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Porous anorthite (CaAl2Si2O8) ceramics, suitable for thermal insulation in buildings, were obtained using waste seashells as a source of CaO, kaolin as a source of Al2O3 and SiO2 and banana peel as a pore former. Changing the volume of banana peel as well as the processing temperature was found to be an effective approach to control the thermo-mechanical properties of the obtained anorthite ceramics. The sintering of powder compacts containing up to 30 wt% banana peel at temperatures ranging from 1100 to 1200 °C resulted in anorthite ceramics possessing up to 45% open porosity, a compressive strength between 13 and 92 MPa, a bulk density between 1.87 and 2.62 g/cm3 and thermal conductivity between 0.097 and 3.5 W/mK. It was shown that waste materials such as seashells and banana peel can be used to obtain cost-effective thermal insulation in buildings.

Lanthanide-doped apatite biomaterials are highly promising in medicine because of their excellent chemical and optical properties. In this study, Eu(III)-doped fluorapatite particles have been successfully synthesized by a wet method at room temperature. The characterization study from XRD showed that obtained powder is monophasic fluorapatite. Biomaterials based on fluorapatite (Ca10(PO4)5F2) doped with lanthanide elements are ideal contrast agents for a variety of biomedical applications, e.g. detection, imaging, cell tracking, and therapy [1]. Eu(III) received a great deal of interest because of several desirable properties like emission in the visible region, long luminescent lifetime, and less sensitivity to quenching by singlet oxygen [2].

Technetium-99 (99Tc), as one of the important high-yield fission products, is a significant threat to the environment and human health. It is produced in large amounts by nuclear fission of 235U or 239Pu in nuclear reactions, though the quantity of Tc produced by the spontaneous fission of 238U or by decay of 99Mo in the nature which is very small. 99Tc in the environment originates from nuclear weapons tests, discharges from nuclear power plants, nuclear medicine and radiobiology. These activities generate large volumes of low and intermediate radioactive waste which can cause a significant impact on the environment if disposed without suitable treatment. Immobilization of 99Tc into a relatively small volume waste is vital for long term permanent disposal. High mobility and long half-life of 99Tc considered to be one of the most important radionuclides in safety assessment of environmental radioactivity as well as nuclear waste management. Effective removal of radioactive technetium (99Tc) from contaminated water is of enormous importance from an environmental and public health perspective, yet many current methodologies are highly ineffective. This paper summarizes physico-chemical separation procedures emphasizing those that are the most used in practice. Classic sorbents such as activated carbons, ion exchange resins as well, as new materials, such as metal−organic frameworks and graphene based membranes are described in the paper.

Environmental pollution is increasing day by day due to industrial activities. Heavy metals are pollutants of special concern due to their toxicity, persistence, and bioaccumulation in nature. Nickel is a heavy metal that is mostly used in industries because of its anticorrosion behavior. As a consequence, nickel ions are present in the wastewater from mining, electroplating, battery manufacturing and metal finishing industries. Nickel ions are nonbiodegradable, and as such, they are present in surface water. Their high concentrations can have a dangerous impact on human health and aquatic life. In this work, a promising method for the removal of Ni ions from wastewater and their incorporation into a stable crystal structure was described. Ni-exchanged form of LTA zeolite was prepared by the standard procedure of ion exchange. After the ion exchange, powder samples were heated at temperatures of 900 to 1300 ºC in order to obtain a stable crystal structure of Ni-spinel, NiAl2O4. XRF analysis was used to study ion exchange efficiency. Characterization of raw as well as thermally treated powder samples of Ni-exchanged LTA zeolite was conducted by XRPD, DTA/TG, FT-IR and SEM analysis.

Praseodymium doped calcium hydroxyapatite (PrHAP) nanopowder was synthesized by the co-precipitation method and characterized by X-Ray Diffraction, Fourier Transform Infrared, and Fluorescence Spectroscopy. Characterization studies from XRD and FTIR spectra showed that obtained crystals are monophase hydroxyapatites and that the sample particles are of nano size. A fluorescence study has shown that PrHAP particles have fluorescent emission under UV‐ Visible excitation. These results may open new avenues for developing bioactive materials for bone regeneration and fluorescent probes for bio-imaging applications.

