The scientific activity deals with the analisys of some aspects
of the process industry. The approach to the problems is both
experimental by reproducing the investigated processes in
laboratories and theoretical by developing and solving the relevant
mathematical models.
With this respect some different numerical methods have been
investigated that can be effectively applied to the solution of the
sets of governing equations for the transport of mass, momentum,
radiant energy and heat.
Many results have been applied for the industrial
applications of the investigated processes.
The main themes of research can be categorized as
follows:
- Engineering of photochemical and photocatalytic reactors.
- Radiant energy transfer in participating, non reacting, still
or moving fluids.
- Modeling of some production processes in the microelectronics
industry.
- Solvent diffusion in a polymeric matrix.
- Transport phenomena in membrane processes (pervaporation and dialysis).
- In situ vetrification of highly polluted soils.
- Process intensification by integration of different
processes.
- Green photocatalytic synthesis of fine chemicals.
- Advanced oxidation processes for water treatment in various
fields such as recirculating aquaculture systems.
- Photocatalytic ozonation with control of the formation of
bromate.
The Advanced Oxidation Processes (AOP) are an extremely
interesting technology with future present applications in the
detoxification of aqueous and gaseous streams and future possible
applications for the industrial production of some important
chemicals. The utilization of AOP in this field can be advantageous
under many aspects, such as: the convenience of carrying out the
reactions under safe and mild conditions (e.g. low temperature,
atmospheric pressure, without chemical additives except the
photocatalyst, which is typically a non toxic material) and the
possibility of utilizing, as an energy source for the activation of
the reaction, the largely available and free solar radiation.
However, even if several practical applications of the AOP have
appeared in the last years for the degradation of recalcitrant
organic pollutants from aqueous or gaseous streams, the research in
the field of chemical reactions for the production of chemical
compounds of industrial importance is still at the beginning and
many problems have to be studied and solved. In particular it would
be necessary to attain satisfactory values of the yield of the
process in order to make these technologies competitive and to
scale up from the laboratory results to the industrial
production.
In recent times, the interest has grown strongly towards the use
of photocatalytic materials for the detoxification and the
abatement of pollutant in gas phase and liquid phase inside
specific apparatuses or by "functionalizing" some materials that
are commonly exposed to the solar radiation during their ordinary
utilization. In the latter case the attracting idea is to use
innovative materials showing photocatalytic activity for buildings,
covering, varnishes, clothes, wallpapers, carpets, window glasses
etc. In this way the photocatalytic properties of the materials can
be utilized to directly eliminate the polluting or toxic substances
(e.g. the chemicals responsible of the well known "sick building
syndrome") and also many pathogenic or spoiling agents from
the surrounding environment in contact with these active (when
lighted) surfaces. This application appears extremely intersting,
it is virtually without drawbacks and can lead to substantial
improvements of the "quality of life" at home or at work.
However, from a practical perspective, both the activity of these
materials and the way they are utilized (that is the process)
should be improved.
Therefore the research deals with the optimization of the
process with particular attention towards the "effective"
utilization of both the photocatalyst in the reactor and of the
impinging radiation. This study will give also important
indications on the characteristics that the catalytic materials
should have to meet this goal.
To this aim, different types of reactors are studied and tested
and their design is enhanced according to the mathematical model of
the process which considers the different phenomena taking place
inside the reactor. In particular the study takes into account the
kinetics of the reaction (which must be assessed and is in general
a function of the local concentration of the reagents and of the
intensity of the radiation) and hence the distribution inside the
reactor of the reagents, of the photocatalyst and of the radiation.
In fact, if just one of these factors (photocatalyst, light
and reagent) is locally lacking, the reaction does not take place
in that point with a consequent, significant, decrease of the
yield.
The basis of the design and analysis of the photocatalytic reactors is the knowledge of the reaction kinetics. To this aim new guidelines have been drawn for the assessment of the kinetic law of "slurry" photocatalytic reactions with the evaluation of the relevant kinetic parameters and the calculation of the rate of photon absorption.
In order to enhance the rate of conversion and the yield of the
reaction it is possible to couple a separation process to the
photocatalytic process. In fact it has been demonstrated that the
coupling of reaction and separation in an "integrated process"
gives an increase of the yield.
A different research deals with the development
of a prototype of an ISV (In Situ Vitrification)
plant. The ISV process is a thermal process based on the
Joule effect aimed at the reclamation of polluted soils. It
combines the high temperature (around 2000 °C) treatment of noxious
waste with the possibility of immobilizing it into a glass
matrix, which is produced by the cooling of treated soil mass.
An example of a successful application of the ISV process is the
treatment of asbestos.
Compared with other vitrification technology, the ISV permits
the treatment of "in-situ" polluted soils. So a mobile
power supply equipped with a system for the abatment of
the possible pollutant gaseous compounds has been
designed to this aim. Experimental results concerning
pre-pilot and real-scale tests have been analyzed by a mathematical
model of the process which takes into account the energy
transfer in the soil. In this way it has been possible to
correlate the behavior of the non-linear electrical
load with the properties of the soil which undergoes the
melting process. In particular, the tests performed permitted to
identify three distinct phases of the process namely a
primer, an unstable and a stable phases.
The non-linear behavior of the electrical conductivity of the
melted mass has been explained by the model. The energy
effectiveness of the process has been largely enhanced by
appropriately reducing the radiative losses from the soil melt at
very high temperature.
The "green" synthesis of fine chemicals, such as aromatic
aldehydes, represents a new original field of research, with
important possible industrial applications. The synthesis is
carried out by coupling a membrane process (pervaporation) with
photocatalysis. The synergistic mechanisms which act in the
integrated process to get a process intensification have been
identified and discussed. The results show that, through an
optimization of the integrated process, a substantial
increase of the conversion, of the selectivity and of the
yield are obtained. Furthermore it has been demonstrated that
additional positive features make this process sustainable and
eco-friendly.
The "photocatalytic ozonation" is another integrated process
which has been deeply investigated, since the coupling between
ozonation and photocatalysis produces some very interesting
results: a significant enhancement of the yield of
purification and sterilization and an effective control of the
formation of undesired byproducts such as bromate and other
brominated compounds. Therefore, photocatalytic ozonation is
very promising for practical applications in several water
treatments. For instance, the characteristics of
photocatalytic ozonation appear particularly interesting for
the waters of swimming pools and of both freshwater and
seawater recirculating aquaculture systems.The parameters that
affect the performances of this process have been studied and
optimized.
