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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, H2O2, 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.

Abstract Mineral carbonation is a potentially attractive sequestration technology for the permanent safe disposal and immobilization of CO2. In this technology, CO2 is chemically reacted with calcium, sodium, and magnesium containing materials to form thermodynamically stable and environmentally harmless minerals, usually carbonates. In our research, mechanical activation of red mud was carried out in order to enhance its reactivity by means of mechanochemical reactions (surface activation), and its sequestration behaviour was investigated using carbon dioxide gas at 25 °C temperature and at high pressure (5 bar) in an autoclave. The reacted red mud was characterized by Fourier-transformed infrared spectrometer, scanning electron microscopy, X-ray diffraction, laser particle size analyzer, BET specific surface area measurement, and pH measurement. It was found that mechanical activation improved the CO2 sequestration ability by 1.7 wt% of red mud, as demonstrated by the above investigations. The pH of red mud slurry can be lowered by reacting it with carbon dioxide. During our measurements, the pH of the suspension decreased from 10 to 6.81. Furthermore, the carbonation process can be successfully used to decrease the amount of harmful PM10 (particles with a diameter of 10 μm or less) and PM2.5 (particles with a diameter of 2.5 μm or less) fraction. The proportion of 10 μm particles can be reduced by 40% and that of 2.5 μm by 20%. Graphic Abstract

Graphite, one of the polymorphic forms of carbon, has become a versatile industrial material of nowadays due to its particular attributes. It is used mainly in the automobile industry, metal extractive industry and in the high-tech industry. Moreover, it is also included in the list of critical raw materials for the EU. Our aim was to prove the presence of graphite by thermal analysis beyond X-ray powder diffraction (XRD) and Raman spectroscopy. Thermogravimetry yields comparable results with quantitative XRD. The formation conditions are described by Raman spectrometry and microscopy examinations of drill core samples from Szendrőlád (Szendrő Mts, NE-Hungary; (Szendrőlád Limestone Formation, middle-late Devonian, shelf-basin facies). Polished rock slabs were made for optical microscopy, scanning electron microscopy with energy dispersive spectrometry (SEM–EDS) and Raman spectroscopy. X-ray powder diffraction (XRD) and thermal analysis (DTA-TG) measurements were made on powders. Based on our results, the graphite is epigenetic; its quantity varies between 1.5–3 mass% in the samples. It was developed in 20–50 μm sized flakes, which are often arranged in > 300 μm sized aggregates. Graphite was formed during regional metamorphism from the organic matter-rich shales. The average formation temperature, calculated from the results of Raman spectroscopy, is around 410 °C (± 30 °C). The Raman measurements also indicated the presence of a partially graphitized (disordered graphite) material beside graphite.

Tanulmányunk célja a Szendrői-hegységben található Meszes település melletti Vasbánya-hegy felszíni feltárásaiból (Szendrői Fillit Formáció) gyűjtött fekete fillitek vizsgálata optikai és elektronmikroszkópiával, illetve röntgen-pordiffrakcióval a kőzetekben található grafitra és kritikus elemekre fókuszálva. Vizsgálataink alapján a grafit pikkelyes formában, 50-150 µm-es nagyságban volt észlelhető. A kritikus elemeket tekintve, a minták tartalmaztak titánt (főként TiO2-ként, ritkán ilmenitként, valamint fengitbe beépülve), nióbiumot (TiO2-ba beépülve), stronciumot (fluorapatitban és monacitban), valamint ritkaföldfémeket (xenotimban, monacitban és goethitben).

Cu/AlN–Al2O3 nano-multilayer (NML) was deposited by magnetron sputtering method on 42CrMo4 steel samples, starting with a 15 nm AlN–Al2O3 layer and followed by 200 alternating layers of 5 nm thick Cu and 5 nm thick AlN–Al2O3 layers. The microstructure and thermal behaviour of the as-deposited and heat-treated multilayer was studied. Starting from about 400 °C, extensive coarsening of Cu nanocrystallites and the migration of Cu within the multilayer were observed via solid-state diffusion. Part of the initial Cu even formed micron-sized reservoirs within the NML. Due to increased temperature and to the different heat expansion coefficients of Cu and the AlN–Al2O3, the latter cracked and Cu appeared on the top surface of the NML at around 250 °C. Below 900 °C, the transport of Cu to the top surface of the NML probably took place as a solid-state flow, leading to faceted copper micro-crystals. However, above 900 °C, the Cu micro-crystals found on the top of the NML have rounded shape, so they were probably formed by pre-melting of nano-layered Cu due to its high specific surface area in the NML. Even if the Cu crystals appear on the top surface of the NML via solid-state flow without pre-melting, the Cu crystals on the top surface of the NML can be potentially used in joining applications at and above 250 °C.

