Document gDvzv7rqYkzk9d9nr85EJ9n4V

AR226-3360 ATMOSPHERIC LIFETIMES AND DEGRAD MECHANISMS OF FLUOROTELOMER ALCOHOLS C^F^C^CR^Ofi Valerie Bossoutrot*, Tanya Kelly^ Isabelle Magneron*, Wahid Howard Sidebottom#, Klaus Wirtz and Georges Le Br * Laboratoire de Combustion et Systemes Reactifs, CNRS Orle # Chemistry Department, University College, Dublin (IRL Centro de Estudios Ambientales del Mediterraneo, Valencia SETAC Prague 18-22 April 2004 .ontext: 1 A .i -^Sis^ Long chain perfluorinated carboxylic acids (PFCAs, Cj^C(0)OH observed in fish and mammals PFCAs : not generally used directly in consumer or industrial materials - presumably degradation products of precursor chemicals : potentially FTOHs Fluorotelomer alcohols (FTOHs, C^F^CH^CH^OH): -Uses: intermediates in manufacture of diverse products - Production: 5x106 kg yr1 (80% polymeric applications) (20% non polymeric ) - Observed in the atmosphere (up to 135 pg m"3) - Atmospheric sources : degradation o^ polymer and non polymeric that incorporate FTOHs (?) - Expected to partition into the atmosphere (low water solubility, hig Assessment of environmental impact of FTOHs requires inform their atmospheric persistence and degradation products This work Rate constants for the reactions : OH +3,3,3 trifluropropanol (^CH^CBRH) OH + tridecafluorooctanol (C^CH^CH^OH) OH +3,3,3 trifluoropropanal ^CH^CHO) => persistence : T = 1/k [OH] Degradation products of the OH- and Cl-initiated oxidatio of CF3CH2CH20H in air Experimental methodology - Rate constant measurements - Relative rate studies : FEP chambers (50 and 150 L) irradiated by lamps Hp^ + ligut (254 nm) -^ 2 OH or 03 + light (254 nm) -^ 0 CD) + 0^ 0 CD) + H^O -> 2 OH - Absolute rate studies : Pulsed laser photolysis-laser induced fluorescence : H^ + ^ (248 nm) -^ 2 OH pLEYFIL = ew `Thermocouple' d Er Pression AI aser Sortie fluide d 5 Na:vaG || CYoseniiave [ ers N Doubleur = Laser a Controle| Saozkeuex || ExPchoi=tmoelryesdee m sm mJ E H-- H 2] > 282 nm J C [= F =E T | T"cErnyttoorgmieenfsiluqqiudueea XK Pompage Pho= tomultip" licateur Fitre Micro Ordinateur oy ai Tension (6x254 nm et 6x365 nm) - Product studies - FEP chambers (50 and 150 L) GC and FTIR analysis ofreactants and products after sampling - Outdoor chamber EUPHORE (200 m3) HONO + light (>300nm) -> OH + NO C1C(0)C(0)C1 + light (> 300 nm) -> 2 CO + 2 Cl In situ FTIR analysis ofreactants and products Concentration-time profiles for the reaction of OH radical with C and various reference compounds at 298 K. 0.0 0.2 0.4 0.6 0.8 In {[Reference^ / [Reference] J OH + CF3CH2CH20H -> Products OH + Reference --> Products 1.0 ki kz la([CVyC1l^CfljOQ},/[C^CVL^C1l^Ofl]t) = ki/k^ ln([Reference](/[R ki = (1.08 0.04) x 10-12 cm3 molecule-^-1 Absolute rate constant measurements for the reaction of OH radical w and CF3CH2CHO at 298 K. 10000 8000 6000 ^! 4000 2000 -\ 10 20 OH + OH + [Substrate] /1014 molecule cm"3 CF3CH2CHpH -> Products CF3CH2CHO -> Products 30 ki fc k5 = ki [CV^CR^CR^OR] + k^' or k' = k3 [ CF3CH2CHO] + k^5 ki = (0.89 0.03) x 10-12 cm3 molecule-1 s-1 k3 == (2.96 0.04) x 10-12 cm3 molecule-! s-1 Rate constant for the reaction ofOlPradical with C^CH^CH^OH using the relative rate method Reference Compound n-hexane Analytical technique FTIR GC-FID FTIR GC-FID ^TDO / ^Ref 0.15 0.01 0.26 0.02 0.17 0.02 0.21 0.02 k "TD (10-12cm3 mol 0.82d= 1.42 0 0.93 0 1.140 n-butyl formate FTIR GC-FID FTIR GC-FID 0.22 0.01 0.29 0.02 0.27 0.03 0.24 0.05 0.78 0 1.03 0 0.96 0.85 k = (0.99 0.18) x 10-12 cm3 molecule-1 s-1 at 298K Rate constant data Ad atmospheric lifetimes k (10"12 cn^molec.