Comprehensive study on effect of YAG amount on densification, creep resistance and mechanical properties of Al2O3-YAG composite pressureless sintered at 1600 o C was conducted. The main goal was to optimize the amount of YAG in order to fabricate a composite with improved creep resistance and sufficiently good mechanical properties. The composite was made by mixing a commercially available Al2O3 powder with fine YAG powder obtained by glycine-nitrate combustion synthesis. Increased driving force for sintering of fine YAG powder allowed fabrication of dense Al2O3-YAG composite containing up to 30 vol% YAG. The presence of YAG was found to be effective in improving creep resistance as well as mechanical properties of Al2O3-YAG composite such as hardness and elastic modulus. While fracture strength of the composite can be as high as that of monolithic Al2O3 (~ 300 MPa), fracture toughness of composite decreased continuously as the YAG content increased. The decrease was ascribed to transgranular fracture of both YAG and Al2O3 grains in samples containing larger amounts of YAG. The proper balance between fracture toughness and creep resistance was found in composite containing 18 vol% YAG which had considerably improved creep resistance accompanied by a relatively small decrease in fracture toughness which reached value of ~ 3 MPa·m1/2. Hardness and elastic modulus were found to be 15 GPa and 371 GPa, respectively.

Anorthite ceramics was fabricated from calcium exchanged Na-LTA zeolite. The powder compacts of Ca-LTA zeolite were sintered at different temperatures ranging between 1100 and 1400°C. It was found that the temperature of 1100°C was sufficiently high to trigger formation of anorthite which stayed stable even at temperature as high as 1400°C. The highest relative density and the lowest open porosity were measured in samples sintered at 1200°C for 3 h. The effect of milling time of Ca-LTA zeolite precursor on density, microstructure and mechanical properties of samples sintered at 1200°C for 3 h was investigated. The particle size refinement appeared to be beneficial in accelerating densification process and improving mechanical properties. The density, compressive strength and hardness of anorthite ceramics obtained from non-milled precursor were measured to be 70.5 %TD, 64 MPa and 1.45 GPa, respectively. On the other side the anorthite ceramics obtained from 24-hour-long milled zeolite precursor had density of 83.9 %TD, compressive strength of 101 MPa and hardness of 3.44 GPa.

Cordierite-acicular mullite composites containing 0, 25, 50, 75 and 100 wt% of mullite were fabricated from waste MoSi2 and commercial powders of Al2O3 and spinel (MgAl2O4). Careful oxidation of pulverised waste MoSi2 rendered a precursor mixture of MoO3 and amorphous SiO2, which served as pore forming agent and SiO2 source, respectively. Evaporation of MoO3 at ∼750 °C allowed production of highly porous cordierite-mullite ceramic composite after sintering in air at 1350 °C for 4 h. The combination of equiaxed cordierite grains and elongated (prism-like) mullite grains, resulted in unique microstructure with open porosity between 53.3 and 55.6 vol% which makes the obtained composite convenient for application as diesel particulate filter material. The presence of mullite affected four key thermo-mechanical properties which determine the thermal shock resistance of cordierite-mullite composite. The best thermal shock resistance was measured in composite containing 75 wt% of mullite. It was a result of improved thermal conductivity (1.081 W/mK) and bending strength (3.62 MPa) and relatively low values of coefficient of thermal expansion (3.8 × 10−6 K−1) and elastic modulus (2.27 GPa).

Enhanced degradation of organic dye was achieved using two different kinds of waste materials: waste tire granules and spent sealed radioactive sources. Waste tire granules were used as raw material for the production of waste tire char (WTC), which was further utilized as an adsorbent matrix for synergetic adsorption/irradiation degradation of organic dye. The spent radioactive sources were radiographic sealed sources that originate from the industry which generate the high energy radiation. Methylene Blue (MB) was used as an organic model compound. Synthesized WTC has turbostratic structure, irregular shaped particles and developed mesoporous surface. Complete degradation of 0.02 dm3 of 100 mg dm−3 MB solution, having WTC dose of 1.25 g dm−3, was achieved with delivered doze of only 60 Gy. The applied doses were 100 times smaller than those presented in the literature. Degradation pathway was determined: OH radicals that originate from radiolysis of water and from the surface of WTC played the crucial role in the radiocatalytic degradation of MB. Breakage of the aromatic ring of MB appeared by the scission of the double C‒S+˭C bond as a result of the attack of OH species on adsorbed and electronically reorganized MB molecule. © 2020 Elsevier B.V.

