[Evaluation of Interaction between Phosphate Ion and Metal Complex-layered Hydroxide]

Area of Science:

• Materials Science
• Environmental Chemistry
• Inorganic Chemistry

Background:

• Eutrophication, driven by excess phosphate, is a major environmental concern.
• Phosphate recovery from water is essential for resource management and pollution control.
• Layered hydroxides show potential for adsorbing pollutants from aqueous solutions.

Purpose of the Study:

• To synthesize and characterize a nickel-aluminium-zirconium complex-layered hydroxide (NAZ).
• To investigate the adsorption capacity of NAZ for phosphate ions.
• To elucidate the adsorption mechanism of phosphate ions onto NAZ.

Main Methods:

• Synthesis of NAZ using a specific inorganic sulfate mixing ratio.
• Physicochemical characterization using SEM, BET surface area, hydroxyl group analysis, and pore volume measurement.
• Phosphate adsorption experiments followed by elemental distribution analysis and XPS to determine the adsorption mechanism.

Main Results:

• NAZ exhibited a specific surface area of 51.9 m²/g, 1.08 mmol/g hydroxyl groups, and 0.27 μL/g pore volume.
• Phosphate adsorption onto NAZ was more effective than onto calcined NAZ.
• Elemental analysis confirmed phosphorus adsorption and revealed a decrease in sulfur, indicating ion exchange.

Conclusions:

• Phosphate ion adsorption onto NAZ was confirmed by increased phosphorus intensity and new phosphorus peaks post-adsorption.
• A strong positive correlation (r=0.960) between adsorbed phosphate and released sulfate ions supports ion exchange as a key mechanism.
• The findings offer a viable method for phosphate removal and recovery, aiding in eutrophication control and water resource management.