2. DEGRADATION OF POLLUTANTS
The use of zero-valent iron for wastewater treatment has been increasingly studied. However,
the exact mechanism of degradation of contaminants in the presence of iron is not fully
understood. There are many works proposing that the degradation mechanism comprises of
heterogeneous reactions. The reactions occur when the reactant molecules reach the iron solid
surface. They then associate with the surface at sites that may be either reactive or nonreactive.
Competition can also occur between the reactant solute of interest and other solutes
for the available sites [6]. The reactive sites refer to those where the breaking of bonds in the
reactant solute molecule take place (i.e. chemical reaction) whilst non-reactive sites are those
where only sorption interactions occur and the solute molecule remains intact.