Higher Ce Content Research Articles

Magnetic properties and coercivity mechanism of high Ce-content CeNdFeB film with Tb diffusion

Magnetic properties and coercivity mechanism of an anisotropic Ce–Nd–Fe–B film with a high Ce content (70 at. % Nd is replaced by Ce) have been investigated. After grain boundary diffusion with Tb layers, an enhancement of coercivity from 4150 to 9250 Oe is observed. Combining the initial magnetization curves, micromagnetic theory, and in-siut observation of magnetic domains in the demagnetization process, it is confirmed that the coercivity mechanism for the high-Ce-content magnets is the mixed type dominated by the pinning mechanism. Moreover, as the thickness of the Tb diffusion layer increases, the pinning center of domain walls changes from narrow planar inhomogeneities to wide planar inhomogeneities. A growing role of pinning plays in determining the coercivity of samples with increasing the thickness of Tb layer due to the increase in magnetocrystalline anisotropy after Tb substitution in the RE2Fe14B phase. In addition, the CeFe2 intergranular phase leads to the enhancement of coercivity due to decoupling the hard magnetic phase grains. Our results provide an insight into the coercivity mechanism of high-Ce-concentration Ce–Nd–Fe–B magnetic materials and promote the comprehension of the effect of Tb diffusion in the magnetization reversal process.

Optical and magnetic properties of fluoride-doped CeO2 obtained by an oxidative insertion method

• CeO 2 : F sample is synthesized using molten flux promoted oxidative insertion method. • PXRD and Raman spectral measurements confirmed the fluorite structure of CeO 2 :F. • Besides Ce and O, EDX analysis also revealed the presence of 18 at. % of fluoride. • PL and magnetic studies revealed a lower concentration of O vacancies in CeO 2 :F. • The F-doped sample had a higher concentration of Ce 3+ in CeO 2 :F. In the present study, we generated a fluoride-doped CeO 2 sample through the molten hydroxide flux promoted oxidative insertion approach using CeF 3 as the precursor. We analyzed the results and compared them with pure CeO 2 prepared by the same approach starting from Ce(NO 3 ) 3 . High-resolution powder X-ray diffraction, FTIR, and Raman spectral measurements confirmed both samples’ fluorite structure. The CeO 2 resulted from the oxidative flux treatment of CeF 3 had 18 at.% of fluoride ion-doped in it. The optical band gap narrowed marginally from 2.98 to 2.88 eV upon fluoride doping in CeO 2 . The blue emission intensity decreased with fluoride doping, indicating a reduction in oxygen vacancies compared to undoped CeO 2 . F-doped CeO 2 showed ferromagnetic behavior with magnetization, H c, and M r values higher than the undoped sample. A higher concentration of Ce 3+ and a lower concentration of oxygen vacancies were the consequences of fluoride doping in CeO 2 by this synthetic method.

Investigation on High CE Content (Nd-Pr-Ce)2fe14b Melt-Spun Ribbons with High Coercivity

Investigation on High CE Content (Nd-Pr-Ce)2fe14b Melt-Spun Ribbons with High Coercivity

Solubilization of struvite and biorecovery of cerium by Aspergillus niger

Cerium has many modern applications such as in renewable energies and the biosynthesis of nanomaterials. In this research, natural struvite was solubilized by Aspergillus niger and the biomass-free struvite leachate was investigated for its ability to recover cerium. It was shown that struvite was completed solubilized following 2 weeks of fungal growth, which released inorganic phosphate (Pi) from the mineral by the production of oxalic acid. Scanning electron microscopy (SEM) showed that crystals with distinctive morphologies were formed in the natural struvite leachate after mixing with Ce3+. Energy-dispersive X-ray analysis (EDXA), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) confirmed the formation of cerium phosphate hydrate [Ce(PO4)·H2O] at lower Ce concentrations and a mixture of phosphate and cerium oxalate decahydrate [Ce2(C2O4)3·10H2O] at higher Ce concentrations. The formation of these biogenic Ce minerals leads to the removal of > 99% Ce from solution. Thermal decomposition experiments showed that the biogenic Ce phosphates could be transformed into a mixture of CePO4 and CeO2 (cerianite) after heat treatment at 1000 °C. These results provide a new perspective of the fungal biotransformation of soluble REE species using struvite leachate, and also indicate the potential of using the recovered REE as biomaterial precursors with possible applications in the biosynthesis of novel nanomaterials, elemental recycling and biorecovery.Key points• Cerium was recovered using a struvite leachate produced by A. niger.• Oxalic acid played a major role in struvite solubilization and Ce phosphate biorecovery.• Resulting nanoscale mineral products could serve as a precursor for Ce oxide synthesis.

