• 关键词：腐殖酸  光化学反应  单线态氧  量子产率  影响因素

• 基金项目：国家水体污染控制与治理科技重大专项项目(No.2012ZX07103-002);国家自然科学基金项目(No.41271462,41030529)

• 白泽琳
• 北京大学城市与环境学院, 地表过程分析与模拟教育部重点实验室, 北京 100871

• 何伟
• 北京大学城市与环境学院, 地表过程分析与模拟教育部重点实验室, 北京 100871

• 李一龙
• 北京大学城市与环境学院, 地表过程分析与模拟教育部重点实验室, 北京 100871

• 刘文秀
• 北京大学城市与环境学院, 地表过程分析与模拟教育部重点实验室, 北京 100871

• 杨晨
• 北京大学城市与环境学院, 地表过程分析与模拟教育部重点实验室, 北京 100871

• 徐福留
• 北京大学城市与环境学院, 地表过程分析与模拟教育部重点实验室, 北京 100871

• 摘要：研究了腐殖酸浓度、pH、温度和光照强度对光诱导腐殖酸产生单线态氧潜力的影响,并对腐殖酸紫外-可见光谱特征E2:E3与单线态氧量子产率的关系进行了分析.结果表明:腐殖酸浓度增加会促进单线态氧的产生,pH是腐殖酸产生单线态氧的重要影响因素,单线态氧平衡浓度([¹O₂]_ss)在pH=7时最高,随酸(或碱)性增强而减小;在模拟的实际环境温度(1.5、5、10、15和25℃)中,[¹O₂]_ss随绝对温度值(K)升高呈增长趋势,但在283K(10℃)后趋于平衡;光照强度增大对[¹O₂]_ss具有促进作用;在氙灯模拟日光照射实验中,最小(0.8×10⁴lux)和最大(15.5×10⁴lux)光强下[¹O₂]_ss值相差一个数量级.单线态氧量子产率与腐殖酸的E2:E3值呈显著正相关,这可能与腐殖酸中小分子芳香族在光敏化过程中能量转移效率更高有关.综上可推测夏季(温度高和光照强度大)更有利于水环境中腐殖酸类溶解性有机质产生活性氧物质,促进对有机污染物的光降解.

• Abstract：The determining factors (including concentration of humic acid, pH, temperature and light intensity),for singlet oxygen production through photochemical reaction in humic acid solutions were studied. The correlation between optical properties of humic acid and quantum yield of singlet oxygen was also discussed. The results show that the increase of humic acid concentration will promote the production of singlet oxygen. The pH value was one of the crucial factors in the photochemical reaction. The singlet oxygen steady-state concentration ([¹O₂]_ss) was found highest in humic acid solution at pH=7 and decreased as the increase of acidity or alkalinity. In simulated actual temperature range of aqueous environment (1.5, 5, 10, 15, and 25 ℃), [¹O₂]_ss had an increasing tendency with the increase of temperature, but approached to an equilibrium after 283 K (10 ℃). Light intensity had obviously positive impacts on the photochemical reaction. Under the situation of simulated sunlight using xenon lamps, an order of magnitude difference of [¹O₂]_ss was found between the lowest (0.8×10⁴ lux) and the highest (15.5×10⁴ lux) light intensity. Quantum yields of singlet oxygen were found to be significantly correlated with E2:E3(p<0.01), indicating that aromatic substances with low molecular weight in humic acid have higher efficiency in energy-transfer process and producing singlet oxygen. In summary, on the base of above results, it can be speculated that summer (high temperature and light intensity) is more favorable for the production of reactive oxygen species by the dissolved organic matters and thus promote the photo-degradation of organic pollutants.

• Key words：humic acid  photochemical reaction  singlet oxygen  quantum yield  influencing factors

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