Hazardous industrial wastes are the most common source of environmental pollution. Waters originating from unregulated landfills and places of inadequate disposal of this type of wastes can pollute the water sources and affect the human health. In this study, electroplating waste sludge (ES) and various Fe-rich wastes were used as starting materials for the synthesis of inorganic pigments. Obtained black Cr1.3Fe0.7O3 pigments possess adequate properties required for use as inorganic pigments.

Cesium aluminosilicate phases are of the great interest as possible host for Cs immobilization in radioactive waste management. The possibility to use zeolite as a host material for radioactive Cs immobilization was investigated. Cs-exchanged forms of clinoptilolite and 13X which were prepared by ion-exchange treatment were compacted. The powders compacts of exchanged zeolites were thermally treated at 1200 °C. The XRD analysis showed that Cs was successfully immobilized after heat treatment by formation of stable cesium-aluminosilicate ceramic forms. Thermal and mechanical properties of the sintered samples were investigated. From the perspective of these characteristics, Cs-exchanged zeolite (clinoptilolite and 13 X) can be considered as a potential material for safe waste disposal.

Ispitan je mehanizam visoko temperaturskih faznih transformacija cezijum (Cs) izmenjenih zeolita tipa LTA i klinoptilolita (CLI). Analizirane su osobine dobijenih faza u pogledu termalne stabilnosti i otpornosti na luţenje jona cezijuma. Rezultati pokazuju da su dobijene stabilne kristalne alumosilikatne strukture polucita (CsAlSi2O6) i faze CAS (CsAlSi5O12) koje mogu biti matrice za imobilizaciju Cs jona..., The mechanism of high-temperature phase transformation of cesium (Cs) exchanged zeolites such as LTA and clinoptilolite (CLI) was investigated. Thermal stability of obtained phases and their resistance to Cs ion leaching was also analysed. It was shown that the obtained stable, crystalline alumosilicate structures of pollucite (CsAlSi2O6) and CAS phase (CsAlSi5O12) can be used as matrices for Cs ion immobilisation...

Dense CsAlSi5O12 was successfully obtained by hot pressing of Cs-exchanged clinoptilolite at 900 degrees C. Simultaneous application of high temperature and mechanical pressure allowed formation of CsAlSi5O12 at temperature considerably lower than 1150 degrees C which was the lowest reported temperature of CsAlSi5O12 formation in pressureless sintered Cs-exchanged clinoptilolite. CsAlSi5O12 formation was preceded by complete amorphisation of Cs-exchanged clinoptilolite in temperature range between 700 and 900 degrees C. Bearing in mind that clinoptilolite possesses high affinity for Cs cation it is believed that hot pressing of Cs-exchanged clinoptilolite might be an efficient way to immobilize radioactive Cs by its incorporation into crystal lattice of stable CsAlSi5O12. The samples sintered at 950 degrees C had relative density about 84% of theoretical density and open porosity of only 6% which is expected to result in low Cs leaching rate.

Porous acicular mullite (3Al(2)O(3)center dot 2SiO(2)) ceramics containing Cu3Mo2O9 as a soot oxidation catalyst was fabricated by a novel approach using commercial powders of Al2O3 and CuO, and powder obtained by controlled oxidation of ground waste MoSi2. The obtained material consisted of elongated mullite grains which are known to be effective in carbon soot removal from diesel engine exhaust. The presence of in situ created Cu3Mo2O9 was found to catalyze the carbon burnout which is an extremely important feature when it comes to filter regeneration, i.e., the captured soot removal. The carbon burnout temperature in the sample containing 12 wt% CuO was by 90 degrees C lower than that in the sample without CuO. Effect of sintering temperature as well as the effect of amount of CuO additive on mullite properties were studied. It was found that the increase in amount of CuO in samples sintered at 1300 degrees C decreased porosity and increased compressive strength of the porous mullite ceramics. The addition of 12 wt% CuO increased the strength of the porous mullite ceramics up to 70 MPa, whereas the porosity was reduced from 62% in the mullite without CuO to 44% in the mullite ceramics containing 12 wt% CuO. Although affected by the amount of CuO, the microstructure still consisted of elongated mullite grains.

