Salvatore Silvano Emmi

Salvatore Silvano Emmi
Italian National Research Council | CNR · Institute for Organic Syntheses and Photoreactivity ISOF

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68
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January 1973 - present
Italian National Research Council
Position
  • Research Associate

Publications

Publications (68)
Article
Full-text available
Many emerging contaminants pass through conventional wastewater treatment plants, contaminating surface and drinking water. The implementation of advanced oxidation processes in existing plants for emerging contaminant remediation is one of the challenges for the enhancement of water quality in the industrialised countries. This paper reports on th...
Article
Full-text available
The performances of remediation processes initiated by ionizing radiation on ofloxacin are investigated in ambient conditions. The effectiveness of the decomposition of ofloxacin has been assessed both by γ-rays and electron beam in various aqueous solutions differentiated by the dissolved gases (Air or oxygen saturated) and H2O2. By HPLC it is sho...
Conference Paper
Full-text available
This work regards the degradation of a mixture of four emerging pollutants (ofloxacin, carbamazepine, benzophenone-3 and benzophenone-4) in water by means of ionizing and non-ionizing radiation technologies. The efficiency of the treatments has been determined by following the disappearance of the parent molecules by HPLC and evaluating the degree...
Conference Paper
Full-text available
The present paper deals with the remediation of water polluted by relatively poor biodegradable pharmaceuticals and personal care products. Specifically here we exploit the ability of the EB method to achieve their mineralization in atmospheric conditions at room temperature. Also we aim to i) explore and compare the performances of the EB system i...
Conference Paper
Full-text available
The present study reports the photodegradation of surfactants, facing the issue in two steps. Initially, anionic, non ionic, and cationic surfactants have been treated separately. The second step performed the treatment of second rinsing water from laundry machine. This effluent contained traces of standard dirt, anionic, non ionic, and other deter...
Data
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International Trade Fair of Material & Energy Recovery and Sustainable Development Advanced Oxidation Processes for the remediation of water contaminated by emerging pollutants SUMMARY The destruction of selected emerging pollutants (pharmaceuticals and UV filters) in spiked water has been achieved by means of Advanced Oxidation Processes. The ener...
Article
Full-text available
Unless the radiolytic reducing species are neutralised or converted into oxidising species, an EB remediation system cannot be considered a true Advanced Oxidation Processes (AOP). A water/H2O2 system irradiated by UVC mercury lamps constitutes a widely used OH production method. Employing H2O2 in radiolysis as well, an enhancement of the oxidative...
Conference Paper
Full-text available
Summary The destruction of selected emerging pollutants (pharmaceuticals and UV filters) in spiked water has been achieved by means of Advanced Oxidation Processes. These processes can be generated by irradiating water solutions with UV-light, g-rays, electron-beams, or even ultrasounds. The energy transmitted with these processes interacts mainly...
Article
Potentiometric and spectroscopic (UV-Vis, CD and EPR) studies were carried out on copper(II) complexes with chicken prion protein N-terminal fragments, Ac-(PHNPGY)(4)-NH(2), and the mutated residue, Ac-(PHNPGF)(4)-NH(2), to assess the role of tyrosine in the copper coordination. Both thermodynamic and spectroscopic results indicate that chicken pri...
Article
The oxidation process of the cyclic acetal sorbitylfurfural (SF) has been thoroughly examined from the kinetic, spectroscopic and theoretical point of view. Oxidation has been initiated by the radiolitically produced OH radical in the presence of variable oxygen amounts. Two competing reaction pathways are evidenced which lead to quite different pr...
Article
Rate coefficients (k) of CH2OH, CH3CHOH, (CH3)2COH and Cl2- radical addition to maleic and fumaric acids were investigated between pH 1 and 8. Strong pH dependences observed were attributed to changes in protonation states of acids: H2X, HX− and X2−. k of CH2OH, CH3CHOH, (CH3)2COH addition to fumaric acid decreased in the order kH2F>kHF->kF2- in ag...
Chapter
Full-text available
Water pollution may be remediated by combining physico-chemical and biological methods. The Electron beam treatment (E-beam or EB) is a physico-chemical method which pursues the rehabilitation of polluted water and wastewater by the oxidative action of the OH radical and, by that, falling in the class of the Advanced Oxidation Processes (AOPs or AO...
