Currently Project Manager with the object to achieve "zero pollution" in a small surface treatment enterprise, with a Post-Doc at the University of Franche-Comté, Besançon, France, on "Remediation of wastewater from surface treatment industry and paper mill", he received his PhD on “Chemical Technologies and Innovative Processes” from the University of Messina, Italy. During his research he visited the University of Tokyo (Japan), the Universities of Turin and Naples (Italy) and the Monash University, Melbourne (Australia), focusing on catalysis for energy and environment.
Abstract: Chromium compounds represent an important class of chemicals and are widely used in many industrial processes. Their release in the aquatic environment constitutes a concerning source of toxicity for flora and fauna. Chromium exists mainly in the trivalent and hexavalent forms, with the latter being much more soluble and toxic and requiring specific treatment before discharge. A review of the literature data reveals that there are few treatment methods applicable on an industrial scale, mainly because of efficiency and maintenance issues. Among them, the reduction at acidic pH by NaHSO3 and the further precipitation of the more insoluble Cr3+ species formed at neutral pH is the most employed technique, given the opportunity to automatically
monitor the reaction by means of simple pH and ORP sensors. On this account, we optimized the setting of pH and ORP parameters, applying the method to synthetic solutions and real industrial wastewater from surface-treatment industries. The experimental results showed that optimization of the parameters (i.e., pH ) 2.5 and ORP ) 280 mV) leads to a reduction of reducing agent employment and fewer chemical compounds in the solution and final sludge.
Abstract: Batch sorption experiments using a starch-based sorbent were carried out for the removal of heavy metals present in industrial water discharges. The influence of contact time, mass of sorbent and pollutant load was investigated. Pollutant removal was dependent on the mass of sorbent and contact time, but independent of the contaminant load. The process was uniform, rapid and efficient. Sorption reached equilibrium in 60 min irrespective of the metal considered (e.g. Zn, Pb, Cu, Ni, Fe and Cd), reducing concentrations below those permitted by law. The material also removed residual turbidity and led to a significant decrease in the residual chemical oxygen demand (COD) present in the industrial water discharge. The germination success of lettuce (Lactuca sativa) was used as a laboratory indicator of phytotoxicity. The results show that the sorption using a starch-based sorbent as non-conventional material, is a viable alternative for treating industrial wastewaters.
Abstract: A series of nanostructured MnCeOx catalysts with superior textural and redox properties in comparison to
coprecipitated systems was synthesized via the âredox-precipitationâ route (Chem. Mater. 2007, 19, 2269).
Characterization data prove that the redox-precipitated system consists of uniformly sized (d â 20 nm) spherical
nanoparticles ensuring large surface area (120-260 m2/g) and pore volume (0.5-0.6 cm3/g), and a regular
pore size distribution in a wide range of Mn/Ce ratios (1/3 to 3/1). The lack of long-range crystalline order
and a homogeneous chemical composition signal that Mn and Ce oxides form composite nanodomains with
a molecular dispersion of the active phase. Superior MnOx accessibility, strong MnOx-CeO2 interaction, and
higher average oxidation number of both Mn and Ce ions strongly promote the reactive surface oxygen
availability and the CO oxidation activity in the range of 323-423 K, also accounting for the better stability
of the redox-precipitated system under reaction conditions.
Abstract: Anewsynthesis route driving redox-precipitation reactions amongMnVII,CeIII andMnII precursors in basic aqueous solution yields MnCeOx catalysts (Mn loading, 9â33 wt%) with improved textural and structural properties in comparison to the conventional coprecipitation technique. Irrespective of the Mn loading, BET, X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) findings prove that the newmethod ensures a very high reproducibility in all themain physicochemical properties of MnCeOx catalysts. Enabling a monolayer dispersion of the active phase, the ââredox-precipitationââ method
greatly promotes the reducibility and the surface affinity of the MnCeOx system towards gas-phase oxygen.
Abstract: A class of MnCeOx catalysts has been synthesized via the new redox-precipitation route in alternative to
the conventional co-precipitation technique. The effects of preparation method, composition and
calcination temperature on catalyst texture, dispersion and reduction pattern properties have been
addressed. Redox-precipitated systems exhibit high surface area (SA, 120â170 m2/g), large pore volume
(PV, 0.4â0.5 cm3/g) and a âânarrowââ pore size distribution (PSD) in a wide range of the Mn/Ce ratio (1/3â3/
1). A quasi-molecular dispersion markedly improves oxide-support interactions and reducibility of the
active phase. Redox-precipitated systems show a superior performance in the catalytic wet oxidation of
phenol with oxygen (CWAO) at 373 K in terms of substrate and total organic carbon (TOC) elimination
and mineralization (i.e., CO2 formation) selectivity. Carbon mass-balance from TG-DSC data of used
catalysts and CO2 selectivity values signal that the CWAO of phenol proceeds via a LâH reaction path, the
oxidation of C-containing species being the rate limiting step (r.l.s.). Then, an optimum average pore
diameter (APD, 10â15 nm) enhances the rate of the adsorption step, while a straight relation between
CO2 selectivity and reducibility prove that dispersion and redox properties of the active phase control the
mineralization activity of the MnCeOx system.
