Tao Liang, Wang Shan-Li, Li Fang-Bai, Yu Nin-Ya, Wu Ke
Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Guangdong Institute of Eco-environmental Science & Technology Guangzhou 510650 P. R. China
Department of Agricultural Chemistry, National Taiwan University Taipei 10617 Taiwan Republic of China.
RSC Adv. 2018 Feb 15;8(14):7465-7472. doi: 10.1039/c7ra13201h. eCollection 2018 Feb 14.
In a natural environment, Fe(ii) adsorbed onto the surfaces of natural particles to form various surface complex species can influence the transformation of contaminants. The reductive reactivity of the [[triple bond, length as m-dash]Fe(iii)]/[[triple bond, length as m-dash]Fe(ii)] couples are close correlated with the surrounding conditions. In this study, we investigated the effects of Si(iv) on the reductive reactivity of [[triple bond, length as m-dash]Fe(iii)]/[[triple bond, length as m-dash]Fe(ii)] couples adsorbed onto γ-AlO. Experiments were conducted under different conditions to investigate the effects of Si(iv) on the reactivity of [[triple bond, length as m-dash]Fe(iii)]/[[triple bond, length as m-dash]Fe(ii)] couples for 2-nitrophenol (2-NP, selected as the model pollutant) reduction in γ-AlO suspensions. Kinetics results revealed that chemical adsorption is the rate limiting step in Fe(ii) and Si(iv) adsorption processes and the reduction of 2-NP is an endothermic reaction. The linear correlations between the reduced peak oxidation potential ( ) ( SCE) and 2-NP reduction rate (ln ), and between the adsorbed Fe(ii) density ( ) and ln , illustrated that and are two key factors in the inhibiting effects of Si(iv) on the reductive reactivity of Fe(iii)/Fe(ii) couples on γ-AlO. The results of Fe -edge X-ray absorption spectroscopy revealed that the increase of Si(iv) concentration resulted in the gradual change in the composition of the adsorbed Fe species from pure [triple bond, length as m-dash]AlOFe (γ-AlO surface-bound Fe(ii) species with higher reductive reactivity) to a mixture of [triple bond, length as m-dash]AlOFe and [triple bond, length as m-dash]SiOFe (SiO surface-bound Fe(ii) species with lower reductive reactivity), leading to the decrease in , the positive shift in , the increase in activation energy ( ), and consequently the decrease in the reduction rate (ln ) of 2-NP.
在自然环境中，吸附在天然颗粒表面形成各种表面络合物的二价铁（Fe(ii)）会影响污染物的转化。[三键，长度用m破折号表示]铁（iii）]/[三键，长度用m破折号表示]铁（ii）]电对的还原反应活性与周围环境密切相关。在本研究中，我们研究了硅（iv）对吸附在γ - 氧化铝上的[三键，长度用m破折号表示]铁（iii）]/[三键，长度用m破折号表示]铁（ii）]电对还原反应活性的影响。在不同条件下进行实验，以研究硅（iv）对γ - 氧化铝悬浮液中[三键，长度用m破折号表示]铁（iii）]/[三键，长度用m破折号表示]铁（ii）]电对还原2 - 硝基苯酚（2 - NP，选为模型污染物）反应活性的影响。动力学结果表明，化学吸附是二价铁和硅（iv）吸附过程中的速率限制步骤，2 - NP的还原是一个吸热反应。还原峰氧化电位（）（对饱和甘汞电极）与2 - NP还原速率（ln）之间以及吸附的二价铁密度（）与ln之间的线性相关性表明，和是硅（iv）对γ - 氧化铝上铁（iii）/铁（ii）电对还原反应活性抑制作用的两个关键因素。铁边X射线吸收光谱结果表明，硅（iv）浓度的增加导致吸附的铁物种组成从纯的[三键，长度用m破折号表示]AlOFe（具有较高还原反应活性的γ - 氧化铝表面结合的二价铁物种）逐渐变为[三键，长度用m破折号表示]AlOFe和[三键，长度用m破折号表示]SiOFe（具有较低还原反应活性的SiO表面结合的二价铁物种）的混合物，导致降低，正移，活化能（）增加，进而导致2 - NP的还原速率（ln）降低。
