Atmospheric chemistry of trifluorodicarbonyls initiated by Cl atoms: Reactivity trends, mechanism, and acid formation yields.

Rate coefficients of the gas-phase reactions of Cl atoms with a series of fluorinated diketones (FDKs): CFC(O)CHC(O)CH (TFP), CFC(O)CHC(O)CHCH (TFH) and CFC(O)CHC(O)CH(CH) (TFMH), have been measured at (298 ± 2) K and under atmospheric pressure. The experiments were performed using the relative-rate method with a GC-FID detection system. From different determinations and references used, the following rate coefficients were obtained (in cm/(molecule·sec)): k(TFP + Cl) = (1.

Single and combined phytoextraction of lead and cadmium on submerged plants Potamogeton pusillus L.: removal, bioaccumulation pattern, and phytotoxicity.

Under the present investigation, the submerged plant Potamogeton pusillus has been tested for the removal of lead (Pb) and cadmium (Cd). P. pusillus removal efficiency and accumulation capacity were examined in separated Pb and Cd solutions, at 0.

Experimental and Theoretical Kinetic Studies of the Ozonolysis of Selected Allyl Sulfides (HC═CHCHSR, R = CH, CHCH): The Effect of Nascent OH Radicals.

Rate coefficients of the O-initiated oxidation of allyl methyl sulfide (HC═CHCHSCH, AMS) and allyl ethyl sulfide (HC═CHCHSCHCH, AES) were determined at atmospheric conditions by "in situ" FTIR. The relative kinetic experiments were performed using methylcyclohexane (McH) and carbon monoxide (CO) as nascent OH radical scavengers and in the absence of any scavenger, to determine the impact that the formation of OH radicals has on the rate coefficients. In the absence of scavengers, values of = (5.

FTIR product study of the Cl-initiated oxidation products of CFC replacements: (/)-1,2,3,3,3-pentafluoropropene and hexafluoroisobutylene.

A product study of the reactions of (/)-1,2,3,3,3-pentafluoropropene ((/)-CFCF[double bond, length as m-dash]CHF) and hexafluoroisobutylene ((CF)C[double bond, length as m-dash]CH) initiated by Cl atoms were developed at 298 ± 2 K and atmospheric pressure. The experiments were carried out in a 1080 L quartz-glass environmental chamber coupled FTIR spectroscopy to monitor the reactants and products. The main products observed and their yields were as follows: CFC(O)F (106 ± 9)% with HC(O)F (100 ± 8)% as a co-product for (/)-CFCF[double bond, length as m-dash]CHF, and CFC(O)CF (94 ± 5)% with HC(O)Cl (90 ± 7)% as a co-product for (CF)C[double bond, length as m-dash]CH.

Degradation mechanism of 2-fluoropropene by Cl atoms: experimental and theoretical products distribution studies.

The gas-phase reaction products of 2-fluoropropene (2FP) with Cl atoms have been determined for the first time at 298 K and atmospheric pressure using a 1080 L quartz-glass photoreactor coupled with FTIR spectroscopy to monitor reactants and products. Acetyl fluoride and formyl chloride were observed as the main products with yields of (106 ± 10)% and (100 ± 11)%, respectively. Electronic structure calculations of reactants, intermediates, products and transition states on a detailed mechanism of the reaction were performed by DFT procedures (BMK, M06, M062X/D3), as well as accurate composite methods on both the addition and abstraction reaction channels.

Kinetics, product distribution and atmospheric implications of the gas-phase oxidation of allyl sulfides by OH radicals.

Relative rate coefficients of the OH radical -initiated oxidation of allyl methyl sulfide (AMS, HCCHCHSCH) and allyl ethyl sulfide (AES, HCCHCHSCHCH) have been measured at atmospheric pressure of synthetic air and 298 K: k= (4.98 ± 1.42) and k= (6.

Diurnal photodegradation of fluorinated diketones (FDKs) by OH radicals using different atmospheric simulation chambers: Role of keto-enol tautomerization on reactivity.

Rate coefficients for the gas-phase reactions of OH radicals with a series of fluorinated diketones have been determined for the first time at (298 ± 3) K and atmospheric pressure using the relative method and FTIR spectroscopy and GC-FID to monitor both reactants and references. The following values, in 10 cm molecule s, were obtained for 1,1,1-trifluoro-2,4-pentanedione (TFP), 1,1,1-trifluoro-2,4-hexanedione (TFH) and 1,1,1-trifluoro-5-methyl-2,4-hexanedione (TFMH), respectively: k(TFP + OH) = (1.3 ± 0.

OH-initiated degradation of methyl 2-chloroacetoacetate and ethyl 2-chloroacetoacetate: Kinetics, products and mechanisms at 298 K and atmospheric pressure.

Rate coefficients for the gas-phase reactions of OH radicals with CHC(O)CHClC(O)OCH (k) and CHC(O)CHClC(O)OCHCH (k) were measured using the relative technique with different reference compounds. The experiments were performed at (298 ± 2) K and 750 Torr of nitrogen or synthetic air by in situ FTIR spectroscopy and GC-FID chromatography. The following rate coefficients (in units of cmmolecule s) were obtained: k= (2.

Degradation of a series of fluorinated acrylates and methacrylates initiated by OH radicals at different temperatures.

Rate coefficients for the gas-phase reactions of OH radicals with a series of fluorinated acrylates and methacrylates: 2,2,2-trifluoroethylmethacrylate ( ), 1,1,1,3,3,3-hexafluoroisopropylacrylate ( ), 1,1,1,3,3,3-hexafluoroisopropylmethacrylate ( ), and 2,2,2-trifluoroethylacrylate ( ) have been measured for the first time as a function of temperature in the range 290-308 K. The kinetic data obtained were used to derive the following Arrhenius expressions (in units of cm per molecule per s): = (2.13 ± 0.

Product distribution and mechanism of the OH initiated tropospheric degradation of three CFC replacement candidates: CHCF[double bond, length as m-dash]CH, (CF)C[double bond, length as m-dash]CH and (/)-CFCF[double bond, length as m-dash]CHF.

The OH radical initiated photodegradation of 2-fluoropropene (CHCF[double bond, length as m-dash]CH), 3,3,3-trifluoro-2-(tri-fluoromethyl)propene ((CF)C[double bond, length as m-dash]CH) and (/)-1,2,3,3,3-pentafluoropropene ((/)-CFCF[double bond, length as m-dash]CHF) has been investigated for the first time using a 1080 L quartz-glass environmental chamber at 298 ± 2 K and atmospheric pressure of synthetic air coupled with FTIR spectroscopy to monitor reactants and products. The major products observed in the OH reaction were CHC(O)F (98 ± 5)% together with HC(O)H (89 ± 7)% as a co-product, CFC(O)F (103 ± 8)% together with HC(O)F (96 ± 7)% as a co-product and CFC(O)CF (91 ± 8)% together with HC(O)H (98 ± 12)% as a co-product from the C-C bond cleavage channel of the intermediate hydroxyalkoxy radical, formed by addition of OH to the terminal carbon of the double bond which is designated C of 2-fluoropropene, (/)-1,2,3,3,3-pentafluoropropene and 3,3,3-trifluoro-2-(tri-fluoromethyl)propene, respectively. The present results are compared with previous studies for the reaction of OH with the separate isomers () and () of 1,2,3,3,3-pentafluoropropene.