Mónica Gonzalez

• National University of La Plata

Herein, we investigated the photocatalytic removal of methyl orange (MO) under 350 nm irradiation with carbon nitride (CN) nanoparticles from urea. Participation of photogenerated charge carriers and secondary reactive species in MO degradation process was evaluated by scavenging and photoelectrochemical assays. The experiments suggest that HO• rad...

Silicon nanoparticles (SiNPs) show tunable photoluminescence (PL), water-dispersibility, high photostability, and low cytotoxicity, thus constituting promising candidates for bioimaging applications. Because SiNP PL depends finely on particles' crystallinity and surface composition, specific tuning of PL properties has remained elusive. Herein, usi...

The key aspects of porous silicon and freestanding crystalline silicon nanoparticles for biological applications are discussed, with the following subjects being addressed: most simple and scalable synthesis procedures; importance of surface derivatization enhancing colloidal, chemical, photophysical stability, and capacity for reactive oxygen spec...

The use of metal-based and, particularly, Al2O3 nanoparticles (Al2O3-NP) for diverse purposes is exponentially growing. However, the growth of such promissory market is not accompanied by a parallel extensive investigation related to the impact of this pollution on groundwater and biological systems. Pseudomonas species, ubiquitous, environmentally...

Magnetic 45S5 bioactive glass (BG) based scaffolds covered with iron- loaded hydroxyapatite nanoparticles (Fe-HA-BG) were obtained and its cytotoxicity investigated. Iron-loaded hydroxyapatite nanoparticles (Fe-HA) were synthesized by a wet chemical method involving the simultaneous addition of Fe2+/ Fe3+ ions. BG based scaffolds were prepared by t...

The use of metal-based and, particularly, Al 2 O 3 nanoparticles (Al 2 O 3− NP) for diverse purposes is exponentially growing. However, the growth of such promissory market is not accompanied by a parallel extensive investigation related to the impact of this pollution on groundwater and biological systems. Pseudomonas species, ubiquitous, environm...

We present a photoactive composite material for water decontamination consisting of non-purified commercial multiwalled carbon nanotubes (CNT(NP)s) supported on an electrospun polymeric mat made of core-sheath polyacrylonitrile-polypyrrole nanofibers. This is the first system that specifically exploits the superior photocatalytic activity of CNT(NP...

The effects of environmental factors such as sunlight irradiation and the presence of humic acid (HA) on the physicochemical properties of commercial multiwall carbon nanotubes (MWCNT) suspended in a simulated inorganic matrix (SIM) and their impacts on bacteria growing in biofilms were evaluated. Both solar irradiation and the presence of HA lead...

Immobilization of PEG-covered Silicon Dots, PEGSiDs, on glass substrates was performed following a simple strategy involving particle embedding by a sol-gel process forming a silica film on glass slides. The obtained films, denoted as fSiOx-PEGSiD, constitute a water-wettable, strongly supported, photoluminescent glass coating. The films showed hig...

Carbon nanodots (CD) can be prepared from simple organic precursors and renewable natural products through user-friendly processes. Functional groups, structure, and morphology of CD determine their fundamental properties. The understanding of the correlation of the latter properties with the nature of precursor materials and synthesis methods is s...

A highly selective nanocarrier for targeted drug transport and delivery to calcium-containing surfaces, as bone mineral matrix, is described. The nanocarrier, a calcium phosphate (CaP) nanoshell, is capable of interacting with calcium ions contained in enriched surfaces (Ca2+ modified mica surface, hydroxyapatite nanoparticles (Ap) films on glass,...

Cite This Article: Dittler, M.L.; Rodríguez, H.B.; Cipollone, M.; Grillo, C.A.; Gonzalez, M.C. Phosphonopropionic acid coating as platform for the efficient grafting of (bio)molecules to hydroxyapatite nanoparticles. Biomed Eng Int 2020, 2, 0030-0048. Abstract: A new synthesis strategy intended to increase apatite available surface groups for the...

Magnetite‒Porous Silicon 100−150 nm size nanoparticles (MPSi) were obtained combining luminescent and magnetic properties from silicon and magnetite, respectively. MPSi hybrids were characterized by high-resolution transmission electron microscopy, atomic and magnetic force microscopy and X-ray photoelectron spectroscopy. The presence of magnetite...

