Place and role of the agricultural sector in the national and regional economic structure

The agricultural sector is an important branch that leads to significant changes in the national and regional economic structure, as well as in trend formation impacting the economic development of the country. The changes related to the sectoral structure of the branch determine the place the country occupies with respect to its economic development. The present study aims to analyze and compare the relative share of some main economic indicators defining the place and the role of the agricultural sector in the economy of the EU and Bulgaria, the relationship of agriculture to the other sectors, and to evaluate the dynamic changes in the sectoral structure over a longer time period. The study shows that Bulgaria still lags behind the other EU member states from the perspective of restructuring economy and allocating resources from the agricultural sector to the other two sectors

Effect of graphene material structure and iron oxides deposition method on morphology and properties of graphene/iron oxide hybrids

In this work, various facile approaches were applied to prepare hybrids of graphene nanoplatelets (GNPs) and graphene oxide (GO) with iron oxides (IO) nanoparticles (NPs). The IO NPs were synthesized and deposited on the graphene surfaces via: (1) co-precipitation using Fe (II) and Fe (III) salts, (2) homogeneous precipitation of Fe2O3 from FeCl3 solution, (3) the attaching of Fe2O3 NPs functionalized with 3-aminopropyltrimethoxysilane to graphene surfaces of GO and GNPs. The effects of the graphene material and preparation procedure on the structural characteristics of the hybrids were studied. Their morphology was studied by scanning electron microscopy and transmission microscopy. Lattice parameters and crystallite sizes of the synthesized hybrid materials were assessed by X-ray diffraction. Raman spectroscopy was used to determine the change of order degree of graphene structures as a results of IO NPs deposition and interactions IO NPs with graphene sheets. Binding energy for IO NPs and graphene structures were determined by photoelectron X-ray spectroscopy. Thermogravimetric analysis was applied to find differences in the thermal stability of hybrids. The hybrids are proposed as nanofillers to polymer composites, however they have large potential applications as supercapacitors, advanced anode materials for lithium-ion batteries, magnetically targeted drug delivery, and magnetic resonance imaging

Place and role of the agricultural sector in the national and regional economic structure

The agricultural sector is an important branch that leads to significant changes in the national and regional economic structure, as well as in trend formation impacting the economic development of the country. The changes related to the sectoral structure of the branch determine the place the country occupies with respect to its economic development. The present study aims to analyze and compare the relative share of some main economic indicators defining the place and the role of the agricultural sector in the economy of the EU and Bulgaria, the relationship of agriculture to the other sectors, and to evaluate the dynamic changes in the sectoral structure over a longer time period. The study shows that Bulgaria still lags behind the other EU member states from the perspective of restructuring economy and allocating resources from the agricultural sector to the other two sectors

Investigation of Hydrogen Storage Characteristics of MgH2 Based Materials with Addition of Ni and Activated Carbon

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—nickel and activated carbon derived from POW—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

Assessment of the Possibilities for Removal of Ni (II) from Contaminated Water by Activated Carbon foam Derived from Treatment Products of RDF

Carbon foam is a sophisticated porous material with wide applications that depend on its structure, low density, thermal conductivity and electrical characteristics. This study deals with the preparation of carbon foam by the thermo-oxidative modification with HNO3 of mixtures containing different organic materials with appropriate chemical characteristics—furfural and tar pitch derived from RDF. Carbon foam is characterized by thermogravimetry, differential scanning calorimetry, elemental analysis, Raman spectroscopy, N2 sorption, infrared spectroscopy and scanning electron spectroscopy. The investigation of adsorption activity of carbon foam towards nickel (II) in water solution is carried out. Experimental results fit very well with the Langmuir adsorption model. The carbon foam, obtained from tar pitch derived from RDF and furfural, shows a high adsorption capacity towards nickel ions (203.67 mg/g). The high adsorption capacity could be explained by the properties of the adsorbent—moderately high surface area, micro-mesoporous texture and presence of oxygen-containing surface groups

Investigation of the Adsorption Process of Triclosan from an Aqueous Solution, Using Nanoporous Carbon Adsorbents, Obtained after Treatment of Organic Household and Vegetable Waste

The absorption of triclosan on the surface of four different carbon adsorbents, obtained on the base of plant and household waste (RDF), provided by Sofia Waste Plant, was investigated. The obtained results indicate that the most important parameters, which determine the process of triclosan adsorption by adsorbent surface are pore texture, the size of the accessible surface for the molecules of triclosan, and the chemical nature of the adsorbent surface. It was found that the obtained adsorbents can be successfully applied for the extraction of triclosan from waste and drinking water. The possibilities for solid products, obtained by thermal treatment of household and vegetable waste, to be applied successfully in a water purification technique are discussed

Investigation of the Possibilities for Removal of Phenolic Toxic Compounds from Water by Nanoporous Carbon from Polymer By-Products

Nanoporous carbon is synthesized on the base of phenol-formaldehyde resin and polyolefin wax, a by-product from industrial production of polyethylene at low pressure. The adsrption of phenol derivates from aqueous solutions on obtained carbon material was studied. The adsorption capacity of the carbon is related to the surface area and composition of the synthesized material, as well as to the nature of the adsorbent. The obtained adsorbent is characterized by high surface area and porosity, and it demonstrates high adsorption capacity towards aromatic compounds. All studied phenolic compounds show high affinity towards carbon, confirming that the retention mechanism occurs via non-specific interactions between the electronic density of the adsorbent and molecules of aromatic pollutants. Electrostatic interactions may also appear depending on pH of the solution pH and charge distribution of the carbons; and these effects has a strong influence on the final performance of the carbon

Investigation of the Possibilities for Removal of Phenolic Toxic Compounds from Water by Nanoporous Carbon from Polymer By-Products

Nanoporous carbon is synthesized on the base of phenol-formaldehyde resin and polyolefin wax, a by-product from industrial production of polyethylene at low pressure. The adsrption of phenol derivates from aqueous solutions on obtained carbon material was studied. The adsorption capacity of the carbon is related to the surface area and composition of the synthesized material, as well as to the nature of the adsorbent. The obtained adsorbent is characterized by high surface area and porosity, and it demonstrates high adsorption capacity towards aromatic compounds. All studied phenolic compounds show high affinity towards carbon, confirming that the retention mechanism occurs via non-specific interactions between the electronic density of the adsorbent and molecules of aromatic pollutants. Electrostatic interactions may also appear depending on pH of the solution pH and charge distribution of the carbons; and these effects has a strong influence on the final performance of the carbon