Article
The radical cation of (phenoxymethyl)oxirane (PGE⋅+) is generated by pulse radiolysis in dichloromethane solution and by direct action of radiation on the title compound. In the pure system its UV–vis spectrum is characterized by two bands at 340 and 430 nm, such that the electronic structure corresponds to a dipole bearing the positive charge on t...
Article
2-Hydroxy-2-propyl radical reacts with highly different rate coefficients (k) with the three protonation forms of maleic and fumaric acids. With protonated fumaric acid k is high, (2.1 ± 0.4) × 109 mol−1 dm3 s−1 due to the nucleophilic character of IP reaction and the electron withdrawing –COOH groups. With mono- and dianion molecules the k′s are s...
Article
Full-text available
Application of radiation processing for drinking water, wastewater, and groundwater treatment is a cost effective process which may insure adequate availability of that resource worldwide. This paper summarizes the results of a Coordinated Research Project (organized by the IAEA) with participants from 10 countries with the purpose of describing th...
Article
The reaction of 2-hydroxy-2-propyl (IP) radical with 12 acrylate type monomers in aqueous solutions was investigated by means of pulse radiolysis: the molecular structure effects and the mechanisms were evaluated. Radicals were generated either in the reaction of hydrated electron with acetone and subsequent protonation or in the H abstraction reac...
Article
Chemical radiolytic oxidation induced by OH addition on 1-(2-furan-2-yl-5-hydroxy-6-hydroxymethyl-[1,3]dioxan-4-yl)-ethan-1,2-diol (sorbitylfurfural, SF) leads, in the presence of controlled amounts of oxygen, to a permanent functional modification of the target molecule. The yield of conversion reaches 60% of the starting material. LC-MS analysis...
Article
The high-energy radiation-induced degradation of an H-acid derivative azo dye, Apollofix-Red SF-28 (AR-28) was studied in aqueous solution by using pulse radiolysis with kinetic spectroscopic detection for transient measurements. Gamma radiolysis with UV-VIS spectroscopy and gradient ionpair HPLC separation with diode array detection were applied f...
Article
Ionising radiations, employed in a broad range of dose-rate, together with a complex non-linear computation of reaction mechanisms, allow the determination of boundary values of rate constants concerning sorbitylfurfural (SF) reactivity towards a wide series of oxidant and/or virtually harmful radicals. SF reacts with some radicals (H, SO4-˙, CO3-˙...
Article
The rate constant (k) of the H+tert-butanol reaction at pH∼1–2 was measured by the time profile of the absorbance build-up of the tert-butanol radical and by competitive reactions for H atoms between maleic acid and tert-butanol. The determined rate constant, k=(1.15±0.2)×106mol−1dm3s−1, is nearly an order of magnitude higher than the previously pu...
Article
Full-text available
The rate coefficients of H atom addition to 20 acrylate type monomers were measured in dilute aqueous solutions by pulse radiolysis technique. All the measured values were in a relatively narrow range (2×109–1×1010mol−1dm3s−1). The rate coefficients changed in the following order: crotonates≈maleates
Article
Full-text available
The characteristic UV-VIS absorption peaks of ter-, quater- and quinquethiophene radical cations have been investigated by pulse radiolysis in CCl4, CHCl3, and CH2Cl2. A band shift ranging from 5 to 25 nm towards longer wavelengths is evidenced, as dielectric constant ε increases. Electronic transitions are reasonably reproduced by semiempirically...
Article
The OH radical-induced oxidation of p-cresol to p-methylphenoxyl radical was studied in aqueous solution in a wide pH range by means of pulse radiolysis combined with optical spectroscopy. OH-adduct cyclohexadienyl type radicals were identified as intermediates of the reaction. In the acidic pH range the first-order rate coefficient of phenoxyl rad...
Article
Sorbitylfurfural (Furalglucitol), widely used in the cosmetic industry as antioxidant and antiinflammatory agent, reacts with hydroxyl radical in neutral aqueous solution with a rate constant almost at the diffusional limit, k1 = 7.3 × 109 M-1 s-1. Despite the unselective character of the OH radical, addition to the 5‘ position in the furanic ring...
