Chemical Speciation and Environmental Risk of Cd in Soil Stabilized with Alkali-modified Attapulgite
BACKGROUND Heavy metal pollution in soil has been a serious threat to human health and ecological environmental safety. Stabilization remediation has become an important means of remediation of heavy metal contaminated soil due to the high efficiency and low cost. Attapulgite modified by alkali with...
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| Format: | Article |
| Language: | English |
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Science Press, PR China
2022-01-01
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| Series: | Yankuang ceshi |
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| Online Access: | http://www.ykcs.ac.cn/en/article/doi/10.15898/j.cnki.11-2131/td.202108270108 |
| _version_ | 1797953965177962496 |
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| author | TAO Ling TONG Yun-long YU Fang-ke YANG Wan-hui WANG Yi-rong WANG Li REN Jun |
| author_facet | TAO Ling TONG Yun-long YU Fang-ke YANG Wan-hui WANG Yi-rong WANG Li REN Jun |
| author_sort | TAO Ling |
| collection | DOAJ |
| description | BACKGROUND Heavy metal pollution in soil has been a serious threat to human health and ecological environmental safety. Stabilization remediation has become an important means of remediation of heavy metal contaminated soil due to the high efficiency and low cost. Attapulgite modified by alkali with an improved performance, provides an important basis for its stabilization and remediation of heavy metal contaminated soil. OBJECTIVES To analyze the changes in physical and chemical properties of attapulgite before and after modification, and to study the effects of attapulgite modified by NaOH on the chemical speciation changes and environmental risks of Cd in contaminated soil, and to explore the stabilization effects of attapulgite modified by NaOH on Cd in the soil. METHODS Different proportions of NaOH were used to modify attapulgite. The surface characteristics, crystal structure and functional groups of the materials were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. Stabilization experiments were carried out on artificially prepared heavy metal Cd contaminated soil to study the effects of NaOH-modified attapulgite on the changes of chemical speciation of Cd and environmental risks in contaminated soil. RESULTS By adding the modified material with the mass ratio of NaOH to attapulgite of 1:2, the pH value of the soil was significantly increased by 0.85 units. The exchangeable Cd content decreased by 46.28% and the residual Cd content increased by 1.98 times. The risk assessment code (RAC) and potential risk index (PRI) of Cd in soil decreased the most from 36.70% and 207.90 to 20.08% and 86.40, respectively, which effectively reduced the transfer capacity and environmental risk of Cd in soil. According to SEM, XRD and FTIR analyses, after modification, the surface roughness of attapulgite increased, chemical bonds such as Si-O-Si bonds were opened, so active sites for adsorption of heavy metals increased. Attapulgite modified by alkali immobilized Cd mainly through adsorption, and the reaction of silanol and hydroxide with Cd2+ generated precipitate, so as to achieve the effect of stabilizing and repairing Cd contaminated soil. CONCLUSIONS Alkali-modified attapulgite can effectively stabilize Cd in soil, which has a significant application prospect in remediation of heavy metal contaminated soil. |
| first_indexed | 2024-04-10T23:10:18Z |
| format | Article |
| id | doaj.art-a02bb412f1e04cc8afbc3e6f69f84bb8 |
| institution | Directory Open Access Journal |
| issn | 0254-5357 |
| language | English |
| last_indexed | 2024-04-10T23:10:18Z |
| publishDate | 2022-01-01 |
| publisher | Science Press, PR China |
| record_format | Article |
| series | Yankuang ceshi |
