Abstract
Hydroxyl radical (•OH) is known to be a very powerful oxidizing agent for efficiently removing persistent organic pollutants (POPs) from water. It is the second strongest oxidizing agent after fluorine with a standard reduction potential of E°(•OH/H2O) = 2.8 V/SHE.Some common techniques for generation of hydroxyl radical (•OH) can be listed as follows: (i) the chemical oxidation processes in homogeneous phase (H2O2/Fe2+ and H2O2/O3), (ii) the photocatalytic processes in homogeneous or heterogeneous phase (H2O2/UV, O3/UV, TiO2/UV and Fe2+/H2O2/UV), (iii) the sonochemical processes, and (iv) the electrochemical processes (Zhou and Smith 2002).