Eggshell-derived hydroxyapatite/CeO₂ composite for efficient fluoride removal from water

Area of Science:

• Environmental Science
• Materials Science
• Chemistry

Background:

• Excessive fluoride in drinking water presents significant human health risks.
• Effective methods for fluoride removal from water are crucial for public health and environmental safety.

Purpose of the Study:

• To develop and evaluate a novel composite material, Es/CeO2, for efficient fluoride ion removal from aqueous solutions.
• To investigate the adsorption mechanism and performance of Es/CeO2 in real water samples.

Main Methods:

• Preparation of Es/CeO2 composite using waste eggshells and a hydrothermal method.
• Characterization of the adsorbent's properties using various analytical techniques.
• Fluoride adsorption experiments conducted at room temperature and neutral pH, analyzed using Langmuir isotherm and pseudo-second-order kinetic models.

Main Results:

• The Es/CeO2 adsorbent achieved a high fluoride adsorption capacity of 17.8 mg g⁻¹ at an initial concentration of 30 mg L⁻¹.
• Adsorption process followed the Langmuir isotherm model and was best described by the pseudo-second-order kinetic model.
• XPS analysis revealed a dual adsorption mechanism involving ion exchange and chemical complexation.
• The material demonstrated good performance in real water samples and stability over five adsorption-desorption cycles.

Conclusions:

• Es/CeO2 composite, derived from waste eggshells, is a promising adsorbent for efficient fluoride removal.
• The dual adsorption mechanism contributes to its effectiveness in complex environmental conditions.
• This material shows significant potential for practical application in defluoridation of drinking water.