Efficiently Removing Heavy Metals from High-Salinity Wastewater via Ionic Liquid-Based Aqueous Biphasic Systems

Area of Science:

• Environmental Chemistry
• Separation Science
• Green Chemistry

Background:

• Ionic liquid-based aqueous biphasic systems (IL-ABSs) are emerging alternatives for metal ion separation.
• High inorganic salt concentrations in industrial wastewater pose challenges for traditional IL-ABS applications.
• Heavy metal contamination in high-salinity effluents necessitates efficient and sustainable remediation strategies.

Purpose of the Study:

• To develop and evaluate an IL-ABS for heavy metal separation from simulated high-salinity wastewater.
• To investigate the feasibility of using tributyltetradecylphosphonium chloride ([P44414]Cl) in IL-ABS for efficient metal ion removal.
• To demonstrate a novel approach for treating challenging industrial effluents.

Main Methods:

• Formation of an IL-ABS using tributyltetradecylphosphonium chloride ([P44414]Cl).
• Utilizing simulated high-salinity wastewater containing NaCl and Na2SO4.
• Phase diagram analysis to determine biphasic system formation conditions.
• Extraction and stripping experiments to quantify heavy metal removal efficiency and kinetics.

Main Results:

• The IL-ABS required relatively high salt concentrations for phase formation.
• Extraction proceeded via an anion exchange mechanism.
• Over 99.5% extraction efficiency for zinc and cadmium was achieved in under 1 minute across a wide pH range (2-7).
• Stripping efficiency exceeded 99.5% upon contact with NaOH solution.

Conclusions:

• The developed IL-ABS is highly effective for separating heavy metals from high-salinity wastewater.
• This method overcomes the limitation of high inorganic salt addition typically associated with IL-ABS applications.
• The study presents a promising, rapid, and efficient approach for treating industrial effluents contaminated with heavy metals.