Silver recovery as Ag⁰ nanoparticles from ion-exchange regenerant solution using electrolysis

Area of Science:

• Environmental Science
• Materials Science
• Electrochemistry

Background:

• Consumer products containing silver (Ag) release Ag into the environment, causing ecotoxicological risks.
• Sustainable Ag recovery is crucial for mitigating environmental hazards and conserving resources.

Purpose of the Study:

• To develop an efficient method for recovering Ag nanoparticles from spent solutions.
• To recycle the regenerant solution for reuse in a closed-loop system.
• To characterize the recovered Ag nanoparticles and assess the regeneration efficiency of the reclaimed solution.

Main Methods:

• Silver recovery using a simple undivided electrolytic cell from a spent thiourea (TU) solution.
• Optimization of process parameters: current (0.05 A) and stirring speed (600 r/min).
• Recycling of the reclaimed regenerant solution for resin regeneration over multiple cycles.

Main Results:

• Achieved ~94% Ag recovery with ~2% TU loss.
• Recovered Ag nanoparticles are monodisperse, spherical, with a mean diameter of ~6 nm.
• Reclaimed regenerant solution demonstrated >90% regeneration efficiency over 4 cycles.

Conclusions:

• Electrolytic recovery of Ag nanoparticles is an effective and sustainable method.
• The closed-loop system allows for efficient recycling of the regenerant solution and resin.
• This process offers a viable solution for managing Ag waste and promoting a circular economy.