Cretaceous-Paleogene boundary (KPB) Fish Clay at Højerup (Stevns Klint, Denmark): Ni, Co, and Zn of the black marl

The black marl of the Fish Clay at Højerup is mainly made up of biogenic calcite and cheto-Mg-smectite. We suggest that the formation of the smectite occurred during the latest Maastrichtian (or earlier) and that it represents a short period of rapid redeposition through coastal erosion occurring at the Cretaceous-Paleogene boundary (KPB) sea level lowstand. The smectite of the black marl shows enhanced concentrations of Ni, Co, and Zn. The predominant source of these metals was probably the impact-ejecta fallout deposited on the top of nearby soil which was leached by the impact-induced-acidic surface waters. Most of the content of Ni and Co in the smectite is derived from the chondritic component of the fallout, but the ultimate origin of Zn may have been the impact-target rocks. Incorporation of the metals into the smectite took place during the KPB but before its redeposition at the Fish Clay site. The biogenic calcite-rich fraction of the black marl also shows high concentrations of Ni, Co, and Zn. The ultimate source of the metals was also probably the impact-ejecta fallout on the nearby soil at Stevns Klint. Enrichments of Ni in the biogenic calcite-rich/smectite fractions of the black marl represent the sudden input of the metal into the seawater at the KPB

Alkali activation of different type of ash as a production of combustion process

Presented study deals with the final structure and radiological properties of different fly-ash based geopolymers. Lignite fly-ash (lignite Kolubara – Serbia) and wood fly ash were obtained in combustion process together with commercial fly-ash. Synthesis of the geopolymers was conducted by mixing fly-ash, sodium silicate solution, NaOH and water. The samples were strengthened 60 °C for 48 hours after staying at room temperature in covering mold for 24 hours. The X-ray diffraction, Fourier transform infrared and SAM measurements were conducted on the samples after 28 days of geopolymerization process. The X-ray diffraction measurements of lignite fly-ash samples show anhydrite as the main constituent, while wood fly-ash samples consist of calcite, albite and gypsum minerals. Besides determination of physicochemical properties, the aim of this study was radiological characterization of lignite fly-ash, wood fly-ash and the obtained geopolymer products. Activity concentration of 40K and radionuclides from the 238U and 232Th decay series, in ash samples and fly-ash based geopolymers, were determined by means of gamma-ray spectrometry, and the absorbed dose rate, D, and the annual effective dose rate, E, were calculated in accordance with the UNSCEAR 2000 report

Synthesis and characterization of high-entropy A2B2O7 pyrochlore with multiple elements at A and B sites

Single nano high-entropy pyrochlore-type compound (A2B2O7) with 7 different rare-earth cations at site A and 3 different metal cations at site B with equiatomic amounts (7A1/7)2(3B1/3)2O7 is successfully obtained. The powder with nominal composition (La1/7Sm1/7Nd1/7Pr1/7Y1/7Gd1/7Yb1/7)2(Sn1/3Hf1/3Zr1/3)2O7 was fabricated by reacting metal nitrates (site A) and metal chlorides (site B) with glycine during the combustion reaction. The XRD analysis revealed that the powder attained during synthesis is in an amorphous state. To induce crystallization of the obtained pyrochlore structure, the post-calcination process at 600-1500 °C was conducted and studied. Results of this study showed that the monophase pyrochlore (A2B2O7) structure is obtained during the calcination at 900 °C. The high-density ceramic pellet with 97% of theoretical density and free of any additives was obtained through pressureless sintering at 1650 °C for 4 h in the air using the powder calcined at 900 °C

Synthesis and characterization of monophase CaO-TiO2-SiO2 (sphene) based glass-ceramics

