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Graphite samples covered with glassy-carbon layers, have stayed for 2 years and 4 months under different conditions - terrestrial conditions and on the International Space Station. The influence of outer space on glassy carbon coatings was studied by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Raman and infrared spectroscopy. The results show presence of some defects and heteroatoms (traces of O, F, Na, Cl) after staying in space, probably due to radiation and other effects. SEM data provide valuable information about the existence of undamaged glassy carbon layer with thickness of 20 μm. There are no structural changes in the layers of glassy carbon after stay in space. Data show that these materials can be successfully applied for electrical field measurements in ionosphere.

Refuse-derived fuel (RDF) is a mixed industrial waste, which often contains combustible materials (cellulose, polymers, rubber, biomass, etc.). The RDF waste precursor is subjected to thermo-oxidation treatment at 300℃, followed by carbonizations at 600℃, and high temperature hydropyrolysis at 800℃. The obtained nanoporous carbon material was subjected to detailed characterization by low temperature nitrogen sorption, elemental analysis, etc. Carbon derived from RDF is distinguished by micro/mesoporous texture and moderately high surface area (650 m2 g-1). The catalyst obtained is tested in the process of methanol decomposition, leading to production of hydrogen as a fuel. The influence of the physico-chemical characteristics of the synthesized carbon on the catalytic activity of carbon-based cobalt catalyst is studied.

Carbon foam is an advanced porous material with multiple high-technology applications, due to its cell structure, light weight, very good thermal and chemical stability, high thermal and electrical conductivity, as well as exceptional electromagnetic and acoustic properties. The present work aims to find suitable treatment, allowing the formation of a large number of micro- and mesopores in carbon foams, obtained by recently developed synthesis method without the use of pressure and stabilization stage. High compressive strength materials were synthesized after heat treatment up to 1000◦C. It was found that the heat treatment in the presence of water vapour of the obtained carbon foam samples allows a significant increase in specific surface area and the volume of the micro- and mesopores. This gives the possibility for successful application of the synthesized material in water and air purification, as a catalyst support, construction material, and in other fields.

Thermochemical conversion of lignocellulosic biomass is considered as a good opportunity to obtain liquid raw materials for biofuels and biochemicals. During this pyrolysis process a solid product, biocarbon, is obtained. Nowadays there is a growing interest in biocarbon, due to the potential benefits of its application in soil as a stimulant and CO2 trap. The physicochemical and porous properties of biocarbon are suitable for development of effective and inexpensive sorbents for the removal of contaminants from water. Biocarbon has promising sorption properties for various pollutants in water, including polycyclic aromatic hydrocarbons and heavy metals. Banana and orange peels, as well as cocoa flakes, were used as precursors. The carbonization was carried out at temperatures from 500 ° C to 900 ° C. Some of the samples were subjected to physical and chemical activation. The obtained carbon adsorbents are characterized by adsorption of iodine, BET, etc. It is planned to study the possibilities for the successful application of the obtained carbon materials as adsorbents for water and air purification, catalysts, hydrogen depots, etc.

A novel procedure for the conversion of waste algae waste, remaining from biodiesel production, into gas, liquid products and porous carbon has been developed. The precursor, algae waste is studied by thermogravimetric and differential thermal analysis. First algae material is subjected to pyrolysis at 550 °C, and the composition of evolving gas and liquid products is studied—dominant content of polar compounds in the liquid products is determined. The solid product after pyrolysis is subjected to hydro-pyrolysis (physical activation with water vapor) at different temperatures. The pore structure of the obtained carbon after activation at pre-determined optimal temperature is investigated by nitrogen adsorption porosimetry, which demonstrate moderate surface area, microporosity and mesoporosity, developed during activation process. Presence of oxygen functional groups with weak acidic and basic nature is established.