Carbon nanosheets (CNs) were successfully synthesized from nettle stem (NS) which is an inexpensive material with a high carbon content that is abundantly available in nature. CNs were produced using chemical (potassium hydroxide activation and acid exfoliation) and thermal treatments. Sulfuric (H2SO4), phosphoric (H3PO4) and nitric (HNO3) acid solutions were used for exfoliation. CNs exfoliated by H3PO4 have higher specific surface area (789 m2 g−1) compared to CNs exfoliated by H2SO4 (705 m2 g−1) and HNO3 (106 m2 g−1). In this work, NSCNs were found to be a potential candidate for electrode material in electrochemical capacitors. The maximum specific capacitance of the NSCNs exfoliated by H3PO4 is found to be 27.3 F g−1 at a current density of 0.05 A g−1, while the specific capacitance of NSCNs exfoliated by H2SO4 and HNO3 is 9.34 F g−1 and 1.71 F g−1, respectively. Energy density (0.06–0.95 Wh kg−1) and power density (20.9–26.7 W kg−1) of NSCNs are confirmed to be supercapacitor materials and can be applied in energy storage devices.

Abstract One of the main challenges in the field of heterogeneous catalysis is the involvement of thin solid films and membranes and their application in flow systems. In this regard, we report here the application of self-supported bacterial cellulose (BC) reinforced nanosized platinum (Pt)/N-doped bamboo-like carbon nanotube (NBCNT) hybrid catalyst membrane with a thickness of 35 ± 5 µm in the hydrogenation of n-butene. To synthetized the BC-NBCNT/Pt nanohybrid membrane catalyst a simple impregnation route was applied in a two-step process. As-prepared material was tested in a continuous flow system and the conversion was followed directly by using Fourier transform infrared spectroscopy. Furthermore, the fabricated films were characterized by scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy and specific surface area measurement (Brunauer–Emmett–Teller). Hydrogenation performance was studied on both single and double films. Results revealed that 97% conversion of n-butene can be achieved using these bacterial cellulose reinforced hybrid membranes. Graphic abstract

By applying ultrasonic cavitation, palladium particles were deposited onto the surface of two different types of carbon nanotubes (nitrogen-doped bamboo-shaped carbon nanotubes, N-BCNT and multiwalled carbon nanotubes, MWCNT). To achieve this, palladium ions have been reduced by the adsorbent (N-BCNT or MWCNT) itself. Hydroxyl functional groups were identified on the surface of the MWCNTs, while amine groups have been found on the N-BCNTs. The Zeta potential was lower (−9.8 mv) in the case of the N-BCNT sample, than for MWCNT (−6.1 mV), which was in accordance with their different dispersibility in aqueous phase. The incorporated nitrogen atoms and their oxidized forms within the N-BCNT structure lead to increased adsorption capacity and thus, this type of nanotube is more efficient adsorbent for Pd particles, than MWCNT. The higher adsorption capacity of the N-BCNTs can be explained by the presence of nitrogen atoms which increase the interaction between the Pd and nanotubes. Both Pd/nanotube systems show high catalytic activity (after 30 min – 99% aniline yield) in hydrogenation of nitrobenzene to aniline. Thus, palladium coated carbon nanotubes were synthetized in a one-step reduction procedure, and the produced composites are applicable as catalysts in heterogeneous hydrogenation reactions.

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Maghemite particles were synthesized by using a combined combustion method and sonochemical step. Maghemite was used as carrier to prepare supported Pt and Pd catalysts after deposition via a sonochemical step. The catalysts were immediately ready to be used (metals were catalytically active) for the 2,4-dinitrotoluene hydrogenation to produce 2,4-toluenediamine. The most active catalysts were the Pd/maghemite and bimetallic Pd-Pt/maghemite. The catalysts were easily separable after reaction due to their magnetic properties.

