◽

Hydrogen Isotope ◽

Petroleum Hydrocarbon ◽

Isotope Fractionation ◽

Isotope Effects ◽

Filter Material ◽

Hydrocarbon Biodegradation ◽

Stable Isotope Fractionation ◽

Filter Materials

AbstractMaintaining and supporting complete biodegradation during remediation of petroleum hydrocarbon contaminated groundwater in constructed wetlands is vital for the final destruction and removal of contaminants. We aimed to compare and gain insight into biodegradation and explore possible limitations in different filter materials (sand, sand amended with biochar, expanded clay). These filters were collected from constructed wetlands after two years of operation and batch experiments were conducted using two stable isotope techniques; (i) carbon isotope labelling of hexadecane and (ii) hydrogen isotope fractionation of decane. Both hydrocarbon compounds hexadecane and decane were biodegraded. The mineralization rate of hexadecane was higher in the sandy filter material (3.6 µg CO2 g−1 day−1) than in the expanded clay (1.0 µg CO2 g−1 day−1). The microbial community of the constructed wetland microcosms was dominated by Gram negative bacteria and fungi and was specific for the different filter materials while hexadecane was primarily anabolized by bacteria. Adsorption / desorption of petroleum hydrocarbons in expanded clay was observed, which might not hinder but delay biodegradation. Very few cases of hydrogen isotope fractionation were recorded in expanded clay and sand & biochar filters during decane biodegradation. In sand filters, decane was biodegraded more slowly and hydrogen isotope fractionation was visible. Still, the range of observed apparent kinetic hydrogen isotope effects (AKIEH = 1.072–1.500) and apparent decane biodegradation rates (k = − 0.017 to − 0.067 day−1) of the sand filter were low. To conclude, low biodegradation rates, small hydrogen isotope fractionation, zero order mineralization kinetics and lack of microbial biomass growth indicated that mass transfer controlled biodegradation.

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