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- Title
Enhanced adsorption of Cu<sup>2+</sup> on purple soil by amphoteric-modified materials.
- Authors
Xuelian Li; Wenbin Li; Hongyan Deng; Ting Li; Dan Wang
- Abstract
To investigate the effect of adding amphoteric materials on Cu2+ adsorption of purple soil (P), we selected dodecyl betaine (BS-12) as the amphoteric modifier and modified bentonite (B), diatomite (D), activated carbon (C), maifanite (M), and active calcium silicate (S) using 100%BS-12 (as measured by the cation exchange capacity of the material) to obtain five kinds of amphoteric materials. Then, the amphoteric materials were added to P at the mass ratios of 1% and 2% to form 10 mixed soil samples of 1%B100BS and 2%B100BS (P mixed with 1% and 2% amphoteric modified B, respectively, the same below), 1%D100BS and 2%D100BS, 1%C100BS and 2%C100BS, 1%M100BS and 2%M100BS, and 1%S100BS and 2%S100BS (with P as a contrast). Batch method was used to study the isothermal adsorption and thermodynamic characteristics of Cu2+ on different mixed soil samples as a function of different temperatures, pH, and ionic strengths. The following results were obtained. (1) The adsorption isotherms of Cu2+ on different mixed soil samples fitted well the Langmuir and Freundlich models, and the maximum adsorption amount (qm) was between 89.12 and 137.16 mmol/kg, respectively. At the same addition ratio, the adsorption capacity of Cu2+ on tested soil samples showed the follow trend: B100BS > D100BS > C100BS > S100BS > M100BS > P. Compared with 1% addition ratio, the adsorption amount was better under the addition ratio of 2%. (2) When the temperature increased from 20°C to 40°C, the adsorption amount of Cu2+ on all the mixed soil samples increased with rising temperature. The thermodynamic parameters indicated that the adsorption of Cu2+ on mixed soil samples was spontaneous, endothermic, and entropy increasing. (3) The adsorption amount of Cu2+ on the tested soil samples increased with the increase in pH from 3 to 5. With the increase in ionic strength, the adsorption amount of Cu2+ on all mixed soil samples initially increased and then decreased, and the peak value was at 0.1 mol/L.
- Subjects
ACTIVATED carbon; ADSORPTION (Chemistry); ADSORPTION isotherms; SOIL sampling; ADSORPTION capacity; BENTONITE
- Publication
Desalination & Water Treatment, 2020, Vol 196, p278
- ISSN
1944-3994
- Publication type
Article
- DOI
10.5004/dwt.2020.26049