Grantee Research Project Results

Destruction of PCBs, CAHs, CFCs and Organic Nitro/Nitrate Wastes in Soils and Bulk with Ca/NH3 at Ambient Temperature

EPA Grant Number: R826180
Title: Destruction of PCBs, CAHs, CFCs and Organic Nitro/Nitrate Wastes in Soils and Bulk with Ca/NH3 at Ambient Temperature
Investigators: Pittman, Charles U.
Institution: Mississippi State University
EPA Project Officer: Aja, Hayley
Project Period: February 1, 1998 through January 31, 2001 (Extended to January 31, 2002)
Project Amount: $317,027
RFA: Exploratory Research - Environmental Chemistry (1997) RFA Text | Recipients Lists
Research Category: Water , Land and Waste Management , Air , Safer Chemicals

Description:

PCBs, CAHs and CFCs will be quantitatively dechlorinated in CaNH3 solutions neat. Contaminated soils will be treated in Ca/NH3 - soil slurries to mineralize all halogen at ambient temperature. Organic nitro and nitrate wastes, neat or in soils, will be reduced to amino compounds or reductive dimers in Ca/NH3. The objective is to develop an ex-situ method which is rapid at ambient temperatures to decontaminate soils containing PCBs, CAHs, CFCs and organic nitro/nitrate wastes using a single Ca/NH3 solution in which soils would be slurried. Decontamination of neat contaminants or in-situ injection into DNAPLS is a second objective. The method must tolerate substantial amounts of water and humic acids.

Approach:

Dissolving Ca into liquid NH3 generates solvated electrons which are extremely powerful reducing agents. They dehalogenate PCBs, CAHs and CFCs by electron capture followed by loss of chloride or fluoride. Thus, all halide will be mineralized without any dioxin formation and the organic residues will contain hydrogen in place of halogen. Reduction of nitro or nitrates to amino functions or reductive dimers will also occur. Reductive dehalogenation is orders of magnitude faster than reaction of the solvated electrons with water in an ammonia medium. NH3 can be recovered and recycled. Various reaction modes will be carried out and the efficiency of Ca consumption for remediation versus reaction with water will be established.

Expected Results:

Slurrying soils contaminated with PCBs, CAHs and CFCs (or neat treatment of these compounds) at ambient temperature should result in near quantitative dehalogenation and halide mineralization in minutes. Soils are readily slurried in liquid NH3 in contrast to water. If the chemistry is successful practical ex-situ application on-site to excavated soils is anticipated using known ammonia technology and the potential for direct injection into DNAPLS is anticipated. Portable slurry reactors using known ammonia technology appears possible.

Publications and Presentations:

Publications have been submitted on this project: View all 22 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 5 journal articles for this project

Supplemental Keywords:

Ca/NH3, slurry, remediation, cleanup, chemicals, toxics, PCB, CAH, CFC, organo nitro/nitrate, soils, solvated electron reduction., Scientific Discipline, Waste, Remediation, Environmental Chemistry, dechlorination, organic nitro/nitrate, chemical contaminants, contaminated soil, DNAPLs, CFCs, slurry, Ca/NH3

Progress and Final Reports:

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.