By monitoring the decay of SO4•- after flash photolysis aqueous solutions S2O82- at different pH values, kinetics reaction radicals with gallic acid and gallate ion was investigated. The bimolecular rate constants for reactions sulfate were found to be (6.3 ± 0.7) × 108 (2.9 0.2) 109 M-1 s-1, respectively. On basis oxygen-independent second-order on their absorption spectra, organic formed as intermediates these assigned corresponding phenoxyl radicals. DFT calculations in gas phase solution...

Abstract The kinetics of the reactions oxoiron(IV) (FeO 2+ ) with phenol, nitrobenzene, m ‐, o and p ‐nitrophenol in 1 M HClO 4 was investigated by stopped‐flow technique. rate constants these decrease increasing one‐electron reduction potentials corresponding radical cations substrates Hammett parameter NO 2 group phenol ring. A reaction mechanism is proposed, which accounts for observed trends nature products. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 488–494,

Silicon nanoparticles of 1–5 nm size (SiNPs) were synthesized by a bottom-up (BU) approach involving chemical wet method. The contribution different emitters to the overall excitation–emission matrix was analyzed on assumption that pure substances existing in unique form show an excitation wavelength-invariant emission spectrum. occurrence differing and aggregation supported transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), time-resolved single photon counting,...

Abstract The kinetics and reaction mechanism of phosphate radicals with substituted benzenes, PhX (X=OH, Me, H, Cl, MeO, CHO), were studied by flash photolysis continuous irradiation aqueous solutions containing potassium peroxodiphosphate (K 4 [(PO 3 ) 2 O ]). rate constants for the reactions aromatic contaminants measured intermediates products detected. A correlation between logarithm constant every substrate H PO . , HPO .− .2− dissociation K a $\rm{ H_2 PO_4^ -}$ HPO_4^{2 - }}$ was...

Butoxylated silica nanoparticles (BSN) were prepared by esterification of the silanol groups fumed with butanol. These particles characterized FTIR, BET, TEM, and TOC. BSN suspensions in water:acetonitrile mixtures used as quenchers benzophenone (BP) phosphorescence time-resolved experiments at excitation wavelengths 266 337 nm. The signals obtained presence fitted to biexponential decays. Both decays accelerated increasing amounts BSN. A model including reversible adsorption BP on supported...

Electrochemical modification of the Ti surface to obtain TiO2 nanotubes (NT-Ti) has been proposed enhance osseointegration in medical applications. However, susceptibility microbial adhesion, linked biomaterial-associated infections, and high band gap energy, which allows light absorption almost exclusively ultraviolet (UV) region, limit its Modifying semiconductor with metals such as Ag suggested both for antimicrobial purposes absorbing visible region. The formation NT-Ti micropatches...

The capability of paramegnetic iron-containing hydroxyapatite (Fe-nAp) and waste bioorganic subtrates templeted (SBO-Fe-nAp) nanoparticles, as Pb(II) cations adsorbants were investigated compared to those synthetic (nAp).Surface bulk characterization techniques XPS, XRD, electrophoretic mobility, FTIR spectroscopy, DLS, TEM used investigate the adsorption mechanisms involved ICP-AES determine concentrations in aqueous solutions.The apatite-based nanoparticles found be efficient materials for...

Silica particles with surface thiol groups (Sil−SH) were prepared by silylation of silanol using 3-mercaptopropyltrimethoxysilane. The characterized FTIR, Raman, and XPS spectroscopies; thermogravimetry; solid state 13C 29Si NMR spectroscopy. Laser flash excitation at 266 nm Sil−SH water suspensions in the presence sodium peroxodisulfate generated sulfur-centered radicals that attached to silica surface. These detected their absorption maxima (330 nm) transient optical techniques. Absorbance...

A series of photoinduced H-atom abstraction reactions between anthraquinone-2,6,-disulfonate, disodium salt (AQDS) and differently charged micellar substrates is presented. After a 248 nm excimer laser flash, the first excited triplet state AQDS rapidly formed then quenched by hydrogen atom from alkyl chain micelle surfactant, leading to spin-correlated radical pair (SCRP). The SCRP detected 500 ns after flash using time-resolved (direct detection) electron paramagnetic resonance (TREPR)...

Hydrogen peroxide and the persulfate dianion both undergo photochemical cleavage reactions in aqueous solution, creating a pair of hydroxyl (HO•) or sulfate anion () radicals, respectively. These radicals can abstract H-atoms electron transfer presence organic substrates, leading to carbon-centred free radicals. The chemically induced spin polarization (CIDEP) pattern created during time-resolved paramagnetic resonance (TREPR) experiments involving these species is always observed be low...

Sulfate radicals, SO4•-, were generated using flash photolysis of aqueous S2O82- solutions and the reactions inorganic radicals with surface suspended silica nanoparticles (NP) investigated. In presence colloidal no absorption traces due to SO4•- are observed at 100 μs after light. However, two transient species maxima around 320 600 nm formed. A kinetic analysis experimental results indicate that adsorbed on NP surface, leading formation an adduct, λmax ≈ (ε 7000 cm-1 M-1), showing similar...

Reactions of chlorine radicals might play a role in aqueous aerosols where core 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 phase reactions silica nanoparticles (NP) humic acid (HA) with atoms, Cl*, dichloride radical anions, Cl2*-. Silica NP HA may be taken rough models for HULIS contained atmospheric particles, respectively. Both Cl*...

ABSTRACT The values of the rate constants for reactions sulfate (2.5 × 10 9 M −1 s ) and hydrogen phosphate (2.2 8 radicals with silica nanoparticles are obtained by flash photolysis experiments suspensions containing S 2 O 2− or P 4− , respectively. interaction these leads to formation transients, probably adsorbed radicals, absorption maxima at around 320 350 nm, A different mechanism takes place less oxidizing dithiocyanate nanoparticles. These selectively react dissociated silanol groups...

The photolysis of silica suspensions pH approximately 8 containing peroxodisulfate ions leads to the generation two "surface transients" with a distinct spectrum and reactivity. Time-resolved continuous irradiation experiments similar dispersions also variable concentrations vinyl acetate (VA) or 4-vinyl pyridine (4-VP) allowed evaluation contribution silica/water interfacial reactions kinetics structural pattern polymers synthesized using sulfate radicals as initiators. rate constants...