16 figures, 6 tables.-- Supplementary material available., Ceria-iron oxide mesoporous materials with Fe:Ce molar ratio of 5:5 and 9:1 were synthesized by hydrothermal method using CTAB as a template and subsequently modified with NiO (molar ratio Ni:Fe = 1:2) by incipient wetness impregnation technique. In order to increase the electro-capacitive properties and reduce the intrinsic impedance of the metal oxides, the samples were consecutively modified by reduction in hydrogen to obtain highly dispersed Ni–Fe alloys into ceria matrix. By exploiting the high permeability of carbon inside ferrous alloys, the metal phase has been further modified into ferrous carbides and metal alloys encapsulated within carbon nanofibers. For this purpose, a reaction, already widely studied for the production of hydrogen, was used, that is the decomposition of methanol vapors. In fact, this decomposition, in addition to producing syn-gas and methane, changes the catalysts in use through a chemical vapor deposition-carbon coating process. This fact, has been used by us to demonstrate how the newly obtained metal-carbon nanocomposites can be used for electro-catalytic purposes. The modified phases of the two molar ratios of the Fe–Ni–Ce catalysts were tested in the Oxygen Evolution Reaction (OER) in an alkaline environment (1 M KOH), showing a satisfactory and progressive increase in activity and a surprising decrease in the overpotential at 10 mA/cm2 of current density. The morphological, textural and physicochemical properties of the samples were characterized in details by XRD, N2-physisorption, TG-TPO, TEM, EDX, FTIR, XPS, Raman and Moessbauer spectroscopies., This research was funded by the BIKE project, which received funding from the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement no. 813748.

The current investigation is focused on the preparation of activated carbons from biomass waste such as cherry stones, walnut shells and mixture of both precursors in different ratio. Their application as a host matrix of zinc ferrite nanoparticles was studied. The effect of the activated carbon texture and surface characteristics on the state of the loaded zinc ferrite phase was investigated by Boehm method, XRD, nitrogen physisorption, M¨ossbauer spectroscopy and TG–TPR analysis. The catalytic properties of the obtained modifications were tested in methanol decomposition with a potential for hydrogen production. The results of the physicochemical analysis showed the formation of finely dispersed ZnFe2O4 phase, despite the peculiarities of the carbon support. The catalytic activity was higher for the walnut shell based materials, and was probably promoted by the facile development of mesoporous texture in them

Magnesium-based materials are promising as hydrogen storage media due to their high theoretical hydrogen absorption capacity, abundance and low price. The subject of this study are the hydrogen sorption characteristics of the composites 80 wt % MgH2-15 wt % Ni-5 wt % activated carbon (synthesized from polyolefin wax, a waste product of polyethylene production at low pressure which will be denoted further in the text as POW) and 90 wt % MgH2-5 wt % Ni-5 wt % POW, prepared by ball milling under argon atmosphere. Structure, phase and surface composition of the samples before and after hydrogenation are determined by XRD and TEM. The maximum absorption capacity value of the composites at a temperature 573 K and after 60 min. of hydrogenation are 5.3 wt % H2 for the material with higher Ni content and 5.5 wt % H2 for the other sample. The presence of both additives&mdash, nickel and activated carbon derived from POW&mdash, has a positive impact on hydrogenation kinetics and the capacity achieved. The results from TEM characterization, e.g., the polycrystalline SAED (selected area electron diffraction) show the presence of graphite, Mg and monoclinic Mg2NiH4.

This study is aimed at the development of intelligent integrated scheme for full utilization of biomass for clean energy production. The proposed approach includes production of activated carbon based catalysts for methanol decomposition as a source of hydrogen, where both activated carbon and methanol, could be produced from biomass. In order to elucidate the impact of different activated carbon characteristics on the formation of the catalytic active phase, carbons with different texture and surface functionality are purposely obtained by changes in the activation temperature during the carbon preparation and its post-synthetic treatment with nitric acid. Peach stones, widely available in Bulgaria and Balkans region, are chosen as activated carbons precursor. Iron, zinc and ferrite modifications of thus obtained carbons are prepared by incipient wetness impregnation technique and nitrogen physisorption, XRD, HRTEM, UV-Vis, FTIR, Moessbauer spectroscopy, TPR with hydrogen and Boehm method are used for samples characterization. It is established that the state and catalytic activity of the supported metal oxide particles could be easily controlled by the procedure of the activated carbon preparation and this effect strongly depends on the nature of the loaded metal oxide. In case of iron modifications, the increase of the activation temperature during the carbon preparation promotes the formation of more finely dispersed, accessible for the reactants and active in methanol decomposition magnetite particles. The dispersion and the accessibility of the zinc oxide species in zinc modifications are improved by the formation of additional amount of surface acidic groups during the carbon pre-treatment with nitric acid. The combination of lower temperature of carbon activation with nitric acid pre-treatment promotes the formation of highly active ferrite nanoparticles in the binary modifications.

