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Title: Coupled Kinetics of Ferrihydrite Transformation and As(V) Sequestration under the Effect of Humic Acids: A Mechanistic and Quantitative Study

Abstract

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. In conclusion, 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 inmore » the environment.« less

Authors:
 [1];  [1];  [1];  [1]; ORCiD logo [2];  [3]; ORCiD logo [4]; ORCiD logo [1];  [1]; ORCiD logo [1]
  1. South China Univ. of Technology, Guangdong (People's Republic of China)
  2. Univ. of Wyoming, Laramie, WY (United States)
  3. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  4. Stanford Univ., Menlo Park, CA (United States)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1490874
Grant/Contract Number:  
AC02-76SF00515; 41573090; 2016ZT06N569
Resource Type:
Accepted Manuscript
Journal Name:
Environmental Science and Technology
Additional Journal Information:
Journal Volume: 52; Journal Issue: 20; Journal ID: ISSN 0013-936X
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES

Citation Formats

Hu, Shiwen, Lu, Yang, Peng, Lanfang, Wang, Pei, Zhu, Mengqiang, Dohnalkova, Alice C., Chen, Hong, Lin, Zhang, Dang, Zhi, and Shi, Zhenqing. Coupled Kinetics of Ferrihydrite Transformation and As(V) Sequestration under the Effect of Humic Acids: A Mechanistic and Quantitative Study. United States: N. p., 2018. Web. doi:10.1021/acs.est.8b03492.
Hu, Shiwen, Lu, Yang, Peng, Lanfang, Wang, Pei, Zhu, Mengqiang, Dohnalkova, Alice C., Chen, Hong, Lin, Zhang, Dang, Zhi, & Shi, Zhenqing. Coupled Kinetics of Ferrihydrite Transformation and As(V) Sequestration under the Effect of Humic Acids: A Mechanistic and Quantitative Study. United States. doi:10.1021/acs.est.8b03492.
Hu, Shiwen, Lu, Yang, Peng, Lanfang, Wang, Pei, Zhu, Mengqiang, Dohnalkova, Alice C., Chen, Hong, Lin, Zhang, Dang, Zhi, and Shi, Zhenqing. Wed . "Coupled Kinetics of Ferrihydrite Transformation and As(V) Sequestration under the Effect of Humic Acids: A Mechanistic and Quantitative Study". United States. doi:10.1021/acs.est.8b03492. https://www.osti.gov/servlets/purl/1490874.
@article{osti_1490874,
title = {Coupled Kinetics of Ferrihydrite Transformation and As(V) Sequestration under the Effect of Humic Acids: A Mechanistic and Quantitative Study},
author = {Hu, Shiwen and Lu, Yang and Peng, Lanfang and Wang, Pei and Zhu, Mengqiang and Dohnalkova, Alice C. and Chen, Hong and Lin, Zhang and Dang, Zhi and Shi, Zhenqing},
abstractNote = {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. In conclusion, 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.},
doi = {10.1021/acs.est.8b03492},
journal = {Environmental Science and Technology},
number = 20,
volume = 52,
place = {United States},
year = {2018},
month = {9}
}

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Figures / Tables:

Figure 1 Figure 1: Kinetics of (a) hematite and goethite formation, (b) As(V) partitioning, and (c) HA distribution during the Fe mineral transformation kinetic experiments. % As(V) and HA distribution was calculated based on the total As(V) and HA added in the kinetic experiments

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Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.