Effects of soil colloids on the aggregation and degradation of engineered nanoparticles (Ti3C2Tx MXene)

Dan Zhou; Mengmeng Liang; Xingyue Bao; Tiezhu Sun; Yi Huang

doi:10.1016/j.envres.2022.113886

Effects of soil colloids on the aggregation and degradation of engineered nanoparticles (Ti₃C₂T_x MXene)

Environ Res. 2022 Nov;214(Pt 1):113886. doi: 10.1016/j.envres.2022.113886. Epub 2022 Jul 12.

Authors

Dan Zhou¹, Mengmeng Liang², Xingyue Bao², Tiezhu Sun², Yi Huang³

Affiliations

¹ State Environmental Protection Key Laboratory of Synergetic Control and Joint Remediation for Soil & Water Pollution, College of Ecology and Environment, Chengdu University of Technology, Chengdu 610059, China; State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu 610059, China.
² State Environmental Protection Key Laboratory of Synergetic Control and Joint Remediation for Soil & Water Pollution, College of Ecology and Environment, Chengdu University of Technology, Chengdu 610059, China.
³ State Environmental Protection Key Laboratory of Synergetic Control and Joint Remediation for Soil & Water Pollution, College of Ecology and Environment, Chengdu University of Technology, Chengdu 610059, China; State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu 610059, China. Electronic address: huangyi@cdut.cn.

PMID: 35839912
DOI: 10.1016/j.envres.2022.113886

Abstract

Soil colloid is a nonnegligible factor when evaluating the environmental risk of engineered nanoparticles (ENPs) in the groundwater. In this study, the environmental fate of an emerging ENP (Ti₃C₂T_x MXene) in the groundwater was investigated for the first time, which currently poses a severe environmental risk due to its cytotoxicity but has received little attention. The colloidal dispersion stability and degradation kinetics of Ti₃C₂T_x MXene in the groundwater were evaluated by considering the effects of soil colloids prepared from sodium humate (SH), montmorillonite (MT), and a natural soil (NS) under variable solution chemistry. The results showed that the affinity of soil colloids with Ti₃C₂T_x followed an SH > MT > NS sequence. Increasing SH concentration led to Ti₃C₂T_x disaggregation by enhancing the electrical and steric repulsive forces, while MT and NS resulted in hetero-aggregation because of the elevated collision frequency. SH and MT enhanced the critical coagulation concentrations of Ti₃C₂T_x by 100 and 10 folders, respectively, via surface coating process, while NS slightly reduced due to the bridging effects induced by the soluble cations. The soil colloids promoted Ti₃C₂T_x degradation compared with their absence and in an SH > MT ≫ NS sequence. SH and MT were through forming Ti-O-C and Si-O-Ti bonds with Ti₃C₂T_x via their carboxyl and hydroxyl groups, respectively, rendering the Ti₃C₂T_x surface more reactive and faster degradation. NS showed a weak promotion effect because of its less affinity with Ti₃C₂T_x and limited organic matter and clay contents with hydroxyl and carboxyl groups. This study demonstrated the unstable environmental behaviors of Ti₃C₂T_x in the groundwater and mitigated its environmental risk concerns.

Keywords: Degradation; Dispersion stability; Montmorillonite; Natural soil; Sodium humate.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Clay
Colloids
Nanoparticles*
Soil*
Titanium

Substances

Colloids
Soil
Titanium
Clay