^s"1) CF3CH2CBPH C^CH^OH CF3CH2CHO -1.0 -1.0 - 3.0 Length ofC^F^+i group has no impact on the reactivity ofF (in agreement with Ellis et al. EST 2003, 37, 3816) => k (OH + C^^C^CIL^OH) - 10-12 ^ (CA^iCH^CH^OH) = 12 days Pduct study Concentration-time profiles of reactants and products from the reaction of Cleinitiated oxidation of CF,CH,CH,0H in air at EUPHORE. os cronanon o cana . oO CRCHO Lo a CRO ]2 oe IN~.-- 5 02 0. K To PI * ---- - Proline mites CF,CH,CH,0H -- CF,CH,CHO -- CF,CHO -- CF,0 A [Product] p p P P P ^8 8 c$ o^ B 8 p a p cS p 0^ p B Concentration ppm o o o o o -' 0 1\3 4^. 05 00 0 o Q----------i----------1----------1-- m on 1' ^3 A [Product] - Experiments on Cl- and OH-initiated oxidation ofCF3CH2CH20H in ai in the laboratory photoreactors gave similar data as at EUPHORE. - Experiments on Cl- and OH-initiated oxidation ofCF3CH:2CHO showed as the primary product with a yield close to unity. The present product study has shown that: - CF3CH2CHO is the only product (unity yield) of the Cl- and OH-ini of CF3CH2CH20H, in the absence or presence of N0^ - CF3CHO is the major product of the degradation ofCF3CH2CHO, in the absence of NO, and a yield of .85 +/-0.05 in the presence ofNO - These data are consistent with those of Hurley et al. J.Phys. Chem. A 2004, 108, 1973 -vsav Oxidation mechanism of CF__3CH2CH20H OH/(C1) + CF3CH2CH20H -^ CF3CH2CHOH + Hp/(HCl) CF3CH2CHOH + 02 -> CF3CH2CHO + Hp OH/(C1) + CF3CH2CHO -^ CF3CH2C(0) + H? CF3CH2C(0) + 0^ + M ^ CF3CH2C(0)02 + M CF3CH2C(0)02 + RO^ -^ CF3CH2C(0)0 + RO + 0^ CF3CH2C(0)0 -> CF3CH2 + C02 CF3CH2 + CX,+ M -> CF3CH202 + M CF3CH202 + RO^ ^ CF3CH20 + RO + 0^ CF3CH? + 0^ -> CF3CHO + HO^ Jw the presence ofNO^ CF3CH2C(0)02 + NO -> CF3CH2C(0)0 + N0^ CF3CH202 + NO -> CF3CHp + N0^ CF3CH2C(0)02 + N0^ + M ^ CF3CH2C(0)02N02 + M OH/(C1) + CF3CHO (+ O^) -> CF3C(0)02 + Hp/(HCl) CF3C(0)02 + RO^ -> CF3C(0)0 + RO + C^ CF3C(0)0 -> CF3 + CO^ CF3 + 0^ + M -> C^ft^ + M CF302 + RO^ -> CF30 + RO + 0^ CF30 -^ CF^O J^ the presence ofNO^: CF3C(0)02 + NO -^ CF3C(0)0 + N0^ CF302 + NO -^ CF30 + N0^ CF30 + NO -> CF^O + FNO CF3C(0)02 + N0^ + M -^ CF3C(0)02N02 + M "Sagis^ " Atmospheric implications - CF^CH^CH^OH CF3CH2CH20H will be removed by OH (T - 12 days) CF3CH^CHO produced will be removed mainly by OH (T - 4 days). Photolysis is a minor process (r > 15 days, Sellevag et al PCCP 2004, 6 12 In the presence ofNO^, small amount of CF3CH^O^NO^ will be form In the absence ofNO^ carboxylic acid could be formed: CF3CH2C(0)02 + HO^ -> CF3C(0)OH + 03 Yield of-25% (Sulbaek et al Chem. Phys. Lett. 2003, 381, 14) CF3CHO will be the major oxidation product. It will be removed by OH (T possibly photolysis (r > 27 days, Sellevag et al 2004), and may be uptaken (rain and cloud): - OH reaction will produce CF^O and peroxynitrate in the presence ofNOx, oftrifluroacetic acid at low NOx: CF3C(0)02 + HO^ -> CF3C(0)OH + 03 - Photolysis is likely to produce CF3 which will yield CF^O - Uptake by water is a source ofCF3COOH Atmdffpheric implications W <w^ c^m FTOHs FTOHs will be removed by OH (r ^ 12days) ^^n+i01^0110 produced is expected to be removed by OH like CF3CH2 Photolysis would be a slower process (from experiments at EUPHORE) In the absence ofNO^ carboxylic acid could be formed: C,F^ CR^O)0, + HO^ -^ C,F^CH2C(0)OH + 03 Yield unknown C^F^^CHO would be the major oxidation product. It will be removed by (T ^ 25 days, from Sulbaek et al 2003) and likely by photolysis (rate unkn Uptake by water should be insignificant (long chain aldehydes are fairly u - OH reaction will produce CF^O and peroxyacylnitrate in the presence of a source of carboxylic acid at low N0^: Cn^AOA + HO^ -^ C,F^C(0)OH + 03 Yield unknown - Photolysis is likely to produce Cj^n+i which will yield CF^O = The capacity of FTOHs to form PFCAs will need low N0^ concentratio OH reaction/photolysis rate ratio and yields of PFCAs from peroxyacyi + remain to be determined. Acknowledgments Total company (Dr Jean Marie Libre),and Telomer Research Prog