The concept of application of crumbled carbon foam obtained from polymer precursor as a filler in polymer/carbon composite was described. The carbon foam used as powdered reinforcement of composites was prepared from epoxy resin cross-linked with phenol–formaldehyde resin (novolac) in a self-foaming process followed by carbonization at not very high temperature and ambient pressure. The structure of the carbon foam filler and resultant composites was studied by microscopic and spectroscopic methods. In the final composites, there were observed good quality dispersion of micronized grains of carbon foam, with the sizes that preserve their specific porous structure, in epoxy matrix and excellent adhesion at interfacial areas. The influence of the CF filler on the properties of resultant composites were investigated. Due to valuable properties of carbon foam, resultant composites occurred to have interesting characteristics: densities similar to those of pure polymer matrix, advantageous thermal and viscoelastic properties and enhanced tribological features.

The absorption-desorption characteristics during prolonged cycling towards hydrogen of composite 95 wt% Mg- 5 wt% activated carbon (synthesized from polyolefin wax, a waste product of polyethylene production at low pressure- POW) obtained by ball milling under Ar atmosphere are investigated. Even at first few cycles of hydriding the 95 wt% Mg- 5 wt% POW is reached about 7 wt% of hydrogen absorption capacity and after 80 cycles of hydriding-dehydridng the hydrogen absorption capacity remains high. At the 2nd cycle the sample absorbed 7.1 wt% and 6.4 wt% at 80th cycle. Probably some deterioration of the material occurs because of sintering and oxidation. The presence of activated carbon derived from POW influences positively on hydrogen absorption/desorption properties of magnesium, leading to enhanced rate of hydriding reaction and high absorption capacity during prolonged cycling.

The effect of dimension of carbon foam (CF) grains used as a filler of epoxy matrix on the morphology and thermomechanical and tribological properties of final composites was described. The carbon foam proposed as particle reinforcement of composites was prepared from epoxy resin of diglycidyl ether of bisphenol A type cured with phenol-formaldehyde resin (novolac) in a self-foaming process followed by carbonization. Structures of the carbon foam filler and resultant composites were studied by microscopic and spectroscopic methods. Three different carbon foam grain fractions, below 200 μm, 200–315 μm and below 315 μm, keeping CF porous structure and specific properties, were used to obtain new composite materials. There were observed good quality dispersion of CF grains in epoxy matrix and excellent adhesion at interfacial areas, regardless of carbon foam fraction. In the effect, these composites have enhanced thermomechanical and tribological properties and relatively low density compared to carbon-polymer composites produced so far. It was found that all CF fractions used reduced friction coefficient of resultant composites compared to pure epoxy matrix, however the influence of individual filler fraction on composite's COF was different. The morphology of worn surfaces of epoxy composites after friction tests showed that the effect depends on grain fraction of CF filler as well as on the load used.

Activated carbons (AC) were synthesized by a pyrolysis process and activation with water vapor of agricultural wastes, namely, apricot stones, peach stones, and olive stones, for CO2 capture from a simulated flue gas. Kinetic and thermodynamic adsorption tests were carried out in a lab-scale fixed-bed column under operating conditions typical of a flue gas (i.e., P = 1 atm, CO2 = 3–30%, T = 30°C). Experimental results showed that the AC derived from olive stones is characterized by a slightly faster saturation, due to a higher contribution of meso-macropores, while the AC derived from the apricot stones had the highest adsorption capacity, likely ascribed to a higher micropore volume and a narrower pore size distribution. Regeneration studies conducted on the AC derived from apricot stones showed that CO2 adsorption is a reversible process and that the time to achieve a desired CO2 recovery percentage is mainly controlled by temperature and, at less extent, by desorbing agent flow rate.

Carbon foam is an advanced porous material with multiple high-technology applications, due to its cell structure, light weight, high thermal stability, high thermal and electrical conductivity, as well as exceptional electromagnetic and acoustic properties. This work is dedicated to development of a new method for synthesis of carbon foam from a mixture of organic substances with suitable chemical properties and appropriate oxidation treatment, which allows synthesis of foam without the use of high pressure and stabilization step. The appropriate treatment conditions (thermo-oxidative modification with conc. H2SO4 or conc. HNO3 of mixtures of furfural and industrial coal tar pitch in different proportions), allowing the formation of porous structure of the resulting carbon foam, are established. The properties of the synthesized carbon foam can be controlled by varying the composition of the starting mixture and the type of oxidant. The formation mechanism of the porous structure of carbon foams is considered. Obtained carbon foam samples are characterized by XRD, Scanning Electron Microscopy, TG and DSC analysis, elemental analysis. The proposed new, less energy consuming synthesis method enables the production of carbon foam with very good physico-chemical properties.