Cellulose grains were carbonized and applied as catalyst supports for nickel- and magnetite-promoted bimetallic palladium- and platinum-containing catalysts. The bimetallic spherical aggregates of Pd and Pt particles were created to enhance the synergistic effect among the precious metals during catalytic processes. As a first step, the cellulose bead-based supports were impregnated by nitrate salts of nickel and iron and carbonized at 973 K. After this step, the nickel was in an elemental state, while the iron was in a magnetite form in the corresponding supports. Then, Pd and Pt particles were deposited onto the supports and the catalyst surface, precious metal nanoparticles (10–20 nm) were clustered inside spherical aggregated particles 500–600 nm in size. The final bimetallic catalysts (i.e., Pd–Pt/CCB, Pd–Pt/Ni–CCB, and Pd–Pt/Fe3O4–CCB) were tested in hydrogenation of chlorate ions in the aqueous phase. For the nickel-promoted Pd–Pt catalyst, a &gt, 99% chlorate conversion was reached after 45 min at 80 °C. In contrast, the magnetite-promoted sample reached an 84.6% chlorate conversion after 3 h. Reuse tests were also carried out with the catalysts, and in the case of Pd–Pt/Ni–CCB after five cycles, the catalytic activity only decreased by ~7% which proves the stability of the system.

Bioapatite, the main inorganic component of bone, is similar to hydroxyapatite (HAp, Ca5[PO4]3(OH)) having some [CO3]2− content which plays an important role in leaching/precipitation processes in many biological lesions. We studied the leaching of powdered bovine tibia in soda-saturated (nahcolite, NaHCO3) water as a function of concentrations and treating periods. The reaction products were characterized by X-ray (XRD) and electron diffraction (SAED) techniques as well as high resolution transmission electron microscopy (HRTEM) and energy dispersive spectroscopy (EDS). We found evidence for dissolution of bone and precipitation of Ca-carbonate. The rate of carbonate precipitation was found to be a function of both the mass ratio of nahcolite/bone and the leaching time. According to XRD, calcite formed as a new crystalline phase at the expense of bioapatite. Based on HRTEM images, residual nanocrystalline apatite and unstable Ca-carbonate were also recognised, allowing the reconstruction of the intermediate stages of the leaching process. We propose a reaction sequence for the transformations of bioapatite in carbonated, alkaline media that may contribute to the understanding of the lesion processes of bone.

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...

Abstract This work presents an easy, one-step procedure for catalyst preparation. A small fraction of palladium ions was reduced to Pd nanoparticles and deposited onto the surface of nitrogen-doped carbon nanotubes (N-BCNT) by acoustic cavitation using high-intensity ultrasound in aqueous phase, where N-BCNT served as a reducing agent. The formation of elemental palladium and palladium oxides were confirmed and the particle size is N-methylaniline was formed as by-product in a small quantity (8 mmol/dm3). By decreasing the reaction temperature (at 273 K and 283 K), the reaction rate was also lower, but it was favourable for aniline selectivity, and not formed n-methylaniline. All in all, Pd/N-BCNT catalyst was successfully produced by using a one-step sonochemical method, where further activation was not necessary as the catalytic system was applicable in nitrobenzene hydrogenation. Graphic Abstract

Nitrogen-free multi-wall carbon nanotubes (MWCNTs) and N-doped bamboo-like carbon nanotubes (BCNTs) were synthesized by using catalytic vapor deposition (CVD) and used as catalyst support materials. Pd, Rh, Ru, and Ir have been deposited onto the nanotubes to achieve metal/nanotube catalysts. The catalytic activity of the samples was fine-tuned by changing the type of support. BCNT supported Pd and Rh (Pd/BCNT, Rh/MWCNT) catalysts were found to be the most active for liquid phase hydrogenation of octadecene amongst these samples. The initial olefin hydrogenation rate of the Pd/BCNT sample was slightly higher than the corresponding MWCNT-supported catalyst. Based on the hydrogenation reaction, the performance of these catalyst had been ranked as follows: Pd/BCNT ≈ Rh/MWCNT > Pd/MWCNT > Rh/BCNT > > Ir/MWCNT > Ru/BCNT > Ir/BCNT > Ru/MWCNT. The structural properties of chemisorbed Pd on MWCNT and N- BCNT were also characterized by means of computational chemical methods in order to shed some light on the nature of metal binding properties of N-doped and undoped surfaces. The calculations shown preference towards the edges of the surfaces which is in good agreement with the experimental findings.

