Pulse Radiolysis of HgBr2 in Aqueous Solutions

Abstract

Pulse radiolysis of aqueous HgBr2 solutions was investigated in the range from visible to 260 nm. HgBr2 is reduced by eaq−, H, CO2−, and some alcohol radicals except t-butyl alcohol radical to yield a transient species, HgBr, having an absorption spectrum with a maximum at 350 nm (ε350=(4.3±0.2)×103 M−1 cm−1) . k(eaq−+HgBr2) was determined by the pseud-first order decay of eaq− observed at 500 nm as (4.0±0.3)×1010 M−1 s−1. The reactivities of the other reducing species toward HgBr2 were estimated to be in the order eaq−>CO2−>\dotEtOH≈i-\dotPr-OH>MeOH by comparing the absorption yields of HgBr in equimolar HgBr2 solutions containing the parent substances of the respective species. HgBr was found to decay following a second order rate law (2k=(1.0±0.1)×1010 M−1 s−1), producing Hg2Br2. HgBr2 reacts also with the OH radical to give a transient species which shows a similar spectrum to that of Br2−. It is considered that the transient may be HgBr3 instead of Br2−.

Gas-Phase Photolysis of Hg(I) Radical Species: A New Atmospheric Mercury Reduction Process

“…Interestingly, these radicals were also detected in the aqueous-phase pulse radiolysis of HgCl 2 38 and HgBr 2 . 39,40 An estimation of the 350 nm absorption cross-section of HgCl and HgBr in aqueous-phase provided values 38,40 of 0.9 and 1.6 × 10 −17 cm 2 , respectively, consistent with those computed here for the gas-phase species.…”

“…The transient absorption spectra of HgBr in the 240–520 nm range , shows an intense absorption at ∼350 nm (band B) virtually identical to that computed here, but no data are available on absorption coefficients. Interestingly, these radicals were also detected in the aqueous-phase pulse radiolysis of HgCl 2 and HgBr 2 . , An estimation of the 350 nm absorption cross-section of HgCl and HgBr in aqueous-phase provided values , of 0.9 and 1.6 × 10 –17 cm 2 , respectively, consistent with those computed here for the gas-phase species.…”

Brewster angle-cavity ringdown spectroscopy for low temperature plasma measurements in multiphases

“…Hence, k 10 is calculated to be (4-18)× 10 −16 cm 3 molecule −1 s −1 . Given the lack of measurement of reaction R10 in the literature [55], our measurement represents the first investigation of R10 and should be further validated. However, an analogous experiment was conducted with terephthalic acid (TPA) solutions and similar temporal profiles from absorbance of TPA solutions at different [TPA] were observed.…”