摘要
采用实验室模拟的方法研究了高压汞灯模拟日光照射下铁()-二元有机酸盐配合物在天然海水中的光化学反应.结果发现,在二元有机酸盐配体的存在下,铁()发生光化学反应生成还原态的铁(),铁()会被溶液中的氧再氧化为铁().铁()的光还原反应速率受到配体浓度、pH、光强以及温度的影响.在二元有机酸与Fe()浓度配比大于2的情况下,Fe()-二元有机酸盐配合物的光还原反应初期铁()浓度的增长符合一级动力学反应规律,100min后浓度趋于稳定,方程式为[Fe()]t=kOA[OA]·[Fe()]ini×[1-exp{-(kOA[OA]+kox)t}]/(kOA[OA]+kox).光强升高和pH降低都能加快光还原反应速率,而改变温度则基本上对光还原反应速率无影响,证明铁()的光还原反应为自由基引发的电子转移过程.
The study on the photochemical reaction of Fe （ Ⅲ ）-organic acid complex in seawater was carried out by exposing the reaction solution to a high pressure lamp under different experimental conditions. The photo-reduction rate constants of Fe （ Ⅲ ） were affected by various factors including organic acid （OA） concentration, pH, light intensity and temperature. When the molar ratio of organic acid to Fe（ Ⅲ ） was above 2, the photo-reduction reaction of Fe （ Ⅲ） exhibited a first-order reaction kinetic pattern at the initial stage, and remained nearly stable after 100 min, which could be described by the equation： [Fe（Ⅲ）]t=kOA[OA][Fe（Ⅲ）]ini×[1-exp{-（kOA[OA]＋kox）t}]／（kOA[OA]＋kox）. At near pH=7, the activity of organic acids examined declined by the sequence below： tartaric acid〉adipic acid〉succinic acid〉malic acid〉malonic acid. Increase of irradiation intensity and decrease of pH value could enhance the photo-reduction rate of Fe（ Ⅲ ）. On the contrary, when the temperature varied, the photo-reduction rate remained unchanged, which proved that the process of photo-reduction of Fe （ Ⅲ ） was a ligand-to-metal chargetransfer process.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
2005年第8期1532-1536,共5页
Chemical Journal of Chinese Universities
基金
国家自然科学基金(批准号:40176023)资助.
关键词
铁(Ⅲ)
二元酸盐配合物
有机酸
氧化还原
自由基
光化学反应
海水
Fe （ Ⅲ ）
Binary acid salt complex
Organic acid
Redox reaction
Free radical
Photochemical reaction
Seawater
