99 research outputs found
Influence of the underground mining waste on the environmental tailings and wastewater characterization
In presented paper influence of the underground mining waste on the environmental was investigated. From that point tailings and wastewater characterization was performed on samples taken from lead and zinc mine Grot, Serbia. In order to obtain experiments necessary for characterization, representative samples were taken from three different parts of the tailings: outlet pipe of the flotation facility (JOF), hydro cyclone overflow (JHC) and crest of dam (JKB). Characterization of the tailing samples include: thermal (differential thermal analysis and thermo gravimetric analysis (DTA/TGA) and infrared analysis (FTIR), determination of the chemical composition and content of the heavy metals and qualitative roentgen analysis (XRPD). Also, wastewater samples have been taken from the tailings and concentrations of heavy metals in the taken samples were determined by using inductively coupled plasma mass spectrometry (ICPMS)
Removal of Ethyl Xanthate Anions from Contaminated Aqueous Solutions Using Hazardous Waste Slag Generated by Lignite Combustion
This paper presents the results of the application of hazardous waste slag generated by lignite combustion for the adsorption of ethyl xanthate anions (EX) from aqueous solutions. The starting material (RWS) was washed (WWS) and modified (MWS) and then characterized in detail by using different chemical and physicalāchemical techniques (determination of chemical composition and content of heavy metals, X-ray diffraction (XRD), infrared spectroscopy (FTIR), determination of textural properties and point of zero charge). Besides the chemical stability of EX, the influence of the initial pH, mass of the adsorbent, initial concentration, and time on the EX anion removal was tested. The characterization results showed that applied waste slag is a hazardous material with complex mineral and structural properties but with good buffer properties and pH stability, which is also characteristic of the MWS sample. The adsorption experiments showed that modification with Cu(NO3)2 and Fe(NO3)3 significantly increases the adsorption capacity of the starting slag. Under applied experimental conditions, the maximal adsorbed amount of EX anions on the MWS was 210 mg/g, while equilibrium was obtained after 700 min. The Freundlich model and pseudo-second-order model best fit the results, suggesting the complex mechanism of EX removal by the MWS sample
Geopolymer/CeO2 as Solid Electrolyte for IT-SOFC
As a material for application in the life sciences, a new composite material, geopolymer/CeO2 (GP_CeO2), was synthesized as a potential low-cost solid electrolyte for application in solid oxide fuel cells operating in intermediate temperature (IT-SOFC). The new materials were obtained from alkali-activated metakaolin (calcined clay) in the presence of CeO2 powders (x = 10%). Besides the commercial CeO2 powder, as a source of ceria, two differently synthesized CeO2 powders also were used: CeO2 synthesized by modified glycine nitrate procedure (MGNP) and self-propagating reaction at room temperature (SPRT). The structural, morphological, and electrical properties of pure and GP_CeO2-type samples were investigated by X-ray powder diffraction (XRPD), Fourier transform infrared (FTIR), BET, differential thermal and thermogravimetric analysis (DTA/TGA), scanning electron microscopy (FE-SEM), energy dispersive spectrometer (EDS), and method complex impedance (EIS). XRPD and matrix-assisted laser desorption and ionization time-of-flight (MALDI-TOF) analysis confirmed the formation of solid phase CeO2. The BET, DTA/TGA, FE-SEM, and EDS results indicated that particles of CeO2 were stabile interconnected and form a continuous conductive path, which was confirmed by the EIS method. The highest conductivity of 1.86 Ć 10ā2 Ī©ā1 cmā1 was obtained for the sample GP_CeO2_MGNP at 700 Ā°C. The corresponding value of activation energy for conductivity was 0.26 eV in the temperature range 500ā700 Ā°C
Development of a new system of solid ionic conductors based on multi-doped ceria for application in IT-SOFCs
