The mechanisms and monitoring of zeolite remediating chemical oxygen demand, NH4+, and Pb2+

Author(s)
Bate Bate, Jianshe Ye, Junnan Cao, Yuqing You, Jingjing Cao, Shuai Zhang, Liang-Tong Zhan, Chi Zhang, Na Hao
Abstract

Zeolite is utilized as an effective filling material in a permeable reactive barrier (PRB) at contaminated sites. Evaluation of the long-term performance of such barrier demands thorough understanding of the remediation mechanisms and real-time monitoring technique. In this study, the processes of zeolite remediation of three typical major contaminants from municipal solid waste sites (Chemical Oxygen Demand (COD), NH

4

+, and Pb

2+, respectively) were simulated with column test, analyzed with microscopic methods (MIP, BET, SEM, XPS, FTIR, and XRD) and monitored with the spectral induced polarization (SIP) technique. Zeolite remediates COD simulant, KC

8H

5O

4, through cation exchange of K

+ and surface complexation of C

8H

5O

4

−. Patchy distribution of K

+ with size range of 16–60 μm was both observed and calculated from the peak frequency of imaginary conductivity of SIP responses, which was attributed to the preferential complexation of C

8H

5O

4

− at low velocity regions (dents) on zeolite surfaces. Zeolite remediates NH

4

+ mainly through ion exchange due to the higher affinity of NH

4

+ to zeolite surfaces than that of Na

+. Zeolite remediates Pb

2+ mainly through surface complexation, with clusters of complexed Pb (II) of wide size range (a few μm to 25 μm) residing on zeolite particle surfaces. The real conductivity of SIP responses for zeolite under contaminant flow-through is primarily sensitive to the ionic strength of influx fluid. A mean size of near 270 μm was calculated from SIP responses in all three cases, which was attributed to the pore throat of zeolite. Spectral induced polarization demonstrated its capability of monitoring three processes of zeolite remediating COD, NH

4

+, and Pb

2+, respectively, and held promise of non-invasively monitoring of long-term performance of contaminant containing barriers.

Organisation(s)
Department of Meteorology and Geophysics
External organisation(s)
Zhejiang University (ZJU), Georgia Southern University
Journal
Journal of Applied Geophysics
Volume
199
ISSN
0926-9851
DOI
https://doi.org/10.1016/j.jappgeo.2022.104615
Publication date
2022
Peer reviewed
Yes
Austrian Fields of Science 2012
105906 Environmental geosciences
Keywords
ASJC Scopus subject areas
Geophysics
Portal url
https://ucrisportal.univie.ac.at/en/publications/bd971813-ed4f-4585-8cab-539901009d3b