State Key Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University , Beijing 100871, China.
Environ Sci Technol. 2011 Apr 15;45(8):3317-24. doi: 10.1021/es104107c. Epub 2011 Mar 23.
Recent studies have shown that heterogeneous reactions of hydrogen peroxide (H(2)O(2)) on aerosol surfaces may play an important role in tropospheric chemistry. The data concerning the kinetics and mechanisms of these reactions, however, are quite scarce so far. Here, we investigated, for the first time, the heterogeneous reactions of gaseous H(2)O(2) on SiO(2) and α-Al(2)O(3) particles, two major components of mineral dust aerosol, using transmission-Fourier Transform Infrared (T-FTIR) spectroscopy, and high-performance liquid chromatography (HPLC). It is found that H(2)O(2) molecularly adsorbs on SiO(2), and a small amount of molecularly adsorbed H(2)O(2) decomposes due to its thermal instability. For α-Al(2)O(3), catalytic decomposition of H(2)O(2) evidently occurs, but there is also a small amount of H(2)O(2) molecularly adsorbed on the particle surface. The BET uptake coefficients of H(2)O(2) on both particles appear to be independent of gaseous H(2)O(2) concentration (1.27-13.8 ppmv) and particle sample mass (2.8-6.5 mg for SiO(2) and 8.6-18.9 mg for α-Al(2)O(3)), but are strongly dependent on relative humidity with the values ranging from (1.55 ± 0.14) × 10(-8) and (1.21 ± 0.04) × 10(-7) at 2% RH to (0.61 ± 0.06) × 10(-8) and (0.76 ± 0.09) × 10(-7) at 76% RH for SiO(2) and α-Al(2)O(3), respectively. On the basis of the experimental results and literature data, the potential mechanisms for heterogeneous decomposition of H(2)O(2) were proposed, and the atmospheric implications of these reactions were discussed. It is found that heterogeneous reaction of H(2)O(2) on both mineral oxides plays a significant role in processing mineral aerosols, although its role as a sink for ambient H(2)O(2) is probably limited.
最近的研究表明，过氧化氢（H2O2）在气溶胶表面的非均相反应可能在对流层化学中发挥重要作用。然而，到目前为止，关于这些反应的动力学和机制的数据还相当缺乏。在这里，我们首次使用传输傅里叶变换红外（T-FTIR）光谱和高效液相色谱（HPLC）研究了两种主要的矿物尘气溶胶成分，即二氧化硅（SiO2）和α-氧化铝（α-Al2O3）颗粒上的气态 H2O2 的非均相反应。研究发现，H2O2 分子吸附在 SiO2 上，由于其热不稳定性，少量的分子吸附 H2O2 会分解。对于α-Al2O3，H2O2 明显发生催化分解，但颗粒表面也有少量 H2O2 分子吸附。两种颗粒上 H2O2 的 BET 吸收系数似乎都不依赖于气态 H2O2 浓度（1.27-13.8 ppmv）和颗粒样品质量（2.8-6.5 mg 用于 SiO2 和 8.6-18.9 mg 用于α-Al2O3），但强烈依赖于相对湿度，范围从 2% RH 时的（1.55±0.14）×10（-8）和（1.21±0.04）×10（-7）到 76% RH 时的（0.61±0.06）×10（-8）和（0.76±0.09）×10（-7）。基于实验结果和文献数据，提出了 H2O2 非均相分解的潜在机制，并讨论了这些反应的大气影响。研究发现，H2O2 在两种矿物氧化物上的非均相反应在处理矿物气溶胶方面起着重要作用，尽管它作为环境 H2O2 的汇的作用可能有限。