Composition of ore-forming fluids in the Huangshuian carbonatite-related Mo-(REE) deposit: Insights from LA-ICP-MS analyses of fluid inclusions

The carbonatites in the southern margin of the North China Craton are distinguishable by containing abundant quartz and are closely spatially associated with Mo-(REE) deposits. Unveiling the nature of ore-forming fluids is key to understand the genesis of these Mo-(REE) deposits and to explore their potential genetic relationships with the quartz-rich carbonatites, but such issues were currently not convincingly addressed. Here, we provide detailed petrographic, microthermometric and LA-ICP-MS analyses of the fluid inclusions hosted in the primary quartz from the carbonatites in the Huangshuian Mo-(REE) deposit which is the largest Mo-(REE) one in the region, containing 0.4 million tons of Mo metal with REEs as the major by-product. Our results show that the fluid inclusions in the quartz of the carbonatites are two- and three-phase CO2-bearing types with high homogenization temperatures (average at 396 °C) and low salinities (average at 3.88 wt% NaCl equiv). The LA-ICP-MS analyses of these inclusions reveal that the primary fluids contain high concentrations of La, Ce, Pr, Nd, Sr, and Ba, similar to typical carbonatite-related fluids. In addition, they are characterized by high Y, Cu, Pb, and Zn. Such a metal association is broadly consistent with the mineral assemblages of the Huangshuian Mo-(REE) deposit, such as the widespread barite, bastnäsite, xenotime, chalcopyrite, galena, and sphalerite, strongly supporting the close genetic relation of the deposit with the quartz-rich carbonatites. Although the concentrations of Mo are extremely low in these inclusions (below the detect limit), it was constrained to be gradually enriched in evolved fluids. Considering that the recorded fluids in quartz represent earliest generation of fluids exsolved from carbonatite magmas, our new results highlight that quantifying metal budgets of fluid inclusions could be a robust way to evaluate fertility of carbonatites that are widespread in the southern margin of the North China Craton.

Highly Dispersive Cerium Atoms on Carbon Nanowires as Oxygen Reduction Reaction Electrocatalysts for Zn-Air Batteries.

Highly efficient noble-metal-free electrocatalysts for oxygen reduction reaction (ORR) are essential to reduce the costs of fuel cells and metal-air batteries. Herein, a single-atom Ce-N-C catalyst, constructed of atomically dispersed Ce anchored on N-doped porous carbon nanowires, is proposed to boost the ORR. This catalyst has a high Ce content of 8.55 wt % and a high activity with ORR half-wave potentials of 0.88 V in alkaline media and 0.75 V in acidic electrolytes, which are comparable to widely studied Fe-N-C catalysts. A Zn-air battery based on this material shows excellent performance and durability. Density functional theory calculations reveal that atomically dispersed Ce with adsorbed hydroxyl species (OH) can significantly reduce the energy barrier of the rate-determining step resulting in an improved ORR activity.

Genetic model of carbonatite hosted rare earth elements mineralization from Ambadongar Carbonatite Complex, Deccan Volcanic Province, India