Nitrogen-doped bamboo-like carbon nanotube (N-BCNT) coating was synthesized onto the surface of zeolite beads by using Catalytic Chemical Vapour Deposition (CCVD) method to develop a “support on support” (SoS) system. These complex structured materials were used as supports during the preparation of hydrogenation catalysts. Rhodium, palladium and platinum nanoparticles were deposited homogeneously onto the surface of the N-BCNTs of the SoS (final metal content 2 wt%). The catalytic activity of these samples was compared in the hydrogenation of nitrobenzene. The Pt/N-BCNT-zeolite sample was the most active (182 mol nitrobenzene after 30 min). The activity of the other two catalysts at 20 bar was well below this value, 99.5 mol after 60 min and 96 mol after 120 min for Pd and Rh, respectively. The aniline selectivity was different for the three catalysts and they facilitate the formation of various by-products (e.g. N-methylaniline, cyclohexylamine). The usage of the Pd and Pt/N-BCNT-zeolite catalysts are more convenient, as only one main by-product was formed. It was confirmed that the zeolite supported N-BCNTs are efficient catalyst supports in hydrogenation processes. Furthermore, by using this special SoS structure to support the catalytic metals the applicability is widened and the catalyst removal is easier.

Glassy carbon foam (GCF) catalyst supports were synthesized from waste polyurethane elastomers by impregnating them in sucrose solution followed by pyrolysis and activation (AC) using N2 and CO2 gas. The palladium nanoparticles were formed from Pd(NO3)2. The formed palladium nanoparticles are highly dispersive because the mean diameters are 8.0 ± 4.3 (Pd/GCF), 7.6 ± 4.2 (Pd/GCF-AC1) and 4.4 ± 1.6 nm (Pd/GCF-AC2). Oxidative post-treatment by CO2 of the supports resulted in the formation of hydroxyl groups on the GCF surfaces, leading to a decrease in zeta potential. The decreased zeta potential increased the wettability of the GCF supports. This, and the interactions between –OH groups and Pd ions, decreased the particle size of palladium. The catalysts were tested in the hydrogenation of nitrobenzene. The non-treated, glassy-carbon-supported catalyst (Pd/GCF) resulted in a 99.2% aniline yield at 293 K and 50 bar hydrogen pressure, but the reaction was slightly slower than other catalysts. The catalysts on the post-treated (activated) supports showed higher catalytic activity and the rate of hydrogenation was higher. The maximum attained aniline selectivities were 99.0% (Pd/GCF-AC1) at 293 K and 98.0% (Pd/GCF-AC2) at 323 K.

Poly(ethylene terephthalate) (PET) materials with different molecular weights were isothermally crystallized from melt by systematically varying the temperature and duration of the treatment performed in the differential scanning calorimeter (DSC). Multiple endotherm peaks were observed on the subsequent heating thermograms that were separated from each other on the basis of their melting temperature versus crystallization temperature and melting temperature versus crystallinity function. By this new approach five sub-peak sets were identified and then comprehensively characterised. Wide-Angle X-Ray Diffraction (WAXD) analyses revealed that the identified sub-peak sets do not differ in crystalline forms. By analysing the crystallinity and the melting temperature of the sub-peak sets as a function of crystallization time, crystallization temperature and intrinsic viscosity, it was concluded that below the crystallization temperature of 460 K the sub-peak sets that were formed during primary or secondary crystallization transform partially or completely to a third sub-peak set during the heating run of the measurement, while above this temperature, the sub-peak set formed during primary crystallization gradually transforms to a more stable structure, with higher melting temperature. These formations and transformations are described with mathematically defined parameters as well.

The Úrkút manganese ore deposit (Transdanubian Range, Hungary) is one of the largest manganese accumulations to be formed during the Toarcian Oceanic Anoxic Event. In the past 60 years, the area was investigated intensively. The core storage facility of the manganese mine had more than 20,000 sample pieces. Most of these samples have never been investigated. During this study, which is the first widespread clay mineral study in the footwall of the Úrkút manganese ore deposit, we investigated 40 samples from seven boreholes (footwall rocks, black/gray shales below and above the first ore bed, and manganese carbonate ores). Although previous studies assumed that smectite is associated only with the ore beds, our research revealed its appearance in the footwall (Pliensbachian) as well. Simultaneously, tripoli (the local name of completely bleached chert) can also be found in the footwall. Based on the investigated samples, a sharp geochemical difference was detected between Pliensbachian and Toarcian sediments. In this paper, we try to trace the relationship between the smectite content of the footwall and the ore bed and compare these results with the observed geochemical changes. Based on the new data, we assume that the ore accumulation was caused by a flow system (upwelling-controlled ore formation).