Agriculture residues (grape seeds, peach, apricot and olive stones) were used as a precursor of activated carbons with tunable textural characteristics and relatively low surface functionalities (predominantly carbonyl and hydroxyl groups). Thus obtained activated carbons were modified with iron species and tested as catalysts in methanol decomposition. Nitrogen physisorption, XRD, UV–Vis, FTIR, Moessbauer spectroscopy, TPR with hydrogen and Boehm method were applied for complex characterization of the initial activated carbon supports, their iron modifications and the transformations during the catalytic process. The final phase composition and the related with this catalytic activity and selectivity of these materials was considered as a result of complex transformations of active phase by the influence of activated carbon support and reaction medium and this is in close relation with the dispersion and location of iron species into the porous matrix. The decisive role of activated carbon texture characteristics, which is much more significant than the surface functionalities, on the formation of iron catalytic sites is established, and the variation in the nature of the agriculture precursor is assumed as a simple approach for tailoring their properties.

The present work was aimed at developing new reactive polymer materials suitable to be used as supports for enzyme covalent immobilization. Thus, new bicomponent polymer membranes were developed using poly(acrylonitrile- co -vinyl acetate) (PAN- co -PVAc) in mixture with polyvinyl alcohol (PVA). First of all, PAN- co -PVAc/PVA blends were dissolved in DMSO, until a homogenous polymer solution was obtained. To prepare membranes, these solutions were cast on a glass plate followed by the immersion of this plate in a coagulation bath containing a 50%–50% (volume %) water–isopropyl alcohol mixture. In this way membranes containing OH functional groups were obtained. Before tyrosinase immobilization, membranes were functionalized with glutardialdehyde; hence CHO binding sites were inserted and membrane became reactive for the enzyme. In order to prove that both, functionalization and immobilization reactions, were successful, the modifications produced by these reactions were investigated by various techniques i.e. Fourier Transform Infrared Spectrometry, Thermal Gravimetric Analysis, Differential Scanning Calorimetry and Atomic Force Microscopy. The occurrence of important changes in membrane features confirmed the success of both reactions. Furthermore, the activity of bonded enzyme was determined by pyrocatechol method and compared to the activity of the free enzyme.

In this work, CO2 adsorption tests are carried out in a lab-scale fixed-bed reactor from a simulated flue-gas, at four temperature levels (30, 45, 60 and 80 °C) and different CO2 concentrations (3–30 %). Three different activated carbons (AC) derived by agricultural raw materials, namely peach stones, olive stones and apricot stones, were synthesized by a combination of pyrolysis and activation by water vapour. The textural characterization of the AC samples by N2 adsorption at −196 °C shows that the AC derived from apricot stones has the highest micropore volume, almost shifted toward ultramicropores, while the AC derived from olive stones shows the highest contribution of meso and macropores. Adsorption tests show that the AC derived from apricot stones has the highest CO2 adsorption capacity at 30 °C, due to its microstructural properties. Differently, at higher temperatures, the AC derived from apricot and peach show similar performances, due to their similar content of basic functional groups and pHPZC values. In all the cases, the Freundlich model provides very good data interpretation. The kinetic patterns reveal that the adsorption rate is mainly related to the mean Sauter particle diameter of the AC samples and, at less extent, to their meso and macropore content. Finally, a modelling analysis allowed individuating the intraparticle diffusion as the adsorption rate-limiting step.

Ordered mesoporous silica of SBA-15 type and activated carbon, prepared from waste biomass (peach stones), are used as host matrix of nanosized iron and cobalt particles. The effect of preparation procedure on the state of loaded nanoparticles is in the focus of investigation. The obtained materials are characterized by Boehm method, low temperature physisorption of nitrogen, XRD, UV–Vis, FTIR, Mossbauer spectroscopy and temperature programmed reduction with hydrogen. The catalytic behaviour of the samples is tested in methanol decomposition. The dispersion, oxidative state and catalytic behaviour of loaded cobalt and iron nanoparticles are successfully tuned both by the nature of porous support and the metal precursor used during the samples preparation. Facile effect of active phase deposition from aqueous solution of nitrate precursors is assumed for activated carbon support. For the silica based materials the catalytic activity could be significantly improved when cobalt acetylacetonate is used during the modification. The complex effect of pore topology and surface functionality of different supports on the active phase formation is discussed.

