Coupled Kinetics of Ferrihydrite Transformation and As(V) Sequestration under the Effect of Humic Acids: A Mechanistic and Quantitative Study,Environmental Science & Technology

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Coupled Kinetics of Ferrihydrite Transformation and As(V) Sequestration under the Effect of Humic Acids: A Mechanistic and Quantitative Study
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2018-10-03 , DOI: 10.1021/acs.est.8b03492
Shiwen Hu ₁ , Yang Lu ₁ , Lanfang Peng ₁ , Pei Wang ₁ , Mengqiang Zhu ₂ , Alice C. Dohnalkova ₃ , Hong Chen ₄ , Zhang Lin ₁ , Zhi Dang ₁ , Zhenqing Shi ₁

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In natural environments, kinetics of As(V) sequestration/release is usually coupled with dynamic Fe mineral transformation, which is further influenced by the presence of natural organic matter (NOM). Previous work mainly focused on the interactions between As(V) and Fe minerals. However, there is a lack of both mechanistic and quantitative understanding on the coupled kinetic processes in the As(V)–Fe mineral–NOM system. In this study, we investigated the effect of humic acids (HA) on the coupled kinetics of ferrihydrite transformation into hematite/goethite and sequestration of As(V) on Fe minerals. Time-resolved As(V) and HA interactions with Fe minerals during the kinetic processes were studied using aberration-corrected scanning transmission electron microscopy, chemical extractions, stirred-flow kinetic experiments, and X-ray absorption spectroscopy. Based on the experimental results, we developed a mechanistic kinetics model for As(V) fate during Fe mineral transformation. Our results demonstrated that the rates of As(V) speciation changes within Fe minerals were coupled with ferrihydrite transformation rates, and the overall reactions were slowed down by the presence of HA that sorbed on Fe minerals. Our kinetics model is able to account for variations of Fe mineral compositions, solution chemistry, and As(V) speciation, which has significant environmental implications for predicting As(V) behavior in the environment.

中文翻译：

腐殖酸作用下水铁矿转化和As（V）螯合的耦合动力学：机理和定量研究

在自然环境中，As（V）螯合/释放的动力学通常与动态的Fe矿物转化相关，这进一步受到天然有机物（NOM）的影响。先前的工作主要集中在As（V）和Fe矿物之间的相互作用。但是，对于As（V）-Fe矿物-NOM系统中的耦合动力学过程，缺乏机理和定量的理解。在这项研究中，我们调查了腐殖酸（HA）对水铁矿转变成赤铁矿/针铁矿和将As（V）螯合在Fe矿物上的耦合动力学的影响。使用像差校正扫描透射电子显微镜，化学提取，搅拌流动力学实验研究了动力学过程中时间分辨的As（V）和HA与Fe矿物的相互作用。和X射线吸收光谱。根据实验结果，我们建立了Fe矿物转化过程中As（V）命运的力学动力学模型。我们的结果表明，Fe矿物中As（V）形态变化的速率与水铁矿转化速率有关，并且由于吸附在Fe矿物上的HA的存在，使整体反应变慢了。我们的动力学模型能够解释铁矿物质组成，溶液化学和As（V）形态的变化，这对于预测环境中的As（V）行为具有重要的环境意义。我们的结果表明，Fe矿物中As（V）形态变化的速率与水铁矿转化速率有关，并且由于吸附在Fe矿物上的HA的存在，使整体反应变慢了。我们的动力学模型能够解释铁矿物质组成，溶液化学和As（V）形态的变化，这对于预测环境中的As（V）行为具有重要的环境意义。我们的结果表明，Fe矿物中As（V）形态变化的速率与水铁矿转化速率有关，并且由于吸附在Fe矿物上的HA的存在，使整体反应变慢了。我们的动力学模型能够解释铁矿物质组成，溶液化学和As（V）形态的变化，这对于预测环境中的As（V）行为具有重要的环境意义。

更新日期：2018-10-04

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