This paper focuses on the investigation of the co-utilization of two major industrial waste materials, power station fly ash and red mud. Experimental studies were carried out to establish the correlation between the physical properties of a geopolymer product and a mixture composition. The effect of mechanical activation and the red mud dosage on the geopolymerisation was investigated. Geopolymerisation of mechanically activated fly ash has been carried out with various proportions of red mud ranging between 0–30 % by weight. The compressive strength of fly ash based geopolymer increased until 15% of red mud addition. The optimal red mud addition in fly ash geopolymer was determined. The influence of red mud on phase composition and chemical bonds of the resulted geopolymer were determined by XRD analysis and FTIR studies. Due to the geopolymerisation reactions, new phases like hydroxy-cancrinite, faujasite and thenardite appeared in the product., U radu je ispitana zajednička uporaba dvaju glavnih industrijskih otpada kod elektrana – lebdećega pepela i crvene isplake. Eksperimentalno je pokazano kako postoji korelacija između fizičkih svojstava dobivenih geopolimera te udjela takvih otpada. Stoga je ispitana uloga mehaničke aktivacije lebdećega pepela i udjela crvene isplake tijekom geopolimerizacije. Taj postupak načinjen je s različitim udjelima crvene isplake – od 0 do 30 težinskih postotaka. Tlačna čvrstoća geopolimera s lebdećim pepelom povećava se do 15 % nakon dodavanja crvene isplake. Također su određeni i optimalni omjeri. Utjecaj isplake na fazni sastav i kemijske veze unutar geopolimera određen je XRD analizom i FTIR studijama. U njima su prepoznati novi minerali naziva hydroxycancrinit, faujasit i tenardit.

A catalyst nanocomposite was synthesized based on zeolite supported nitrogen-doped carbon nanotubes (N-CNT) decorated with palladium nanoparticles. Zeolite beads impregnated with nickel nitrate solution were used as CCVD catalyst support during the synthesis of N-CNT. Then the zeolite supported N-CNT was decorated with palladium nanoparticles and the final nanocomposite was tested in nitrobenzene hydrogenation. The structure of the nanocomposite was characterized by SEM. The surface of the zeolite beads is extensively covered by N-CNT. The particle size distribution of the palladium nanoparticles on the surface of N-CNT is relatively homogenous (

Nitrogen‐doped, bamboo‐like carbon nanotubes (BCNTs) were synthesized from butylamine by catalytic chemical vapor deposition (CCVD method). The nanotubes were oxidized by H2SO4/HNO3 treatment and used to prepare calcium alginate gelled BCNT spheres. These beads were first carbonized and then Pd, Rh and Ni nanoparticles were anchored on the surface of the spheres. These systems were then applied as catalysts in CO2 hydrogenation. The BCNT support was examined by Raman spectroscopy, dynamic light scattering (DLS) and X‐ray photoelectron spectroscopy (XPS). The prepared catalysts were characterized by HRTEM and SEM. The oxidation pretreatment of BCNTs was successful, with the electrokinetic potential of the water‐based dispersion of BCNTs measuring −59.9 mV, meaning the nanotube dispersion is stable. Pyridinic and graphitic types of incorporated nitrogen centers were identified in the structure of the nanotubes, according to the XPS measurements. The Pd‐containing BCNT sphere catalyst was the most efficient in the catalytic studies. The highest conversion was reached on the Pd catalyst at 723 K, as well as at 873 K. The difference in the formation rate of CO was much less at 873 K between the Pd and Rh compared to the 723 K values. Accordingly, the application of Pd‐containing BCNT/carbon‐supported catalyst favored the generation of CO. However, the Ni‐BCNT/carbon catalyst leads to the formation of CH4 as the major product.

The kinetics of transformation of 5 w% TiB2 nano-particles (50 nm diameter) dispersed and pressed (1.5 GPa) in the of Ti matrix (150 µm diameter) into TiB nano-whiskers was studied as a function of temperature (800–900–1000 °C) and time (5–720 min) in 25 experiments in total, by vacuum sintering. The classical one-step Avrami kinetics does not properly describe this transformation due to the formation of oxide inhibitors from contaminants. However, the same results could be perfectly described by a complex Avrami kinetics supposing two parallel steps of transformations: i). fast transformation along the initially metallic Ti/TiB2 interface and ii). delayed transformation along contaminated Ti/TiB2 interface. Data for kinetic calculation was obtained by X-ray diffraction and Rietveld refinement on the sintered samples. Extrapolating the experimental results by the complex Avrami model beyond the measured temperature interval it was found that at and above about 1050 °C, the second step is missing due to the fast dissolution of oxide films in the beta-Ti matrix, leading to very fast kinetics.

