We performed direct solvent-free amination of multi-walled carbon nanotubes (MWCNTs) with nonylamine, dodecylamine, octadecylamine, 4-phenylbutylamine and 1,8-ocanediamine at a temperature of 150-170 degrees C and reduced pressure. Thermogravimetric analysis and temperature-programmed desorption-mass spectrometry revealed that a major amine fraction decomposes in a temperature interval of 250-500 degrees C, thus existing on multi-walled carbon nanotubes as chemically bonded species; a minor amine fraction was found in physisorbed form. The new derivatization technique combines simplicity in implementation and attractive features of "green" chemistry. It requires no additional chemical activation, but thermal activation instead; it is relatively fast since it can be completed in about 2 h; the high temperature allows one to spontaneously remove excess amine from the nanotube and minimize the possibility of physical adsorption; there is no need to use an (organic) solvent medium. In the case of diamines (represented in this study by 1,8-ocanediamine), the functional groups introduced can be potentially used as chemical linkers for anchoring metal complexes and nanoparticles to multi-walled carbon nanotubes, for adsorption and concentration of trace metal ions.
LCAO MO SCF calculations using the 3-21G basis were used to study the electronic and three-dimensional structure of several polycyclic aromatic hydrocarbons as models for the surface of activated charcoal. Localized carbon-carbon double bonds capable of adding electrophilic reagents were found on the periphery of these molecules. The reactivity of the peripheral C=C bonds was evaluated relative to consecutive bromination reactions of the C 54 H 18 molecule.Activated charcoal (AC) is a promising material for the manufacture of adsorbents, supports, catalysts, and stationary phases for chromatography due to the possibility of controlling its textural properties and surface chemistry [1]. The chemistry of products derived from AC is a function of the presence of various surface functional groups [2]. Materials with given desired properties may be obtained by varying the amount and composition of these groups in a broad range.The structure of activated charcoal may be represented as a condensed polycyclic aromatic system containing terminal localized double bonds [3,4], which hold promise as sites for the chemical modification of AC [5,6]. Certain synthetic methods may be used to create a functional coating to impart desired chemical and catalytic properties to activated charcoal. In order to obtain new AC materials with given properties, we must know the electronic and three-dimensional structure of the active sites and their capacity to interact with various chemical reagents. Such information may be obtained by quantum-chemical modeling to describe the interaction of AC with potential modifier molecules. Several experimental studies have now appeared suggesting similarity between the chemical properties of AC and aromatic hydrocarbons [3][4][5][6]. Nevertheless, there have not been comprehensive theoretical studies relative to the reactivity of the AC surface due to localized double bonds.In the present work, quantum-chemical calculations were carried out to evaluate the reactivity of AC active sites in the chemical modification of its surface. RESULTS AND DISCUSSIONThe electronic and three-dimensional structure of polycyclic condensed aromatic hydrocarbons consisting of 7, 19, and 37 rings (AC models) was examined to determine the properties of AC active sites in bromination reactions (Fig. 1). These 32 0040-5760/08/4401-0032
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