Polydopamine modified cerium-based MOFs/ chitosan aerogel beads for the efficient phosphate removal
Jiaqi Shen1, Yuxin Gu1, Yue Yang1
1School of Civil Engineering, Chang'an University, Xi'an, 710061, China.
Chemosphere
|October 15, 2023
Summary
This study developed cerium-based metal-organic frameworks (MOFs) within chitosan gel beads, enhanced with polydopamine (PDA), for effective phosphate removal. The optimized CS-CM2@PDA adsorbent demonstrated superior phosphate adsorption capacity and performance in column studies.
Area of Science:
- Materials Science
- Environmental Chemistry
- Adsorption Science
Background:
- Metal-organic frameworks (MOFs) show promise for phosphate removal but face application challenges due to their ultrafine powder form.
- Chitosan (CS) and polydopamine (PDA) are explored as matrices and coatings to improve MOF handling and adsorption properties.
Purpose of the Study:
- To fabricate and evaluate chitosan gel beads incorporating cerium-based MOFs (CM1 and CM2) and coated with PDA for enhanced phosphate adsorption.
- To investigate the role of Ce(III)/Ce(IV) ratio and PDA coating in improving adsorption capacity, mechanical strength, and practical application performance.
Main Methods:
- Fabrication of chitosan gel beads containing two types of cerium-based MOFs (CM1 and CM2) with varying Ce(III)/Ce(IV) ratios.
- Coating the chitosan-MOF beads with polydopamine (PDA) to enhance stability and adsorption.
- Characterization of adsorbents and evaluation of phosphate adsorption capacities through batch and fixed-bed column studies.
Main Results:
- The CS-CM2@PDA adsorbent, with a higher Ce(III) content, achieved a maximum phosphate adsorption capacity of 146.8 mg/g, significantly outperforming pure CS and CS@PDA.
- CS-CM2@PDA demonstrated superior performance in fixed-bed column studies, treating approximately 1166 BV, attributed to strong inner-sphere interactions between Ce(III) and phosphate.
- PDA coating played a crucial role in the reduction of oxidized Ce(IV) to Ce(III), thereby increasing the availability of active sites for phosphate binding.
Conclusions:
- The developed CS-CM2@PDA composite material effectively addresses the limitations of MOFs, offering excellent phosphate removal capabilities.
- The study highlights the synergistic effect of chitosan, cerium-based MOFs, and PDA in creating a high-performance adsorbent for phosphate remediation.
- The findings suggest a promising application prospect for these engineered MOF-based materials in treating phosphate-contaminated water.
