Heterogeneous selenite reduction by zero valent iron steel wool

Area of Science:

• Environmental Science
• Water Chemistry
• Materials Science

Background:

• Coal mine drainage can contain elevated selenium concentrations.
• Circumneutral pH mine drainage poses challenges for selenium removal.
• Zero valent iron steel wool (ZVI-SW) is a potential treatment material.

Purpose of the Study:

• Investigate selenite ion removal from aqueous solutions using ZVI-SW.
• Determine the efficiency and mechanism of selenium removal under anoxic conditions.
• Evaluate the impact of solution pH on the selenium removal kinetics.

Main Methods:

• Bench-scale kinetic experiments.
• Wet chemical analysis.
• Microscopic and spectroscopic techniques (X-ray photoelectron spectroscopy).

Main Results:

• ZVI-SW effectively removed selenite (SeIV) at pH 6-8.5.
• A two-step removal mechanism involving electrochemical and heterogeneous reduction was identified.
• Solution pH influenced the kinetic rate, with faster rates at pH > 8.
• Approximately 65% of SeIV was reduced to elemental selenium (Se0).

Conclusions:

• ZVI-SW is an efficient material for removing selenite from circumneutral mine drainage.
• The two-step reduction mechanism is pH-dependent.
• Further research can optimize ZVI-SW application for selenium remediation.