Carbon black (CB) supported palladium-platinum catalysts were prepared with and without nickel(II) oxide or iron(III) oxide promoter materials. By applying ultrasonic cavitation highly efficient CB supported catalysts were created. The designed catalyst preparation is a one-step procedure, as post-treatments (e.g. calcination, hydrogen activation) are not necessary. The activation of the catalysts occurs during their preparation due to the ultrasonic cavitation. Thus, a fast and simple catalyst preparation procedure have been developed. The activity of the catalysts was compared in nitrobenzene hydrogenation at different temperatures in the range of 283-323 K at 20 bar hydrogen pressure. In terms of selectivity and aniline yield, no significant differences were detected even when promoters were present. By using the NiO promoter, the activation energy was extremely low (7.6 ± 0.7 kJ mol-1). The selectivity was over 99% in every case, and 99.6% aniline yield was achieved without any promoters (99.7% with NiO), while less than 1.0% by-products were formed. The reaction rate was high with every catalyst, and no significant differences were detected. All in all, the prepared catalysts show excellent catalytic activity in the hydrogenation of nitrobenzene.

Cobalt, copper, and nickel ferrite spinel nanoparticles have been synthesized by using a combination of sonochemical treatment and combustion. The magnetic nanoparticles have been used as supports to prepare ~4 wt% palladium catalysts. The ferrites were dispersed in an ethanolic solution of Pd(II) nitrate by ultrasonication. The palladium ions were reduced to metallic Pd nanoparticles, which were then attached to the surface of the different metal oxide supports. Thus, three different catalysts (Pd/CoFe2O4, Pd/CuFe2O4, Pd/NiFe2O4) were made and tested in the hydrogenation of 2,4-dinitrotoluene (DNT). A possible reaction mechanism, including the detected species, has been envisaged based on the results. The highest 2,4-diaminotoluene (TDA) yield (99 n/n%) has been achieved by using the Pd/NiFe2O4 catalyst. Furthermore, the TDA yield was also reasonable (84.2 n/n%) when the Pd/CoFe2O4 catalyst was used. In this case, complete and easy recovery of the catalyst from the reaction medium is ensured, as the ferrite support is fully magnetic. Thus, the catalyst is very well suited for applicationy in the hydrogenation of DNT or other aromatic nitro compounds.

This is the fourth paper presenting new mosaic-like mineralogical data from the Carpathian–Pannonian region. Data are arranged by countries and localities. Every section gives a description (including XRPD, EMPA and SEM-EDX results) of the minerals and a concise description of their parageneses. Every discussed mineral is first described from the given locality and in many times even from the whole region.From Hungary the following minerals are reported: freieslebenite and beaverite-(Cu) from the Rudabánya ore deposit, planerite–aheylite–faustite–turquoise solid-solution members from the Parádfürdő ore deposit.From Romania the following minerals are identified: conichalcite (with high Pb content, conichalcite–duftite solid solution), duftite and mottramite–duftite solid-solutions from the Băiţa Bihor ore deposit, pseudomalachite pseudomorph after azurite as well as vauquelinite from the Ocna de Fier ore deposit.From Slovakia the following minerals are described: axinite-(Fe) from the Maglovec diorite-porphyrite quarry, bultfonteinite from the Vechec andesite quarry and botallackite from the Dobšiná ore deposit.

The main goal of the presented research was the preliminary investigation of possibility of red mud - Hungarian dump sites Almasfuzito (sample A) and Ajka (sample B) - application as a pigment or as a raw material for use in the construction materials industry. Also, the aim of this work was the characterization of red mud as industrial waste generated by the Bayer process in the aluminum industry - which may cause environmental problems if appropriate treatment is not carried out. The main mineral phases of both red mud are hematite (Fe2O3), calcite (CaCO3), gibbsite (Al(OH)3) and they consists of particles of median particle size 2.1 mm (sample A) and 2.5 mm (sample B) and have a characteristic red color, which was the reason for its testing for use in the industry of building materials as a pigment for standard concrete mixtures. The radionuclides content in the samples was determined by gamma spectrometry, and the radiological hazards originating from 238U, 232Th, 40K in the samples, were assessed through the radium equivalent activity, and the external radiation hazard index. The absorbed dose rate and the annual effective dose were calculated in accordance with the UNSCEAR 2010 report and the results are presented in this paper. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 45012 and Grant no. III 45005]

