V.V. Voevodsky Institute of Chemical Kinetics and Combustion, 3 Institutskaya St., 630090 Novosibirsk, Russian Federation; Novosibirsk State University, 2 Pirogova St., 630090 Novosibirsk, Russian Federation.
Novosibirsk State University, 2 Pirogova St., 630090 Novosibirsk, Russian Federation; Nikolaev Institute of Inorganic Chemistry, 3 Acad. Lavrentiev Ave., 630090 Novosibirsk, Russian Federation.
Chemosphere. 2017 Aug;181:337-342. doi: 10.1016/j.chemosphere.2017.04.103. Epub 2017 Apr 24.
Photooxidation of As(III) in ternary As(III) - Fe(III) - Fulvic acid system at pH 4 was investigated by optical spectroscopy, steady-state photolysis (365 nm) and atomic-emission spectrometry with inductively coupled plasma techniques. It was found that at all values of [FA]/[Fe] ratio the main photoactive species is OH radical formed by photolysis of Fe(III) hydroxocomplexes. Addition of fulvic acid leads to mainly negative effect on As(III) photooxidation due to the following reasons: (i) slow dark reduction of photoactive Fe(III) species with formation of scattering particles and photoinert Fe(II) species; (ii) formation of photoreductive Fe(III)-FA complexes incapable to oxidize As(III), (iii) competition of both FA and Fe(III)-FA complexes for UVA quanta with FeOH complex and for OH radicals with As(III). Aging of ternary system is also very important parameter leading to one order decrease of quantum yields of both Fe(II) formation and As(III) photooxidation.
在 pH 4 的三元 As(III)-Fe(III)-腐殖酸体系中，通过光光谱、稳态光解（365nm）和原子发射光谱与电感耦合等离子体技术研究了 As(III)的光氧化。结果发现，在所有[FA]/[Fe]比值下，主要的光活性物质是由 Fe(III)羟络合物光解形成的 OH 自由基。腐殖酸的添加主要对 As(III)的光氧化产生负面影响，原因如下：（i）光活性 Fe(III)物种在暗还原过程中缓慢，形成散射颗粒和光惰性 Fe(II)物种；（ii）形成不能氧化 As(III)的光还原 Fe(III)-FA 配合物；（iii）FA 和 Fe(III)-FA 配合物与 FeOH 络合物竞争 UVA 量子，与 As(III)竞争 OH 自由基。三元体系的老化也是一个非常重要的参数，导致 Fe(II)形成和 As(III)光氧化的量子产率均降低一个数量级。
