Second-Order Kinetic Rate Coefficients for the Aqueous-Phase Hydroxyl Radical (OH) Oxidation of Isoprene-Derived Secondary Organic Aerosol Compounds at 298 K
Second-Order Kinetic Rate Coefficients for the Aqueous-Phase Hydroxyl Radical (OH) Oxidation of Isoprene-Derived Secondary Organic Aerosol Compounds at 298 K
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DOI：
10.1021/acs.est.1c04606
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发表时间：
2021-09-29
影响因子：
11.4
通讯作者：
Nguyen, Tran B.
中科院分区：
文献类型：
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作者：
Abellar, Karizza A.;Cope, James D.;Nguyen, Tran B.
释放到大气中的最丰富的非甲烷挥发性有机化合物异戊二烯（C5H8）的羟基自由基（OH）氧化产生了许多化学物质，这些化学物质通过气-颗粒分配分配到凝聚相，或通过多相/多相化学形成凝聚相化合物，产生二次有机气溶胶（SOA）。气溶胶水或云/雾滴中的SOA物种可能通过与OH自由基的水反应进一步氧化，以及其他命运。异戊二烯光化学级联中化合物的速率系数在气相中受到很好的约束；然而，对于缩合相产物的水中OH速率系数存在信息空白，这妨碍了对异戊二烯衍生SOA的氧化命运进行大气模拟。本文研究了异戊二烯大气氧化高no和低no通道形成的六种主要SOA化合物和一种类似物的OH引发氧化动力学速率系数（k(OH)），其中大部分被合成和纯化用于研究：（k(1)） 2-甲基四醇[MT: 1.14 （+/- 0.17） × 10(9) M-1 s(-1)], (k(2)) 2-甲基-1,2,3-三羟基-4-硫酸盐[MT-4- s: 1.52 （+/- 0.25） × 109 M-1 s(-1)], (k(3)) 2-甲基-1,2-二羟基-3-硫酸盐[MD-3-S：0.56 (+ / - 0.15) x 10 (9) m - 1 s (1)), (k) (4) 2-methyl-1, 2-dihydroxy-but-3-ene[身边:4.35 (+ / - 1.16)x 10 (9) m - 1 s (1)), (k) (5) 2-methyl-2, 3-dihydroxy-1, 4-dinitrate [MD-1 4-DN: 0.24 (+ / - 0.04) x 10 (9) m - 1 s (1)), (k (6) 2-methyl-1, 2, 4-trihydroxy-3-nitrate [MT-3-N: 1.12 (+ / - 0.15) x 10 (9) m - 1 s(1)),和(k (7)) 2-methylglyceric酸(公司:pH 2:1.41 (+ / - 0.49) x 10 m - 1 s (1) (9);pH值5:0.97 （+/- 0.42）× 10(9) M-1 s(-1)]。二阶速率系数是根据纯水中赤藓糖醇的已知kOH测定的。采用核磁共振（NMR）和高效液相色谱-高分辨质谱（HPLC-HRMS）测定各试剂的衰变。异戊二烯衍生的SOA化合物的水光氧化率很大，在实现到全局模型时可能会影响SOA预算。
The hydroxyl radical (OH) oxidation of the most abundant nonmethane volatile organic compound emitted to the atmosphere, isoprene (C5H8), produces a number of chemical species that partition to the condensed phase via gas-particle partitioning or form condensed-phase compounds via multiphase/heterogeneous chemistry to generate secondary organic aerosols (SOA). The SOA species in aerosol water or cloud/fog droplets may oxidize further via aqueous reaction with OH radicals, among other fates. Rate coefficients for compounds in isoprene's photochemical cascade are well constrained in the gas phase; however, a gap of information exists for the aqueous OH rate coefficients of the condensed-phased products, precluding the atmospheric modeling of the oxidative fate of isoprene-derived SOA. This work investigated the OH-initiated oxidation kinetic rate coefficients (k(OH)) for six major SOA compounds formed from the high-NO and low-NO channels of isoprene's atmospheric oxidation and one analog, most of which were synthesized and purified for study: (k(1)) 2-methyltetrol [MT: 1.14 (+/- 0.17) x 10(9) M-1 s(-1)], (k(2)) 2-methyl-1,2,3-trihydroxy-4-sulfate [MT-4-S: 1.52 (+/- 0.25) x 109 M-1 s(-1)], (k(3)) 2-methyl-1,2-dihydroxy-3-sulfate [MD-3-S: 0.56 (+/- 0.15) x 10(9) M-1 s(-1)], (k(4)) 2-methyl-1,2-dihydroxy-but-3-ene [MDE: 4.35 (+/- 1.16) x 10(9) M-1 s(-1)], (k(5)) 2-methyl-2,3-dihydroxy-1,4-dinitrate [MD-1,4-DN: 0.24 (+/- 0.04) x 10(9) M-1 s(-1)], (k(6)) 2-methyl-1,2,4-trihydroxy-3-nitrate [MT-3-N: 1.12 (+/- 0.15) x 10(9) M-1 s(-1)], and (k(7)) 2-methylglyceric acid [MGA: pH 2:1.41 (+/- 0.49) x 10(9) M-1 s(-1); pH 5:0.97 (+/- 0.42) x 10(9) M-1 s(-1)]. The second-order rate coefficients are determined against the known kOH of erythritol in pure water. The decays of each reagent were measured with nuclear magnetic resonance (NMR) and high-performance liquid chromatography-high resolution mass spectrometry (HPLC-HRMS). The aqueous photooxidation fates of isoprene-derived SOA compounds are substantial and may impact the SOA budget when implemented into global models.