Sphene based glass-ceramics (CaTiSiO5), an excellent candidate for a host lattice of ceramic materials and for nuclear waste immobilization, has been prepared from a powder mixture of CaCO3, TiO2 and SiO2 using vibro-milling for homogenization. Starting powders were melted at 1400?C for 2 h, cooled to room temperature, grounded again, then crystallized by thermal treatment yielding a sphene glass-ceramic. The evolution of the phase composition during thermal treatment was investigated by X-ray powder diffraction (XRPD), FT-IR, Raman and thermal analyses (TG-DTA). Pure synthetic single phase sphene was formed at 800?C for 4 h, even it is very hard to obtain monophase powder at such low temperature. Powder morphology was analyzed by scanning electron microscopy (SEM)

Physicochemical and radiological characterization of kaolin and its polymerization products

The aim of this study was determination of physical-chemical and radiological characteristics of kaolin and products of alkali-activated thermally treated kaolin (geopolymer). Also, the objective of presented research was to investigate the possibility of kaolin application as a pigment or as a raw material for obtaining geopolymer materials as a relatively new ones in a building material industry. Physicochemical characterization of one set of samples was conducted using X-ray diffraction (XRD), Fourier transform infra-red (FTIR) and X-ray photoelectron spectroscopy (XPS). Activity concentration of naturally occurring radionuclides in kaolin, metakaolin and geopolymer were determined. The absorbed dose rate (D) and the annual effective dose rate (EDR), calculated in accordance with the UNSCEAR 2000 report, are also presented in this paper. Kaolin was heat-treated on 750oC and specific activity of natural radionuclide in metakaolin increased up to 1.6, while measured specific activities in geopolymer were the lowest

Bacterial Cellulose-Cerium Oxide Hydrogel for Tailored Redox Balance in Biomedical Extremes

Program and book of abstracts / 2nd International Conference on Innovative Materials in Extreme Conditions i. e. (IMEC2024), 20-22 March 2024 Belgrade, Serbia

Geochemistry of the cretaceous-tertiary boundary (Fish clay) at Stevns Klint (Denmark): Ir, Ni and Zn in kerogen

Geochemical analyses of trace metals (Ir, Ni and Zn) in the kerogen of the black marl of the Cretaceous-Tertiary boundary succession (Fish Clay) at Stevns Klint (Hojerup Church) were undertaken. The data for this kerogen were in accordance with a previous hypothesis(1) that this (insoluble) geoorganic polymer was derived from humic substances (mainly humic acids) of a nearshore soil. Substantial proportions of Ir, Ni and Zn within the kerogen structure were probably contained in these substances arriving at the sedimentary site. It is proposed that these humics were probably transported by acid surface waters (induced by the KT asteroid impact) into the shallow marine basin of Stevns Klint. It is also suggested that local leaching/weathering of the asteroidal impact fallout oil the land near these waters played an important role in providing Ir, Ni and Zn for these substances. Apparently, Ir, Ni and Zn of the kerogen were created by the chondritic component of the impact ejecta fallout

The Effect of Alkaline Activator Molarity and Aging Time on the Structure of Inorganic Polymer