In our experiments, high nitrogen content N-doped multiwall carbon nanotubes (N-CNTs) were synthetized by chemical vapour deposition (CVD) method, after these nanotubes were used as dehydrogenation catalyst support. The chemical nature of the nitrogen atoms in graphitic lattice of N doped CNT was characterized with X-ray photoelectron spectroscopy (XPS) analysis, the pyridinic and graphitic nitrogen atoms were located in nanotube wall. The lattice defects of N-CNT structure were checked with Raman spectroscopy, according to which many defect were present in structure of N-CNTs, owing to the incorporated nitrogen atoms. The formed oxidized N-doped CNT samples were studied by Fourier transform infrared (FT-IR) spectroscopy, according to the test, many oxygen content surface functional groups were identified (COOH, OH and C=O). Palladium nanoparticle morphology and surface on the catalyst substrates were characterized by high resolution transmission electron microscopy (HRTEM) and X-Ray diffraction (XRD) methods. The diameters of palladium particles were slightest in case of carbon nanotube supported catalyst (2 nm), smaller than case of activated carbon, due to absence of microporosity and presence of functional groups on the N-CNT surface. The catalytic activity of the CNT supported catalysts was compared to an active carbon and norit supported samples. The dehydrogenation of C2H6 has been investigated on Pd deposited on various carbon supported catalysts at 573–973 K. On the Pd/CNT catalyst the highest selectivity was reached to ethene (85 %) at 973 K. The most active Pd/Ac achieved 64 % conversion at 973 K.

In this work, silver (Ag) was reduced in nano-size on the surface on titanium (Ti) powder by chemical reduction method, which is a new, efficient and reproducible method. The amount of the Ag nanoparticles was at least 1.9 at. % in the Ti-Ag implant material and the typical size of these nanoparticles was under 50 nm. Owing to the powder metallurgy methods porous structure can be created and the relative density of the cold-pressed and sintered samples was 81 ± 1%. The mechanical properties were as follows: HV0.01 (363 ± 78), ultimate compressive true stress (470 ± 4 MPa) and Yield strength (277 ± 12 MPa). After the sintering process, TiAg and Ti2Ag phases were formed owing to the diffusion. The antibacterial features of Ag coated Ti powder, the sintered Ti-Ag alloy and its etched form were investigated. The strong antibacterial property was observed in the case of Ag coated Ti powder. It also turned out that E. coli bacteria in close contact of these Ti-Ag alloy surfaces cannot survive and the observed antibacterial properties may not be associated with the release of water soluble component from the alloy. Due to this local antibacterial feature of Ti-Ag alloys, they can be a good candidate for antibacterial implant material with potential biocompatibility.

Self-supported and flexible bacterial cellulose (BC) based hybrid membranes were synthesized and decorated with zinc oxide/multi-walled carbon nanotube (ZnO–MWCNT) composite additives in order to modify and tune their surface and bulk properties. Two types of ZnO–MWCNT additives with different morphologies were used in a wide concentration range from 0 to 90% for BC-based hybrids produced by filtration. The interaction between BC and ZnO–MWCNT and the effect of concentration and morphology of additives on the properties like zeta potential, hydrophilicity, electrical conductivity, etc. would be an important factor in various applications. Furthermore, the as-prepared hybrid membranes were characterized with the use of scanning electron microscopy (SEM), focused ion beam scanning electron microscopy (FIB-SEM), energy dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD) and surface area measurement (BET). Applying the presented synthesis routes, the surface properties of BC-based membranes can be tailored easily. Results reveal that the as-prepared BC–ZnO–MWCNT hybrid membranes can be ideal candidates for different kinds of applications, such as water filtration or catalysts.

The role of organic solvents in governing the crystallization and morphology of semi-crystalline poly-l-lactide (PLLA) sheets was systematically investigated. Three different organic solvents, ethyl acetate (EA), o-dichlorobenzene (ODCB), and nitrobenzene (NB), with a solubility parameter analogous to PLLA and with a high capability of swelling, were chosen. It has been witnessed that the degree of crystallization and crystal morphology depends highly on the degree of swelling and evaporation rate of the solvent. Besides, the temperature and time of treatment played a significant role in the crystallization of polymers. The effect of different solvents and curing times are reflected by the measured X-ray diffraction (XRD) peaks and the differences are best shown by the unit cell size. The largest variation is observed along the c-axis, indicating shorter bonds, thus, showing better conformation after NB and ODCB treatment. The percentage of crystallinity calculated using the classical relative crystallinity index of XRD shows closer values to those calculated with differential scanning calorimetry (DSC) data, but a huge variation is observed while using the LeBail deconvolution method. The strong birefringence of polarised optical micrograph (POM) and the crystal morphology of scanning electron micrograph (SEM) also evidenced the orientation of polymer crystallites and increased crystallinity after solvent-supported heat treatment.