Carbonatites and associated alkaline rocks are the primary sources for REE mineralization. The Ambadongar Carbonatite Complex (ADCC) from NW Deccan Volcanic Province (DVP) constitutes the largest Carbonatite Associated REE Deposits (CARD) in India. ADCC belongs to the final stages of the Late Cretaceous alkaline-carbonatite magmatism associated with main Deccan basalt volcanic activity. The ADCC is an envisioned diatreme structure in which four carbonatitic phases are recognized, mainly calcio-carbonatites and ferro-carbonatites. Each successive carbonatite phase shows higher REE enrichment. The primary REE mineralization with bastnäsite as the dominant REE phase is hosted by pervasive hydrothermally altered ferro-carbonatite plugs. The secondary mineralogy formed with barites in the main orebody during late- to post-magmatic hydrothermal fluid alteration is fluorite, quartz, ankerite, and other REE-bearing minerals like bastnäsite, parisite, synchysite, strontianite, florencite, monazite and columbite.Carbonatite samples contain 18.61% to 52.42% of CaO, and the LOI varies from 5.28% to 38.79%. Most can be classified as calcio-carbonatites. Since all the samples also contain an appreciable amount of Fe2O3 (4.13% to 20.20%) and MnO (0.07% to 5.46%), some may be classified as ferro-carbonatites. Total REE content varies from 0.6 to 4%, with a high Ce concentration and LREE/HREE ratio. The highest values for La, Ce, Pr, and Nd are 1.95%, 1.56%, 0.16%, and 0.45%, respectively.Metasomatism of SCLM from asthenospheric melts followed by the low degree partial melting of the SCLM region is responsible for fertile carbonatite generation in ADCC. The multiphase liquid immiscibility of carbonatite melts from carbonate-silicate magma followed by immiscibility of REE rich carbonatite melt and REE deficient fluoride-rich aqueous fluids explain the higher level of REE enrichment in each successive phases of carbonatites in ADCC.The mineralizing fluids were probably the result of residual magmatic volatiles that brought mainly REE and later SiO2 into the overprinted rocks. Ambadongar carbonatites' stable isotopic compositions agree with a magmatic origin (δ13C = −4.1 ± 1.9‰ [PDB] and δl8O = 10.3 ± 1.7‰ [SMOW]). The C–O stable isotopic modeling indicates re-equilibration under hydrothermal conditions between 180 °C and 70 °C. Significant amounts of REE fluorocarbonate minerals, relatively Sr- and Th-rich, were deposited during re-equilibration. The REE fluorocarbonate bastnäsite-(Ce) occurs as late individual crystals, overgrown on the synchysite and parisite polycrystals. Textural and chemical reactions between the REE fluorocarbonates provide insights into rare-earth elements' mobility during fluid-rock interaction. Early crystallization of synchysite/parisite indicates the high activity of Ca2+, OH−, (SO4)2−, Al and Si in the fluid. Later, the fluid was characterized by increased activity of F−, (SO4)2−, REE and Si, and decreased activity of Ca2+ as reflected in the association of barite, fluorite, quartz, and bastnäsite typical of strongly overprinted ferro-carbonatites.Re-equilibration and recrystallization of the primary minerals in the presence of OH−, (SO4)2−, F−, REE, Al, and Si carried in solution by the hydrothermal fluid is the leading cause behind the refixing of REE in the form of REE fluorocarbonate in REE rich ferro-carbonatites.

Photoluminescence and scintillation properties of Ce-doped SrY2O4 single crystals

Photoluminescence (PL) and scintillation properties of Ce:SrY2O4 single crystals were investigated. The PL quantum yield (QY) of the 2 % Ce-doped sample was the highest, and it decreased in the high Ce concentrations samples. The undoped SrY2O4 single crystal exhibited a broad emission band at 380 nm due to host defects, and the scintillation decay time constant was about 4.2 μs. The pulse height spectrum of 137Cs γ-rays using the undoped SrY2O4 single crystal revealed the scintillation light yield of 830 photons/MeV.

Regulation of Ce (Ⅲ) / Ce (Ⅳ) ratio of cerium oxide for antibacterial application

SummaryAntibiotics have been considered as effective weapons against bacterial infections since they were discovered. However, antibiotic resistance caused by overuse and abuse of antibiotics is an emerging public health threat nowadays. Fully defeating bacterial infections has become a tough challenge. In this work, cerium oxide was fabricated on medical titanium by thermolysis of cerium-containing metal-organic framework (Ce-BTC). Regulation of Ce (Ⅲ)/Ce (Ⅳ) ratios was realized by pyrolysis of Ce-BTC in different gas environment, and the antibacterial properties were studied. The results indicated that, in acidic conditions, ceria with a high Ce (Ⅲ)/Ce (Ⅳ) ratio owned high oxidase-like activity which could produce reactive oxygen species. Moreover, ceria with high Ce (Ⅲ) content possessed strong ATP deprivation capacity which could cut off the energy supply of bacteria. Based on this, ceria with a high Ce (Ⅲ)/Ce (Ⅳ) ratio exhibited superior antibacterial activity