Amino functionalization is a first step modification aiming to achieve biomedical applications of sili- con nanoparticles, for example, for photodynamic therapy or radiotherapy. Nevertheless, toxicity and low quantum yields due to the positive charge of amino groups emerge as a problem that could be solved with subsequent derivatizations. Folic and...

In the present study we report the photophysical properties of colloidal ensembles of silicon quantum dots (SiD) and gold nanoparticles (AuNP), particularly focused on investigating metal-enhanced photoluminescence effects. AuNP with different sizes, (27 ± 10) and (88 ± 12) nm, and ca. 3.4 nm size SiD with different surface groups, either covered w...

Continuous photolysis experiments and transient absorption spectroscopy were performed in combination with other techniques including HRTEM, XPS, Raman, TGA, and ESR spectroscopy, to investigate the role of residual metals and amorphous carbon on the photochemical process taking place after 350–355 nm light irradiation of as obtained commercial mul...

Silicon blue-emitting nanoparticles (NPs) are promising effectors for photodynamic therapy and radiotherapy, because of their production of reactive oxygen species (ROS) upon irradiation. Results: Amino-functionalized silicon NPs (NH2SiNP) were intrinsically nontoxic below 100 μg/ml in vitro (on two tumor cell lines) and in vivo (zebrafish larvae...

A co-precipitation synthesis method was used to obtain iron oxide nanoparticles coated with Yerba Mate (Ilex paraguariensis) extract. These particles have a core-shell structure with the iron oxide phase surrounded by an organic shell provided by an organic component which come from the Yerba Mate extract. Obtained nanoparticles were exhaustively c...

Single-crystal 15 nm size magnetite nanoparticles were synthesized and coated with Yerba Mate (Ilex paraguariensis) extract to evaluate their use as versatile antioxidant magnetic nanoadsorbents. The obtained particles, Mnp@YM, were found to be composed of a crystalline magnetite core surrounded by a shell composed of Fe3O4, FeO, and Fe2O3 oxides....

The encapsulation of fluorescent dyes inside silica nanoparticles is advantageous to improve their quality as probes. Inside the particle, the fluorophore is protected from the external conditions and its main emission parameters remains unchanged even in the presence of quenchers. On the other hand, the amine-functionalized nanoparticle surface en...

Grafting of polyethylene glycol (PEG) to ultrasmall photoluminescent silicon dots (SiDs) is expected to improve and expand the applications of these particles to aqueous environments and biological systems. Herein we report a novel one-pot synthesis of robust, highly water compatible PEG-coated SiDs (denoted as PEG-SiDs) of (3.3 ± 0.5) nm size. The...

Silicon nanoparticles (including silicon clusters and 1–4 nm size silicon nanocrystals, SiCs) combine size - dependent photoluminescence, the capacity for singlet oxygen and superoxide radical anion generation, and the richness of silicon surface derivatization. Surface modifications as coating/linking with folate, antibodies, adjuvants, and a plet...

Metal-enhanced singlet oxygen, O2(¹Δg), generation is a desirable effect to augment the amount of O2(¹Δg) produced upon irradiation of organic sensitizers. Herein, we employed pectin for stabilizing 9 nm silver nanoparticles and showed that these particles are able to form a ground-sate complex with riboflavin (Rf). Pump-probe transient absorption...

Waste-derived, soluble bio-based substances (SBO), are effective low-cost photosensitizers that could find application in pollutant photodegradation. For this reason, it is important to understand if and to what extent irradiation could modify their properties. The exposure of SBO to simulated sunlight induced important spectral and structural modi...

Iron-containing silicon nanoparticles were synthesized in an attempt to understand the effect of iron on the silicon nanoparticle (SiNP) photoluminescence and singlet-oxygen generation capacity. A wet chemical oxidation procedure of the sodium silicide precursor, obtained from the thermal treatment in anaerobic conditions of a mixture of sodium, si...

Photoluminescent silicon nanoparticles 1–2 nm in size were synthesized by a wet chemical procedure and derivatized with propylamine (NH2SiNP). Surface NH2 groups were used as linkers for additional poly(ethylene glycol) (PEG) and folic acid (Fo) attachment (PEG-NHSiNP and Fo-NHSiNP, respectively) to enable efficient targeting of the particles to tu...