Activated carbons (AC) from various waste agriculture precursors with different texture and surface characteristics were obtained by different preparation procedures. These AC were used as a host matrix of mono- and bi-component copper and cobalt nanoparticles. The effect of carbon properties on the formation of copper/cobalt phases was studied by Boehm method, XRD, nitrogen physisorption, UV–Vis, FTIR, TPR–TG analysis and methanol decomposition as a catalytic test. The elucidation of activated carbons from waste biomass as catalyst support was based on the comparative study with similar materials supported on mesoporous silica KIT-6. It was demonstrated that contrary to KIT-6, the reduction properties of AC support hinders the formation of spinel CuCo2O4 phase in the bi-component materials, but provides formation of mixture of finely dispersed and highly active and selective in methanol decomposition Cu2O and CoO nanoparticles.

High quality micro-mesoporous activated carbon was prepared from waste bio-mass (peach shells) and used as a host matrix of cobalt ferrite nanoparticles. The obtained materials were characterized by N 2 physisorption, XRD, FTIR and Moessbauer spectroscopy and tested as catalysts for hydrogen production from methanol. Depending on the Co/Fe ratio formation of pure CoFe 2 O 4 or a mixture of CoO and ferrite phases were observed for carbon supported bi-component materials, while under the same condition the silica support provides the formation of non-stoichiometric ferrite phase. The catalytic active phase which is formed by the influence of the reaction medium represents a complex mixture of non-changed ferrite, magnetite, Co–Fe alloy and/or Fe 3 C in different proportions.

Activated carbons were prepared from waste coal treatment by-products by different preparation and activation procedures and applied as a host matrix of nanodispersed cobalt and iron species. Thus obtained composites were characterized by nitrogen physisorption, XRD, UV–Vis, FTIR, TPR and tested as catalysts in methanol decomposition to hydrogen and CO. It was established that the activated carbon, prepared from waste coal treatment by-products could be successfully used for the preparation of highly active catalysts for methanol decomposition. The facilitated effect of surface functionality decrease on the dispersion and catalytic activity of loaded metal species was demonstrated.

High-pressure DSC was applied to study the hydriding and dehydriding behavior of Mg 95 mass%–C 5 mass% composites, synthesized by ball milling with two different kinds of carbon additives (activated carbon derived from apricot stones AS and from bean pods BP) and magnesium with different particle sizes. The composites containing finer magnesium experience absorption capacity deterioration with hydriding/dehydriding cycling, but for the Mg–AS, this worsening is in lower degree compared to Mg–BP. The activated carbon derived from the AS, used for the composites preparation, has more pronounced positive effect on the hydrogen sorption characteristics of magnesium (with both finer and coarser particles), compared with the carbon derived from BP, due to its better protection of the Mg surface from oxidation and particles agglomeration during hydriding/dehydriding cycling.

A possibility for utilization of natural asphaltites, based on production of carbon adsorbents, was investigated. Various combinations of physical and chemical activation as well as demineralization procedures were used to obtain final products from natural asphaltites. Carbon adsorbents with developed pore structure and with alkaline character of the surface, as well as tar and gas products, were obtained by water vapor pyrolysis of natural asphaltites. The obtained carbon adsorbents show good adsorption properties; however, this performance is somewhat limited, probably due to their high mineral and sulfur content. It was established that hydropyrolysis is not appropriate method for production of carbon adsorbents on the base of asphaltites from Sirnak deposit due to the material coking. However, a two-stage process, including carbonization and subsequent activation, is appropriate for obtaining of carbon adsorbent with developed pore structure from Sirnak asphaltites. At the same time, hydropyrolysis is suitable for obtaining of activated carbon using asphaltites from Silopi deposit. Different oxygen groups were detected on the activated carbon surface, and their effect on surface properties of the samples was discussed.

An activated carbon for CO2 adsorption from flue gas was synthesized using an industrial by-product (coal tar pitch) and furfural. The produced activated carbon possesses a well-developed pore structure and an alkaline character, as testified by the presence of different oxygen containing functional groups on the carbon surface. Adsorption tests have been carried out in lab-scale fixed-bed column, at different temperatures and CO2 concentrations, in order to investigate both kinetic and thermodynamic aspects. Moreover, regeneration studies have been conducted in order to verify the possibility of activated carbon reutilization, to determine its CO2 adsorption capacity within consecutive cycles of adsorption–desorption and to assess the optimal operating conditions for CO2 recovery by desorption. It was established that the synthesized activated carbon has a good CO2 adsorption capacity, likely related to its surface area and composition, as well as to the intrinsic nature of the solid. Adsorption rate increases with CO2 concentration and temperature, even if an increase in temperature significantly reduces the adsorption capacity. Experimental results confirmed that CO2 adsorption is a reversible process and that desorption temperature is the main controlling parameter. It was demonstrated that the regenerated carbon can be used in consecutive adsorption–desorption cycles without any significant loss in its CO2 adsorption capacity. Finally, the most suitable operating set parameters for CO2 recovery has been defined.