Synthesis of C21H38ClN Assisted Si Pillared Clays and the Effects of CeO2 Addition on Its Supported Palladium Catalyst for Benzene Oxidation

Mesoporous silica-pillared clays (SPC) were prepared with C21H38ClN cationic surfactant as template and supported PdOx catalysts were prepared by impregnation method. The influence of addition of CeO2 on benzene combustion was evaluated. The samples were characterized by N2 adsorption–desorption, XRD, XPS, HRTEM and TPSR. Compared with the raw montmorillonite, the d001 value of SPC increased from 0.96 to 3.45 nm. Furthermore, the surface area was increased from 30 to 835 m2/g and the pore volume was increased from 0.11 to 1.30 cm3/g, respectively. The addition of CeO2 increased oxygen vacancies and improved the dispersion of PdOx on SPC, and the optimal addition of CeO2 was 10%. Therefore, of all the catalysts, 0.3%Pd/10%Ce/SPC could completely oxidize benzene at 280 °C, showing the highest catalytic activity. This catalyst showed high activity for benzene oxidation in wet conditions with or without Cl− displaying good durability, which should be related to the presence of Ce3+ on the surface of catalyst after reaction. The excellent pore structure of SPC, improved dispersion of PdOx and high concentration of Ce3+ on the catalyst surface were the key factors for the high catalytic activity of 0.3%Pd/10%Ce/SPC. Mesoporous silica-pillared clays (SPC) were synthesized and SPC supported CeO2 and PdO catalysts were prepared by impregnation method. The 0.3% Pd/10% Ce/SPC catalyst displayed the highest activity for benzene combustion.

Elastic and thermodynamic properties of cerium‐doped yttrium aluminum garnets

AbstractCerium‐doped yttrium aluminum garnets (Y3‐xCexAl5O12, Ce:YAGs) are promising yellow light‐emitting components of solid‐state white light‐emitting diodes. Although there have been numerous studies examining the effects of Ce concentrations on the luminescent properties of Y3‐xCexAl5O12, the impacts of Ce dopant on the elastic and thermodynamic properties are not well understood. In this work, we used resonant ultrasound spectroscopy (RUS) to determine the effects of Ce doping (0.025, 0.1, 1 at. %) on the elastic and thermodynamic properties of Y3‐xCexAl5O12. The elastic moduli calculated via the Voigt–Reuss–Hill (VRH) method demonstrated that low Ce dopant concentrations (≤0.1 at. %) induced negligible effects on the elasticity of the YAG host matrix, while a high Ce concentration (1 at. %) yielded significant softening. RUS spectral analysis and SEM images suggested that the elastic softening originated from microstructural differences induced at higher Ce dopant concentrations. In addition, we demonstrated an increase in elastic anisotropy at higher Ce concentrations, which further elucidated the correlations between structure and elasticity of Y3‐xCexAl5O12. Debye temperatures (θD), heat capacities (Cp), and thermal conductivities (κ) were calculated for Ce:YAGs through the relations of RUS‐derived parameters (sound velocities, elastic moduli) and previously determined thermal expansion coefficients. Ce:YAG was found to have a significant reduction in θD, Cp, and κ at Ce concentrations ≥1 at. %. Lastly, extrapolation of Cp and κ to higher temperatures allowed the modeling of thermal stress experienced by Y3‐xCexAl5O12 disks up to 1073.15 K.

Toward the Recovery of Platinum Group Metals from a Spent Automotive Catalyst with Supported Ionic Liquid Phases

We present a novel approach for the separation and recovery of Pt and Pd leached from a spent automotive catalyst relying on conventional and polymerized supported ionic liquid phases (SILPs and polySILPs, respectively). A variety of parameters with possible effects on the separation behavior, namely, acidity and concentration of the platinum group metal (PGM) containing solution, as well as different SILP and polySILP loadings, were evaluated for the separation of PGMs in the presence of high concentrations of Al, Fe, Zn, and Ce. The polySILP material demonstrated the ability to separate the PGMs from major accompanying interferences in a single separation step, while problems arising from ionic liquid leaching in the case of SILPs could be avoided. Moreover, the use of supported ionic liquid phases allowed the drastic reduction of the amount of required ionic liquid compared to conventional liquid–liquid separation, while avoiding problems arising from emulsion formation. Subsequent stripping experiments lead to further purification of the PGMs and finally desorption from the solid material into a pure solution. Eventually, the concept of chemisorbed polySILPs provides a new and convenient approach for the recycling of platinum group metals.

