Trichloroethylene oxidation performance in sodium percarbonate (SPC)/Fe2+ system.

Area of Science:

• Environmental Chemistry
• Water Treatment Technologies
• Remediation Science

Background:

• Trichloroethylene (TCE) is a common groundwater contaminant.
• In-situ chemical oxidation (ISCO) is a viable remediation strategy.
• Sodium percarbonate (SPC) activated by iron(II) offers a promising ISCO approach.

Purpose of the Study:

• To investigate the efficacy of Fe(II)-catalyzed SPC for TCE oxidation in groundwater.
• To evaluate the impact of key operational parameters and groundwater matrix constituents on the remediation process.

Main Methods:

• Laboratory-scale experiments were conducted to assess TCE degradation.
• Varied SPC/TCE/Fe2+ molar ratios, initial pH, and common groundwater anions (Cl-, HCO3-, SO4(2-), NO3-) were tested.
• The influence of natural organic matter (humic acid) was also evaluated.

Main Results:

• Complete TCE oxidation was achieved within 5 minutes at 20°C using a SPC/TCE/Fe2+ molar ratio of 5:1:10.
• The process showed minimal sensitivity to initial pH (3-11).
• Bicarbonate and chloride ions negatively impacted TCE removal, with bicarbonate having a stronger inhibitory effect. Sulfate and nitrate showed negligible effects. Humic acid exhibited a slight inhibitory effect at tested concentrations.

Conclusions:

• Fe(II)-catalyzed SPC is a highly effective ISCO technique for TCE-contaminated groundwater.
• Complete dechlorination of TCE to carbon dioxide and hydrocarbon was confirmed.
• The presence of bicarbonate in groundwater matrices requires careful consideration for optimal application.