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| Comparative study on the surface adsorption characteristics of different ferrous minerals for As（Ⅲ）and As（Ⅴ）and their mechanisms |
| Received:January 01, 2023 |
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| KeyWord:adsorption characteristic;adsorption mechanism;arsenic;magnetite;pyrite;siderite |
| Author Name | Affiliation | E-mail | | SU Guangquan | School of Geography and Planning, Sun Yat-sen University, Guangzhou 510006, China | | | JU Lin | School of Geography and Planning, Sun Yat-sen University, Guangzhou 510006, China | | | ZHENG Xiangyu | School of Geography and Planning, Sun Yat-sen University, Guangzhou 510006, China | | | YAO Aijun | School of Geography and Planning, Sun Yat-sen University, Guangzhou 510006, China | yaoaijun@mail.sysu.edu.cn | | YANG Jingliu | School of Geography and Planning, Sun Yat-sen University, Guangzhou 510006, China | | | ZHAO Man | School of Environmental Science and Engineering, Guangdong Provincial Key Lab for Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510006, China | | | WANG Shizhong | School of Environmental Science and Engineering, Guangdong Provincial Key Lab for Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510006, China | | | TANG Yetao | School of Environmental Science and Engineering, Guangdong Provincial Key Lab for Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510006, China | | | QIU Rongliang | School of Environmental Science and Engineering, Guangdong Provincial Key Lab for Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou 510006, China
Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou 510642, China
Guangdong Provincial Key Laboratory of Agricultural & Rural Pollution Abatement and Environmental Safety, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China | |
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| Abstract: |
| The remediation potential of ferrous minerals for arsenic（As）in reducing paddy soils is not entirely understood. To explore the adsorption characteristics of three different ferrous minerals, magnetite, siderite, and pyrite, for As（Ⅲ）and As（Ⅴ）, isothermal adsorption experiments and kinetic adsorption experiments were carried out under different pH conditions（pH=3.00, 5.00, and 7.00）. Additionally, potentiometric titration experiments were conducted to explore the surface charge properties of the three ferrous minerals. The three ferrous minerals exhibited isothermal adsorption for As（Ⅲ）and As（Ⅴ）, with the adsorption curves fitted well by the Langmuir model. Under weakly acidic conditions（pH=5.00）, the adsorption capacity of the ferrous minerals for As（Ⅲ）and As（Ⅴ）followed the order：magnetite （As（Ⅲ）：23.38 mg·g-1; As（Ⅴ）：71.33 mg·g-1）> siderite（As（Ⅲ）：11.63 mg·g-1; As（Ⅴ）：21.69 mg·g-1）> pyrite（As（Ⅲ）：10.72 mg· g-1; As（Ⅴ）：7.75 mg · g-1）, with magnetite exhibiting the highest adsorption capacity for both As（Ⅲ）and As（Ⅴ）. Under neutral conditions（pH=7.00）, pyrite and siderite demonstrated the highest adsorption capacity for As（Ⅲ）and As（Ⅴ）, respectively. Magnetite and siderite had higher adsorption strengths for As（Ⅲ）than pyrite, while pyrite had the highest adsorption strength for As（Ⅴ）. The point of zero charge and total variable charge of the three ferrous minerals were in the order：magnetite（pH=9.76; 1.025 mol·g-1）> siderite（pH= 7.52; 0.240 mol·g-1）> pyrite（pH=4.03; 0.084 mol·g-1）, while the surface active site density was in the order：pyrite（90.59 site·nm-2）> siderite（42.77 site · nm-2）> magnetite（7.94 site · nm-2）. The adsorption capacity of ferrous minerals for As（Ⅲ）and As（Ⅴ）was influenced by the soil pH, total variable charge, and point of zero charge. Both non-specific and specific adsorption were important means for the adsorption of magnetite and siderite for As（Ⅲ）and As（Ⅴ）, while specific adsorption was a more important means for the adsorption of As（Ⅲ）and As（Ⅴ）by pyrite. Results showed that the three ferrous minerals had different remediation potentials under various pH values. Magnetite showed remediation potential for As（Ⅲ）and As（Ⅴ）under acidic conditions, while pyrite showed remediation potential for As（Ⅲ）and siderite showed remediation potential for As（Ⅴ）under neutral conditions. |
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