The fluorescence emission spectra and fluorescence quantum yields of hemicyanine dyes LDS 698, LDS 722, and LDS 730 were measured in different media. No transient species was detected in the laser flash-photolysis experiments performed with Ar-saturated solutions of the dyes in methanol. However, in the presence of 0.08 M potassium iodide, the abso...

This study examines the possibility of using a biobased product isolated from urban solid wastes as a material for environmental technological applications. To this end, Fe3O4 nanoparticles (NPs) coated with different amounts of soluble biobased products (SBO) were synthesized as a low-cost nanoadsorbent for the removal of pollutants in wastewater....

This paper describes the synthesis of paramegnetic iron-containing hydroxyapatite nanoparticles and their increased Cu2+ sorbent capacity when using Ca2+ complexes of soluble bio-organic substrates from urban wastes as synthesis precursors. A thorough characterization of the particles by TEM, XRD, FTIR spectroscopy, specific surface area, TGA, XPS,...

The effect of soluble bio-based organic substances (SBO) isolated from urban wastes on photochemical wastewater treatments was investigated using a mixture of six emerging pollutants (EPs), namely acetaminophen, caffeine, acetamiprid, clofibric acid, carbamazepine and amoxicillin. Solar simulated experiments showed that although SBO were able to en...

The values of the bimolecular rate constants for the reactions of 2,2'-azino-bis(3-ethylbenz-thiazoline-6-sulfonic acid) radical cation with epicatechin (((2.4 ± 0.2)) s(-1) M(-1)), and epigallocatechingallate ((29 ± 5) s(-1) M(-1)) were obtained by spectrophotometric measurements. We propose a correlation between the Gibbs energy ΔG(o) for the one...

The effect of derivatization and temperature on the photoluminescence of 1-2 nm size silicon particles of different origin is investigated in an attempt to understand the effect of surface on the particles photoluminescence. To this purpose, silicon nanoparticles were synthesized by electrochemically (top-down) and wet chemical (bottom-up) procedur...

Silicon nanoparticles synthesized by two different methods were surface modified with 3-mercaptopropyltrimethoxysilane. The particles of ∼2 nm size exhibit photoluminescence (PL) in the UV-Vis range of the spectrum. The most intense PL band at 430 nm with an emission lifetime of 1-2 ns is attributed to the presence of the surface defects Si-O-Si, g...

Soluble bio-organic substances (SBO) isolated from urban biorefuses have been investigated in photocatalytic processes for wastewater treatment using a cationic dye, namely crystal violet (CV) as target compound. The SBO have been found to enhance the photobleaching of CV solutions with an optimal SBO concentration of ca. 20 mg L−1. Mechanistic inv...

The reaction of phosphor-containing pesticides such as methidathion (MT) and dimethoate (DM) with dichloride radical anions (Cl(2)(-)) was investigated. The second order rate constants (1.3 ± 0.4) × 10(8) and (1.1 ± 0.4) × 10(8) M(-1) s(-1) were determined for the reaction of Cl(2)(-) with MT and DM, respectively. A reaction mechanism involving an...

The effect of Hg(2+) on the fluorescence intensity of three fulvic acids (Pahokee Peat, Pony Lake and Suwannee River) was studied. The fluorescence intensity decreased in the presence of added Hg(2+), while the fluorescence lifetimes were independent of the concentration of Hg(2+) in solution. These results are indicative of ground-states associati...

The laser flash photolysis technique (λ(exc)=355nm) was used to investigate the mechanism of the HgCl(2) reduction mediated by CO(2)(-) radicals generated from quenching of the triplet states of 1,4-naphthoquinone (NQ) by formic acid. Kinetic simulations of the experimental signals support the proposed reaction mechanism. This system is of potentia...

The photodegradation of a mixture of the emerging pollutants (EPs) clofibric acid, amoxicillin, acetamiprid, acetaminophen, carbamazepine, and caffeine was studied under irradiation with a xenon lamp. The quantum efficiencies of the EPs were determined when irradiated individually. Experiments with the mixture of the EPs showed that indirect photop...

The reaction of three chloronicotinoid insecticides, namely Imidacloprid (IMD), Thiacloprid (THIA) and Acetamiprid (ACT), with carbonate radicals (CO·₃⁻) was investigated. The second order rate constants (4 ± 1) × 10⁶, (2.8 ± 0.5) × 10⁵, and (1.5 ± 1) × 10⁵ M⁻¹ s⁻¹ were determined for IMD, THIA and ACT, respectively. The absorption spectra of the o...

