Highly efficient fluoride adsorption from aqueous solution by nepheline prepared from kaolinite through...

Area of Science:

• Materials Science
• Environmental Chemistry
• Water Treatment

Background:

• Fluoride contamination in water poses significant health risks.
• Developing efficient and cost-effective adsorbents for fluoride removal is crucial.
• Nepheline, a feldspathoid mineral, has potential as an adsorbent material.

Purpose of the Study:

• To synthesize nepheline from raw kaolinite using an alkali-hydrothermal method.
• To investigate the fluoride adsorption performance of the synthesized nepheline.
• To understand the adsorption mechanism and thermodynamic properties.

Main Methods:

• Direct alkali-hydrothermal transformation of raw kaolinite (RK) with NaOH solution.
• Characterization of synthetic nepheline (SN) structure, morphology, and surface area.
• Fluoride adsorption experiments under varying conditions (pH, temperature, concentration, time).

Main Results:

• Successfully synthesized highly crystalline nepheline with uniform morphology (BET surface area: 18 m²/g).
• Achieved a maximum fluoride adsorption capacity of 183 mg/g at 323 K, fitting the Langmuir isotherm model.
• Adsorption kinetics followed a pseudo-second order rate law, reaching equilibrium in 90-180 minutes.

Conclusions:

• Synthetic nepheline is a highly effective adsorbent for removing fluoride ions from aqueous solutions.
• The adsorption process is influenced by temperature, initial concentration, and pH.
• The material demonstrates excellent potential for practical water treatment applications.