Counterion condensation in hydrosols of single-crystalline detonation nanodiamond particles obtained by air annealing of their agglomerates

The pattern of previously recorded dependences of the specific surface charge and electrophoretic mobility of monodisperse detonation nanodiamond particles on pH of aqueous KCl solutions suggests that counterions are condensed on the particle surface. Counterion condensation is considered in terms of the Levin model, and the experimental ratios between the densities of the electrokinetic and surface charges of dispersed particles, as well as the fractions of condensed counterions, are calculated as depending on pH and KCl concentration in nanodiamond hydrosols. The obtained dependences lead to the conclusion that counterion condensation on the surface of detonation nanodiamond particles does indeed take place.     

Biotinylated nanodiamond: simple and efficient functionalization of detonation diamond

We have developed a simple and efficient method for the covalent functionalization of detonation nanodiamond. After homogenization of the surface by borane reduction, the surface was modified with (3-aminopropyl)trimethoxysilane. Subsequent grafting of biotin yielded covalently biotinylated nanodiamond, which was characterized by FTIR spectroscopy, X-ray powder diffractometry, thermogravimetry, and elemental analysis. The activity was tested with horseradish peroxidase-labeled streptavidin. The surface loading of biotin was found to be 1.45 mmol g-1. The new material opens the way to covalently bonded diamond bioconjugates for labeling, drug delivery, and other applications.     

Adsorption and structural characteristics of the surface of modified nanodiamond powders

The adsorption of benzene and water vapors on the surface of detonation nanodiamond powders that differed in particle size, degree of their strong aggregation, and chemical state of their surface was studied. Specific features of the processes of adsorption of polar and nonpolar molecules on chemically modified surfaces of nanodiamonds are analyzed.     

A nickel-substituted form of nanodiamonds and its catalytic activity in decomposition of hydrogen peroxide

Adsorption of nickel (II) ions with nanodiamonds obtained by the detonation synthesis was studied. A nickel-substituted form of nanodiamonds was obtained. The catalytic activity exhibited by nickel ions (II) in the form of the surface complexes with nanodiamond functional groups in decomposition of hydrogen peroxide was determined.     

Adsorption characteristics of a nanodiamond for oxoacid anions and their application to the selective preconcentration of tungstate in water samples.

A nanodiamond with a mean particle size of 4 nm, which was prepared by the detonation of a nanodiamond, has been characterized and used as a collector for tungstate in water samples. An aqueous solution of nanodiamond was found to be stable over the pH range from 3 to 10. Coagulation of the nanodiamond could be brought about by adding an electrolyte solution. The adsorption characteristics of nanodiamond have been elucidated to be attributable to amino groups on its surface by the elemental-analysis data and the zeta potential measured in weak acid media. The unique adsorption properties of the nanodiamond for oxoacid anions were applied to a selective preconcentration method for tungstate in water samples. An appropriate amount of nanodiamond was added to a sample solution at pH 5 and a calcium chloride solution was added to aggregate nanodiamond. The sample solution was then allowed to stand for 2 h and centrifuged. The nanodiamond was transferred onto a membrane filter, washed with a diluted calcium chloride solution and treated in advance of an ICP-AES measurement by either of the following procedures: (a) redispersion of the nanodiamond into dilute nitric acid with an ultrasonic washer and (b) ashing of the membrane filter and the coagulated nanodiamond at 700 degrees C, followed by a treatment of the ash with hydrochloric and tartaric acids. The average recovery of tungstate from 100-ml artificial river-water was found to be 99% at the 0.25 ppm level with an RSD of 2.2% (n = 3). The concentration factor at present is 10.     

Purification of detonation nanodiamond material using high-intensity processes

New procedures were developed for chemical treatment of detonation nanodiamonds and diamond-containing detonation blend to remove water-insoluble metal-containing impurities. The detonation nanodiamond material is treated with complexing agent solutions under cavitation conditions and at high temperature and pressure. Sodium 2,3-dimercaptopropanesulfonate (Unithiol), disodium dihydrogen ethylenediaminetetraacetate, thiourea, potassium thiocyanate, dicyandiamide, and hexamethylenetetramine are used as complexing agents. The complexing agent concentration in solution is 0.5–20 wt % at the nanodiamond material to complexing agent weight ratio higher than 0.2. The use of aqueous solutions of the complexing agents at high temperatures and pressures appeared to be the most efficient.     

