Mesoporous silica originating from a gaseous ammonia epoxide ring opening and the thermodynamic data on some divalent cation adsorptions

Sales, José A.A.; Petrucelli, Giovanni C.; Oliveira, Fernando J.V.E.; Airoldi, Cláudio

doi:10.1016/j.jcis.2007.06.082

Cited by 23 publications

(7 citation statements)

References 43 publications

(51 reference statements)

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“…Three typical 29 Si signals were observed (see ESI, Fig. S2 ‡), referring to silica network, being assigned to Si(OSi) 4 , Q 4 , Si(OSi) 3 OH, Q 3 and Si (OSi) 2 (OH) 2 , Q 2 chemical species at −110, −99 and −95 ppm, 21,22 respectively. Although low signal-to-noise ratio is observed, it is possible to detect the typical species from the silica framework due to silanol and siloxane bonding.…”

Section: Resultsmentioning

confidence: 99%

Triplet state of 4-methoxybenzyl alcohol chemisorbed on silica nanoparticles

Arce

Bertolotti

Oliveira

et al. 2012

Photochem Photobiol Sci

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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 silica nanoparticles with 4-methoxybenzyl alcohol. These particles were characterized by different techniques. To evaluate their toxicity, the inhibition of the natural luminescence emission of the marine bacterium Vibrio fischeri in suspensions of the particles was measured. Laser flash-photolysis experiments (λ exc = 266 nm) performed with NP suspensions in acetonitrile-aqueous phosphate buffer mixtures showed the formation of the lowest triplet excited state of the chemisorbed organic groups (λ max = 390 nm). DFT calculations of the absorption spectrum of this radical support the assignment. From the calculated triplet energy, a thermodynamically favorable energy transfer from these triplet states to oxygen to yield singlet molecular oxygen is predicted. A value of 0.09 was measured for the quantum yield of singlet molecular oxygen generation by air-saturated suspensions of the nanoparticles in the mixture of solvents acetonitrile-aqueous phosphate buffer. The quantum yield of singlet molecular oxygen generation by the free 4-methoxybenzyl alcohol in the same solvent is 0.31. † Dedicated to Prof. Kurt Schaffner on the occasion of his 80th birthday. ‡ Electronic supplementary information (ESI) available: TEM images, 29 Si NMR in solid state of the modified nanoparticles. Percentage of luminescence inhibition vs. the concentration of benzyl alcohol. FTIR spectra of 4-methoxybenzyl alcohol experimental and simulated. Experimental IR wavenumbers for NP and 4-methoxybenzyl alcohol. See

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Section: Resultsmentioning

confidence: 99%

Triplet state of 4-methoxybenzyl alcohol chemisorbed on silica nanoparticles

Arce

Bertolotti

Oliveira

et al. 2012

Photochem Photobiol Sci

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“…A variety of organofunctional molecules anchored on various solid supports, such as crysotile fibers [3], natural talc [4] synthetic phyllosilicate [5], mesoporous silica [6], silicic acid [7] and hydroxyapatite [8] are successfully employed in trace metal separation and concentration methodologies. For such purpose, silica gel is mostly used not only due to the facility of immobilization process, but also to be relatively simple in comparison to organic polymers [9], with faster metal ion-exchange kinetics, good swelling resistance in different solvents, and chemical stability [10].…”

Section: Introductionmentioning

confidence: 99%

Designed pendant chain covalently bonded to silica gel for cation removal

Dey

Airoldi

2008

Journal of Hazardous Materials

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“…Three typical signals were observed (see Fig. 2A), referring to silica network, being assigned to Si(OSi) 4 , Q 4 , Si(OSi) 3 OH, Q 3 , and Si(OSi) 2 (OH) 2, Q 2 , chemical species at −110, −99 and −95 ppm (27,28), respectively. Although low signal‐to‐noise ratio is observed, it is possible to detect the typical species from the silica framework due to silanol and siloxane bonding.…”

Section: Resultsmentioning

confidence: 99%

Generation of Chemisorbed Benzyl Radicals on Silica Nanoparticles

Arce

Rosso

Oliveira

et al. 2010

Photochem & Photobiology

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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 spectroscopy, and transmission electron microscopy. NP suspensions in water/acetonitrile mixtures were used as quenchers of benzophenone (BP) phosphorescence in time-resolved experiments at the excitation wavelength of 266 nm. The phosphorescence signals obtained in the presence of the nanoparticles were fitted to biexponential decays. Both decays were accelerated in the presence of increasing amounts of NP. A model, including the reversible adsorption of BP on the NP, which was supported by computer simulations accounts for the observed results. Laser flash-photolysis experiments with excitation at 266 nm of NP suspensions in water/acetonitrile in the presence of BP generated benzyl radicals that were attached to the silica surface. These radicals were detected at their absorption maxima (320 nm) by transient optical techniques.

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Mesoporous silica originating from a gaseous ammonia epoxide ring opening and the thermodynamic data on some divalent cation adsorptions

Cited by 23 publications

References 43 publications

Triplet state of 4-methoxybenzyl alcohol chemisorbed on silica nanoparticles

Triplet state of 4-methoxybenzyl alcohol chemisorbed on silica nanoparticles

Designed pendant chain covalently bonded to silica gel for cation removal

Generation of Chemisorbed Benzyl Radicals on Silica Nanoparticles

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