Res. Chem. Intermed.
, Vol. 28, No. 2,3, pp. 247–256 (2002)
Also available online - www.vsppub.com
Intermediate free radicals in the oxidation of wastewaters
, LUCIA CALUCCI
, CLAUDIO LUBELLO
and CALOGERO PINZINO
Dipartimento di Chimica Organica, Polo Scientico, via della Lastruccia 13, Sesto Fiorentino,
50019 Firenze, Italy
Istituto dei Processi Chimico-Fisici del CNR, via G. Moruzzi 1, 56124 Pisa, Italy
Dipartimento di Ingegneria Civile, Università di Firenze, via S. Marta 3, 50139 Firenze, Italy
Received 18 October 2001; accepted 30 November 2001
Abstract—The cleaning action on wastewater as obtained through oxidation methods has been
investigated by means of EPR spectroscopy to achieve qualitative and quantitative information on
the radicals produced upon utilising peracetic acid and hydrogen peroxide with and without UV
irradiation. The DEPMPO spin trap was employed to detect hydroxyl and carbon-centred short
living radicals during water disinfection, either in the absence or in the presence of UV-C irradiation.
Moreover, three different kinds of water (wastewater, demineralized water, distilled water) were
analysed in order to assess the contribution of Fenton reactions to the radical production. The
spectroscopic results are discussed in relation to the ef ciency of the different oxidising agents and
UV irradiation in wastewater disinfection evaluated as
, faecal and total coliforms
: Radicals; oxidation; EPR; wastewater.
Peracetic acid (PAA) is a strongly oxidising biocide that has been extensively used
for sterilisation in food industries and hospitals . PAA-based products consist
of equilibrium mixtures of peracetic acid, hydrogen peroxide, acetic acid and water
in different proportions. In them, hydrogen peroxide plays different roles, being
implied in the restoration of the equilibrium between the different species after
consumption of PAA but also acting as an oxidising biocide itself.
Chemical and physical treatments are combined to produce highly reactive
intermediates able to oxidise organic pollutants and to inactivate or kill bacteria
and viruses  in the so-called Advanced Oxidation Processes (AOPs).
To whom correspondence should be addressed. E-mail: roberto.bianchini@uni .it