Search Results (6)

The thermal decomposition processes of coprecipitated Cu-Ni-Al and Cu-Ni-Fe hydroxides and the formation of the mixed oxide phases were followed by thermogravimetry and derivative thermogravimetry analysis (TG – DTG) and in situ X-ray diffraction (XRD) in a temperature range from 25 to 800 °C. The as-prepared samples exhibited layered double hydroxide (LDH) with a rhombohedral structure for the Ni-richer Al- and Fe-bearing LDHs and a monoclinic structure for the CuAl LDH. Direct precipitation of CuO was also observed for the Cu-richest Fe-bearing samples. After the collapse of the LDHs, dehydration, dehydroxylation, and decarbonation occurred with an overlapping of these events to an extent, depending on the structure and composition, being more pronounced for the Fe-bearing rhombohedral LDHs and the monoclinic LDH. The Fe-bearing amorphous phases showed higher reactivity than the Al-bearing ones toward the crystallization of the mixed oxide phases. This reactivity was improved as the amount of embedded divalent cations increased. Moreover, the influence of copper was effective at a lower content than that of nickel. Full article

In this study, Nickel oxide-based catalysts (Ni_xO_x) were synthesized and used for the in-situ upgrading process of heavy crude oil (viscosity 2157 mPa·s, and API gravity of 14.1° at 25 °C) in aquathermolysis conditions for viscosity reduction and heavy oil recovery. All characterizations of the obtained nanoparticles catalysts (Ni_xO_x) were performed through Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), X-Ray and Diffraction (XRD), and ASAP 2400 analyzer from Micromeritics (USA), methods. Experiments of catalytic and non-catalytic upgrading processes were carried out in a discontinuous reactor at a temperature of 300 °C and 72 bars for 24 h and 2% of catalyst ratio to the total weight of heavy crude oil. XRD analysis revealed that the use of nanoparticles of NiO significantly participated in the upgrading processes (by desulfurization) where different activated form catalysts were observed, such as α-NiS, β-NiS, Ni₃S₄, Ni₉S₈, and NiO. The results of viscosity analysis, elemental analysis, and ¹³C NMR analysis revealed that the viscosity of heavy crude oil decreased from 2157 to 800 mPa·s, heteroatoms removal from heavy oil ranged from S—4.28% to 3.32% and N—0.40% to 0.37%, and total content of fractions (ΣC₈–C₂₅) increased from 59.56% to a maximum of 72.21%, with catalyst-3 thank to isomerization of normal and cyclo-alkanes and dealkylation of lateral chains of aromatics structures, respectively. Moreover, the obtained nanoparticles showed good selectivity, promoting in-situ hydrogenation-dehydrogenation reactions, and hydrogen redistribution over carbons (H/C) is improved, ranging from 1.48 to a maximum of 1.77 in sample catalyst-3. On the other hand, the use of nanoparticle catalysts have also impacted the hydrogen production, where the H₂/CO provided from the water gas shift reaction has increased. Nickel oxide catalysts have the potential for in-situ hydrothermal upgrading of heavy crude oil because of their great potential to catalyze the aquathermolysis reactions in the presence of steam. Full article

The present study proposes a simple synthesis technique for producing bunsenite cadmium oxide nanoparticles. A variety of techniques were used to determine the structure, morphology, elemental content, and optical properties of bunsenite cadmium oxide nanoparticles. The samples’ XRD spectra at 500 °C and above confirmed the presence of cubic bunsenite and cadmium oxide structures. The crystallite size was increased from 29 nm to 62 nm as the calcined temperature increased from 500 °C to 800 °C. The dispersion of the particles of bunsenite cadmium oxide improved with an increasing calcination temperature. An equivalent increasing trend was indicated by the mean grain size displayed via field emission scanning electron microscopy (FESEM) micrographs. Furthermore, the UV-Vis spectra showed that multiple energy band gaps attenuated as the calcination temperature increased. The mean particle size, as measured by transmission electron micrographs, appeared to increase in tandem with the calcination temperature. The obtained bunsenite and cadmium oxide nanoparticles have potential for employment in a wide range of semiconductor applications. Full article

Fluid Catalytic Cracking (FCC) has traditionally been a key refining process in generating transportation fuels. Recently, the focus on FCC has been further intensified as it plays an increasingly important role in the generation of key building blocks for the petrochemical industry. Nickel is considered as one of the most challenging contaminants in FCC and originates from Ni-containing compounds in petroleum fractions, not only during unit operation but also in handling of the equilibrium and spent catalysts. Despite this critical role it plays throughout the complete lifecycle of an FCC catalyst, the nature of Ni is not yet well understood at various stages of its journey after depositing on the catalyst surface. The main objective of this contribution is the qualitative and quantitative identification of the various possible phases of Ni that are usually present in an equilibrium FCC catalyst (Ecat). A series of conventional and advanced analytical techniques have been employed, including XRF, ICP-AES, PXRD, FT-IR, UV-Vis-NIR, SEM-EDS, TEM/HRTEM and STEM/EXDS, XPS, RAMAN and TPR-H₂, on prototype Ni-impregnated SiO₂, Al₂O₃ and USY zeolite samples, Ni-impregnated and lab-deactivated FCC samples, and equilibrium FCC catalysts obtained from different refineries. Detailed analysis of the obtained results on the basis of background information, showed the strengths and weaknesses of the various methods. It was shown that powder x-ray diffraction (pxrd) can be effectively used for the quantitative determination of the NiO (bunsenite) phase at levels representative of equilibrium FCC catalysts. A comparison of conventional versus boron-based Ni-passivation is presented. It was shown that catalysts from boron-based technology (BBT) can keep Ni at a less-reducible state, effectively hindering its deleterious role in FCC operations. Full article

