A maghemite supported palladium catalyst was prepared and tested in nitrobenzene hydrogenation. The catalyst support was made by a newly developed combined technique, where sonochemical treatment and combustion have been used. As a first step, maghemite nanoparticles were synthesized. Iron(II) citrate was treated in polyethylene glycol by high-intensity ultrasound cavitation to get a homogeneous dispersion, then the product was combusted. The produced powder contained maghemite nanoparticles with 21.8 nm average particle size. In the second step of catalyst preparation, the magnetic nanoparticles were dispersed in the ethanolic solution of palladium(II) nitrate. The necessary energy for the reduction of Pd²⁺ ions was achieved in the “hot spots” by acoustic cavitation, thus catalytically active palladium was formed. The prepared maghemite supported Pd catalyst have been tested in nitrobenzene hydrogenation at three different temperatures (283 K, 293 K and 303 K) and constant pressure (20 bar). At 293 K and 303 K, the conversion and selectivity of nitrobenzene was above 99% and 96%, respectively. However, the selectivity was only 73% at 273 K because the intermediate species (azoxybenzene and nitrosobenzene) have not been transformed to aniline. All in all, the prepared catalyst is successfully applied in nitrobenzene hydrogenation and easily separable from the reaction media.

Sonochemistry in combination with a combustion procedure was used to prepare superparamagnetic iron oxide nanoparticles. Two different iron precursors, ferrocene and iron(II)-acetate were dispersed in polyethylene-glycol (PEG) with different molecular weight (200–1000) by using a high efficiency ultrasonic technique. The sonochemical treatment initiated the precipitation of iron-hydroxide particles, then the PEG based colloids were burnt to create the iron oxide nanoparticles. Three phases were observed in the samples, magnetite (Fe₃O₄), hematite (α-Fe₂O₃), and maghemite (γ-Fe₂O₃) and their ratio can be modified by changing the iron precursor and the type of PEG. Elektrokinetic (Zeta) potential and the particle size of the synthesized iron oxide nanoparticle samples were measured and the one (A1) based on iron(II)-acetate and PEG200 have been selected to test in DNA purification, because it has negative and small size distribution. The synthesized superparamagnetic nanoparticles have been used successfully in biological isolation (DNA, deoxyribonucleic acid purification), and thus, the developed synthetic procedure is more than suitable for such applications.

The aim of this work was to examine the applicability of nitrogen-doped bamboo-shaped carbon nanotubes (BCNTs) as conductive additive in bearing grease. To synthesize BCNTs, catalytic chemical vapour deposition (CCVD) method was used by applying butylamine as nitrogen containing carbon source. During the preparation of the polydimethylsiloxane (PDMS)-based lubricants BCNT (1.5 wt% or 3 wt%) and Li-soap (5 wt% or 10 wt%, lithium-stearate) or colloidal silicon dioxide (1 wt% and 1.5 wt% Aerosil 200) was added and mixed by using a highly efficient ultrasonic technique. By adding lithium-soap to the BCNT loaded greases their lubricity improved. The electrical conductivity of greases was measured in stationary state and in rotating bearing (during operation) by using an in-house developed instrument. The nanotube containing samples have shown good electrical conductivity (7–18.5 mS). The friction torque was also calculated based on the measurements of our in-house developed instrument. Efficient friction has been achieved with the 1.5 wt% BCNT loaded samples (6.1 and 5.1 Nmm). Thus, small amount of BCNT is enough to develop a conductive grease formula. All in all, the 3% BCNT and 1.0% colloidal SiO₂ containing PDMS base-oil with 50 mm/s viscosity is well suitable for loading of ball bearings.

Carbon foam was synthesized by the carbonization of 4-nitroaniline. The reaction is an alternative of the well-known “carbon snake” (or sugar snake) demonstration experiment, which leads to the formation of nitrogen-doped carbon foils due to its nitrogen content. The synthesized carbon foils were grinded to achieve an efficient catalyst support. Palladium nanoparticles were deposited onto the surface of the support, which showed continuous distribution. The prepared Pd nanoparticle decorated carbon foils showed high catalytic activity in nitrobenzene hydrogenation. By applying the designed catalyst, total nitrobenzene conversion, a 99.1 n/n% aniline yield, and an exceptionally high selectivity (99.8 n/n%) were reached. Furthermore, the catalyst remained active during the reuse tests (four cycles) even without regeneration.

Carbonized ion exchange resin beads were prepared as catalyst for gas phase hydrogenation processes. Amberlite IR 120 polystyrene based sulfonated ion exchange beads were carbonized at 900 °C. The process of carbonization was monitored by FTIR combined thermogravimetric analysis. During the carbonization formed sulfur dioxide, carbon dioxide and organic compounds. The carbon pearls were used as catalyst support for Pd nanoparticles. The catalyst was characterized by scanning electron microscopy and X-ray diffractometry. The diameters of the palladium nanoparticles on the catalyst surface were between 15 and 50 nm, but bigger aggregates were also detected. The catalyst was tested during the gas phased heterogeneous catalytic hydrogenation of 1-butene. The hydrogenation process was followed by FTIR measurements, 93% conversion was reached after 10 min.

The paper comprises new analytical data on the nature and occurrence of gold in solid pyrobitumen, closely associated with the main gold-bearing sulfide arsenic ores of the Bakyrchik gold deposit (Kazakhstan), related to post-collisional magmatic-hydrothermal origin. Gold mineralization of the deposit occurs mainly in the form of an “invisible” type of gold in the structures of arsenian pyrite and arsenopyrite, and the form of gold-organic compounds of pyrobitumen in carbonaceous-terrigenous sequences of Carboniferous formation. Microscopic and electron microscopic analysis, Raman and FT-Infrared analysis, mineralogical and three-step sequential extraction analysis (NH₂OH·HCl, H₂O_2,HNO₃ + HCl) has been carried out using 9 ore samples (from 3 different types of ores) for a comprehensive study of pyrobitumen and sulfide arsenic ores focusing mainly on organic matter. The sequentially extracted precious metal content of pyrobitumen reaches up to 7 ppm gold and other metals like Ag 4 ppm, Pt 31 ppb, and Pd 26 ppb, forming metal–organic compounds, while arsenic sulfide minerals incorporate 11 ppm gold, 39 ppm Ag, 0.49 ppm Pt. The enrichment of gold associating with organic matter and sulfide ore minerals was confirmed in this study. Organic matter was active in the migration of gold and the capture of gold by pyrobitumen. Moreover, the reductive organic matter agent released gold, most likely for the sulfide arsenic ore minerals. Pyrobitumen was a decisive factor in the concentration, transportation, and preservation of gold in the deposit.