Infrared spectroscopic studies of the heterogeneous reaction of ozone with dry maleic and fumaric acid aerosol particles

Abstract

Dicarboxylic acids, either directly emitted or formed in chemical processes, are found to be a significant component of tropospheric aerosols. To assess any potential chemical transformation of short unsaturated dicarboxylic acids in tropospheric heterogeneous chemistry, maleic and fumaric acid were selected as surrogates in this study. A novel aerosol flow tube apparatus is employed to perform kinetic studies of the oxidation of these organic compounds by gas-phase ozone. The system consists of a particle generation system, a vertically oriented glass flow tube and an infrared observation White cell with a Fourier transform infrared (FTIR) spectrometer for the detection system. A flow of single component organic aerosols with mean diameters ranging between 0.7 and 1.1 microm is introduced in a flow tube, in which the particles are subsequently exposed to a known concentration of ozone for a controlled period of time. A band assignment of infrared vibrational frequencies for dry maleic and fumaric acid aerosol spectra is presented. These studies are complemented with off-line analysis on the reaction products. The reaction exhibited pseudo-first-order kinetics on gas product formation, and the pseudo-first-order rate coefficients displayed a Langmuir-Hinshelwood dependence on gas-phase ozone concentration for both materials. By assuming a Langmuir-Hinshelwood behaviour, the following parameters were obtained: for the reaction of maleic acid aerosols, K(O3) = (3.3 + 0.5) x 10(-16) cm3 molecule(-1) and k(I)(max) = (0.038 + 0.004) s(-1); for the reaction of fumaric acid aerosols, K(O3) = (1.6 + 0.5) x 10(-16) cm3 molecule(-1) and k(I)(max) = (0.048 + 0.007) s(-1), where K(O3) is a parameter that describes the partitioning of ozone to the particle surface and k is the maximum pseudo-first-order coefficient at high ozone concentrations. Apparent reactive uptake coefficients were estimated from the pseudo-first-order rate coefficient and a trend of decreasing uptake coefficients with increasing ozone concentrations was observed, in good agreement with literature values.

A review of experimental techniques for aerosol hygroscopicity studies

“…Fourier transform infrared spectroscopy (FTIR), a vibrational absorption spectroscopy, has been widely employed in laboratory (Goodman et al, 2000;Eliason et al, 2003;Asad et al, 2004;Hung et al, 2005;Najera et al, 2009;Li et al, 2010;Tan et al, 2016;Tang et al, 2016b) and field work (Maria et al, 2002;Russell et al, 2011;Takahama et al, 2013Takahama et al, , 2019Kuzmiakova et al, 2016) to characterize the chemical composition of aerosol particles. It can also be used in aerosol hygroscopicity studies.…”

An Overview of Dynamic Heterogeneous Oxidations in the Troposphere

“…Chemisorption processes, such as these, are apparent through a hyperbolic relationship between the concentration of the gas and the reaction rate. This is often described by the Langmuir-Hinshelwood adsorption mechanism, which provides information regarding the partitioning of the reactant gas between the gas phase and the particle phase, followed by the reaction between the adsorbed gas and species in and on the aerosol [75,76].…”

Heterogeneous chemistry and reaction dynamics of the atmospheric oxidants, O3, NO3, and OH, on organic surfaces

“…Other research teams extended this work to specific surface-bound compounds (including polycyclic aromatics, 43,[53][54][55][56][57][58] biogenic volatile organics, 59 biomass burning products, 60 and fungicides 61 ) and functionalities at well-characterized aerosol surfaces. [62][63][64][65][66] Within the body of literature on O 3 reactions with aerosols, investigations of the ozonolysis of oleic acid aerosols are of particular interest because these particulates appear in relative high abundance in certain regions of the atmosphere. [67][68][69][70] From these studies, reactive uptake coefficients have been determined to be generally on the order of 10…”