Drinking water nitrosamines in a large metropolitan region in Brazil

Vizioli, Beatriz De Caroli; Hantao, Leandro Wang; Montagner, Cassiana Carolina

doi:10.1007/s11356-021-12998-4

Cited by 10 publications

(3 citation statements)

References 29 publications

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“…Also, the dipole moments compare well with the experiment (calculated values in parentheses): μ a = 0.178 ± 0.007 (0.174) D and μ c = 0.800 ± 0.020 (0.867) D for the equatorial form, and μ a = 1.069 ± 0.015 (1.098) and μ c = 0.521 ± 0.007 (0.550) D for the axial form. 66 The energy difference between the two chair conformers is relatively small; results from CCSD(T*)-F12a/aug-cc-pVTZ// M06-2X/aug-cc-pVTZ calculations (hereafter abbreviated as CC//M062X) place ΔH ax−eq = 2.72 and ΔG ax−eq = 2.43 kJ mol −1 at 298 K, which compares to the experimental results ΔH = 2.22 ± 0.13 kJ mol −1 from van't Hoff analyses of intensity variations in gas phase infrared absorption bands over the 50−210 °C range, 67 and ΔG = 3.07 ± 0.30 kJ mol −1 from relative intensity measurements of rotational transitions by microwave spectroscopy at 293 and 239 K. 66 The barrier to eq−ax inversion of the >NH group is calculated to be ΔE v=0 ⧧ = 19.65 kJ mol −1 (ΔG ⧧ = 19.54 kJ mol −1 ), which compares to 25.5 ± 0.8 kJ mol −1 from a 13 C NMR study of piperidine dissolved in a 1:1 blend of CHFCl 2 and CHF 2 Cl. 68 The conformational pathways in piperidine are excellently treated by Stortz 69 and will not be reiterated here; in addition to the two chair forms, there are six skew, pairwise pseudoenantiomeric conformations (denoted 3 S 1 , 5 S 1 , and 2 S N ) having ∼25 kJ mol −1 higher energies linked by boat forms ( 3,N B, B 1,4 , and B 3,N ); the barriers between the chair forms and the skew forms ( N H 1 , 3 H 4 / 3 E, E 3 , and E N ) are ∼50 kJ mol −1 .…”

Section: Resultsmentioning

confidence: 97%

“…One of the ions signals observed, m/z 114.092 (C 6 H 12 NO + ), corresponds to a compound containing more carbon atoms than PIP, and it is attributed to piperidine-1-carbaldehyde resulting from condensation of PIP and formic acid, either in the particle phase or on the chamber walls. In 3 of the 4 experiments, the m/z 114.092 ion signal is an order of magnitude larger than the m/z 115.087 PIP-NO signal, and, the 13 C isotopic signal of C 6 H 12 NO + , in particular, hampers the analysis and the quantification of PIP-NO.…”

Section: -Nitrosopiperidine Photolysis Studiesmentioning

confidence: 98%

“… 11 A comprehensive examination of nitrosamines in a Korean water system, including sewage treatment plants, river water, and seawater reported PIP-NO concentrations of ∼100 ng L –1 in the sewage treatment plants influent and ∼5 ng L –1 in the effluent, whereas the concentrations in the river water and seawater was reported to be <1 and ∼2 ng L –1 , respectively. 12 More recently, PIP-NO was reported with an average of 22 ng L –1 in 4 of 5 drinking water samples collected from 13 cities in the state of São Paulo, Brazil, 13 and in 47 of 117 samples of treated water throughout China (average 2.9 ng L –1 ). 14 To the best of our knowledge, neither 1-nitropiperidine (PIP-NO 2 ) nor the piperidine imine, 2,3,4,5-tetrahydropyridine (PIP-IM), have ever been reported in environmental samples.…”

Section: Introductionmentioning

confidence: 99%

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Experimental and Theoretical Study of the OH-Initiated Degradation of Piperidine under Simulated Atmospheric Conditions

Tan,

Zhu,

Mikoviny

et al. 2024

J. Phys. Chem. A

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The OH-initiated photo-oxidation of piperidine and the photolysis of 1-nitrosopiperidine were investigated in a large atmospheric simulation chamber and in theoretical calculations based on CCSD(T*)-F12a/aug-cc-pVTZ//M062X/ aug-cc-pVTZ quantum chemistry results and master equation modeling of the pivotal reaction steps. The rate coefficient for the reaction of piperidine with OH radicals was determined by the relative rate method to be k OH-piperidine = (1.19 ± 0.27) × 10 −10 cm 3 molecule −1 s −1 at 304 ± 2 K and 1014 ± 2 hPa. Product studies show the piperidine + OH reaction to proceed via H-abstraction from both CH 2 and NH groups, resulting in the formation of the corresponding imine (2,3,4,5tetrahydropyridine) as the major product and in the nitramine (1-nitropiperidine) and nitrosamine (1-nitrosopiperidine) as minor products. Analysis of 1-nitrosopiperidine photolysis experiments under natural sunlight conditions gave the relative rates j rel = j 1-nitrosoperidine /j NOd 2 = 0.342 ± 0.007, k 3 /k 4a = 0.53 ± 0.05 and k 2 / k 4a = (7.66 ± 0.18) × 10 −8 that were subsequently employed in modeling the piperidine photo-oxidation experiments, from which the initial branchings between H-abstraction from the NH and CH 2 groups, k N−H /k tot = 0.38 ± 0.08 and k C 2 −H /k tot = 0.49 ± 0.19, were derived. All photo-oxidation experiments were accompanied by particle formation that was initiated by the acid−base reaction of piperidine with nitric acid. Primary photo-oxidation products including both 1-nitrosopiperidine and 1-nitropiperidine were detected in the particles formed. Quantum chemistry calculations on the OH initiated atmospheric photo-oxidation of piperidine suggest the branching in the initial H-abstraction routes to be ∼35% N 1 , ∼50% C 2 , ∼13% C 3 , and ∼2% C 4 . The theoretical study produced an atmospheric photo-oxidation mechanism, according to which H-abstraction from the C 2 position predominantly leads to 2,3,4,5-tetrahydropyridine and H-abstraction from the C 3 position results in ring opening followed by a complex autoxidation, of which the first few steps are mapped in detail. H-abstraction from the C 4 position is shown to result mainly in the formation of piperidin-4-one and 2,3,4,5-tetrahydropyridin-4-ol, whereas H-abstraction from N 1 under atmospheric conditions primarily leads to 2,3,4,5-tetrahydropyridine and in minor amounts of 1-nitrosopiperidine and 1-nitropiperidine. The calculated rate coefficient for the piperidine + OH reaction agrees with the experimental value within 35%, and aligning the theoretical numbers to the experimental value results in k(T) = 2.46 × 10 −12 × exp(486 K/T) cm 3 molecule −1 s −1 (200−400 K).

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