The adsorption of detergents—sulfonic and phenolic compounds—from aqueous solutions by activated carbons (AC), obtained on the base of different precursors, was studied. The carbon adsorbents used were prepared by water vapor pyrolysis of different raw materials: peach stones, olive stones, natural asphaltite, mixtures from coal tar pitch, and furfural. It was established that all the samples of ACs have close values of high adsorption capacities toward the studied detergents. Some factors affecting the adsorption process—the time of treatment and the amount of the adsorbent—were investigated. It was established that the amount of adsorbent has no significant influence on the adsorption process.

The adsorption of ethyl acetate, a volatile organic compound, on activated carbons, synthesized from various precursors based on by-products and waste materials—polymer, biomass, coal tar pitch—was studied. The activated carbons were prepared by thermochemical treatment of the precursors, carbonization, and subsequent activation with water vapor. Surface and textural properties of obtained carbon adsorbents were characterized by low-temperature N2 adsorption, Boehm’s method, etc. The activated carbons are distinguished by relatively high surface area and developed pore structure. The adsorption investigations were performed with water solutions of ethyl acetate, and the obtained results fit well the Langmuir model, as well as the Freundlich model. All activated carbons demonstrated considerably high adsorption capacity in the range 160–450 mg/g. The obtained data indicate that the adsorption ability of activated carbon toward ethyl acetate depends on the surface area, and it increases with increasing the content of mesopores, where ethyl acetate molecules are preferably adsorbed.

This work reports the microstructural evaluation of carbon foams derived from coal-tar pitch precursors treated with H2SO4 and HNO3 and finally annealed at 1000 °C and 2000 °C. Our experimental investigations combine scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) imaging, X-ray photoelectron spectroscopy (XPS) and micro-spot near-edge X-ray absorption fine structure (μ-NEXAFS) spectroscopy. This set of complementary techniques provides detailed structural and chemical information of the surface and the bulk of the carbon foams. The high-resolution microscopy data indicate the formation of carbonaceous amorphous microspheres (average diameters of 0.28 ± 0.01 μm) embedded in the partially graphitized carbon foam matrix at 1000 °C. The microspheres are enriched with sp-bonded species and their microstructural characteristics depend on the reagent (nitric vs. sulfuric acid) used for pitch treatment. A complete chemical transformation of the microspheres at temperatures >1000 °C occurs and at 2000 °C they are spectroscopically identical with the bulk material (sp2- and sp3-hybridised forms of carbon). The microstructure-property relationship is exemplified by the compressive strength measurements. These results allow a better description of coal-tar pitch-derived carbon foams at the atomic level, and may account for a better understanding of the processes during graphitization step.

A comparison in the hydrogen sorption properties of mechanically activated magnesium composites with additive of 3d-metal containing compounds (Mg 2 Ni 0.8 Co 0.2 and NiCo 2 O 4 ) and activated carbon derived from agricultural by-products (ACAS) is accomplished. The presence of the additives used enhances significantly the hydriding reaction and increases the absorption capacity compared to pure magnesium. The absorption capacity values of the composites studied are as follows: Mg (−44 μm)–5 wt.% ACAS–6.13 wt.%, Mg (−297 μm)–5 wt.% ACAS–5.48 wt.%, Mg(−44 μm)–15 wt.% Mg 2 Ni 0.8 Co 0.2 –4.78 wt.% and Mg (−44 μm)–5 wt.% NiCo 2 O 4 –5.69 wt.% ( T = 573 K, P = 1 MPa, after 60 min of hydriding). The composites preserve their hydrogen sorption capacities during prolonged cycling. The use of the additive of activated carbon instead of 3d-metal containing compounds in magnesium based composites results, on the one hand, in a higher absorption capacity which increases during cycling, but on the other hand, a poorer hydriding kinetics.