Agates from Paleoproterozoic Volcanic Rocks of the Onega Structure, Central Karelia

Agate mineralization in Central Karelia, Northwest Russia is related to the Paleoproterozoic volcanic rocks of the Ludicovian Superhorizon (2.05–1.95 Ga) within the Onega structure. Agates and parental volcanic rocks were studied with optical and electron microscopy, electron microprobe, X-ray diffraction, Raman spectroscopy, and ICP-MS. It is shown that fine-grained quartz, and fibrous and fine-flake chalcedony are the major minerals in the agate structure. Inclusions of coarse-crystalline calcite, and microinclusions of chlorite, iron oxides and hydroxides, hydroxylapatite, epidote, mica (phengite), apatite, pyrite, chalcopyrite, titanite, and leucoxene are present in agates. The presence of contrast rhythms within agate amygdules is marked by compositional variation in impurity mineral phases and different microtextures of silica layers represented by different-grained aggregates of quartz, fine-flake and fibrous chalcedony, and quartzine. This indicates stage-by-stage mineral crystallization at variable temperatures and pressures during agate formation, which may also reflect the heterogeneity of the initial hydrothermal fluid. High concentrations of Ti, Cr, Mn, Ni, and Cu (10–120 ppm) and the low concentrations of Li, Co, Ga, Zn, Sr, Zr, Mo, and Sn (0.5–10 ppm) are characteristic of quartz–chalcedony agates. Calcite in agates is characterized by high concentrations of Mn (1253–6675 ppm), Sс, Ti, Ni, Sr, Y, La, Ce, and Nd (5–56 ppm). The chondrite-normalized REE distribution pattern in agates shows a decay profile from La to Lu and a negative Eu anomaly in some samples. Low contents of rare metals and REE in agates compared to parental volcanic rocks indicate a gradual chemical depletion of circulating fluids during agate formation.

Two-stage magmatism and tungsten mineralization in the Nanling Range, South China: Evidence from the Jurassic Helukou deposit

Abstract The Helukou deposit, with proven reserves of 33 752 t WO3, is one of the newly exploited medium-scale tungsten (W) deposits in the Guposhan ore field, Nanling Range of South China. Skarn-type and less abundant altered granite-type tungsten orebodies were identified in this deposit. The ore mineralization in this district was a product of two-stage magmatism, as shown by LA-ICP-MS U-Pb dating of zircons and Re-Os dating of molybdenite. The former yielded U-Pb ages of 184.0 ± 3.6 Ma (MSWD = 0.15) and 163.8 ± 1.5 Ma (MSWD = 0.41) for fine-grained biotite granite and muscovite granite, respectively, as well as a U-Pb age of 181.5 ± 2.1 Ma (MSWD = 0.75) for zircon grains from altered granite-type tungsten ore. The latter yielded molybdenite Re-Os ages of 183.5 ± 2.8 Ma (without MSWD owing to a limited number of samples) and 163.4 ± 2.8 Ma (MSWD = 0.71) for altered granite-type and skarn-type tungsten deposits, respectively. Thus, two separate tungsten mineralization events occurred during the Early Jurassic and Middle Jurassic. Trace-element compositions suggest that scheelite I was controlled by the coupled substitution reactions of 2Ca2+ = Na+ + REE3+ and Ca2+ + W6+ = Nb5+ + REE3+, whereas scheelite II was controlled by the coupled reactions of 2Ca2+ = Na+ + REE3+ and 3Ca2+ = ☐Ca + 2REE3+ (where ☐ is a site vacancy). High Mo and low Ce contents suggest that both scheelite I and scheelite II were precipitated from oxidizing magmatic-hydrothermal fluids. Based on the mineral assemblage of the altered granite-type ores and geochemical characteristics of scheelite I [i.e., negative Eu anomalies (0.02–0.05; mean = 0.03 and STD = 0.01), and high 87Sr/86Sr ratios (0.70939–0.71932; mean = 0.71345 and STD = 0.00245)], we infer that fluid-rock interaction played an important role in modifying Early Jurassic ore-forming fluids. Scheelite II exhibits a geo-chemical composition [i.e., 87Sr/86Sr ratios (0.70277–0.71471; mean = 0.70940 and STD = 0.00190), Eu anomalies (0.14–0.55; mean = 0.26 and STD = 0.09), and Y/Ho ratios (16.1–33.7; mean = 27.9 and STD = 2.91)] similar to that of the Middle Jurassic Guposhan granites, suggesting inheritance of these features from granite-related magmatic-hydrothermal fluids. These results provide new insights into the two-stage magmatic and metallogenic history of the Nanling Range during the Jurassic Period.