Nanosized multi-doped ceria with composition Ce0.8Nd0.0025Sm0.0025Gd0.005Dy0.095Y0.095O2-Ī“ (CNSGDY) as perspective solid ionic conductor was obtained by modified glycine-nitrate procedure (MGNP) and room temperature self-propagating reaction (SPRT). The pressed pellets of both powders were sintered at 1550Ā°C for 2 h in an air atmosphere. The obtained sintered samples were characterized by XRPD, Raman spectroscopy, FESEM, EDS and EIS methods. Despite a high temperature of sintering, XRPD and FESEM analyses of the samples confirmed appropriate dimensions of grains with fluorite structure. Overall concentration of introduced dopants (x = 0.2) in the structure of CeO2 after the sintering process was confirmed by EDS analysis. After sintering, Raman spectroscopy confirmed retention of the oxygen vacancies in the ceria lattice, which is in accordance with the improvement of ionic conductivity of solid ionic conductors. The highest value of total conductivity was obtained for the sintered MGNP sample at 700Ā°C (4.22 Ć 10ā2 S cmā1), with the corresponding activation energy of 0.26 eV
The influence of short thermal treatment on structure, morphology and optical properties of Er and Pr doped ceria pigments: Comparative study
Potential non-toxic pink and red ceramic pigments based on CeO2 were successfully synthesized by selfpropagating room temperaturemethod and thermally treated at 600, 900 and 1200Ā°C for 15min. The structure, morphology and optical properties, as well as thermal stability of Ce1-xErxO2-Ī“ and Ce1-xPrxO2-Ī“(x = 0.05) were examined. Single-phase composition of all obtained CeO2 pigments was confirmed using XRPD method and Raman spectroscopy and it was not dependent on temperature. The mechanism of structural behaviour was thoroughly examined using Raman and FTIR spectroscopy. Nanometric dimensions of the crystallites of all pigments were confirmed using XRPD, TEM and FE-SEM analysis. Colour properties were dependent on the temperature treatment, and their position in the chromaticity diagram was studied using UV/VIS spectrophotometry. Colour efficiency measurements were supplemented by colorimetric analysis. It is proved that all samples are thermally stable in the investigated temperature range (up to 1200Ā°C), and their potential application as environmentally friendly pigments of desired colour is confirmed
Waste Slag from Heating Plants as a Partial Replacement for Cement in Mortar and Concrete Production. Part IāPhysicalāChemical and PhysicalāMechanical Characterization of Slag
Numerous factors influence the complexity of environmental and waste management problems, and the most significant goal is the reuse of materials that have completed their ālife cycleā and the reduction in the use of new resources. In order to reduce impact of waste slag on the environment, in the present study, waste slag, generated in heating plants after lignite combustion, was characterized in detail and tested for application as a replacement for cement in mortar or concrete production. For physicalāchemical characterization of slag, different experimental and instrumental techniques were used such as chemical composition and determination of the content of heavy metals, investigation of morphological and textural properties, thermal analysis, X-ray, and infrared spectroscopy. Physicalāmechanical characterization of slag was also performed and included determination of activity index, water requirement, setting time and soundness. A leaching test was also performed. Presented results show that waste slag may be used in mortar and concrete production as a partial cement replacement, but after additional combustion at 650 Ā°C and partial replacement of slag with silica fume in the minimal amount of 12%. The maximal obtained cement replacement was 20% (17.8% slag and 2.2% of silica fume)
Sustainable Application of Waste Sludges from the Wastewater Treatment Plant Generated during the Production of Heating Devices in the Construction Industry
This research presented, for the first time, the results of the successful application of the waste press sludges, WSLP (plant for lacquer and paint) and WSEP (powdery enamel plant), from a wastewater treatment plant generated during heating device production in the construction industry. The results of WSEP characterization and its influence on cement paste, mortar, and concrete properties showed that this material could be used as a cement replacement (with a maximum replacement amount of 20%) in producing mortar and concrete. Although waste WSLP sludge does not possess pozzolanic properties and does not meet the criteria prescribed by the standards for application in mortar and concrete due to its chemical inertness and fineness, as well as its extended setting time, it can be used as a replacement for stone filler or other powdered mineral admixture in the production of self-compacting concrete (SCC) in amounts up to 100%, with a maximum quantity of up to 100 kg/m3. The obtained results indicate that with the appropriate conversion, waste sludges, despite representing hazardous waste, can be used as safe products in the construction industry; i.e., the waste material can become a useful and valuable raw material by applying (respecting) all of the principles of the green economy
