| 湖泊水体中铁(Ⅲ)-草酸络合物驱动有机磷光解释放磷酸根 |
| 摘要点击 1858 全文点击 632 投稿时间：2016-07-05 修订日期：2016-09-08 |
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| 中文关键词 有机磷 草甘膦 Fe(Ⅲ)-草酸络合物 光解 羟基自由基 |
| 英文关键词 organic phosphorus glyphosate Fe(Ⅲ)-oxalate complex photolysis hydroxyl radicals |
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| 中文摘要 |
| 湖泊水体中的有机磷光解释放无机磷对水柱中磷水平具有重要的影响.为了解湖泊水体中的有机磷光解释放无机磷对水柱中磷水平的影响，本文以广泛使用的草甘膦为对象，探讨了自然湖水中草甘膦在Fe（Ⅲ）-草酸络合物光化学作用下的形态转化过程，并研究了水环境因素如铁、草酸盐浓度配比、溶液pH和底物浓度对释放无机磷的影响.结果表明，紫外光和太阳光照射下，Fe（Ⅲ）-草酸络合物均可以实现草甘膦转化为无机磷.紫外光照射60 min和太阳光照射720 min后，反应体系中的磷酸根浓度分别增至0.25 mg·L-1和0.18 mg·L-1.磷酸根释放量随着草甘膦浓度的升高而增大，且增加反应体系中的Fe（Ⅲ）或草酸盐的浓度都可以提高磷酸根的释放量，但反应体系pH的升高则显著抑制这一过程.在反应体系中添加异丙醇，降低了磷酸根的释放量，证实羟基自由基（·OH）是Fe（Ⅲ）-草酸络合体系中的主要活性氧物种.采用以香豆素为·OH分子探针，确定了紫外光/Fe（Ⅲ）-草酸体系和太阳光/Fe（Ⅲ）-草酸体系中·OH的产生速率分别为0.52×10-2 μmol·（L·min）-1和0.03×10-2 μmol·（L·min）-1，其稳态浓度分别为4.74×10-16 mol·L-1和0.27×10-16 mol·L-1. |
| 英文摘要 |
| The phosphate released from organic phosphorus photo-decomposition has a significantly influence on the phosphorus levels in the water column in lakes. In order to reveal the effect of organic phosphorus photo-decomposition on phosphate level in lake water, the phosphate released from organic phosphorus photo-decomposition driven by Fe(Ⅲ)-oxalate complex under UV-Vis and sunlight irradiation was investigated in natural lake water using glyphosate as the model organic phosphorus. The effects of pH and initial concentration of Fe(Ⅲ), oxalate and glyphosate on the phosphate released from glyphosate photolysis were studied. The results showed that phosphate could be released from glyphosate degradation by Fe(Ⅲ)-oxalate complex under UV-Vis and sunlight irradiation. The concentration of phosphate reached 0.25 mg·L-1 and 0.18 mg·L-1 under UV-Vis and sunlight irradiation for 60 and 720 min, respectively. The amount of phosphate released increased with the increase of the initial concentration of Fe(Ⅲ), as well as the increasing oxalate and glyphosate concentration in lake water. However, the increase of pH could significantly inhibit this process in the reaction system. The concentration of phosphorus decreased with the addition of isopropanol, which indicated that the hydroxyl radical (·OH) was one of the main active oxygen species of Fe(Ⅲ)-oxalate complex. The rates of·OH production for Fe(Ⅲ)-oxalate/UV-Vis and Fe(Ⅲ)-oxalate/sunlight systems were 0.52×10-2 μmol·(L·min)-1 and 0.03×10-2 μmol·(L·min)-1, respectively. The steady-state concentrations of hydroxyl radical (·OH) for the Fe(Ⅲ)-oxalate/UV-Vis conditions were 4.74×10-16 mol·L-1 and 0.27×10-16 mol·L-1 for the Fe(Ⅲ)-oxalate/sunlight system. |
