Eva Singovszka

Properties Characterization of Chemically Modified Hemp Hurds

The effect of chemical treatment of hemp hurds slices in three solutions (EDTA (Ethylenediaminetetraacetic acid), NaOH and Ca(OH)2) on the properties of natural material was discussed in this paper. Changes in the morphology, chemical composition and structure as well as thermal stability of hemp hurds before and after their modification were investigated by using FTIR (Fourier transform infrared spectroscopy), XRD (X-ray powder diffraction analysis) and TG (thermogravimetry)/DSC (differential scanning calorimetry). Size exclusion chromatography (SEC) measurements were used for determination of degree of cellulose polymerization of hemp hurd samples. Chemical modification is related to the partial removal of non-cellulosic components of lignin, hemicellulose and pectin as well as waxes from the surface of hemp hurd slices. Another effect of the chemical treatment applied is connected with increasing the crystallinity index of cellulose determined by FTIR and XRD methods. Decrease in degree of cellulose polymerization and polydispersity index in chemically modified hemp hurds compared to the original sample was observed. Increase in thermal stability of treated hemp hurd was found. The most significant changes were observed in alkaline treated hemp hurds by NaOH.

Study of metal ion sorption from acidic solutions

Acid mine drainage waters flowing out of the abandoned sulphide ore mine Smolnik in Slovakia represent a serious source of water and soils contamination. High concentrations of sulphate, iron, copper and other heavy metals are the result of pyrite oxidation connected with sulphuric acid production, which continuously dissolves rock minerals and produces a number of potentially toxic elements. The paper deals with the utilization of four types of natural and synthetic sorbents (produced mainly in Slovak Republic) for Fe, Cu, Al, Mn and Zn removal from acid mine drainage (shaft Pech, locality Smolnik, Slovakia). Prior to the kinetic study, the screening sorption experiment has been performed in order to determine optimum sorption pH. The turf brush sorbent Peatsorb has shown the satisfactory results for the removal of iron, copper, aluminium, zinc and manganese at pH below 4.

Metal Pollution Indices of Bottom Sediment and Surface Water Affected by Acid Mine Drainage

Sediments are normally the final pathway of both natural and anthropogenic components produced or derived from the environment. Sediment quality is a good indicator of pollution in the water column, where heavy metals and other organic pollutants tend to concentrate. Metals are introduced in aquatic systems as a result of the weathering of soils and rocks, from volcanic eruptions, and from a variety of human activities involving the mining, processing, or use of metals and/or substances that contain metal pollutants. Heavy metal concentration in the water column can be relatively low in some cases, but the concentrations in the sediment may be elevated. The presented work aimed to investigate the pollutant levels of some heavy metals (Fe, Mn, Al, Cu, Zn, As, Cd, Pb) in the water and sediments related to acid mine drainage (AMD) produced from an abandoned sulphide mine in Smolnik in Eastern Slovakia. A metal pollution index was used to compare the total content of metals at five sampling stations. The level of partitioning of the metals between the surface water and sediments in the area was calculated using Partition coefficients and the correlation coefficients between the metal pairs in both media were calculated by a Pearson coefficient.

Characterization of Cellulosic Fibres Properties for their Using in Composites

Nowadays, the material recycling is growing trend in development of building materials and therefore using of secondary raw materials for production of new building materials. Transition from application non-renewable sources of raw materials to renewable raw materials in terms of sustainable composite is required. Renewable raw materials include organic sources of raw materials coming from natural plant fibres. This material is used to contribute environmental protection and to save non-renewable resources of raw materials. Wood fibres and cellulose fibres made from waste paper were selected for reinforcing cement-based materials. Application of cellulosic fibres into composites depends on their properties. Therefore, this paper is aimed to study of morphology and properties of cellulosic fibres. The comparison of strength parameters of 28 days hardened composites with 5% adding bleached wood and unbleached recycled fibres with those of reference composite without fibres showed that the values of compressive strength of fibrous cement based specimens were lower by 17 to 29 %.

Quality of the bottom sediments in the area affected by mining activities

The remains of human activities may be seen in several places of the landscape in positive or negative form. Probably the most common phenomenon that fundamentally impacts the country is mining activity. The environmental problems caused by mining have attracted a great deal of research attention and led to development of numerous sediment heavy metal contamination assessment methods, including the index method, the dynamic method, the synthesis methods in chemistry, ecology and toxicology, etc. This research was undertaken in order to determine and analyze selected heavy metals present in sediment samples collected from different sampling localities inside and around water reservoir Ruzin, Slovakia. Reservoir and its inflows are located in the vicinity of region with historical Cu, Fe, Ag, Au-deposit, which was exploited from the 14th century to 1990 and currently causing environmental burden. For the determination of sediments quality different methods (XRD and XRF analysis) have been used. Based on the...

Influence of Acid Mine Drainage on Surface Water Quality

Acid mine drainage (AMD) has been a detrimental by-product of sulphidic ores mining for many years. In most cases, this acid comes primarily from oxidation of iron sulphide, which is often found in conjunction with valuable metals. AMD is a worldwide problem, leading to ecological destruction in watersheds and the contamination of human water sources by sulfuric acid and heavy metals, including arsenic, copper and lead.

The Effect of Sediment Grain Size on Heavy Metal Content in Different Depth in Water Reservoir Ruzin, Slovakia

Particle size is a fundamental property of any sediment, which can provide important information about its nature and provenance. The particle size distribution requires precise determination using a rapid and reliable method with a high resolution. Grain size is the essential factor influencing the heavy metal contents in sediment and is the most fundamental property of sediment particles, affecting their entrainment, transport and deposition. The aim of this paper is to present the results of the effect of particle size on heavy metal (Cu, Zn, Fe, Pb and As) distributions in sediments. Dependence between the distribution of metals in the examined profile of the sediments from Ruzin water reservoir on the different size of particles and depth is unambiguous for Cu, Zn and Fe with exception of Pb and As.

Effects of physical treatment of hemp fibers on fiber structure and biocomposite properties

This article concerning natural cellulose fibers as reinforcement in composite materials in civil engineering. In this paper, the attention is given to industrial hemp specifically to the woody part of hemp plant called hemp hurds. The properties of natural fibers are mainly determined by the chemical and physical composition, such as structure of fibers. The objective of presented research is to characterize raw and physically treated hemp fibers using Fourier transform infrared spectroscopy method. These natural fibers were used as filler into biocomposites and MgO-cement was used as alternative binder. Physico — mechanical properties (compressive strength, thermal conductivity, absorbability) of prepared composites were determined.

Analysis of Building Stone of the Medieval Historical Building

The reconstruction of the historical buildings needs the replacement of the original and damaged materials using possible compatible materials that closely replicates the original ones in its appearance, chemical, physical and mineralogical properties, strength and durability. Thus, a complex approach based on advanced analytical methods is needed to identifying of the suitable materials. The paper is aimed at the study of the chemical and mineralogical properties of the historical stones of the medieval castle in the East Slovakia in order to replacement the original materials by the new ones with similar composition. The carbonates and silicates were confirmed as the main components of the stones by X ray fluorescence (XRF) and Fourier transformation infrared (FTIR) methods. The mineralogical analysis confirmed the presence of the calcite as the dominated carbonate minerals as well as the presence of the quartz and muscovite representing the silicate forms.