Application of Lignite Combustion Waste Slag Generated in Heating Plants as a Partial Replacement for Cement. Part II: PhysicalāMechanical and PhysicalāChemical Characterization of Mortar and Concrete
The presented study is a continuation of the research with the aim of finding a useful
value of hazardous waste slag generated by the combustion of lignite in heating plants and its
application in the construction industry. The different amounts of cement (10%, 15%, 20% and
25%) were replaced with waste slag and silica fumes in mortars and concrete production. Detailed
physicalāmechanical characterization was performed on the mortar and concrete samples according
to standard procedures. Test results indicated that the replacement of cement with slag and silica
fumes reduces the physical and mechanical properties of mortar and concrete, but cement composites
retained the required structural properties. If 15ā20% is considered an acceptable level of compressive
strength decrease, then it can be concluded that waste slag can be implemented in practice and be
used as a construction material, with cement replacement in the maximal amount of 20% (17.8%
of slag and 2.2% of silica fumes). On hardened mortar samples with maximal possible cement
replacement (20%), physicalāchemical characterizations were performed and included X-ray and
infrared spectrophotometry, scanning electron microscopy, and thermal analysis. Results showed the
absence of new phases and the presence of only those which were characteristic for starting samples,
predominantly portlandite, quartz, calcite and calcium silicate-oxid
PURE RED BLOOD CELL APLASIA IN SYSTEMIC LUPUS ERYTHEMATOSUS ā A CASE REPORT
SteÄena aplazija crvene krvne loze (engl. Pure red cell aplasia ā PRCA) rijedak je poremeÄaj najÄeÅ”Äe kroniÄnog
tijeka. Karakteriziran je teŔkom anemijom uz retikulocitopeniju u perifernoj krvi te odsutnost eritroblasta u koŔtanoj
srži. Ostale linije krvotvornih stanica u koŔtanoj srži morfoloŔki su uredne. U sistemskom eritemskom lupusu pojava
PRCA najvjerojatnije je uzrokovana pojavom autoantitijela na eritropoetin i eritroblaste. Ova vrsta anemije obiÄno se
lijeÄi kortikosteroidima iako se uspjeÅ”no upotrebljavaju i ciklofosfamid i ciklosporin. U ovom radu prikazujemo sluÄaj
bolesnice s PRCA-om u sistemskom eritemskom lupusu.Acquired pure red cell aplasia (PRCA) is a rare, generally chronic condition of profound anemia characterized by
a severe reduction in the number of reticulocytes in the peripheral blood and the virtual absence of erythroid precursors
in the bone marrow. All other cell lineages are present and appear morphologically normal. In systemic lupus
erythematosus (SLE) red cell aplasia is probably due to antibodies directed against either erythropoietin or bone marrow
erythroblasts. Th is form of anemia usually responds to steroids, although cyclophosphamide and cyclosporine
have been successfully employed as well. We present the case of a patient with PRCA in SLE
Mineralogical Characterization of the Grot Lead and Zinc Mine Tailings from Aspects of Their Further Use as Raw Material
The possibility of using waste tailings produced by flotation in the lead and zinc mine of Grot, Serbia as a potential source of secondary mineral raw materials was examined. The aim of the research was primarily to carry out a detailed characterization in order to determine the dominant minerals, and, for the first time, to trace the changes occurring in the unit cells of the minerals present in that deposit. There was also a need to determine the exact proportions of the present mineral phases for their further application and utilization as natural resources in environmental protection. Samples were taken from three different sections of tailings: the crest of dam (JKB), outlet pipe of the flotation facility (JOF) and hydrocyclone overflow (JHC). Granulometric separation was performed to facilitate the extraction of certain minerals from waste. The results showed that all samples mainly contained quartz, clinochlore, calcite, albite, pyrite and biotite, but their ratios in each sample varied significantly. After characterization, samples were separated into different fractions and their mineralogical compositions were determined. Depending on the fraction, the mineralogical compositions also changed. Mineralogy and geochemical analysis indicate that waste tailings can be used as a secondary mineral raw materials source applicable in various industries
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