Possible new route for the production of C60 by ultrasound

Facile one-step sonochemical synthesis of ultrafine and stable fluorescent C-dots

This work describes a one-step synthesis of carbon dots (C-dots), which is carried out by sonication of polyethylene glycol (PEG-400) for 0.5-3h. The effect of the various experimental parameters, such as sonication time, amplitude and temperature on the size and the fluorescence of the C-dots was studied. It was found that the average diameter of the C-dots is between 2 and 9 nm, depending on the preparation conditions. The highest quantum yield of emission was ∼ 16%. These high fluorescence properties of the C-dots could be used for bioimaging and for solar cell applications.

Sonochemical preparation of carbon spheres

Spherical morphology of carbon with 150-400 nm size is produced by sonication (480 kHz, 2.5 W) of toluene with water under ambient conditions. Medium range of frequency and weak power of ultrasound is found to be the appropriate conditions for preparing the carbon spheres. Morphological and structural analysis of the product is carried out with TEM, SEM, elemental analysis, TGA, and FT-IR spectroscopy.

The effect of high power ultrasound on an aqueous suspension of graphite

Ultrasound treatment was used to study the decrease of the granulometry of graphite, due to the cavitation, which allows the erosion by separating grains. At a smaller scale, cavitation bubble implosion tears apart graphite sheets as shown by HRTEM, while HO(*) and H(*) radicals produced from water sonolysis, generate oxidative and reductive reactions on these sheet fragments. Such reactions form smaller species, e.g. dissolved organic matter. The methodology proposed is very sensitive to unambiguously identifying the in situ composition of organic compounds in water. The use of the atmospheric pressure chemical ionization (APCI) Fourier transform mass spectrometry (FTMS) technique minimizes the perturbation of the organic composition and does not require chemical treatment for analysis. The structural features observed in the narrow range (m/z<300) were mainly aromatic compounds (phenol, benzene, toluene, xylene, benzenediazonium, etc.), C(4)-C(6) alkenes and C(2)-C(10) carboxylic acids. Synthesis of small compounds from graphite sonication has never been reported and will probably be helpful to understand the mechanisms involved in high energy radical reactions.

Synthesis of amorphous carbon nanoparticles and carbon encapsulated metal nanoparticles in liquid benzene by an electric plasma discharge in ultrasonic cavitation field

A newly-developed method permits an electric plasma discharge to occur with relatively low electric power in insulating organic solutions due to the presence of an ultrasonic cavitation. A stable electric plasma could be generated in an ultrasonic cavitation field containing a thousand tiny activated bubbles, in which the electric conductivity could be improved due to formed radicals and free electrons, using copper electrodes and a titanium ultrasonic horn. This method allowed us to synthesize pyrolytic amorphous carbon nanoparticles smaller than about 30 nm in diameter from benzene liquid. In addition, we synthesized TiC nanoparticles about 50-150 nm in size, and copper nanoparticles smaller than 10 nm, which were encapsulated in multilayered graphite cages. Finally, we used GC-MS and MALDI-TOF-MS to observe and analyze the polymerized compounds and the degree of polymerization of the benzene liquid after the plasma treatment.

The oxidation of fullerene[C60] with various amine N-oxides under ultrasonic irradiation

The reaction of C60 with various amine N-oxides such as 3-picoline N-oxide (Aldrich 98.0%), pyridine N-oxide hydrate (Aldrich 95.0%), quinoline N-oxide (Aldrich 97.0%), isoquinoline N-oxide (Aldrich 98.0%) under ultrasonic irradiation in air at 25-43 degrees C causes the oxidation of fullerene[C60(O)n] (n=1-2 or n=1). The MALDI-TOF MS, UV-vis spectra, and HPLC profile confirmed that the products of fullerene oxidation are [C60(O)n] (n=1-2 or n=1).

Synthesis of a water-soluble fullerene [C60] under ultrasonication

A water-soluble fullerene [C60] is prepared with fullerene [C60] and a mixture of strong inorganic acids at the ratio (v/v) of 3:1 under ultrasonic condition at 25-43 degrees C. The MALDI-TOF MS and 13C-NMR spectra confirmed that the product of a water-soluble fullerene compound was C60.

The oxidation of fullerene [C70] with various oxidants by ultrasonication

The reaction of C70 by ultrasonication with various oxidants such as 3-chloroperoxy benzoic acid (Fluka 99%), 4-methyl morpholine N-oxide (Aldrich 97%), chromium (VI) oxide (Aldrich 99.9%), and oxone monopersulfate compound, at room temperature causes the oxidation of fullerene [C70(O)n] (n = 1-2 or n = 1). The FAB-MS, UV-visible, FT-IR spectra, and HPLC analysis confirmed that products of fullerene oxidation are [C70(O)n] (n = 1-2 or n = 1).

Ultrasound-induced cracking and pyrolysis of some aromatic and naphthenic hydrocarbons

The action of intense ultrasound on solutions of decahydronaphthalene (decalin) or tetrahydronaphthalene (tetralin) causes, in both cases, a dehydrogenation reaction at room temperature. According to thermodynamic calculations, temperatures as high as 500 degrees C are necessary to achieve the same results. The use of Pd and Se as dehydrogenation catalysts has confirmed the dehydrogenation reactions. Benzene and toluene sonication at room temperature causes aromatic ring breakdown with formation of acetylene and other products. The analogy with radiolysis was noticed. A thermodynamic analysis was conducted on the possible reaction products formed from benzene ring cleavage including polymerization products. It was concluded that acetylene formation from benzene is possible for instance at 650 degrees C only if it is accompanied by coke formation. Otherwise temperatures as high as 1700 degrees C are needed. The nature of the 'coke' formed during sonication is discussed, it was revealed by FT-IR spectroscopy to be a crosslinked polystyrene and hence it is a sonopolymer derived from benzene or toluene ring breakdown products reacted with phenyl and polyphenyl radicals. Again the striking analogy between the IR spectrum of irradiated polystyrene and benzene sonopolymer was noticed. The formation of poly-p-phenylene was excluded by the FT-IR pattern which did not match that of an authentic sample.

Sonochemical polymerization of benzene derivatives: the site of the reaction

Sonochemical polymerization of benzene and halogen-substituted benzenes has been studied. The difference of absorption spectra of polymerization products can be explained qualitatively using bond energies of the primary products. The relative rate constant of the polymerization reaction is apparently proportional to the inverse of the vapour pressure of the liquids. Using this relation, we analysed the relative rate constant of the polymerization in benzene/chrolobenzene mixtures. From this, we conclude that sonochemical polymerization proceeds in the vapour phase of a bubble.