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| Characteristics and mechanisms of Cd2+ adsorption by high- and low-silicon straw biochar |
| Received:July 11, 2022 |
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| KeyWord:silicon;straw biochar;Cd2+;adsorption property |
| Author Name | Affiliation | E-mail | | TAN Dan | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China
South China Key Laboratory of Tropical Agricultural Environment, Ministry of Agriculture and Rural Affairs, Guangzhou 510642, China
Guangdong Provincial Key Laboratory of Ecological Circulation Agriculture, Guangzhou 510642, China | | | WANG Heng | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China
South China Key Laboratory of Tropical Agricultural Environment, Ministry of Agriculture and Rural Affairs, Guangzhou 510642, China
Guangdong Provincial Key Laboratory of Ecological Circulation Agriculture, Guangzhou 510642, China | | | MEI Chuang | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China
South China Key Laboratory of Tropical Agricultural Environment, Ministry of Agriculture and Rural Affairs, Guangzhou 510642, China
Guangdong Provincial Key Laboratory of Ecological Circulation Agriculture, Guangzhou 510642, China | | | GAO Liyang | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China
South China Key Laboratory of Tropical Agricultural Environment, Ministry of Agriculture and Rural Affairs, Guangzhou 510642, China
Guangdong Provincial Key Laboratory of Ecological Circulation Agriculture, Guangzhou 510642, China | | | CAI Kunzheng | College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China
South China Key Laboratory of Tropical Agricultural Environment, Ministry of Agriculture and Rural Affairs, Guangzhou 510642, China
Guangdong Provincial Key Laboratory of Ecological Circulation Agriculture, Guangzhou 510642, China | kzcai@scau.edu.cn |
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| Abstract: |
| Materials from wild type(WT, high-Si) and silicon(Si)-defective mutant material(lsi1, low-Si) were pyrolyzed to prepare biochar at 300, 500℃, and 700℃. The adsorption characteristics and mechanisms of high-and low-silicon biochar for Cd2+ were investigated. The total Si concentration of WT and lsi1 were 17.88% and 7.42%, respectively; WT biochar showed higher Si concentration and larger specific surface area and porosity compared with lsi1 biochar. Elemental analysis, electron microscope energy spectrum scanning analysis(SEM-EDS), fourier infrared spectral analysis(FTIR), specific surface area analysis(BET-N2), and other characterization methods showed that, as pyrolysis temperature increased, the yield of biochar decreased, the pH value and specific surface area increased, and the Si-O-Si bond was observed at the 471, 788 cm-1, and 1 090 cm-1 peaks for both high and low silicon biochar. Adsorption experiments showed that both WT and lsi1 biochars had the best effect on Cd2+ adsorption in an aqueous solution at pH 6 and solid-liquid ratio 1 g·L-1. The adsorption kinetic model demonstrated that the dynamics adsorption process of WT and lsi1 biochars were more in line with the quasi-secondary kinetic model(R2>0.9), chemical adsorption played an important role in the absorption of Cd. Furthermore, the isothermal adsorption fitting by Langmuir and Freundlich models could better reflect the adsorption behavior and characteristics of biochar. Combined with the basic physicochemical properties, FTIR and SEM-EDS analysis showed that the Cd adsorption mechanisms of both types of biochar included ion exchange, precipitation, and functional group networking. High temperature and WT biochar had better effects on Cd2+ adsorption, possibly due to their higher Si concentration, large specific surface area and pore volume, higher cation density, and richer functional groups. |
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