Adsorption of Pb(II) and Cr(VI) from Aqueous Solution by Synthetic Allophane Suspension: Isotherm, Kinetics, and Mechanisms
The adsorption of heavy metals on allophane has been extensively studied due to the properties of allophane special. However, the difference in adsorption behaviors and mechanisms of a metal cation and metal anion on allophane remains uncertain. The present study aimed to investigate the removal of...
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MDPI AG
2022-05-01
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| Series: | Toxics |
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| Online Access: | https://www.mdpi.com/2305-6304/10/6/291 |
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| author | Yan Xia Yang Li Ying Xu |
| author_facet | Yan Xia Yang Li Ying Xu |
| author_sort | Yan Xia |
| collection | DOAJ |
| description | The adsorption of heavy metals on allophane has been extensively studied due to the properties of allophane special. However, the difference in adsorption behaviors and mechanisms of a metal cation and metal anion on allophane remains uncertain. The present study aimed to investigate the removal of Pb(II) and Cr(VI) onto synthetic allophane under variable pH, initial Pb(II) and Cr(VI) concentrations, and contact time. The results showed that the maximum adsorption capacity of allophane for Pb(II) and Cr(VI) was 88 and 8 mg/g, respectively. Equilibrium adsorption for Pb(II) was achieved in <2 min, but it took >12 h for Cr(VI). The response to changes in pH indicated the occurrence of electrostatic adsorption occurred during Cr(VI) absorption. XPS analysis suggested that reactions between predominant surface functional groups of allophane (Al-O- and Si-O-) and Pb(II) occurred through the formation of P-O bonds. The uptake mechanism of Pb(II) was based on a chemical reaction rather than a physical adsorption process. Synthetic allophane holds great potential to effectively remove aqueous metal ions for special wastewater treatment applications. |
| first_indexed | 2024-03-09T22:20:21Z |
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| id | doaj.art-93f3906874874a37ad87156c92dbb1ef |
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| language | English |
| last_indexed | 2024-03-09T22:20:21Z |
| publishDate | 2022-05-01 |
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| series | Toxics |
| spelling | doaj.art-93f3906874874a37ad87156c92dbb1ef2023-11-23T19:15:47ZengMDPI AGToxics2305-63042022-05-0110629110.3390/toxics10060291Adsorption of Pb(II) and Cr(VI) from Aqueous Solution by Synthetic Allophane Suspension: Isotherm, Kinetics, and MechanismsYan Xia0Yang Li1Ying Xu2School of Ecology and Environment, Zhengzhou University, Zhengzhou 450001, ChinaSchool of Agriculture and Environment, Massey University, Private Bag 11222, Palmerston North 4442, New ZealandSchool of Ecology and Environment, Zhengzhou University, Zhengzhou 450001, ChinaThe adsorption of heavy metals on allophane has been extensively studied due to the properties of allophane special. However, the difference in adsorption behaviors and mechanisms of a metal cation and metal anion on allophane remains uncertain. The present study aimed to investigate the removal of Pb(II) and Cr(VI) onto synthetic allophane under variable pH, initial Pb(II) and Cr(VI) concentrations, and contact time. The results showed that the maximum adsorption capacity of allophane for Pb(II) and Cr(VI) was 88 and 8 mg/g, respectively. Equilibrium adsorption for Pb(II) was achieved in <2 min, but it took >12 h for Cr(VI). The response to changes in pH indicated the occurrence of electrostatic adsorption occurred during Cr(VI) absorption. XPS analysis suggested that reactions between predominant surface functional groups of allophane (Al-O- and Si-O-) and Pb(II) occurred through the formation of P-O bonds. The uptake mechanism of Pb(II) was based on a chemical reaction rather than a physical adsorption process. Synthetic allophane holds great potential to effectively remove aqueous metal ions for special wastewater treatment applications.https://www.mdpi.com/2305-6304/10/6/291synthetic allophaneadsorption mechanismselective absorptionheavy metal pollution |
| spellingShingle | Yan Xia Yang Li Ying Xu Adsorption of Pb(II) and Cr(VI) from Aqueous Solution by Synthetic Allophane Suspension: Isotherm, Kinetics, and Mechanisms Toxics synthetic allophane adsorption mechanism selective absorption heavy metal pollution |
| title | Adsorption of Pb(II) and Cr(VI) from Aqueous Solution by Synthetic Allophane Suspension: Isotherm, Kinetics, and Mechanisms |
| title_full | Adsorption of Pb(II) and Cr(VI) from Aqueous Solution by Synthetic Allophane Suspension: Isotherm, Kinetics, and Mechanisms |
| title_fullStr | Adsorption of Pb(II) and Cr(VI) from Aqueous Solution by Synthetic Allophane Suspension: Isotherm, Kinetics, and Mechanisms |
| title_full_unstemmed | Adsorption of Pb(II) and Cr(VI) from Aqueous Solution by Synthetic Allophane Suspension: Isotherm, Kinetics, and Mechanisms |
| title_short | Adsorption of Pb(II) and Cr(VI) from Aqueous Solution by Synthetic Allophane Suspension: Isotherm, Kinetics, and Mechanisms |
| title_sort | adsorption of pb ii and cr vi from aqueous solution by synthetic allophane suspension isotherm kinetics and mechanisms |
| topic | synthetic allophane adsorption mechanism selective absorption heavy metal pollution |
| url | https://www.mdpi.com/2305-6304/10/6/291 |
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