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Solid state dehalogenation of PCBs in contaminated soil using NaBH4.
M Aresta1, P Caramuscio, L De Stefano
1METEA Research Centre, Department of Chemistry, University of Bari, via Celso Ulpiani 27, 70126 Bari, Italy. aresta@metea.uniba.it
Waste Management (New York, N.Y.)
|June 5, 2003
Summary
High energy milling effectively removed polychlorinated biphenyls (PCBs) from contaminated soil using sodium borohydride. This method achieved complete PCB abatement, converting them into less harmful substances like biphenyl and sodium chloride.
Area of Science:
- Environmental Chemistry
- Materials Science
Background:
- Polychlorinated biphenyls (PCBs) are persistent organic pollutants causing significant environmental contamination.
- Effective remediation strategies are crucial for managing PCB-contaminated sites.
Purpose of the Study:
- To investigate the efficacy of high energy milling for PCB abatement in contaminated soil.
- To evaluate the influence of sodium borohydride (NaBH4) and milling time on dehalogenation efficiency.
Main Methods:
- Soil samples contaminated with PCBs were treated using high energy ball milling.
- Two sodium borohydride to soil ratios (5% and 2.5% w/w) were tested.
- PCB content and inorganic chloride production were monitored over milling times ranging from 3.5 to 30 hours.
Main Results:
- Complete abatement of PCBs was achieved starting from approximately 2600 mg/kg, with residual concentrations below 0.2 mg/kg.
- The primary reaction products were biphenyl and sodium chloride (NaCl).
- No hazardous organic by-products were detected; boron was recovered as boric acid.
Conclusions:
- High energy milling with NaBH4 is a highly efficient method for the complete remediation of PCB-contaminated soil.
- The process offers a promising, environmentally sound approach for hazardous waste treatment.
- The technique avoids the generation of toxic by-products, ensuring a safer outcome.