组内消息
2014-12-01
结合原位漫反射红外傅里叶变换光谱(DRIFTS)与离子色谱(IC)技术确立了一种测定吸附系数真值的方法。
摘要：氧化镁(MgO)是大气中矿物气溶胶的重要组分之一, 对二次污染物的形成有着重要影响. 本研究采用原位漫反射红外傅里叶变换光谱(DRIFTS)与离子色谱(IC)技术, 研究了二氧化氮(NO2)在MgO颗粒表面的非均相反应. 探讨了无光照、紫外光照、臭氧(O3)、温度及相对湿度(RH)等对该反应的影响机制, 建立了新的测定摄取系数的方法. 结果表明, 无光照时, NO2在MgO颗粒表面生成的主要产物为硝酸盐和亚硝酸盐; 在NO2-MgO-O3和NO2-MgO-hn两种反应体系中主要产物均为硝酸盐, 生成的硝酸根峰面积分别是无光照条件下的1.54倍和3.04倍, O3和紫外光照对硝酸盐的生成均具有促进作用; 在紫外光照条件下, NO2在MgO颗粒物表面生成硝酸根的初始速率随温度的升高而呈单峰变化, 40℃时初始速率最大; 影响NO2与MgO颗粒物反应的敏感因素为紫外光照和臭氧, 其次为相对湿度和温度. 在25℃, RH为5%时, 无光照条件和紫外光照条件下反应初始摄取系数分别为9.01×10-4和5.65×10-3.
韩力慧, 陈媛媛, 贾龙, 程水源, 徐永福,等. NO2在MgO颗粒物表面的非均相反应. 中国科学 化学, 2014, 44(12),2004-2012
Heterogeneous reactions of NO2 on the surface of MgO particles
Abstract：MgO is one of the most important components of mineral aerosol, and it has an important influence on the formation of secondary pollutants. The heterogeneous reaction of NO2 on MgO particles was studied using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and ion chromatography (IC). The influences of no ultraviolet radiation(UV), ultraviolet radiation(UV), ozone (O3), temperature and relative humidity (RH) on the reaction were investigated. A new method has firstly been established to determine uptake coefficients. The main products from the heterogeneous reaction of NO2 on MgO particles were nitrate and nitrite without UV. In NO2-MgO-O3 and NO2-MgO-hv reaction systems, the main product was nitrate, and its infrared adsorption peak areas were 1.54 and 3.04 times higher than that without UV, respectively. O3 and UV were in favor of the formation of nitrate. The initial rate of nitrate, due to the rise of temperature, showed a unimodal pattern with the maximum initial rate at 40℃ under UV. More sensitive factors affecting the reaction of NO2 on MgO particles are UV and ozone, followed by relative humidity and temperature. The initial reactive uptake coefficients of NO2 on MgO particles were determined to be 9.01×10-4 without UV and 5.65×10-3 with UV at 25℃ and 5% RH.
HAN LiHui, CHEN YuanYuan, JIA Long, CHENG ShuiYuan, XU YongFu,et al. Heterogeneous reactions of NO2 on the surface of MgO particles. Scientia Sinica Chimica, 2014, 44(12),2004-2012.
组内消息
2014-01-13
结合光化学烟雾箱实验与数值模拟研究了苯和乙苯在NOx存在条件下的光氧化臭氧生成潜势. 重复实验表明，在乙苯-NOx反应体系中，反应物初始浓度、温度、湿度和光照强度接近的条件下，整个反应过程中臭氧的最大偏差仅为4%，证明了烟雾箱的可重复性较高. 在烟雾箱实验的基础上，使用MCM （master chemical mechanism）模拟了苯和乙苯的光氧化O3生成，并将其结果与实验数据进行了比对分析. 干燥（≤5%）时MCM对苯和乙苯的模拟结果与实验结果较接近，如在苯-NOx反应体系中，MCM模拟的O3峰值比实验值偏大20%；在湿度为5%~70%时，MCM模拟的乙苯光氧化O3峰值与实验值偏高约（10%~25%）. 用MCM模拟了太阳光照条件下苯和乙苯的臭氧生成等值线，得到在它们浓度为（10~50）×10-9，NOx在（10~100）×10-9时，苯和乙苯的6 h臭氧贡献值分别为（3.1~33）×10-9和（2.6~122）×10-9，臭氧峰值范围分别是（3.5~54）×10-9和（3.8~164）×10-9. 此外，模拟得到苯和乙苯的最大增量反应活性（maximum incremental reactivity，MIR）值分别为0.25/C和0.97/C （每单位碳）. 该结果与Carter通过SAPRC机制得到的MIR值趋势一致. 模拟得到苯和乙苯的最大臭氧反应活性（maximum ozone reactivity，MOR）分别为0.73/C和1.03/C. 苯的MOR值远高于Carter使用SAPRC得到的结果，说明根据Carter得到的苯MOR会低估苯的O3潜势.
贾龙, 徐永福. 烟雾箱与数值模拟研究苯和乙苯的臭氧生成潜势. 环境科学, 2014,35(2):495~503 全文下载
Studies of ozone formation potentials for benzene and ethylbenzene using a smog chamber and model simulation
Jia Long,Xu Yong fu
Ozone formation potentials from irradiations of benzene-NOx and ethylbenzene-NOx systems under the conditions of different VOC/NOx ratios and RH were investigated using a characterized chamber and model simulation. The repeatability of the smog chamber experiment shows that for two sets of ethylbenzene-NOx irradiations with similar initial concentrations and reaction conditions, such as temperature, relative humidity and relative light intensity, the largest difference in O3 between two experiments is only 4% during the whole experimental run. On the basis of smog chamber experiments, ozone formation of photo-oxidation of benzene and ethylbenzene was simulated in terms of the master chemical mechanism (MCM). The peak ozone values for benzene and ethylbenzene simulated by MCM are higher than the chamber data, and the difference between the MCM-simulated results and chamber data increases with increasing RH. Under the conditions of sunlight irradiations, with benzene and ethylbenzene concentrations being in the range of (10-50)×10-9 and NOx concentrations in the range of (10-100)×10-9, the 6 h ozone contributions of benzene and ethylbenzene were obtained to be (3.1-33)×10-9 and (2.6-122)×10-9, whereas the peak O3 contributions of benzene and ethylbenzene were (3.5-54)×10-9 and (3.8-164)×10-9, respectively. The MCM-simulated maximum incremental reactivity (MIR) values for benzene and ethylbenzene were 0.25/C and 0.97/C (per carbon), respectively. The maximum ozone reactivity (MOR) values for these two species were obtained to be 0.73/C and 1.03/C, respectively. The MOR value of benzene from MCM is much higher than that obtained by carter from SAPRC, indicating that SAPRC may underestimate the ozone formation potential of benzene.
组内消息
2011-12-14
12月3日至6日，徐永福 课题组成员贾龙与黄丽华参加了在杭州举办的第18届中国大气环境科学与技术大会，并分别作了“苯、甲苯与乙苯的光氧化臭氧生成活性”与“烟雾箱模拟研究丙烷-NOx光氧化反应体系”的报告。通过和与会专家同行的深入交流，了解了烟雾箱在大气环境研究中的基础作用以及最新进展，并了解了大气环境科学目前遇到的机遇与挑战。