Abstract: The effect of the surface structure of the support on the nature and dispersion of iron ions was studied by comparing low-loaded Fe/SiO2 and Fe/Al2O3 catalysts, prepared by the âadsorption-precipitationâ method. This method, based on the electrostatic interaction between iron ions and the negatively charged support surface, is effective in the preparation of highly dispersed iron-supported catalysts, active in alkanes selective oxidation reactions. The samples were characterized by DR UV-Vis and IR spectroscopies, coupled with NO adsorption and to temperature programmed reduction (TPR) measurements. DR UV-Vis and TPR show that after calcination in both catalysts mainly isolated Fe3+ ions, a minor fraction of 2-d FeOx dimers/oligomers and a very small fraction of 3-d oxidic particles are present. The results indicate a higher ability of alumina in dispersing iron-supported species. Despite the multiple sites possibly available for hosting iron cations offered by the
silica support, only two types of iron species were identified by IR of adsorbed NO, differing for the ability to form mono or trinitrosyl complexes (that evolve into dinitrosyl ones, by decreasing NO pressure). The same technique shows that at least five different types of iron species are formed on the alumina surface, four of them able to form only mononitrosyl complexes and one giving di-or trinotrisylic adducts.
Abstract: The effects of chemical composition, calcination temperature, and the addition of potassium on the
physicochemical properties and reactivity of MnCeOx systems in the catalytic wet oxidation (CWO) of phenol
with oxygen (TR ) 373 K; PR ) 1.0 MPa; wcat/wphenol ) 5) have been addressed. Characterization data of
âfreshâ and âspentâ catalysts signal the occurrence of a typically heterogeneous reaction path, the surface
reaction between the adsorbed intermediate(s), and activated oxygen species being the rate-determining step
(rds). Basic relationships among structural properties, the redox pattern, and CWO activity provide evidence
of the main catalyst design requirements. A new synthesis route based on the redox-precipitation reactions
of various Mn and Ce precursors then yields MnCeOx catalysts with improved physicochemical features and
superior CWO activity, in comparison to conventional coprecipitated systems.
Abstract: A novel synthesis route driving redox-precipitation reactions among MnVII, CeIII, and MnII precursors
in basic aqueous solution yields MnCeOx catalysts (Mnat/Ceat, 0.33-2.0) with a (quasi)molecular dispersion
of the active phase and enhanced textural properties in comparison to the conventional coprecipitation
method. The basic characteristics of the redox-precipitation process leading to a solid architecture missing
a substantial âlong-rangeâ crystalline order are discussed. With an excellent reproducibility and irrespective
of the Mnat/Ceat ratio, the redox-precipitation method also ensures unchanged textural, structural, and
chemical properties of the MnCeOx catalysts. As a much improved dispersion of the active phase, the
redox-precipitation route greatly promotes the redox behavior and the surface affinity toward gas-phase
oxygen of the MnCeOx system.
Abstract: The effects of the preparation method (depositionâprecipitation, co-precipitation, incipient-wetness, combustion) and loading (1â5 wt.%) on the structure and redox features of the Au/CeO2 system have been probed by XRD, TEM and TPR techniques. The catalytic pattern in total (TOX) and preferential (PROX) CO oxidation has been assessed by temperature programmed reaction tests in the range 273â473 K. Controlling surface area and residual chlorine, the synthesis route determines the strength of the AuâCeO2 interaction which, reflecting in a hard reduction of the active phase, hinders the CO oxidation functionality. Chlorine removal by washing treatment in diluted alkaline solutions enables an easy reduction of the active phase, levelling off the TOX and PROX performance of the various systems.
Abstract: The interfacial resistances of La1-xSrxCo1-yFeyO3-δ (denoted LSCF(10(1-x)/10x/10(1-y)/10y)) cathodes, and the catalytic activities of a Ni-Ce0.85Y0.15O1.925 (Ni-YDC) anode and an LSCF(2/8/8/2) cathode of a single-chamber solid oxide fuel cells (SOFCs) were investigated. LSCF cathodes with high oxide ion conductivities gave low interfacial resistances. LSCF cathodes with suitable thermal expansion coefficients formed favorable interfacial structures with a ceria-based electrolyte. Ni-YDC showed a higher conversion efficiency for CH4 and a lower selectivity for CO2 than LSCF(2/8/8/2). The single-chamber SOFC based on the Sm-doped ceria electrolyte with the Ni-YDC anode and LSCF(2/8/8/2) cathode showed a maximum power density of 186 mW/cm2 at 800ºC.