The Baiţa metallogenic district in the Bihor Mountains is a historically important mining area in Romania. Uranium mining took place between 1952 and 1998 from various deposits, but very little is known about the geology and mineralogy of these deposits. In this paper, we describe geology and mineralogy of uranium mineralization of the Avram Iancu uranium mine from waste dump samples collected before complete remediation of the site. Texturally and mineralogically complex assemblages of nickeline, cobaltite–gersdorffite solid solution, native Bi, Bi-sulfosalts, molybdenite, and pyrite–chalcopyrite–sphalerite occur with uraninite, “pitchblende,” and brannerite in most of the ore samples. The association of nickel, cobalt, and arsenic with uranium is reminiscent of five-element association of vein type U–Ni–Co–Bi–As deposits; however, the Avram Iancu ores appear to be more replacement-type stratiform/stratabound. Avram Iancu ore samples contain multistage complex, skarn, uranium sulfide, arsenide assemblages that can be interpreted to have been formed in the retrograde cooling stages of the skarn hydrothermal system. This mineralizing system may have built-up along Upper Cretaceous–Paleogene “Banatite” intrusions of diorite-to-granite composition. The intrusions crosscut the underlying uraniferous Permian formations in the stacked NW-verging Biharia Nappe System. The mineralization forms stacked, multilayer replacement horizons, along carbonate-rich lithologies within the metavolcanic (tuffaceous) Muncel Series. Mineral paragenesis and some mineral chemistry suggest moderate-to-high

The Triassic-Jurassic boundary (TJB) is marked by one of the five largest Phanerozoic mass extinctions. To constrain existing models for TJB events, we obtained a stratigraphically highly resolved dataset from a marine section at Kendlbachgraben, Austria.The topmost Triassic Kössen Formation contains low to medium-charged smectite and vermiculite as alteration products of mafic-ultramafic minerals. The clay minerals in the boundary mudstone are kaolinite ⩾ illite + muscovite ⨠ smectite > chlorite. Predominant kaolinite suggests humid climate and abundant terrigenous input. In the lowermost Jurassic, the clay mineral pattern changes to illite + muscovite ⨠ kaolinite ⨠ smectite, which reflects change to less humid and more moderate climate.The topmost Kössen Formation also contains clay spherules. Their composition, shape and size indicate that they are alteration products of airborne volcanic glass droplets solidified in the air, settled in the sea and altered rapidly with negligible transport in terrestrial or marine environments. Our data are consistent with sudden climatic change at the TJB, as a result of large-scale volcanic activity of the Central Atlantic Magmatic Province which produced distal airfall volcanic ash.

Brick samples from nine archaeological sites representing seven contemporary medieval settlements in Bekes County (SE Hungary) were analysed by quantitative X-ray powder diffraction, optical microscopic, scanning electron microscopic and coupled thermal analytical – evolved gas analytical methods. The aims of this study were to give a mineralogical–petrographical characterization of the brick samples, to gain possible information on the raw clay and the admixed materials, and to determine the firing techniques applied in medieval southeastern Hungary. The mineralogical composition of the samples suggests that the locally extracted clay was mixed with fluvial sand and wheat (Triticum monococcum L.) chaff. The moulded bricks were fired in clamps. The different degrees of calcite consumption suggest that the firing temperature ranged from ∼750°C to ∼950°C. Moreover, the well-developed reaction coronas on calcite grains indicate long firing times, lasting perhaps several days.

Properties of powders made from Ti 50 Cu 27,5 Ni 10 Zr 10 Co 2,5 alloy, milled under different conditions for only 3600 s in total were investigated. For this purpose two different milling atmospheres and two different Process Control Agents (PCA) were tested: argon without PCA, air without PCA, argon combined with stearic acid, argon combined with petroleum spirit. Results showed that the size and shape of particles, and the microstrucutre and hardness of partcicles were highly depended on the milling conditions. According to XRD analysis, the maximal amorphous fraction has been achieved in the air atmosphere withouth PCA milled sample (57 wt. %) powder. However the extent of Fe contamination and weight loss during milling powder resulted bigger values. As a result, the optimal combination of morphology, contamination amount and weight lost level has been observed in the case of powder milled in argon atmosphere using stearic acid.

Vegetal materials are generated in high amounts and are applied as additives in clay bricks since ancient times. They have a certain heat contribution to the firing process. As revealed by X-ray Powder Diffraction, main component of vegetal waste materials is cellulose. Thermal and Evolved Gas Analysis revealed the combustion process in its details. Mixtures of clay and vegetal additives prepare for test bodies were analyzed by Thermal Analysis. The thermal effects were quantified by Differential Thermal Analysis and correlated with Thermogravimetry and Derivative Thermogravimetry.