The knowledge of photochemical kinetics in colloidal systems is important in understanding environmental photochemistry on dispersed solid surfaces. As model materials for the chemically sorbed organic compounds present in natural environments, modified silica nanoparticles (NPs) were obtained here by condensation of the silanol groups of fumed sil...

Silicon nanoparticles of 1–5 nm size (SiNPs) were synthesized by a bottom-up (BU) approach involving a chemical wet method. The contribution of different emitters to the overall excitation–emission matrix was analyzed on the assumption that pure substances existing in a unique form show an excitation wavelength-invariant emission spectrum. The occu...

The reactions of Br(2)(˙-), Br˙, HO˙ and N(3)˙ with Aldrich humic acid (AHA) were investigated. The Br/Br(2)(˙-) radicals were obtained in flash-photolysis experiments (λ(exc) = 266 nm) performed with NaS(2)O(8) solutions in the presence of bromide ions. HO˙ and N(3)˙ radicals were generated by pulse radiolysis of N(2)O-saturated solutions. From th...

The capability of silicon nanoparticles to increase the yield of reactive species upon 4 MeV X-ray irradiation of aqueous suspensions and C6 glioma cell cultures was investigated. ROS generation was detected and quantified using several specific probes. The particles were characterized by FTIR, XPS, TEM, DLS, luminescence, and adsorption spectrosco...

Photochemical processes in surface water induced by sunlight affect the redox chemistry of these waters. The humic substances (HS) are almost half of the dissolved organic carbon in natural waters and represent the main fraction of colored dissolved organic carbon that absorbs solar radiation. Upon UV-visible light absorption, the excited states of...

Modified silica nanoparticles (NPs) were obtained by esterification of the silanol groups of fumed silica nanoparticles with 4-hydroxymethyl-N,N-dimethylbenzenamine. These particles were characterized by Fourier transform infrared spectroscopy, 13C and 29Si nuclear magnetic resonance, thermogravimetry, X-ray photoelectron spectroscopy, transmission...

Aquatic photochemistry studies the degradation of contaminants induced by light (either terrestrial sunlight or artificial light used in engineered water treatment systems). In addition to the "direct photolysis" or "direct phototransformation" route there exist a variety of photochemical reactions involving chromophores already present in natural...

Activated sodium peroxydisulfate has the potential to in situ destruct many organic contaminants because of the generation of the stronger oxidant sulfate radical. From photochemical activation of peroxydisulfate in flash-photolysis experiments, the bimolecular rate constants for the reaction of sulfate radical with glyphosate (1.6 × 10(8) M(-1) s(...

The laser flash photolysis technique (λ(exc) = 266 nm) was used to investigate the mechanism of the HgCl(2) reduction mediated by CO(2)(·-) radicals in the temperature range 291.7-308.0 K. For this purpose, the CO(2)(·-) radicals were generated by scavenging of sulfate radicals by formic acid. The absorbance of the reduced radical of methyl viologe...

Functionalized silica nanoparticles (NP) were obtained by esterification of the silanol groups of fumed silica nanoparticles with benzyl alcohol. These particles were characterized by Fourier transform infrared spectroscopy, (13)C and (29)Si NMR spectroscopy, thermogravimetry, total organic carbon, Brunauer-Emmett-Teller analysis, UV-visible spectr...

The reaction kinetics and mechanisms of three neonicotinoid insecticides, imidacloprid (IMD), thiacloprid (THIA) and acetamiprid (ACT), with singlet oxygen and Rose Bengal excited triplet state is reported. The rate constants (5.5 ± 0.5) × 106, (3.9 ± 1) × 107, and (1.3 ± 1) × 106 M−1 s−1 were determined for the chemical reaction of singlet oxygen,...

The effect of molecular oxygen and water on the blue photoluminescence of silicon nanoparticles synthesized by anodic oxidation of silicon wafers and surface functionalized with 2-methyl 2-propenoic acid methyl ester is investigated. The particles of 3 +/- 1 nm diameter and a surface composition of Si(3)O(6)(C(5)O(2)H(8)) exhibit room-temperature l...