A simple one-step method with direct thermal conversion at lower temperatures for preparing a stabile Cs-aluminsilicate phase, known as pollucite, is presented. Cs-exchanged form of Na, Ca-LTA type of zeolite (Cs-LTA) was pressureless sintered and hot pressed at certain temperatures in order to obtain pollucite. XRD and FTIR analysis were used to study structural changes of Cs-LTA before and after thermal treatments. Pressureless sintered sample recrystallized into pollucite phase after heat treatment at 1000 degrees C (3 h) (PLS1000) and hot pressed sample at 750 degrees C (3 h) using pressure of 35 MPa (HP750), indicating reduced temperature of 250 degrees. SEM micrographs confirmed that HP750 has higher density than PLS1000 which leads to higher value of compressive strength. The HP750 showed better resistance to Cs leaching than the PLS1000. Base on these results one can conclude that hot pressing is the promising method for the permanent disposal of Cs radionuclides. (C) 2016 Elsevier B.V. All rights reserved.

The possibility to use natural zeolite - clinoptilolite as a host material for radioactive Cs immobilization has been investigated. Cs-exchanged form of clinoptilolite which was prepared by treatment of clinoptilolite powder with 0.25 M CsCl solution was compacted. Both, powder and powder compact of exchanged clinoptilolite were thermally treated at 1200 C-0. The XRPD analysis showed that Cs was successfully immobilized after heat treatment by formation of stable cesium dodecaoxo-alumopentasilicate in both, powder sample and compact. The newly formed compound showed satisfactory Cs ions retention during leaching test. The sintered compact showed somewhat better resistance to Cs leaching than the thermally treated powder. The compressive strength of sintered compact was close to 200 MPa which is more than enough for easy handling and safe storage.

The removal of Cs (I) ions from aqueous solution was studied using natural diatomite as adsorption materials originated from Rudovci, Serbia. The microstructure of natural diatomite has been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) while the degree of Cs adsorption was evaluated by atomic emission spectroscopy. The cation exchange capacity (CEC) values for natural diatomite was 50 meq/100g. Depending on whether the Cs adsorption occurred in the acidic and alkaline media at a temperature of 298.15 K in acidic media Delta G(0) values was -12.674 kJ/mol, while in alkaline media Delta G(0) was 13.142 kJ/mol and a change of Delta S-0 to 42.51 J/molK in acidic media and 44.08 J/molK in alkaline medium.

The removal of Cs (I) ions from aqueous solution was studied using natural diatomite as adsorption materials originated from Rudovci, Serbia. The microstructure of natural diatomite has been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) while the degree of Cs adsorption was evaluated by atomic emission spectroscopy. The cation exchange capacity (CEC) values for natural diatomite was 50 meq/100g. Depending on whether the Cs adsorption occurred in the acidic and alkaline media at a temperature of 298.15 K in acidic media Delta G(0) values was -12.674 kJ/mol, while in alkaline media Delta G(0) was 13.142 kJ/mol and a change of Delta S-0 to 42.51 J/molK in acidic media and 44.08 J/molK in alkaline medium.

Cesium aluminosilicate phases are of great interest as possible hosts for 137Cs immobilization in radioactive waste management. Cs+ exchanged forms of two synthetic zeolites (4A and 3A) were prepared by standard procedure, and content of exchanged ions was determined by ion chromatography. Obtained samples were investigated by differential thermal gravimetry TG/(DTG) and SEM/EDS analysis. All samples were annealed in the range of 600–1500 °C. High temperature phase transformations of Cs+ exchanged zeolites (LTA) were investigated. Based on data obtained by XRD analysis of the samples, it was concluded that above 1000 °C Cs-LTA (4A and 3A) frameworks recrystallized in a pollucite phase.