Article
Pulse radiolysis with kinetic spectroscopic detection was applied to study the kinetics of the first steps of radiation induced polymerization of cyclohexyl acrylate and cyclohexyl methacrylate in cyclohexane solvent. The reactions were initiated by cyclohexyl radicals produced in the radiolysis of the solvent. The transient absorption spectra of t...
Article
Films of polymethylmethacrylate (PMMA) and polystyrene (PS) containing α-terthiophene (3T) undergo a radiochromic effect when exposed to electrons and gamma rays. The films turn either red–green or red, due to the formation of oligomeric radical cations. In both matrixes, absorbance at 465nm grows linearly with dose when α-terthiophene concentratio...
Article
The radiation-induced UV-vis spectrum of alpha-terthiophene radical cation in solid is reported. The radical cation initiates an oligomerization in the CTA matrix producing permanently coloured conjugated polarons. The specific net absorbance at 465 nm is linearly related with dose up to 2 x 10(6) Gy, for electrons and gamma irradiation. The decrea...
Article
The pseudo-first-order protonation rate coefficients of radical anions of acrylic-type monomers (produced by pulse radiolysis in aqueous acidic solutions) were found to be linearly dependent on the H3O+ concentration with second order rate coefficients of several times 1010 mol-1 dm3 s-1. The rate coefficients showed little structure dependence. On...
Article
Full-text available
The reactions of acrylamide (AAm), methacrylamide (MAAm) and N,N-dimethylacrylamide (N,N-DMAAm) with the eaq−, H and OH intermediates of water radiolysis were studied in dilute solutions and compared with the reactions of acrylic acid esters. eaq− reacts with these compounds by adding to the carbonyl oxygen with rate coefficients of ∼1.5×1010mol−1d...
Article
The radical anions of acrylamide, methacrylamide and 2-hydroxypropyl acrylate were produced by pulse radiolysis of moderately acidic aqueous solutions well below the pKa of the radical anion. The rate coefficients of protonation were determined by UV kinetic spectroscopy at wavelengths where the protonated and ionic forms have considerably differen...
Article
An alpha-terthiophene/cellulose triacetate film system exposed to gamma-rays and electron beam shows two new bands in the visible region of the spectrum. The absorbance at 490 nm is almost stable for a long time and responds linearly to the dose applied up to 400 kGy. A Second band developed at 700 nm depends on dose rate and may indicate a chain-g...
Article
The kinetics of high-energy radiation initiated polymerization of acrylate and methacrylate monomers were studied in dilute cyclohexane solutions. The absorption spectra of the intermediates were obtained by pulse radiolysis with optical detection. In solutions of acrylates at longer times after the pulse the presence of oligomer radicals was obser...
Article
The triplet state (32T) and the radical cation (2T+) of 2,2′-bithiophene (2T) are characterized by pulse radiolysis in CCl4. Two main absorption bands at 360 and 420 nm are respectively attributed to 32T* and to 2T+. The triplet, induced in an excited state through a Förster mechanism, undergoes a conformational rearrangement (k6=(6.8±0.9)×106 s−1)...
Article
The rates of the two consecutive reactions, OH radical addition and H2O/OH− elimination, were studied by pulse radiolysis in highly acidic (pH=1.3–1.9) and alkaline (pH≈11) solutions, respectively, for phenol and for the three cresol isomers. The rate coefficient of the addition as measured by the build-up of phenoxyl radical absorbance and by a co...
Article
Pulse radiolysis with kinetic spectroscopic detection was applied to study the first steps of the polymerization of 2-ethylhexyl acrylate (EHA) in cyclohexane solution. The absorption spectra and the kinetic characteristics of the intermediates were investigated in solutions of different monomer concentrations. Immediately after the pulse the maxim...
Article
Conjugated polymers and oligomers of thiophene have been employed in a number of electronic devices due to the change in their conductivity by several orders of magnitude when oxidized to their cationic states. The radical cations of oligothiophenes (nT), with number of rings n=1–6, have been produced by pulse radiolysis for the first time and thei...
