Comparison of reactive magnesia, quick lime, and ordinary Portland cement for stabilization/solidification of heavy metal-contaminated soils
Stabilization/solidification (S/S) is commonly applied to treat heavy metal-contaminated soils through the use of lime and ordinary Portland cement (OPC). Recently, reactive magnesia (MgO) has emerged as a novel binder for S/S of heavy metal-contaminated soils; however, a comprehensive comparison be...
| Main Authors: | , , |
|---|---|
| Other Authors: | |
| Format: | Journal Article |
| Language: | English |
| Published: |
2020
|
| Subjects: | |
| Online Access: | https://hdl.handle.net/10356/143636 |
| _version_ | 1811695869406216192 |
|---|---|
| author | Li, Wentao Ni, Pengpeng Yi, Yaolin |
| author2 | School of Civil and Environmental Engineering |
| author_facet | School of Civil and Environmental Engineering Li, Wentao Ni, Pengpeng Yi, Yaolin |
| author_sort | Li, Wentao |
| collection | NTU |
| description | Stabilization/solidification (S/S) is commonly applied to treat heavy metal-contaminated soils through the use of lime and ordinary Portland cement (OPC). Recently, reactive magnesia (MgO) has emerged as a novel binder for S/S of heavy metal-contaminated soils; however, a comprehensive comparison between MgO, lime (CaO), and OPC for S/S application is still missing. This study compares the S/S efficiency of MgO, CaO, and OPC for soils contaminated by six individual heavy metals (Pb, Cu, Zn, Ni, Cd, and Mn) through unconfined compressive strength (UCS) test, one stage batch leaching test, and microstructural analysis. The addition of binders can transform soluble heavy metal salts to insoluble hydroxides and their complexes, and hence the leachability of heavy metals decreases. However, the level, to which the leachability can be reduced, is highly pH dependent. Contaminated soils treated with MgO have pH of 9–10.5, at which the leachability of Pb and Zn is much lower than that of OPC- or CaO-treated soils with pH of 10.5–13; for example, the leached Pb and Zn from MgO-treated soils are only 0.1%–3.3% and 0.1%–9.4% of those from OPC-treated soils, respectively. On the other hand, the leached Cd and Mn from OPC-treated soils are 0.1%–28.5% and 0.1–10.7% of those from MgO-treated soils, respectively, due to the high pH and the formation of calcium silicate hydrate (CSH) in OPC-treated soils. OPC and CaO are more effective than MgO in decreasing the Ni leachability at high original concentrations, but less effective at low original concentrations. For all soils except those contaminated by Zn, the OPC generally produces a much higher UCS, up to two orders of magnitude, than the CaO and MgO. The results of study indicate that no single binder can treat all types of heavy metal-contaminated soils perfectly, and the selection of binder is a site-specific problem. |
| first_indexed | 2024-10-01T07:30:19Z |
| format | Journal Article |
| id | ntu-10356/143636 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T07:30:19Z |
| publishDate | 2020 |
| record_format | dspace |
| spelling | ntu-10356/1436362022-05-25T02:08:19Z Comparison of reactive magnesia, quick lime, and ordinary Portland cement for stabilization/solidification of heavy metal-contaminated soils Li, Wentao Ni, Pengpeng Yi, Yaolin School of Civil and Environmental Engineering Engineering::Environmental engineering Stabilization/solidification Contaminated Soil Stabilization/solidification (S/S) is commonly applied to treat heavy metal-contaminated soils through the use of lime and ordinary Portland cement (OPC). Recently, reactive magnesia (MgO) has emerged as a novel binder for S/S of heavy metal-contaminated soils; however, a comprehensive comparison between MgO, lime (CaO), and OPC for S/S application is still missing. This study compares the S/S efficiency of MgO, CaO, and OPC for soils contaminated by six individual heavy metals (Pb, Cu, Zn, Ni, Cd, and Mn) through unconfined compressive strength (UCS) test, one stage batch leaching test, and microstructural analysis. The addition of binders can transform soluble heavy metal salts to insoluble hydroxides and their complexes, and hence the leachability of heavy metals decreases. However, the level, to which the leachability can be reduced, is highly pH dependent. Contaminated soils treated with MgO have pH of 9–10.5, at which the leachability of Pb and Zn is much lower than that of OPC- or CaO-treated soils with pH of 10.5–13; for example, the leached Pb and Zn from MgO-treated soils are only 0.1%–3.3% and 0.1%–9.4% of those from OPC-treated soils, respectively. On the other hand, the leached Cd and Mn from OPC-treated soils are 0.1%–28.5% and 0.1–10.7% of those from MgO-treated soils, respectively, due to the high pH and the formation of calcium silicate hydrate (CSH) in OPC-treated soils. OPC and CaO are more effective than MgO in decreasing the Ni leachability at high original concentrations, but less effective at low original concentrations. For all soils except those contaminated by Zn, the OPC generally produces a much higher UCS, up to two orders of magnitude, than the CaO and MgO. The results of study indicate that no single binder can treat all types of heavy metal-contaminated soils perfectly, and the selection of binder is a site-specific problem. Nanyang Technological University The authors appreciate the grant (M4081914) from Nanyang Technological University, Singapore and the assistance from Shunli Shen, Jian Wei Lui, and Thiam Loong Lim. 2020-09-15T04:39:20Z 2020-09-15T04:39:20Z 2019 Journal Article Li, W., Ni, P., & Yi, Y. (2019). Comparison of reactive magnesia, quick lime, and ordinary Portland cement for stabilization/solidification of heavy metal-contaminated soils. Science of the Total Environment, 671, 741-753. doi:10.1016/j.scitotenv.2019.03.270 0048-9697 https://hdl.handle.net/10356/143636 10.1016/j.scitotenv.2019.03.270 30939327 671 741 753 en Science of the Total Environment 10.21979/N9/XBHJJT © 2019 Elsevier B.V. All rights reserved. This paper was published in Science of the Total Environment and is made available with permission of Elsevier B.V. application/pdf |
| spellingShingle | Engineering::Environmental engineering Stabilization/solidification Contaminated Soil Li, Wentao Ni, Pengpeng Yi, Yaolin Comparison of reactive magnesia, quick lime, and ordinary Portland cement for stabilization/solidification of heavy metal-contaminated soils |
| title | Comparison of reactive magnesia, quick lime, and ordinary Portland cement for stabilization/solidification of heavy metal-contaminated soils |
| title_full | Comparison of reactive magnesia, quick lime, and ordinary Portland cement for stabilization/solidification of heavy metal-contaminated soils |
| title_fullStr | Comparison of reactive magnesia, quick lime, and ordinary Portland cement for stabilization/solidification of heavy metal-contaminated soils |
| title_full_unstemmed | Comparison of reactive magnesia, quick lime, and ordinary Portland cement for stabilization/solidification of heavy metal-contaminated soils |
| title_short | Comparison of reactive magnesia, quick lime, and ordinary Portland cement for stabilization/solidification of heavy metal-contaminated soils |
| title_sort | comparison of reactive magnesia quick lime and ordinary portland cement for stabilization solidification of heavy metal contaminated soils |
| topic | Engineering::Environmental engineering Stabilization/solidification Contaminated Soil |
| url | https://hdl.handle.net/10356/143636 |
| work_keys_str_mv | AT liwentao comparisonofreactivemagnesiaquicklimeandordinaryportlandcementforstabilizationsolidificationofheavymetalcontaminatedsoils AT nipengpeng comparisonofreactivemagnesiaquicklimeandordinaryportlandcementforstabilizationsolidificationofheavymetalcontaminatedsoils AT yiyaolin comparisonofreactivemagnesiaquicklimeandordinaryportlandcementforstabilizationsolidificationofheavymetalcontaminatedsoils |