Laser degradation of pollutants: Polychlorobiphenyls, triazines and polycyclic aromatic hydrocarbons

Abstract

Visible and UV radiations have been widely used to induce chemical reactions in gases, liquids and heterogeneous systems before the development of commercial lasers for use in these regions. The availability of laser sources has allowed extensive studies on chemical reactions and time-resolved techniques to investigate the mechanism of excitation and relaxation of organic molecules in gaseous and condensed phases.A very important field recently investigated is the laser-induced decomposition of organic molecules, present either as gas or as major constituents of or traces in solutions, with the aim of removing toxic species from chemically hazardous wastes. An investigation of laserinduced decomposition of important categories of pollutants such as polychlorobiphenyls, herbicides (triazines) and polycyclic aromatic hydrocarbons will be reported here. The experiments demonstrate the effectiveness of laser-induced techniques for the decomposition of these compounds. In most cases photofragmentation leads to the formation of non-toxic products in very high yields.