The bimolecular rate constants for the reactions of sulfate radicals with epicatechin (EC), epicatechingallate (ECG), and epigallocatechingallate (EGCG) were found to be (1.46 ± 0.06) × 109, (1.20 ± 0.08) × 109, and (1.04 ± 0.07) × 109, respectively. The activation energy [EA = 9 ± 3 kJ mol−1] and preexponential factor [A = (4.8 ± 0.6) × 1010] for...

Silica particles with surface thiol groups (Sil−SH) were prepared by silylation of silanol groups using 3-mercaptopropyltrimethoxysilane. The particles were characterized by FTIR, Raman, and XPS spectroscopies; thermogravimetry; and solid state 13C and 29Si NMR spectroscopy. Laser flash excitation at 266 nm of Sil−SH water suspensions in the presen...

Silicon nanoparticles with strong blue photoluminescence were synthesized by electrochemical etching of silicon wafers and ultrasonically removed under N(2) atmosphere in organic solvents to produce colloids. Thermal treatment leads to the formation of colloidal Si particles of 3 ± 1 nm diameter, which upon excitation with 340 - 380 nm light exhibi...

The kinetics of the reaction of sulfate radicals with the IHSS Waskish peat fulvic acid in water was investigated in the temperature range from 289.2 to 305.2 K. The proposed mechanism considers the reversible binding of the sulfate radicals by the fulvic acid. The kinetic analysis of the data allows the determination of the thermodynamic parameter...

The reactivity of hydroxyl radicals (HO ) towards three neonicotonoid insecticides, namely imidacloprid, thiacloprid and acetamiprid was investigated. These radicals were generated by photolysis of H(2)O(2) solutions. Flash photolysis experiments were used to determine the rate constants of 5.5 x 10(10) M(-1)s(-1), 6 x 10(10) M(-1)s(-1), and 7.5 x...

The photodegradation of the herbicide clomazone in the presence of S(2)O(8) (2-) or of humic substances of different origin was investigated. A value of (9.4 +/- 0.4) x 10(8) m(-1) s(-1) was measured for the bimolecular rate constant for the reaction of sulfate radicals with clomazone in flash-photolysis experiments. Steady state photolysis of pero...

The kinetics and mechanism of the thermal activation of peroxydisulfate, in the temperature range from 60 to 80 degrees C, was investigated in the presence and absence of sodium formate as an additive to turn the oxidizing capacity of the reaction mixture into a reductive one. Trichloroacetic acid, TCA, whose degradation by a reductive mechanism is...

Time-resolved kinetic studies involving the reactions of alloxan (A.H(2)O) with the reducing species superoxide and carbon dioxide radical anions and the reaction of dialuric acid (HA(-)) with sulphate radicals showed that the same radical (AH(.)) was formed either by the one-electron reduction of alloxan or by the one-electron oxidation of dialuri...

Butoxylated silica nanoparticles (BSN) were prepared by esterification of the silanol groups of fumed silica nanoparticles with butanol and characterized by 13C and 29Si NMR and thermogravimetry. The molecular probes benzophenone (BP) and safranine-T were used to investigate the BSN suspensions in water:acetonitrile. Laser flash-photolysis experime...

By monitoring the decay of SO4*- after flash photolysis of aqueous solutions of S2O82- at different pH values, the kinetics of the reaction of SO4*- radicals with gallic acid and the gallate ion was investigated. The bimolecular rate constants for the reactions of the sulfate radicals with gallic acid and the gallate ion were found to be (6.3 +/- 0...

To learn more about the role of the reactive oxygen species (ROS) in the production of bioavailable products of the dissolved organic matter, we investigate here the effect of the photolysis (lambda(exc) > 320 nm) of a soil extract (SE) on the growth of bacteria isolated from the same soil as used for obtaining the extract. Comparative experiments...

The kinetics of the aqueous phase reaction of sulfate radicals with commercial humic acids and with organic matter extracted from vermicompost (VC) was studied by flash-photolysis. The results can be interpreted by a mechanism that in a first step considers the reversible binding of the sulfate radicals by the humic substances. Both the bound and f...

The inhibition of the photo-Fenton (Fe2+/Fe3+, H2O2, UV light) degradation of synthetic phenol wastewater solutions by chloride ions is shown to affect primarily the photochemical step of the process, having only a slight effect on the thermal or Fenton step. Kinetic studies of the reactions of oxoiron (IV) (FeO2+) with phenol indicate that, if FeO...