Cerium uptake, translocation and toxicity in the salt marsh halophyte Halimione portulacoides (L.), Aellen

Halimione portulacoides plants were exposed to dissolved cerium (Ce) in a hydroponic medium for five days. Ce accumulation in plants followed the metal’s increase in the medium although with a very low translocation factor (TF < 0.01) between roots and shoots. Ce median concentrations in roots were 586, 988 and 1103 μg/g (dry wt.), while in shoots the median values reached 1.9, 3.5 and 10.0 μg/g (dry wt.), for plants exposed to 300, 600 and 1200 μg/L of Ce, respectively. No significant differences occurred in the length of roots and shoots among treatment groups, albeit plants exposed to the highest Ce concentration showed a clear loss of turgor pressure on the fifth day. An increase of hydrogen peroxide and malondialdehyde levels were observed in the plant shoots at 1200 μg/L of Ce. The highest concentration also triggered an answer by the shoots’ antioxidant enzymes with a decrease in the activity of superoxide dismutase and an increase in peroxidase. However, no significant change in catalase activity was observed, compared to the control group, which may indicate that peroxidase played a more crucial role against the oxidative stress than catalase. Combined results indicate that H. portulacoides was actively responding to a toxic effect imposed by this higher Ce concentration. Nevertheless, changes in normal environmental conditions, may increase the bioavailability of Ce, while in areas where acid mine drainage may occur, the highest Ce concentration tested in this study may be largely exceeded, placing the sustainability of halophytes and estuarine marshes at risk.

Enhancement of potassium resistance of Ce–Ti oxide catalyst for NH3-SCR reaction by modification with holmium

Alkali metal K in exhaust gas has a deactivation effect on NH3-SCR catalysts. In this work, it is discovered that the addition of Ho on CeTi catalyst can remarkably strengthen its K tolerance. The conclusions of Brunauer–Emmett–Teller (BET) , X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), NH3 temperature programmed desorption (NH3-TPD) and H2 temperature programmed reduction (H2-TPR) analyses demonstrate that the enhancement of K resistance mainly originates from its stronger surface acidity and redox capability, the higher concentration of Ce3+ species and surface chemisorbed oxygen. In situ DRIFT analysis reveals that the introduction of Ho on CeTi can remarkably improve the adsorption of NH3 and NOx species on catalyst surface, accompanied by the intensified reactivity of ad-NH3 species, which should also administer to improve the K resistance.

Synthesis of Ni-Pd decorated spindle-shape CeO2 for catalytic reduction of nitroarene

Facile single-step hydrothermal approach was developed for the synthesis of Ni and Pd decorated spindle-shape defected CeO2 catalyst for reduction of nitroarene compounds. A Ni-Pd/CeO2 catalyst showed superior activity toward nitroarene reduction than its nickel monometallic counterpart (Ni/CeO2). Addition of very small amount of Pd to Ni-CeO2 catalyst largely changed its morphology, size of active nanoparticles (NPs) as well as its catalytic activity. A synergy between active metals (Pd, Ni) and support (CeO2), strong metal-support interactions, ceria defect sites with high concentrations of Ce+3 and oxygen vacancy sites were suggested to promoting the superior activity of Ni-Pd/CeO2 compared to Ni/CeO2 catalyst.

