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Published on: February 27, 2021
Removal of fluoride from aqueous solution using protonated chitosan beads
Natrayasamy Viswanathan1, C Sairam Sundaram, S Meenakshi
1Department of Chemistry, Gandhigram Rural University, Gandhigram 624302, Tamilnadu, India. natrayasamy_viswanathan@rediffmail.com
Journal of Hazardous Materials
|May 16, 2008
Summary
Protonated chitosan beads (PCB) demonstrate superior fluoride removal, achieving a defluoridation capacity of 1664mgF-/kg, significantly outperforming raw chitosan beads. This study highlights PCB as an effective medium for defluoridation, even in real-world water samples.
Area of Science:
- Environmental Chemistry
- Materials Science
Background:
- Fluoride contamination in water poses significant health risks.
- Chitosan is a biodegradable polymer with potential for water treatment applications.
Purpose of the Study:
- To chemically modify chitosan beads via protonation to enhance their defluoridation capabilities.
- To evaluate the performance of protonated chitosan beads (PCB) for fluoride removal from aqueous solutions.
Main Methods:
- Chitosan beads were protonated to create PCB.
- Defluoridation capacity was measured and compared to raw chitosan beads (CB).
- Sorption characteristics, isotherms (Freundlich, Langmuir), thermodynamics, and kinetics (pseudo-second-order, intraparticle diffusion) were analyzed.
- Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray Analysis (EDAX) were used for characterization.
- Eluent efficiency was tested, and PCB performance was validated with field water samples.
Main Results:
- Protonated chitosan beads (PCB) exhibited a maximum defluoridation capacity (DC) of 1664 mgF-/kg, a substantial increase from raw chitosan beads (CB) at 52 mgF-/kg.
- The sorption process was pH-independent but influenced by co-existing anions.
- Fluoride sorption on PCB adhered to both Freundlich and Langmuir isotherms.
- Thermodynamic analysis indicated spontaneous and endothermic fluoride sorption.
- Kinetic studies showed the process follows pseudo-second-order and intraparticle diffusion models.
- 0.1M HCl was identified as the optimal eluent.
Conclusions:
- Protonated chitosan beads (PCB) are a highly effective defluoridating medium with significantly enhanced capacity compared to raw chitosan.
- The sorption mechanism is well-described by Langmuir and Freundlich models, with spontaneous and endothermic characteristics.
- PCB demonstrates practical applicability for fluoride removal, as confirmed by testing with field water samples from fluoride-endemic areas.
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