The kinetics of the oxidation of pyridine, 3-chloropyridine, 3-cyanopyridine, 3-methoxypyridine and 3-methylpyridine mediated by SO4 ( ) radicals are studied by flash photolysis of peroxodisulphate, S2O8(2-), at pH 2.5 and 9. The absolute rate constants for the reactions of both, the basic and acid forms of the pyridines, are determined and discuss...

A method for a photochemically induced mineralization of CCl4 is described in which use is made of reductive radicals. The UVC-photolysis (254 nm) of H2O2 added to aqueous solutions of CCl4 is leading to the homolysis of the oxidant yielding hydroxyl radicals (HO) that subsequently react with added methanol to generate hydroxymethyl radicals (CH2OH...

Reactions of chlorine radicals might play a role in aqueous aerosols where a core of inorganic components containing insulators such as SiO2 and dissolved HUmic-LIke Substances (HULIS) are present. Herein, we report conventional flash photolysis experiments performed to investigate the aqueous phase reactions of silica nanoparticles (NP) and humic...

Butoxylated silica nanoparticles (BSN) were prepared by esterification of the silanol groups of fumed silica nanoparticles with butanol. These particles were characterized by FTIR, BET, TEM, and TOC. BSN suspensions in water:acetonitrile mixtures were used as quenchers of benzophenone (BP) phosphorescence in time-resolved experiments at the excitat...

Advanced oxidation processes, using either UVC/H2O2 or UVC/K2S2O8, both in the presence of H2CO2 or CH3OH are very efficient in mineralizing aqueous solutions of trichloroacetic acid (TCAA) leaving no toxic residues. The main reaction initiating TCAA depletion is its reduction by the radicals CO2- or CH2OH to yield CCl2CO2- radicals and Cl− anions....

The kinetics and mechanism of the oxidation of Glycine (Gly), Alanine (Ala), Tyrosine (Tyr), Tryptophan (Trp) and some di-(Gly-Gly, Ala-Ala, Gly-Ala, Gly-Trp, Trp-Gly, Gly-Tyr, Tyr-Gly), tri-(Gly-Gly-Gly, Ala-Gly-Gly) and tetrapeptides (Gly-Gly-Gly-Gly) mediated by sulfate (SO(4) (-)) and hydrogen phosphate (HPO(4) (-)) radicals was studied, employ...

The values of the rate constants for the reactions of the sulfate (2.5 x 10(9) M(-1) s(-1)) and hydrogen phosphate (2.2 x 10(8) M(-1) s(-1)) radicals with silica nanoparticles are obtained by flash photolysis experiments with silica suspensions containing S(2)O(8)(2-) or P(2)O(8)(4-), respectively. The interaction of these radicals with the silica...

Heterogeneous reactions are widespread in all the environmental compartments: soils, hydrosphere, troposphere and at medium altitudes in the stratosphere. In particular, heterogeneous photochemical processes are concerned with the effect of light on interacting molecules and solid surfaces. Sorption, ion exchange, dissolution, precipitation and red...

The photolysis of silica suspensions of pH approximately 8 containing peroxodisulfate ions leads to the generation of two "surface transients" with a distinct spectrum and reactivity. Time-resolved and continuous irradiation experiments of similar dispersions also containing variable concentrations of vinyl acetate (VA) or 4-vinyl pyridine (4-VP) a...

The photolysis of liquid H2O by vacuum-ultraviolet (VUV) photolysis, and in particular by the radiation emitted by Xe-excimer sources (172 nm) is reviewed, and the impact of the primary radicals (hydroxyl (HO), hydrogen (H) and hydroperoxyl (HO2)) on dissolved organic and inorganic substrates described. Mechanisms of oxidative and reductive reactio...

The oxidation kinetics and mechanism of the phenolic derivatives of alpha,alpha,alpha-trifluorotoluene, 2-trifluoromethylphenol, 3-trifluoromethylphenol (3-TFMP), 4-trifluoromethylphenol and 3,5-bis(trifluoromethyl)phenol, mediated by singlet molecular oxygen, O2(1delta(g)), and hydrogen phosphate radicals were studied, employing time-resolved O2(1...

