Influence of Co-Occurring Heavy Metals on Cobalt Removal and Recovery from Wastewater by Continuous Flow In-Liquid...

Area of Science:

• Environmental Science
• Materials Science
• Chemical Engineering

Background:

• Heavy metals like cobalt in wastewater pose significant environmental and health risks.
• These metals are also valuable resources for recovery and reuse.
• Existing wastewater treatment methods may not be efficient or environmentally friendly.

Purpose of the Study:

• To investigate a novel continuous flow in-liquid plasma discharge (CFILPD) system for simultaneous removal of cobalt, zinc, copper, and lead ions.
• To evaluate the impact of co-existing metal ions on cobalt removal efficiency.
• To characterize the recovered metal composites for potential reuse.

Main Methods:

• A continuous flow in-liquid plasma discharge (CFILPD) reactor was designed with conductive channels and dielectric plates.
• Plasma discharge was generated using argon gas, input power, and controlled liquid flow rates.
• The removal efficiency of cobalt ions was measured under varying concentrations of zinc, copper, and lead ions.

Main Results:

• The CFILPD system demonstrated simultaneous removal of multiple heavy metal ions.
• Increasing concentrations of co-existing metals significantly inhibited cobalt removal, with up to 91% reduction in multi-metal systems.
• Copper exhibited the strongest inhibitory effect on cobalt removal (85% reduction), followed by zinc (53%) and lead (52%).
• Characterization revealed cobalt-metal oxide composites (2.5-3 µm) suitable for potential technological applications.

Conclusions:

• The CFILPD system offers a promising method for simultaneous heavy metal removal from wastewater.
• The presence of other metal ions, particularly copper, can significantly interfere with cobalt removal efficiency.
• Recovered cobalt-metal oxide composites present opportunities for resource recovery and reuse in various applications.