Abstract: The working mechanism of a ceria-supported Cu (Cuat:Ceat=1:10) system in the Catalytic Wet Oxidation (CWO) of phenol with O2 (TR, 130â170 C; PO2, 7 atm) has been thoroughly assessed. Basic relationships amongst pH, extent of leaching and rate of phenol and TOC conversion prove the major contribution of a homogeneous catalytic path by Cu ions on the peculiar CWO pattern of supported copper catalyst. In addition, gas-phase reduction/oxidation tests signal the lack of reversibility of the redox cycle of the CuCeOx system under typical reaction conditions.
Abstract: The activityâstability pattern of a 19 wt.% Ni/MgO catalyst in the pre-reforming (T, 450 â¦C; P, 10 bar) of n-hexane with steam (S/C, 1.5â3.5)
in absence and presence of H2 (H/C, 2) has been investigated. Deactivation profiles of the kinetics of CH4 and CO/CO2 formation indicate that
the activity, selectivity and stability are closely related. Hydrogenation of carbon species to methane is a critical step involving the occurrence
of coking in the pre-reforming of hexane. Thermodynamic analysis of the outlet reaction stream signals that the net coking rate depends
upon the relative kinetics of carbon methanation (MET, C+2H2CH4) and gasification/waterâgas-shift (GAS, C+H2OH2 +CO; WGS,
CO + H2OCO2 + H2) reactions, while negligible appears the contribution of the Bouduard reaction path (DISP, 2COC + CO2).
Abstract: Wastewater treatment and reuse of industrial process water is a critical issue for the suitable development of human activities. The need for an effective water recycling has reinforced the research on tailored low cost pollution abatement since the existing solutions are not already universal. The Catalytic Wet Air Oxidation (CWAO) of organic compounds represents to date the most reliable technique for the abatement of pollutants from wastewater streams. In fact, among the various methods developed during last decades, it is the unique one able to process flows with large range of both pollutant load and feed. It can be carried out in absence of catalysts at severe operating conditions in terms of temperature and pressure, which can be highly decreased using appropriate catalysts. Many compounds were employed in CWAO studies, but phenol has attracted lot of attention, due to its presence in various industrial wastewater streama. Noble metal supported on various systems, as inhert oxides or active carbons, are the most used catalysts in this process but their expensive costs and their tendency to deactivate because of poisoning forced researchers to find out new cheaper and more active systems. Among various metals able to catalyze the mineralization of organic pollutants, copper is one of the most active and it was employed in the formu only when dissolved into the reacting solution, that is when acidic intermediates are formed, lessening the pH and allowing copper to dissolve. The metal leaching from the solid catalyst represents a subsequent source of pollution, given the toxicity of copper and other heavy metals even at low concentrations. Moreover, heterogeneous Cu-based catalyst are not stable because their inability to restore the initial oxidation state of the active phase, that is at the base of oxidative catalysis, as demonstrated by redox characterization tests.
The reactor optimization is compulsory in the CWAO process development due to metal dissolution from the reactor wall, probably being the cause of literature data poor reproducibility of blank test results. Basic correlations among conversion, selectivity and pH of homogeneous tests signal that both catalytic and non-catalytic homogeneous wet air oxidations progress via a poorly selective free-radical reaction path, leading to the ultimate formation of acetic, oxalic and formic acids and CO2. While, a typical surface L-H mechanism accounts for a superior water decontamination efficiency and mineralization selectivity of the heterogeneous MnCeOx system. Given the high number of oxidation states, manganese represents a valid alternative to Cu-based catalysts and many attempts were performed in order to develop the suitable system for the CWAO process. Systematic studies conducted on catalysts formed of manganese and cerium oxides prepared by means of the classic co-precipitation method confirm their efficiency in removing phenol from aqueous solutions even at very mild conditions and indicate the basic requirements of the optimum CWAO catalyst. The mineralization of phenol on the MnCeOx system proceed through the fast adsorption of the substrate on the catalyst surface and then the catalyst lattice oxygen slowly oxidize it to carbon dioxide. This reaction mechanism indicates in the enhancement of the surface exposure and in the improvement of redox properties the key features to improve the system. The exploitation of a new synthesis route which allows the intimate mixing of Mn and Ce precursors allows to obtain a novel MnCeOx system with improved features. This new catalyst shows a higher surface area exposure, an amorphous structure, a greater active phase surface dispersion, a stabilization of the manganese at high oxidation number, improved redox featuresand a strong ability to restore the initial redox features in comparison to the classic co-precipitated system. Catalytic tests confirm the higher activity towards the phenol abatement at mild conditions. In particular, the substrate is effectively converted to CO2 at 423K, showing an incipient carbon dioxide production at 373K, yet, in contrast with a sensible slower rate presented by the previous system. The absence of any intermediates into the reacting solution during reaction time and the high stability after several runs, make the new system âcleanâ and suitable for the development of the process at industrial scale.