The oxidation kinetics and mechanism of the phenolic derivatives of α,α,α-trifluorotoluene, 2-trifluoromethylphenol, 3-trifluoromethylphenol (3-TFMP), 4-trifluoromethylphenol and 3,5-bis(trifluoromethyl)phenol, mediated by singlet molecular oxygen, O2(1Δg), and hydrogen phosphate radicals were studied, employing time-resolved O2(1Δg) phosphorescenc...

The kinetics and reaction mechanism of phosphate radicals with substituted benzenes, PhX (X=OH, Me, H, Cl, MeO, and CHO), were studied by flash photolysis and continuous irradiation of aqueous solutions containing potassium peroxodiphosphate (K4[(PO3)2O2]). The rate constants for the reactions of phosphate radicals with the aromatic contaminants Ph...

Sulfate radicals, SO4•-, were generated using flash photolysis of aqueous S2O82- solutions and the reactions of the inorganic radicals with the surface of suspended silica nanoparticles (NP) investigated. In the presence of colloidal silica no absorption traces due to SO4•- radicals are observed at 100 μs after the flash of light. However, two tran...

Photoacoustic measurements as a function of temperature in the range (294.1–308.2) K were used to determine the enthalpy and volume changes for the photoinduced dissociation at 266 nm of peroxodiphosphate ions in water. The analysis of the data, which considered the temperature dependence of the photodissociation quantum yield and of the thermoelas...

The kinetics of the reactions of oxoiron(IV) (FeO2+) with phenol, nitrobenzene, m-, o-, and p-nitrophenol in 1 M HClO4 was investigated by the stopped-flow technique. The rate constants of these reactions decrease with increasing the one-electron reduction potentials of the corresponding radical cations of the substrates and with the Hammett parame...

Laser and conventional flash photolysis of Na2S2O8 aqueous solutions containing Cl- ions were employed to investigate the reactions of chlorine atoms and Cl2•- radical ions with toluene, benzoic acid, and chlorobenzene. A mechanism is proposed which accounts for the faster decay of Cl2•- in aqueous solutions containing increasing concentrations of...

We report mechanistic studies on the reactivity of CO2.− radicals towards substituted benzenes, XPh, with X = NO2, COOH, COH, CH3, H, Cl and HO. Vacuum ultraviolet (VUV, 172 nm) irradiation of aqueous solutions containing formate was used as a method of CO2.− radical generation for the study of the reaction products, which were determined by gas ch...

The photodegradation of 4-chloro-3,5-dinitrobenzoic acid (CDNBA) in aqueous solution was investigated using advanced oxidation processes (AOP) involving hydroxyl radical production: (i) UV-C photolysis of H2O2 using low or medium pressure Hg arcs (UV/H2O2 process) and (ii) vacuum ultraviolet (VUV) photolysis of water at 185 nm (low pressure Hg arc...

The photolysis of NaâSâO8 aqueous solutions containing Cl⁻ ions is a clean method for kinetic studies of the species Cl{sup {sm_bullet}}/Clâ{sup {sm_bullet}-} in the absence and presence of added aromatic substrates. Laser and conventional flash-photolysis techniques were employed to investigate the aqueous phase reactions of chlorine atoms and C...

The correlation of the reactive component of the bimolecular quenching rate constant, kr, with ΔG for reactions of singlet molecular oxygen with phenols is interpreted in terms of classical and semiclassical theories of electron transfer. Both treatments indicate a diabatic process with a reorganization energy of about 0.46 eV. The observed diabati...

Photolysis of pyrophosphate and tripolyphosphate ions in aqueous solution is proposed to produce electron detachment with formation of pyrophosphate and tripolyphosphate radicals (with quantum yields <0.1 at 266 nm), respectively. Formation of P2O7·3− is observed after photolysis of both polyphosphate ions, because the decomposition of P3O10·4− yie...

The absolute rare constants for the reactions of SO4.- with phenol, iodobenzene and benzoic acid, (2.2 +/- 0.2) x 10(9)M(-1)s(-1), (9 +/- 2) x 10(8)M(-1)s(-1) and (5.4 +/- 0.6) x 10(8)M(-1)s(-1), respectively, were obtained by flash-photolysis of peroxodisulphate. The results are discussed in terms of a Hammett correlation.