Groundwater contamination by potentially harmful elements (PHEs) originating from the weathering of granitic and gneissic rock dissolution poses a public health concern worldwide. This study investigated physicochemical variables and PHEs in the groundwater system and mine water of the Adenzai flood plain region, in Pakistan, emphasizing the fate distribution, source provenance, chemical speciation, and health hazard using the human health risk assessment HHRA-model. The average concentrations of the PHEs, viz., Ni, Mn, Cr, Cu, Cd, Pb, Co, Fe, and Zn 0.23, were 0.27, 0.07, 0.30, 0.07, 0.06, 0.08, 0.68, and 0.23 mg/L, respectively. The average values of chemical species in the groundwater system, viz., H⁺, OH⁻, Ni²⁺, Mn²⁺, Mn³⁺, Cr³⁺, Cr⁶⁺, Cu⁺, Cu²⁺, Cd²⁺, Pb²⁺, Pb⁴⁺, Co²⁺, Co³⁺, Fe²⁺, Fe³⁺, and Zn²⁺, were 1.0 × 10⁻⁴ ± 1.0 × 10⁻⁶, 1.0 × 10⁻⁴ ± 9.0 × 10⁻⁷, 2.0 × 10⁻¹ ± 1.0 × 10⁻³, 3.0 × 10⁻¹ ± 1.0 × 10⁻³, 1.0 × 10⁻²² ± 1.0 × 10⁻²³, 4.0 × 10⁻⁶ ± 2.0 × 10⁻⁶, 4.0 × 10⁻¹¹ ± 2.0 × 10⁻¹¹, 9.0 × 10⁻³ ± 1.0 × 10⁻², 2.0 × 10⁻¹ ± 2.0 × 10⁻³, 7.0 × 10⁻² ± 6.0 × 10⁻², 5.0 × 10⁻² ± 5.0 × 10⁻², 2.0 × 10⁻² ± 1.5 × 10⁻², 6.0 × 10⁻² ± 4.0 × 10⁻², 8.0 × 10⁻³¹ ± 6.0 × 10⁻³¹, 3.0 × 10⁻¹ ± 2.0 × 10⁻⁴, 4.0 × 10⁻¹⁰ ± 3.0 × 10⁻¹⁰, and 2.0 × 10⁻¹ ± 1.0 × 10⁻¹. The mineral compositions of PHEs, viz. Ni, were bunsenite, Ni(OH)₂, and trevorite; Mn viz., birnessite, bixbyite, hausmannite, manganite, manganosite, pyrolusite, and todorokite; Cr viz., chromite and eskolaite; Cu viz., CuCr₂O₄, cuprite, delafossite, ferrite-Cu, and tenorite; Cd viz., monteponite; Pb viz, crocoite, litharge, massicot, minium, plattnerite, Co viz., spinel-Co; Fe viz., goethite, hematite, magnetite, wustite, and ferrite-Zn; and Zn viz., zincite, and ZnCr₂O₄ demarcated undersaturation and supersaturation. However, EC, Ca²⁺, K⁺, Na⁺, HCO₃⁻, Cr, Cd, Pb, Co, and Fe had exceeded the WHO guideline. The Nemerow’s pollution index (NPI) showed that EC, Ca²⁺, K⁺, Na⁺, HCO₃⁻, Mn, Cd, Pb, Co, and Fe had worse water quality. Principal component analysis multilinear regression (PCAMLR) and cluster analysis (CA) revealed that 75% of the groundwater contamination originated from geogenic inputs and 18% mixed geogenic-anthropogenic and 7% anthropogenic sources. The HHRA-model suggested potential non-carcinogenic risks, except for Fe, and substantial carcinogenic risks for evaluated PHEs. The women and infants are extremely exposed to PHEs hazards. The non-carcinogenic and carcinogenic risks in children, males, and females had exceeded their desired level. The HHRA values of PHEs exhibited the following increasing pattern: Co > Cu > Mn > Zn > Fe, and Cd > Pb > Ni > Cr. The higher THI values of PHEs in children and adults suggested that the groundwater consumption in the entire region is unfit for drinking, domestic, and agricultural purposes. Thus, all groundwater sources need immediate remedial measures to secure health safety and public health concerns. Full article

Replenishment of mineral resources, especially gold and rare metals, is critical for progress in the mining and metallurgical industry of Eastern Kazakhstan. To substantiate the scientific background for mineral exploration, we study microinclusions in minerals from gold and rare-metal fields, as well as trace-element patterns in ores and their hosts that may mark gold and rare-metal mineralization. The revealed compositions of gold-bearing sulfide ores and a number of typical minerals (magnetite, goethite, arsenopyrite, antimonite, gold and silver) and elements (Fe, Mn, Cu, Pb, Zn, As, and Sb) can serve as exploration guides. The analyzed samples contain rare micrometer lead (alamosite, kentrolite, melanotekite, cotunnite) and nickel (bunsenite, trevorite, gersdorffite) phases and accessory cassiterite, wolframite, scheelite, and microlite. The ores bear native gold (with Ag and Pt impurities) amenable to concentration by gravity and flotation methods. Multistage rare-metal pegmatite mineralization can be predicted from the presence of mineral assemblages including cleavelandite, muscovite, lepidolite, spodumene, pollucite, tantalite, microlite, etc. and such elements as Ta, Nb, Be, Li, Cs, and Sn. Pegmatite veins bear diverse Ta minerals (columbite, tantalite-columbite, manganotantalite, ixiolite, and microlite) that accumulated rare metals late during the evolution of the pegmatite magmatic system. The discovered mineralogical and geochemical criteria are useful for exploration purposes. Full article