High-efficiency phosphorus removal from real wastewater using ZnAl-layered double hydroxides: Performance and...

Area of Science:

• Materials Science
• Environmental Chemistry
• Water Treatment

Background:

• Phosphate pollution is a significant environmental concern, necessitating efficient removal methods.
• Layered Double Hydroxides (LDHs) are recognized for their anion exchange capabilities and potential in water remediation.
• Investigating ZnAl-LDHs with varying interlayer anions is crucial for optimizing phosphate removal.

Purpose of the Study:

• To evaluate the phosphate uptake performance of ZnAl-Layered Double Hydroxides (LDHs) with nitrate and chloride interlayer anions.
• To characterize synthesized Zn(2)Al-NO3 and Zn(2)Al-Cl materials.
• To assess the influence of operational parameters and competing anions on phosphate removal efficiency.

Main Methods:

• Coprecipitation method for synthesizing Zn(2)Al-NO3 and Zn(2)Al-Cl.
• Characterization of mineral composition, particle size, surface area, and density.
• Batch sorption experiments with Langmuir and Freundlich isotherm and kinetic modeling (Elovich and pseudo-second-order models).

Main Results:

• Phosphate loading capacities reached 72.41 mg P g⁻¹ for Zn(2)Al-NO3 and 72.05 mg P g⁻¹ for Zn(2)Al-Cl.
• Phosphate removal efficiency decreased with increasing pH (6-8) and was interfered by carbonate anions.
• ZnAl-LDH achieved >90% phosphorus removal in real wastewater treatment.

Conclusions:

• Zn(2)Al-Cl is a promising sorbent for phosphate removal from aqueous solutions, especially in real wastewater treatment.
• The phosphate-loaded material can be utilized in fertilizer formulations.
• Chloride as an interlayer anion is preferable over nitrate due to lower environmental impact in treated effluent.