Article
The radical ions from bis(2,4,6-tri-tert-butylphenyl)-1,3-diphosphaallene were investigated through EPR spectroscopy, cyclic voltammetry, and pulse radiolysis. Cyclic voltammetry indicated an oxidation potential of 2.0 V vs. SCE and a reduction potential in the range –1.97 to –2.10 V vs. SCE, depending on solvent. Whilst the starting compound does...
Article
The reaction between the OH radical and furfural and the first stages of the subsequent processes have been investigated in detail. The model proposed for the overall kinetics has been verified by means of linear and nonlinear fittings up to the millisecond range. The identification of the intermediates has been based on ab initio optimized product...
Article
Conjugated polymers and oligomers of thiophene have been employed in a number of electronic devices due to the change in their conductivity by several orders of magnitude when oxidized to their cationic states. The radical cations of oligothiophenes (nT), with number of rings n=1–6, have been produced by pulse radiolysis for the first time and thei...
Article
Pulse radiolysis matched with kinetic spectrometry has been employed to produce and characterize the radical cations of the series of unsubstituted oligothiophenes from one to six rings in dichloromethane dilute solutions. The concentration of radicals has been tuned to low values so as to slow down dimerization processes. The spectra obtained for...
Article
The reactions of hydroxyl radical, hydrogen atom and hydrated electron intermediates of water radiolysis with a hydrogel-forming monomer, methacryloyl-L-proline methyl ester (MA-ProOMe), were studied by pulse radiolysis in dilute aqueous solutions and compared with the reactions of the acrylic derivative (A-ProOMe). The spectral and kinetic charact...
Article
The UV, visible and NIR spectra recorded during electrolysis of TNI in CH2Cl2 have been studied as a function of electrolysis time and of the quantity of charge exchanged. Among the oligomeric species that might be responsible for the behaviour observed, particular attention has been devoted to dimers of TNI characterized by different charges, pres...
Article
The reactions of hydroxyl radical, hydrogen atom, and hydrated electron intermediates of water radiolysis with a hydrogel monomer, acryloyl-proline methyl ester, were studied by pulse radiolysis in dilute aqueous solutions. In reactions of OH and H, α-carboxyalkyl radicals form; they absorb the light with a maximum at 460–480 nm, ϵmax ≈ 1000 mol·dm...
Article
The H-abstraction reaction by the OH radical from methane and various halomethanes (CH3Cl, CH3F, CH2Cl2, CH2ClF, CH2F2, CHCl2F and CHF3) was studied using ab initio unrestricted Hartree-Fock (UHF) and multiconfigurational self-consistent field (MCSCF) computational methods. It was found that the structure of the transition state determined at the U...
Article
N-methyl-10,10-dimethylphenazasiline (SIN) was polymerized by electrochemical oxidation at +1.3 V in methylene chloride. Acid-base equilibria in solution between the heterocyclic nitrogen and the protons produced by the coupling reaction were detected. The oxidized polymer deposits on platinum or ITO electrodes to give strongly adherent and electro...
Article
Chlorine atoms formed during the pulse radiolysis of deaerated methylene chloride at room temperature react with the solvent in the first 70 ns from the pulse at a bimolecular rate constant k4 ≈ 6 × 106 M-1s-1 and are available to otther reactions only at solute concentrations higher than 10-3M. A u.v.-vis. spectrum is detected, the main features o...
Article
The electrochemical behaviour ofN-vinyl-thionaphthene-indole (VTNI) has been investigated and compared with that of other similar heterocyclic molecules. By electro-oxidation of VTNI in methylene chloride at+1.2 V an oxidized dimer or a black oxidized polymer have been obtained, depending on the monomer concentration. The polymeric material is a cr...
Article
The oxidative behaviour of [1]benzothieno[3,2-b]indole (BTI) in methylene dichloride was investigated by an electrochemical technique. The process associated with the voltammetric wave at +1.04 V (vs. s.c.e.) leads to the protonated form of the BTI dimer. After slow deprotonation of this species the resulting dimer undergoes oxidation to give an ox...
Article
This work reports the first example of synthesis by electrochemical techniques of a new photoconducting material : poly-thionaphthene-indole. Polymerization method, structure and photoelectronic properties of the resulting product are reported.