纳米金刚石的表面修饰及应用

纳米金刚石是一种新型的碳纳米粒子,具有硬度高、化学稳定、良好的生物相容性和热传导性等优点,有广阔的应用前景。对于纳米金刚石的应用,大多需要对其进行表面修饰。本文主要结合近年来国内外研究成果,阐述了氢化、羧酸化、羟基化及其他表面修饰等纳米金刚石的表面修饰方法,总结了纳米金刚石在润滑、抛光、生物医学、复合材料等领域的应用。     

Electrosurface properties of single-crystalline detonation nanodiamond particles obtained by air annealing of their agglomerates

A complex study of electrosurface properties has been performed for single-crystalline detonation nanodiamond particles with sizes of 4–5 nm obtained by air annealing of their agglomerates. FTIR spectroscopy and X-ray photoelectron spectroscopy data indicate that the investigated properties result from the presence of two types of ionogenic functional groups on the particle surface, i.e., acidic carboxyl and amphoteric hydroxyl groups. Acid-base potentiometric titration, laser Doppler electrophoresis, and conductometry have been employed to measure the Γ_H⁺(pH) and Γ_OH^-(pH) adsorption isotherms of potential-determining ions, as well as the pH dependences (in a pH range of 3.5–10.5) of the surface charge density, electrophoretic mobility, and specific surface conductivity of detonation nanodiamond particles in aqueous 0.0001–0.01 M KCl solutions.     

Catalytic conversion of C<Subscript>2</Subscript>-C<Subscript>3</Subscript> alcohols on detonation nanodiamond and its modifications

The catalytic activity of detonation nanodiamond and its modifications obtained through treatment with hydrogen or air at elevated temperatures is studied in the conversion of C₂-C₃ alcohols. The catalysts were characterized by means of electron microscopy, optical (FTIR) spectroscopy, elemental analysis and pulse microcatalytic method. It has been established that nanodiamond exhibits high catalytic activity in the conversion of alcohols. The oxidizing and reducing treatment of nanodiamond changes its activity and selectivity, and the activity of oxidized nanodiamond is considerably higher than that of reduced nanodiamond.     

Environmental issues related to preparation of detonation nanodiamonds. Surface and functionalization

Specific features of the preparation of detonation nanodiamond (DND) surface were considered from the viewpoint of their subsequent use in biology and medicine. Particular attention was given to quantitative determination of groups containing a labile proton on the DND particle surface. It was proposed to use only physical drying techniques to improve environmental parameters of DND surface functionalization techniques. The proposed procedure ensured for the first time additional purification of DND from latent carbon, which considerably improved their environmental properties.     

Natural limit of the number of copper ions chemisorbed on the surface of a detonation nanodiamond

The upper limit of the amount of copper ions that can be grafted to the detonation nanodiamond surface has been calculated. A maximum of 34 wt% copper can be grafted to carboxylated and hydroxylated 5 nm nanodiamonds. The results of calculations have been compared with the experimental and published data.     

The effect of simple electrolytes on coagulation of hydrosols of monodisperse negatively charged detonation nanodiamond

The influence of the concentration of potassium and barium chlorides on the aggregation stability of a hydrosol of monodisperse negatively charged detonation nanodiamond with particle sizes of 4?5 nm obtained by annealing of its agglomerates in air has been studied by turbidimetry. The experimental results have been discussed within the classical and generalized Derjaguin?Landau?Verwey?Overbeek theories. The analysis of the pair interaction potentials calculated for ultradispersed particles of detonation nanodiamond has led to the conclusion that the coagulation occurs by the barrier mechanism in the primary potential minimum. It has been assumed that the structural component of the interparticle interaction energy contributes to the total balance of the surface forces.     

Surface characterization of detonation nanodiamond particles

Specific features of formation of stable suspensions of detonation nanodiamond (DND) in media of different polarities were considered. A relation between the dispersity of DND particles and their surface activity was found. The surface activity of diamond nanoparticles (10–100 nm) is significantly (by a factor of 4) lower than that of submicron-sized particles, which indicates satisfactory environmental parameters of nanosized diamonds. An attempt to reduce the surface energy by grafting hydrophobic radicals led to appreciable increase in the dispersity of DND particles, thereby reducing the risk of harmful DND effect on the environment.     

Formation of nanoparticles of platinum group metal alloys in composites based on nanodiamonds

Metal-carbon nanocomposites were synthesized from detonation nanodiamonds (ND) and platinum group metals under the IR pyrolysis conditions. The metal interacted with the nanodiamond surface. The size of metal nanoparticles was shown to depend on the amount of the metal introduced in the precursor. In ND/Pt-Ru, ND/Pt-Rh, ND/Pd-Ru, and ND/Pd-Rh nanocomposites, the metal phase was a solid solution. The lattice constants of the metal phases in the nanocomposites were determined. The quantity of the dissolved metal in the solid solution was evaluated.     