The absorption–desorption characteristics towards hydrogen of obtained by ball milling under argon atmosphere magnesium based composites (containing respectively 95 wt% Mg and 5 wt% activated carbon (AC) derived from bean pods (BP), apricot stones (AS) and mixture of coal tar pitch and furfural (CTPF)), were investigated. Actually there is no substantial difference between the rate of hydriding and the absorption capacity for magnesium composite with AC derived from apricot stones, and for magnesium composite with AC derived from a mixture of coal tar pitch and furfural — the capacity is 6.13 wt% for the former and 5.98 wt% for the latter. More significant difference between the investigated composites was observed for the dehydriding process. The magnesium composite with synthetic carbon (from furfural and coal tar pitch) desorbs at 623 K and 0.15 MPa and the absorbed hydrogen about twice faster than magnesium composite with AC from bean pods. The activated carbon derived from a mixture of coal tar pitch and furfural has the highest specific surface area, and obviously this characteristic has important influence especially on the dehydriding kinetics of magnesium.

New activated nanoporous carbons, produced by carbonization of mixtures of coal tar pitch and furfural with subsequent steam activation, as well as electrochemically active oxide Li4Ti5O12, prepared by thermal co-decomposition of oxalates, were tested and characterized as electrode materials for electrochemical supercapacitors. The phase composition, microstructure, surface morphology and porous structure of the materials were studied. Pure carbon electrodes as well as composite electrodes based on these materials obtained were fabricated. Two types of supercapacitor (SC) cells were assembled and subjected to charge–discharge cycling study at different current rates: (1) symmetric sandwich-type SC cells with identical activated carbon electrodes and different organic electrolytes, and (2) asymmetric hybrid SC cell composed by activated graphitized carbon as a negative electrode and activated carbon–Li4Ti5O12 oxide composite as a positive electrode, and an organic electrolyte (LiPF6–dimethyl carbonate/ethylene carbonate (DMC/EC). Four types of carbons with different specific surface area (1,000–1,600 m2 g−1) and texture parameters, as well as three types of organic electrolytes: Et4NBF4–propylene carbonate (PC), LiBF4–PC and LiPF6–DMC/EC in the symmetric SC cell, were tested and compared with each other. Capacitance value up to 70 F g−1 for the symmetric SC, depending on the electrolyte microstructure and conductivity of the carbon material used, and capacitance of about 150 F g−1 for the asymmetric SC cell, with good cycleability for both supercapacitor systems, were obtained.

Production of carbon adsorbent from agricultural waste (apricot stones) and its application for water purification from organic pollutants are investigated in the paper. Activated carbon (AC) is prepared by pyrolysis of the biomass materials at 700 °C in a flow of steam. Steam pyrolysis is a process, which creates both energy liquid and gaseous products, as well as high-grade activated carbons. The produced AC as solid product is used for removal of phenol and p-nitrophenol. It was found that the adsorption capacity is 152 mg/g for phenol and 179 mg/g for nitrophenol. An hybrid adsorptive-membrane purification of water from phenol is performed, and it is established that this combination considerably increases the effectiveness of the water purification from phenol.

Carbon foams with an anisotropic texture and high mechanical strength were produced using precursors obtained after thermo-oxidation treatment of commercial coal–tar pitch with H2SO4 and HNO3. The investigations of the relation between the properties of the precursor and the structure of obtained foam indicate, that the composition and softening point of the pitch precursor significantly affect the foaming process, foam structure and foam mechanical strength. The composition and properties of the modified pitches allow foam formation at relatively low pressure and fast heating rate during the foaming process without a stabilization treatment. The foaming process of pitch-based carbon foams, pre-treatment of the precursors, and the properties of resultant foams are discussed in this paper.

A 13-step alkaline permanganate degradation of Bulgarian oil shale kerogen concentrate at ambient temperature was carried out. A high yield of oxidation products (90.1%) and a low yield of gaseous products (2.79%) were obtained. IR and (1)H NMR spectroscopic studies have shown that two significantly different types of high molecular products are present in kerogen. Further oxidation of these structures leads to the formation of low molecular aliphatic and aromatic acids, proven by gas chromotography (GC) and gas chromatography-mass spectrometry (GC-MS). The data obtained at these mild conditions allow us to acquire detailed information about the aromatic structures and polymethylene chain lengths in kerogen.The 5-step oxidation of the kerogen at 90 degrees C provides information about stable aromatic structures. Soluble and insoluble polyfunctional acids in acid medium have close molecular masses and spectral characteristics. The amount of benzene and naphthalene carboxylic acids is 11.3% of the organic matter of the oil shale. Publisher's Version Q2 WOS:000269733900003