Optimizing Ni–Ce/HZSM-5 catalysts for ex-situ conversion of pine wood pyrolytic vapours into light aromatics and phenolic compounds

The main objective of the present work is to investigate the influence of nickel to cerium ratio on hydrogen exchanged Zeolite Socony Mobil-5 (HZSM-5) towards the catalytic upgrading of pine derived oxygenated pyrolysis vapours into aromatic hydrocarbon and phenol in pyrolysis oil via ex-situ fixed bed reactor. The presence of CeO2 could change electron density of Ni, promote the reduction of Ni species, accelerate the transfer of carbon species, and suppress the production of carbon deposits (17.53%–25.11%) compared with the parent HZSM-5 catalyst (28.95%); it also improved the hydrodeoxygenation ability of all xNiyCe/HZSM-5(nickel and cerium bimetal modified HZSM-5) catalysts, resulting increases in noncondensable gas content (from 31.46% to 52.99%–65.53%). Ni to Ce ratio of 1:1 and 1:2 produced highest aromatic hydrocarbon (32.14%) and phenols (55.51%) relative peak areas. The acid center of HZSM-5 and the metal acid center of the Ni:Ce = 1:1 catalyst obviously fine-tuned the formation of coke; and promoted hydrocarbon production. Moreover, high Ni content promoted alkylation of benzene at C6–C9 and increased C10+ PAHs relative peak area; high Ce content promoted the formation of olefin and Increasing the cleavage of C–O bonds and promoted hydrogenation or dehydrogenation, reduced polycyclic aromatic hydrocarbons and coke yield, and increased phenols and alkylphenols selectivity.

Early Devonian (415–400 Ma) A-type granitoids and diabases in the Wuyishan, eastern Cathaysia: A signal of crustal extension coeval with the separation of South China from Gondwana

Abstract The evolution of the South China continental crust and its linkage to the assembly and rifting of eastern Gondwana are key issues in the understanding of the early Paleozoic evolution of eastern Asia. We report U-Pb zircon ages and geochemical and Lu-Hf isotopic data for the South Fufang and Yingshang granitoids and the Mayuan diabases from the Wuyishan of eastern South China. The zircons yielded U-Pb ages of ca. 414–404 and ca. 409–401 Ma for the granitoids and diabases, respectively. Petrographic and geochemical features indicate that the granitoids are peraluminous A-type granites, expressed by high Ga/Al ratios and high Zr, Nb, Ce, Y, and rare earth element contents. They show negative zircon εHf(t) values (–15.4 to –5.8), consistent with the derivation from a crustal source. The granitoids likely originated from partial melting of dry granulite residues in the lower crust. The diabases show depletion in Ti, and negative correlations between FeOt and Mg#, and SiO2 and TiO2/FeOt, reflecting clinopyroxene, olivine, and Fe-Ti oxide fractionation. Their negative zircon εHf(t) values (–4.5 to –0.4) indicate an ancient enriched-mantle origin. The diabases likely originated from partial melting of a sub-continental lithospheric mantle. We interpret these A-type granitoids and diabases as post-orogenic, formed during extensional collapse of thickened crust. Their generation indicates that South China experienced crustal extension during the Early Devonian. The extension occurred coevally with global rifting that led to the separation of the continental blocks of eastern Asia from eastern Gondwana, which was associated with the Early Devonian opening of the paleo–Tethys Ocean.

Utilization of metallurgical slag with presence of novel CaO-MgO-SiO2-Al2O3 as a composite sorbent for wastewater treatment contaminated by cerium

The cations of metals are the major pollutants of the lithosphere. Accumulation of cerium in natural water resources might cause serious environmental issue. Another aspect is accumulation of metallurgical slag waste. The metallurgical slag located near Chelyabinsk city in Russia was studied as a potential raw material for preparation of powder and granular calcium magnesium aluminum silicate (CaO-MgO-SiO2-Al2O3) composite sorbents capable to immobilize cerium (Ce3+) ions. Aqueous solutions with a high concentration of Ce3+ ions (1000 mg/L) were applied in sorption experiments. The migration characteristics were studied for calcium (Ca2+), magnesium (Mg2+), silicon (Si4+) and aluminum (Al3+) ions. The degree of Ce3+ ions removal for 24 h reached 93.36% for powdered and 99.98% for granular sorbents. The interaction of sorbents with sorbate was followed by the opposite transition of Ca2+ and Mg2+ ions from sorbent matrix into aqueous solution. The desorption process was investigated in distilled water. The results of study indicated a high degree of irreversible sorption of Ce3+ ions from aqueous solution observed for both powder and granular sorbents. The low price for crumbling metallurgical slag, environmental aspects of storage and high sorption capability enable recycling and use of this material as a sorbent with subsequent purification of large natural objects from Ce3+ ions.