Heterogeneous Uptake Kinetics of Limonene and Limonene Oxide by Sulfuric Acid Solutions

Abstract

The heterogeneous uptake of limonene and limonene oxide (also known as 1,8-cineole) by a range of different aqueous sulfuric acid (H2SO4) solutions (30%-80% (w)) was investigated to develop an understanding of the reactivity of biogenic organic compounds in the atmosphere towards acidic aerosols. Experiments were performed using a rotating wetted-wall reactor coupled to a single photon ionization time-of-flight mass spectrometer. The heterogeneous uptake of the compounds into H2SO4 followed first-order kinetics and the corresponding steady-state uptake coefficients (γ) were calculated for the first time. Limonene oxide was found to be more reactive than limonene towards H2SO4. Reactive uptake was observed for limonene oxide in acidic solution containing greater than 30% (w). The steady-state uptake coefficients of limonene oxide in 30%-50% (w) H2SO4 solutions at room temperature ranged from (7.100± 0.023)×10-5 to (8.150±0.162)×10-3. Furthermore, the reactions of limonene oxide with sulfuric acid in bulk solution were investigated using gas chromatography-mass spectrometry (GC-MS) and electron spray ionization-mass spectroscopy (ESI-MS). Analysis of the products revealed the presence of monoterpenes, terpineols, terpin hydrates, and terpin hydrate diorganosulfate from the bulk solution reaction of limonene oxide with H2SO4. The formation of significantly more hydrophobic organic compounds with lower volatilities suggested that limonene oxide is a significant precursor in the formation of atmospheric secondary organic 1608 WANG Tian-He et al.: Heterogeneous Uptake Kinetics of Limonene and Limonene Oxide by H2SO4 Solutions No.7 aerosols. A transformation mechanism has been proposed based on the products.

Effects of NO<sub>x</sub> and SO<sub>2</sub> on the Secondary Organic Aerosol Formation from Photooxidation of α-pinene and Limonene

“…For example, Kiendler-Scharr et al (2016) shows that the organic nitrate concentrations are high in all the rural sites all over Europe, indicating the important influence of anthropogenic emissions in rural areas which are often enriched in biogenic emissions. The 14 C analyses in several studies show that modern source carbon, from biogenic emission or biomass burning, accounts for large fractions of organic aerosol even in urban areas (Szidat et al, 2009;Weber et al, 2007;Sun et al, 2012), indicating the potential interactions of biogenic emissions with anthropogenic emissions in urban areas. In such cases, anthropogenic NO x alone may suppress the new particle formation and SOA mass from biogenic VOC oxidation, as we found in this study, because in principle the suppression of SOA mass due to suppressed nucleation can occur in the ambient atmosphere, although chamber experiments often cannot accurately simulate the vapor loss on surface in the boundary layer.…”

Evaluation and Application of Dual-Reactor Chamber for Studying Atmospheric Oxidation Processes and Mechanisms

“…VOCs (ionization energy below 10.5 eV) such as aliphatic alcohols, ketones, and aldehydes can also be detected by a home-made vacuum ultraviolet single-photon ionization timeof-flight mass spectrometry (VUV-SPI-TOFMS). 25,26 The size distributions of submicron aerosols are determined by a scanning mobility particle sizer (SMPS), which is composed of an electrostatic classifier (EC, Model 3080, TSI Inc., USA), a long differential mobility analyzer (DMA, Model 3081, TSI Inc., USA) or an alternative short DMA (Model 3085, TSI Inc., USA) and a condensation particle counter (CPC, Model 3776, TSI Inc., USA). The size distributions of micron particles are detected by an aerodynamic particle sizer (APS, Model 3321, TSI Inc., USA).…”