Mechanochemistry: An Old Technology with New Applications to Environmental Issues. Decontamination of Polychlorobiphenyl-Contaminated Soil by High-Energy Milling in the Solid State with Ternary Hydrides

Abstract

Mechanical energy was first used for running chemical reactions three centuries before Christ, for the preparation of mercury. The term mechanochemistry was introduced by Ostwald in 1893. The scientific principles of the technology were discussed by Heinicke in 1984. In this technology, energy transfer takes place through high energy milling of solids that undergo several transformations. Chemical reactions can also take place, that avoids the use of solvents with great benefit from the environmental point of view. As a matter of fact, mechanochemistry has been used so far for the preparation of new materials and running chemical reactions in absence of solvents. More recently, it has been used within the new perspective of application to solving environmental problems. In this paper, the utilization of mechanochemistry as a solid state technology for the dehalogenation of polychlorobiphenyls (PCBs) present in contaminated soil is described. The abatement of PCBs is quantitative. The high energy milling of soil with ternary hydrides represents a valid alternative to the technology based on the use of metal sodium and water, due to the higher safety, and more controlled reaction conditions.