Article
The polymer deriving from thionaphthene-indole has been prepared by electrochemical oxidation of the monomer in methylene chloride on platinum electrode. The oxidized polymer so obtained has been reduced on the same electrode to a neutral polymer, which is processable and soluble in several solvents. Both oxidized and neutral polymers have been cha...
Article
Optical measurements show that oxygen depletion by chloromethyl radicals leaves the system under temporarily anoxic conditions. The consequence of continuous irradiation without oxygen renewal on the type of radical processes involved is briefly discussed.
Article
Full-text available
Hydrogen abstraction from methylene chloride by the.OH radical in aqueous solution is monitored by direct observation of the.CHCl2 radical absorption build-up at 220 nm, yielding a bimolecular rate constant of /5.8±0.2/xlo7 M−1s−1 at room temperature. A spectral band extending from 220 nm to 330 nm is assigned to the dichloromethyl radical.
Article
Degradation induced by ionizing radiations on polyphosphazenes, dissolved in chlorinated methanes, is the subject of this investigation. Both steady gamma and pulse radiolysis techniques have been employed.The labile sites for radical attack in poly[bis(p-tolylamino)] phosphazene were identified as the aniline N-H and benzyl C-H bonds of the pendan...
Article
The reaction of Rh(bpy)33+ with radiation-generated reducing radicals (eaq-, ·CO2-, and (CH3)2ĊOH) in aqueous solution quantitatively and rapidly (k = 109-1010 M-1 s-1) yields Rh(bpy)32+ (λmax 485 nm, εmax 1.0 × 103 M-1 cm-1) which undergoes slow (k = 0.45 ± 0.05 s-1 at pH 3-10) loss of bpy at room temperature. Rh(bpy)32+ reacts with O2 (k = 4.9 ×...
Article
Flash photolysis techniques have been employed to obtain kinetic data for electron transfer between the couples Cr(NN)32+-Fe3+ (aq) at ∼22°C in N2-purged 1 M HCl, aqueous solution for NN = bpy, 4,4′-Ph2bpy, phen, 5-Me(phen), 5-Cl(phen), 5-Br(phen), 5-Ph(phen), and 4,7-Ph2phen (under conditions of total quenching of the luminescent 2E state of Cr(NN...
Article
Full-text available
The reactions of radiolytically generated ..cap alpha..-hydroxyalkyl radicals of the form RâRâCOH, where R = H and CHâ with M(NN)â/sup n+/ complexes, where M = Cr(III), Co(III), Rh(III), and Ru(II) and NN = 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen), proceed via electron transfer and/or addition of the radicals to the complex. The distri...
Article
The reaction of 2,2'-bipyridine (bpy), 1,10-phenanthroline (phen), and their monoprotonated cations (bpyH/sup +/ and phenH/sup +/) with radiation-generated one-electron reducing agents yields radicals, the spectra, kinetics, and acid-base properties of which have been established. BpyH/sub 2//sup +/. has a pK/sub a/ of 5.6 and exhibits an intense a...
Article
Full-text available
Pulse radiolytic reduction of 2.2Prime;-bipyridine (bpy) in neutral and alkaline aqueous solution yields an intense band at {right semidirect product}max 365 nm (ε{lunate}=3.0 × 104 dm3 mol-1 cm-1); in acidic solution the band maximum is at 375 nm (ε{lunate}=4.5 × 104 dm3 mol-1 cm-1). The acidic form of the one-electron reduced intermediate shows p...
Article
Das Absorptionsspektrum des durch Pulsradiolyse erzeugten Titelkations wird untersucht und mit dem des durch Blitzphotolyse in CH3OH, CH3CN und H2O erzeugten verglichen.
Article
Au cours de la radiolyse d'ions Ni(CN)42− en solution aqueuse ceux ci sont réduits en Ni2(CN)64− par l'ion-radical CO2−. On propose le mécanisme réactionnel suivant: equation(7) equation(8) equation(9) 2 6 4− En présence de méthanol comme intercepteur de radicaux le rendement en Ni2(CN)64− est considérablement diminué, ce que l'on explique par une...

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