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Efficient adsorption of Cd2+ from aqueous solution using metakaolin geopolymers
Tian Lan1,2, Pinfang Li1,2, Fazal Ur Rehman1
1College of Resources and Environmental Sciences, China Agricultural University, Beijing, 100193, China.
Environmental Science and Pollution Research International
|October 6, 2019
Summary
Geopolymers synthesized from metakaolin effectively adsorb cadmium (Cd2+) ions. The optimal geopolymer, using a 0.8 M alkali activator modulus, achieved a 70.3 mg/g adsorption capacity and maintained over 85% removal after five cycles.
Area of Science:
- Materials Science
- Environmental Chemistry
- Geochemistry
Background:
- Cadmium (Cd2+) contamination poses significant environmental and health risks.
- Geopolymers offer a promising alternative for adsorbing heavy metals from aqueous solutions.
- Metakaolin-based geopolymers are explored for their potential in wastewater treatment.
Purpose of the Study:
- To investigate the adsorption capacity and mechanism of metakaolin-based geopolymers for cadmium (Cd2+) removal.
- To analyze the influence of alkali activator modulus on geopolymer structure and adsorption performance.
- To determine the optimal conditions and kinetics for Cd2+ adsorption.
Main Methods:
- Geopolymer synthesis using metakaolin with varying alkali activator moduli (0.8-2.0 M).
- Characterization using XRD, SEM-EDS, XPS, FTIR, and BET analyses.
- Adsorption experiments studying pH, temperature, contact time, and initial concentration effects.
Main Results:
- Geopolymer structure and Cd2+ adsorption capacity were significantly influenced by the alkali activator modulus.
- Adsorption kinetics followed the pseudo-second-order model, and equilibrium data fitted the Langmuir model.
- The geopolymer synthesized with a 0.8 M modulus showed the highest Cd2+ adsorption capacity (70.3 mg/g).
- Chemisorption was identified as the dominant adsorption mechanism.
Conclusions:
- Metakaolin-based geopolymers, particularly those synthesized with a 0.8 M alkali activator modulus, are highly effective for cadmium removal.
- The developed geopolymer exhibits excellent reusability, maintaining over 85% removal efficiency after five cycles.
- These findings highlight the potential of tailored geopolymers for sustainable heavy metal remediation.