With Bi(NO3)3 ⋅ 5H2O and Fe(NO3)3 ⋅ 9H2O as starting material and 8 M KOH as mineralizer, the pure-phase BiFeO3 (BFO) powders were synthesized by hydrothermal method at 200 °C. The microstructure, morphology and chemical analysis of the powders were analyzed using Scanning Electron Microscopy (SEM) combined with X-ray microanalysis (by Energy Dispersive Spectrometer – EDS). The phase composition of obtained samples was determined by X-ray diffraction (XRD) analysis. It revealed that synthesized material crystallize in space group R3c with cell parameters a = b = 5.5780(10) Å and c = 13,863(3) Å. The particle size and distribution was determined by small – angle X-ray scattering (SAXS). The magnetic behavior of synthesized material is done by means of SQUID device

Cesium aluminosilicate phases are of great interest as possible hosts for 137Cs immobilization in radioactive waste management. Cs+ exchanged forms of two synthetic zeolites (4A and 3A) were prepared by standard procedure, and content of exchanged ions was determined by ion chromatography. Obtained samples were investigated by differential thermal gravimetry TG/(DTG) and SEM/EDS analysis. All samples were annealed in the range of 600–1500 °C. High temperature phase transformations of Cs+ exchanged zeolites (LTA) were investigated. Based on data obtained by XRD analysis of the samples, it was concluded that above 1000 °C Cs-LTA (4A and 3A) frameworks recrystallized in a pollucite phase.

Well-crystallized single-crystal BiFeO3 (BFO) nanopowder has been successfully synthesized by the hydrothermal and solid state synthesis methods. We analyzed the particles size using granulometric analysis and scanning electron microscopy (SEM). The phase composition of the sintered samples was determined by x-ray diffraction (XRD) analysis. It revealed that synthesized material crystallize in space group R3c with cell parameters a = b = 5.5780(10) Å and c = 13,863(3) Å. The powders behavior was characterized by TG/DTA and Heating stage microscope. The magnetic behavior of synthesized material is done by means of SQUID device and using a vibrating sample magnetometer (VSM).

137Cesium is considered as one of the most hazardous radiotoxic elements for the environment. The aim of this study is to find out the best method to remove radio-active cesium from nuclear waste streams and safely store in non-leaching solids. Cs + exchanged forms of two synthetic zeolites (4A and 5A) were prepared by standard procedure and investigated by SEM/EDS analysis. Thermal-transformations of Cs + exchanged zeolites (LTA) have been studied by means of differential thermal analysis (DTA), thermo-gravimetric analyis (TGA) and x-ray powder diffraction. Based on obtained data, it was concluded that above 1000 0C Cs-LTA (4A and 5A) frameworks recrystallized in a stabile pollucite phase.

The vertical distribution of Ra-226 was investigated in soils from the cultivated and undisturbed areas in Rudovci, municipality Lazarevac, Serbia. There were three profiles, each profile divided on four horizons, what gives 12 soil samples. The specific activity of Ra-226 in soil and sediment samples was determined by using the gamma-spectrometric method. Analysis of the vertical soil profiles indicated that the activity of Ra-226 was not extremely changed with depth. To evaluate the radiological hazards of Ra-226 in the samples, the absorbed dose rate, the annual effective dose rate, the radium equivalent activity, and the external hazards index were calculated according to the UNSCEAR 2000 report.

The exposure of human beings to ionizing radiation from Cs-137 is a continuing and inescapable feature of life on Earth. Artificial radio nuclides are widely distributed in various geological formations and ecosystems such as rock, soil, groundwater, and foodstuffs. In the presents study, the distribution of Cs-137 was measured in soil samples collected from different lithological units of the Rudovci, Lazarevac, Serbia. Analysis of the vertical soil profiles indicated that the activity of Cs-137 was not extremely changed with depth. The activity concentrations of the Cs-137 in measured soil samples ranged from below minimal detectable concentrations up to 38.1 Bq/kg. In order to evaluate the radiological hazards due to Cs-137 in the samples, the absorbed dose rate and the annual effective dose were calculated in accordance with recommendations given in the UNSCEAR 2000 report. The distribution of radionuclides depends upon the rock composition, chemical and physical properties of the soil. The external absorbed gamma dose rates due Cs-137 were found to vary from 0 to 1.16 nGy/h.