In order to obtain more information and to understand the nature of relation between organic and mineral matter in oil shales, the compositions of soluble bitumen fractions obtained by extraction from Bulgarian oil shales before and after demineralization with 10% HCl, concentrated HE and a HF/HCl mixture were investigated. The four extracts were quantitatively examined by IR and H-1 NMR spectroscopy. The investigation of isolated acidic material of the bitumen fractions showed that the fatty acids are present in bitumen fractions as free acids, esters and salts. The amount of free acids in bitumen is very small. The dominant part of bitumen acids is associated with mineral components of the oil shales as well as part of them is included in the mineral matrix, and can be separated only after deep demineralization. The kerogen of the oil shales, obtained after separation of the bitumen fractions and mineral components, was subjected to saponification in order to determine the amount of acids, bound as esters to the kerogen matrix. The major components found were n-carboxylic, alpha,omega,-di-carboxylic, and aromatic acids. The connection of kerogen with mineral components is accomplished by the participation of carboxylic and complicated ester bonds. Experimental data for the composition of bitumen acids give evidence that algae and terrestrial materials are initial sources in the formation of soluble organic matter of Bulgarian oil shale. Publisher's Version Q1 WOS:000260711300006

The preparation of activated carbons from bean pods by chemical (K(2)CO(3)) and physical (water vapor) activation was investigated. The carbon prepared by chemical activation presented more developed porous structure than one obtained by water vapor activation. Carbon adsorbent with very low ash content and developed micropore structure is obtained by thermochemical treatment with conc.H(2)SO(4) of liquid products from carbonization of bean pods and activation with water vapour. Publisher's Version Q4 WOS:000207441900002

CO adsorption on Co–ZSM-5 results in formation of two kinds of Co2+–CO species characterized by bands at 2217 and 2207 cm−1, respectively. The species are highly resistant towards evacuation at ambient temperature. When CO adsorption is performed at low temperature, new kinds of weakly electrophilic Co2+ sites are evidenced by carbonyl bands at 2197 and 2190 cm−1. The bands detected at ambient temperature are negligibly reduced in intensity, suggesting initial stages of formation of geminal Co2+(CO)2 dicarbonyls (most probably absorbing at 2201 cm−1). Reduction of the sample in a CO atmosphere at temperatures of 423–673 K results in creation of a fraction of Co+ cations. The latter form, with CO, stable Co+(CO)2 dicarbonyl species (bands at 2113 and 2042 cm−1). Coadsorption of 12CO and 13CO allows detection of Co+(12CO)(12CO) (2097 and 2013 cm−1) and Co+(13CO)2 (2065 and 1997 cm−1) species. The dicarbonyls are thermally decomposed without formation of a measurable amount of corresponding monocarbonyls. In the presence of CO in the gas phase the Co+(CO)2 dicarbonyl species are converted into tricarbonyls (2137, 2089 and 2079 cm−1) which are characterized by a disordered C3v symmetry. As a result, a variety of mixed carbonyls are produced after 12CO–13CO coadsorption. Lowering of the temperature in the presence of CO results in coordination of a fourth CO molecule to some of the Co+ sites, the tetracarbonyls formed being characterized by a set of bands at 2130, 2105 and 2075 cm−1. The reasons for the high coordinative unsaturation of the Co+ cations in Co–ZSM-5 and the possible role of Co+ cations in the selective catalytic reduction of nitrogen oxides are discussed.

Here, a series of cellular-structured and predominantly mesoporous carbons were prepared via carbonization of glucose–fructose syrup (GFS) with sulfuric acid and subsequent calcination between 400[Formula: see text]C and 700[Formula: see text]C. Comparative results on the microstructure, chemical and textural properties of the newly produced carbons are presented. Furthermore, their adsorption performance for removal of acetaminophen from water was tested and it was found that the carbon calcined at 700[Formula: see text]C has a maximum adsorption capacity (98.7[Formula: see text]mg[Formula: see text]g[Formula: see text]) among all samples due to its suitable textural properties (BET surface area of 418[Formula: see text]m[Formula: see text]g[Formula: see text] and total pore volume of 0.2[Formula: see text]cm[Formula: see text]g[Formula: see text]). This study demonstrates the potential use of GFS as a precursor in the preparation of carbonaceous materials for removal of biologically-active micropollutants from water.