An approach to unification of the physicochemical properties of commercial detonation nanodiamonds

Russian Journal of General Chemistry - In recent years, detonation nanodiamond is regarded as a promising material for biomedical applications. However, a significant problem that stops of...     

Preparation of clear colloidal solutions of detonation nanodiamond in organic solvents

Highly transparent colloidal solutions of detonation nanodiamonds in organic solvents such as tetrahydrofuran (THF), methyl ethyl ketone (MEK) and acetone were attained in this investigation through an easy process, in which the detonation nanodiamond powder was oxidized at 420 °C for 1.5 h and then dispersed into solvents by beads-milling with the addition of the surfactant, oleylamine (OLA). The results of both Fourier transform infrared spectroscopy and zeta potential measurements confirm that a readily apparent number of Lewis acid sites composed of mainly carboxylic acid and cyclic acid anhydrides were derived on the surface of thermally oxidized nanodiamond (T-ND). This acid sites-derived T-ND is chemically active, favoring the formation of charge-transfer complexes with the amino-containing surfactants such as OLA and octadecylamine (ODA). After being dispersed with one of the surfactants, OLA or ODA, the T-ND shows good dispersion stability in organic solvents; however, the dispersion efficiency of the saturated ODA is not as good as that of the unsaturated OLA. By using the dispersant OLA, accompanied with de-agglomeration by beads-milling, a clear colloidal solution of T-ND in solvents of THF, MEK or acetone can be easily attained and stabilized for at least 3 months.     

用动态激光散射法测定悬浮液中颗粒尺寸分布的一些经验

介绍了用动态激光散射仪测定用炸药爆炸法制备的纳米金刚石粉在水悬浮液中的颗粒尺寸分布时,取得的一些经验和教训.指出,在悬浮液样品制备和测定条件选择上的一些重要因素,必须认真对待,才能得到重复性良好的结果.可供从事此项工作的人士参考.     

Quantification of nanodiamonds in aqueous solutions by spectrophotometry and thermal lens spectrometry

Spectrophotometry and thermal lens spectrometry were used to study solutions of several commercial detonation nanodiamonds. It was found that the absorption spectra of solutions of all studied nanodiamond samples obey the Bouger-Lambert-Beer law, which ensures the precise determination of the total mass concentration of unknown nanodiamond solutions using a calibration plot. It was shown that the absorption spectra of nanodiamond solutions exhibit both absorption and scattering components, both significantly affecting signal formation. Conditions were proposed for the spectrophotometric determination of nanodiamonds at 250 nm (l = 1.0 cm). The detection limits were from 60 ng/mL to 2 ??g/mL, depending on the nanodiamond type. Limits of detection of SDND nanodiamonds by spectrophotometry and thermal lens spectrometry were calculated for identical conditions of sample preparation and measurements (488 nm, l = 1.0 cm). These were 10 and 0.6 ??g/mL for spectrophotometry and thermal lens spectrometry, respectively (power of excitation radiation 150 mW).     

Nanocatalysts for photocatalytic air purification systems

Nanocatalysts containing platinum and palladium clusters have been synthesized on the basis of detonation nanodiamond, cubic silicon carbide, and titanium dioxide. Characteristic size of the Pt cluster was close to 4 nm on both nanodiamond (particle size 5 nm) and β-SiC (particle size 13 nm) supports. The catalysts show high catalytic activity in reactions of CO oxidation and photocatalytic oxidation of ethanol at room temperature and low concentrations (<100 mg m³). They are promising in photocatalytic air purification systems for domestic use.     

The Surface Properties of Nanodiamonds As Examined by Gas Chromatography

Two samples of detonation nanodiamond (ND) were studied using gas chromatography. Sample ND-Cr was treated by boiling sulfochromic acid with liquid-phase acid purification. Sample ND-Oz was treated with gaseous ozone. The retention times determined for nine substances of different nature at various temperatures were used to calculate the specific retention volumes and the thermodynamic parameters of adsorption of test compounds on ND-Oz and ND-Cr. The adsorption heats of tested n-hydrocarbons on nanodiamond powders, especially on ND-Oz, are close to those on graphitized carbon black (GTB). For benzene and polar compounds, the specific interaction terms in the total energy of adsorption were determined. These terms are higher for ND-Oz than for ND-Cr; i.e., sample ND-Oz contains more reactive functional groups.