Overlooked encounter process that affects physical behaviors of stabilized nanoscale zero-valent iron during in situ groundwater remediation

Yujie Xie; Miaoyue Zhang; Lihang Ma; Ting Du; Dan Zhou; Ming-Lai Fu; Baoling Yuan; Xiao-Yan Li; Yi-Bo Hu

doi:10.1016/j.jhazmat.2023.132547

Overlooked encounter process that affects physical behaviors of stabilized nanoscale zero-valent iron during in situ groundwater remediation

J Hazard Mater. 2024 Jan 5:461:132547. doi: 10.1016/j.jhazmat.2023.132547. Epub 2023 Sep 12.

Authors

Yujie Xie¹, Miaoyue Zhang², Lihang Ma¹, Ting Du¹, Dan Zhou³, Ming-Lai Fu¹, Baoling Yuan⁴, Xiao-Yan Li⁵, Yi-Bo Hu⁶

Affiliations

¹ Xiamen Key Laboratory of Municipal and Industrial Solid Waste Utilization and Pollution Control, College of Civil Engineering, Huaqiao University, Xiamen, Fujian 361021, China.
² School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510006, China.
³ College of Ecology and Environment, Chengdu University of Technology, Chengdu 610059, China.
⁴ Key Laboratory of Songliao Aquatic Environment, Ministry of Education, Jilin Jianzhu University, Changchun 130118, China.
⁵ Environmental Engineering Research Centre, Department of Civil Engineering, The University of Hong Kong, Pokfulam, Hong Kong Special Administrative Region; Tsinghua-Berkeley Shenzhen Institute, Tsinghua University, Shenzhen 518055, China.
⁶ Xiamen Key Laboratory of Municipal and Industrial Solid Waste Utilization and Pollution Control, College of Civil Engineering, Huaqiao University, Xiamen, Fujian 361021, China. Electronic address: hybhqu@hqu.edu.cn.

PMID: 37717448
DOI: 10.1016/j.jhazmat.2023.132547

Abstract

Dynamic encountering between groundwater matrices and nanoscale zero-valent iron (NZVI) injected for in situ subsurface remediation affects NZVI's mobility and has not been well recognized. Polyacrylic acid (PAA)-stabilized NZVI (NZVI-PAA) and Mg(OH)₂-coated NZVI (NZVI@Mg(OH)₂) were investigated as representative NZVIs stabilized by enhanced electrostatic repulsion and reduced magnetic attraction, respectively. Encounters with divalent cations and humic acid (HA) induced the drastic aggregation and sedimentation (presedimentation) of NZVI-PAA owing to Lewis acid-base interactions and heteroaggregation. In addition, encountered groundwater electrolytes could not effectively provide electrostatic repulsion for NZVI-PAA, resulting in breakthrough ripening dynamics. The presedimentation and ripening behaviors of NZVI-PAA were eliminated and unheeded after mixing the NZVI slurry with groundwater by sonication. In comparison, the encountering process barely impacted NZVI@Mg(OH)₂, for which settling was hindered. Although the particle-collector attraction promoted NZVI@Mg(OH)₂ adsorption on pristine and hybrid-coated sands, the Langmuirian blocking dynamics of the NZVI@Mg(OH)₂ breakthrough demonstrated its high mobility after adsorption sites of sand surface were exhausted. Extended Derjaguin-Landau-Verwey-Overbeek analysis and transport modeling provided insights into overlooked effects of encountering on physical behaviors of different stabilized NZVIs, which should be considered during practical applications under diverse subsurface conditions.

Keywords: Langmuirian blocking; Mobility; Modification; Nanoscale zero-valent iron; Ripening; Sedimentation.