| spelling | doaj.art-a02bb412f1e04cc8afbc3e6f69f84bb82023-01-13T05:56:48ZengScience Press, PR ChinaYankuang ceshi0254-53572022-01-0141110911910.15898/j.cnki.11-2131/td.202108270108yk202108270108Chemical Speciation and Environmental Risk of Cd in Soil Stabilized with Alkali-modified AttapulgiteTAO Ling0TONG Yun-long1YU Fang-ke2YANG Wan-hui3WANG Yi-rong4WANG Li5REN Jun6Key Laboratory of Yellow River Water Environment in Gansu Province, Lanzhou Jiaotong University, Lanzhou 730070, ChinaKey Laboratory of Yellow River Water Environment in Gansu Province, Lanzhou Jiaotong University, Lanzhou 730070, ChinaSchool of Environmental and Science Engineering, Shaanxi University of Science & Technology, Xi'an 710021, ChinaKey Laboratory of Yellow River Water Environment in Gansu Province, Lanzhou Jiaotong University, Lanzhou 730070, ChinaKey Laboratory of Yellow River Water Environment in Gansu Province, Lanzhou Jiaotong University, Lanzhou 730070, ChinaKey Laboratory of Yellow River Water Environment in Gansu Province, Lanzhou Jiaotong University, Lanzhou 730070, ChinaKey Laboratory of Yellow River Water Environment in Gansu Province, Lanzhou Jiaotong University, Lanzhou 730070, ChinaBACKGROUND Heavy metal pollution in soil has been a serious threat to human health and ecological environmental safety. Stabilization remediation has become an important means of remediation of heavy metal contaminated soil due to the high efficiency and low cost. Attapulgite modified by alkali with an improved performance, provides an important basis for its stabilization and remediation of heavy metal contaminated soil. OBJECTIVES To analyze the changes in physical and chemical properties of attapulgite before and after modification, and to study the effects of attapulgite modified by NaOH on the chemical speciation changes and environmental risks of Cd in contaminated soil, and to explore the stabilization effects of attapulgite modified by NaOH on Cd in the soil. METHODS Different proportions of NaOH were used to modify attapulgite. The surface characteristics, crystal structure and functional groups of the materials were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. Stabilization experiments were carried out on artificially prepared heavy metal Cd contaminated soil to study the effects of NaOH-modified attapulgite on the changes of chemical speciation of Cd and environmental risks in contaminated soil. RESULTS By adding the modified material with the mass ratio of NaOH to attapulgite of 1:2, the pH value of the soil was significantly increased by 0.85 units. The exchangeable Cd content decreased by 46.28% and the residual Cd content increased by 1.98 times. The risk assessment code (RAC) and potential risk index (PRI) of Cd in soil decreased the most from 36.70% and 207.90 to 20.08% and 86.40, respectively, which effectively reduced the transfer capacity and environmental risk of Cd in soil. According to SEM, XRD and FTIR analyses, after modification, the surface roughness of attapulgite increased, chemical bonds such as Si-O-Si bonds were opened, so active sites for adsorption of heavy metals increased. Attapulgite modified by alkali immobilized Cd mainly through adsorption, and the reaction of silanol and hydroxide with Cd2+ generated precipitate, so as to achieve the effect of stabilizing and repairing Cd contaminated soil. CONCLUSIONS Alkali-modified attapulgite can effectively stabilize Cd in soil, which has a significant application prospect in remediation of heavy metal contaminated soil.http://www.ykcs.ac.cn/en/article/doi/10.15898/j.cnki.11-2131/td.202108270108attapulgitealkali modificationcadmiumchemical speciationsenvironmental riskscanning electron microscopyx-ray diffractionfourier transform infrared spectroscopy |
| spellingShingle | TAO Ling TONG Yun-long YU Fang-ke YANG Wan-hui WANG Yi-rong WANG Li REN Jun Chemical Speciation and Environmental Risk of Cd in Soil Stabilized with Alkali-modified Attapulgite Yankuang ceshi attapulgite alkali modification cadmium chemical speciations environmental risk scanning electron microscopy x-ray diffraction fourier transform infrared spectroscopy |
| title | Chemical Speciation and Environmental Risk of Cd in Soil Stabilized with Alkali-modified Attapulgite |
| title_full | Chemical Speciation and Environmental Risk of Cd in Soil Stabilized with Alkali-modified Attapulgite |
| title_fullStr | Chemical Speciation and Environmental Risk of Cd in Soil Stabilized with Alkali-modified Attapulgite |
| title_full_unstemmed | Chemical Speciation and Environmental Risk of Cd in Soil Stabilized with Alkali-modified Attapulgite |
| title_short | Chemical Speciation and Environmental Risk of Cd in Soil Stabilized with Alkali-modified Attapulgite |
| title_sort | chemical speciation and environmental risk of cd in soil stabilized with alkali modified attapulgite |
| topic | attapulgite alkali modification cadmium chemical speciations environmental risk scanning electron microscopy x-ray diffraction fourier transform infrared spectroscopy |
| url | http://www.ykcs.ac.cn/en/article/doi/10.15898/j.cnki.11-2131/td.202108270108 |
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