The goal of this research was to produce an environmental friendly, energy saving inorganic polymer using a metakaolin as a precursor. The clean technology which conserve the natural environment was employed for the production of these materials. The used kaolinite is clay obtained from Rudovci, Lazarevac, Serbia. Physicochemical properties of kaolin were investigated in previous work by Nenadović et al. [1]. Metakaolin (MK) was prepared by calcining kaolinite at 750 °C for 1 h. The influence of alkali activation, i.e. different concentration of NaOH as a component of alkali activator mixture on the process of polymerization of metakaolin is investigated. The alkaline solution was prepared from sodium silicate and 2M, 4M, 6M and 8 M NaOH (analytical grade) (volume ratio Na2SiO3/NaOH = 1.6). The inorganic polymer (IP) samples were formed from metakaolin and the four different alkaline solution (solid/liquid ratio was about 1), which were mixed for 15 min and then left at room temperature for one day. Finally, the mixture was kept in a sample drying oven for 2 days at 60 °C. Process of aging time of inorganic polymer samples at 7th, 14th, 21st and 28th days is followed by some analytical methods (XRD, FTIR). X-ray diffraction (XRD) and Fourier transformation infrared spectroscopy (FTIR) were used for characterization of metakaolin and metakaolin based inorganic polymers. After 28th days when the aging time were finished, on the surface of the samples were used scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). XRD analysis almost of all inorganic polymer samples revealed their amorphouslike structure with the position of an amorphous halo in the range 18°-32°, which indicates short range ordering of the reference sample with crystalline admixture of SiO2 (α-quartz, ICSD 89). The FTIR spectra of all samples shows a strong peak at ∼1000 cm−1 which is associated with Si–O–Si asymmetric stretching vibrations and is the finger print of the geopolymerization [2,3]. The FT-IR results show a shift of the Si-O or Si-O-X bands as the molarity of activator increasing during polymerization process, where X can be Si or Al. Both methods and XRD, as well as FTIR, show greater sensitivity to monitoring the effects of molarity, than the aging time within the same molarity to structural changes in inorganic polymer. SEM micrographs (Fig.1) showed a denser matrix, and a lower content of unreacted metakaolin particles due to increasing of molarity of NaOH. Structural reorganization of inorganic polymer samples occurs during the curing or aging in accordance with a polymerization mechanism

Cretaceous-Paleogene boundary (KPB) Fish Clay at Højerup (Stevns Klint, Denmark): Ni, Co, and Zn of the black marl

The black marl of the Fish Clay at Højerup is mainly made up of biogenic calcite and cheto-Mg-smectite. We suggest that the formation of the smectite occurred during the latest Maastrichtian (or earlier) and that it represents a short period of rapid redeposition through coastal erosion occurring at the Cretaceous-Paleogene boundary (KPB) sea level lowstand. The smectite of the black marl shows enhanced concentrations of Ni, Co, and Zn. The predominant source of these metals was probably the impact-ejecta fallout deposited on the top of nearby soil which was leached by the impact-induced-acidic surface waters. Most of the content of Ni and Co in the smectite is derived from the chondritic component of the fallout, but the ultimate origin of Zn may have been the impact-target rocks. Incorporation of the metals into the smectite took place during the KPB but before its redeposition at the Fish Clay site. The biogenic calcite-rich fraction of the black marl also shows high concentrations of Ni, Co, and Zn. The ultimate source of the metals was also probably the impact-ejecta fallout on the nearby soil at Stevns Klint. Enrichments of Ni in the biogenic calcite-rich/smectite fractions of the black marl represent the sudden input of the metal into the seawater at the KPB

Cretaceous-Paleogene boundary Fish Clay at Hojerup (Stevns Klint, Denmark): trace metals in kerogen

Geochemical analyses of trace metals (Ir, Ni, Co, Cr, Zn, Au and Pb) and rare earth elements (La, Ce, Nd, Sm, Eu, Tb, Yb and Lu) in kerogen of the black marl at the Cretaceous-Paleogene boundary Fish Clay at Hojerup have been undertaken. Substantial proportions of the trace metals and rare earths were probably contained in terrestrial humic substances (the kerogen precursor) arriving at the marine sedimentary site. This is in accord with a previous hypothesis that kerogen is mainly derived from humic acids of an oxic soil in of the adjacent coastal areas of eastern Denmark. It is also suggested that humics were transported mainly through fluvial transport into the site of the deposition of the Fish Clay. The local weathering/leaching of the impact-ejecta fallout on the land surface or local terrestrial rocks by impact-induced? acid surface waters perhaps played an important role in providing trace metals and rare earths for these humic substances. Apparently, chondritic Ir, An, Ni, Co, Cr and chondritic and non-chondritic Zn originated from the impact fallout; Pb and rare earth elements were most likely sourced by the rocks exposed in the coastal areas of eastern Denmark