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- Title
Effect of pH on the adsorptive and cycling performance of amphoteric clay-loaded biochar.
- Authors
Wen-bin Li; Hong-yan Deng; Yong Ye; Shu-ni Zhou; Touqeer, Abbas; Jiang-ming Ouyang; Qi Kuang; Wei Liu
- Abstract
To investigate the effect of solution pH on the adsorption and reuse of carbon-based composites, xerophilic and hydrophytic Alternanthera philoxeroides biochars (XAp-C and HAp-C) were loaded with 0%, 50%, and 100% dodecyl dimethyl betaine (BS-12)-modified bentonite (B, 50BSB, and 100BS-B) to form Ap-C/B, Ap-C/50BS-B, and Ap-C/100BS-B, respectively. Then, the isothermal adsorption and morphological changes of Cu2+ and cycling performance by the tested materials under different pH gradients were studied with XAp-C and HAp-C as the control. Results revealed the following. (1) The adsorption isotherms of Cu2+ for the tested materials were all consistent with the Langmuir model, and the maximum adsorption amount remained between 100.82-286.31 mmol/kg. Under the same conditions, the adsorption amount of XAp-C/BS-B was better than that of HAp-C/BS-B, and that of XAp-C/100BS-B was the best. (2) Thermodynamic parameter analysis showed that Cu2+ adsorption of the tested materials was a spontaneous, endothermic, and entropy-increasing reaction process. Kinetic fitting further showed that Cu2+ adsorption conformed to the pseudo-second-order kinetic model. (3) Within pH 2-6, the amount of Cu2+ adsorbed onto the tested materials all initially increased and then decreased, and the value at pH 5 was the best. (4) The Cu adsorbed onto the tested materials primarily existed in exchangeable and organic matter forms, followed by the carbonate form and then the Fe-Mn oxide form. With increased pH, Cu in carbonate form gradually transformed into the organic matter form, whereas Cu in exchangeable and Fe-Mn oxide forms remained basically unchanged. In summary, using XAp-C/100BS-B and adjusting the pH to 5 was the most favorable for Cu2+ adsorption, and the adsorption amount was 62.6% of the raw material after three times of regeneration.
- Subjects
PH effect; BIOCHAR; BETAINE; ADSORPTION isotherms; BENTONITE; SODIUM dodecyl sulfate
- Publication
Desalination & Water Treatment, 2022, Vol 264, p111
- ISSN
1944-3994
- Publication type
Article
- DOI
10.5004/dwt.2022.28559