Fibrous Cerium Research Articles

Influence of production method on the structure and photocatalytic activity of CeO<sub>2</sub>/Au nanocomposite

Two methods for preparing mesoporous CeO2/Au nanocomposites were compared: template synthesis and photochemical modification of fibrous cerium(IV) oxide with gold nanoparticles. The composition, structure, morphology of the obtained nanocomposites, as well as the specific surface area and pore size distribution were studied by a complex of physicochemical methods: X-ray phase analysis, X-ray spectral microanalysis, scanning electron microscopy, low-temperature nitrogen adsorption, and electron spectroscopy. The catalytic properties of the obtained nanocomposites were studied in methyl orange photodegradation reactions. It is shown that the CeO2/Au catalyst obtained by the photochemical modification method has the highest photocatalytic activity both under the action of UV and visible light.

Studies on Electrochemical Properties of Polycarbazole Prepared Via Self-Support Polymerization and Self-Doping

Mixed glassy zirconium-tin phosphate, g-Zr0.64.Sn.0.36(HPO4)2.3H2O(g-ZrSnP), nano fibrous cerium phosphate, Ce(HPO4)2 2,9H2O(nCePf), and mixed glassy zirconium-tin phosphate / fibrous cerium phosphate nanocomposite membrane, [g-Zr0.64 Sn0.36 (HPO4)2]0.25 [Ce(HPO4)2]0.75 ..4.43H2O, were prepared and characterized. By chemical , x-ray diffraction (XRD), thermogravimetric analysis (TGA), and Fourier transform spectroscopy (FTIR), Zirconium tin mole ratio were estimated using (EDAX). Novel [g-Zr0.64 Sn0.36 (HPO4)2]0.25 [Ce(HPO4)2]0.75 / polycarbazole nanocomposite membrane was prepared via self-support polymerization of carbazole, which was promoted by the reduction of Ce(iv) phosphate present in the inorganic matrix. Possible explanation is nCePf present on the surface of the nanocomposite is attacked by carbazole, converted to cerium (III) orthophosphate(CePO4). The resultant polycarbazole was characterized by C,H,N analysis, SEM ,FT-IR. UV-Vis and electrical conductance measurements. From elemental (C,H,N) analysis, the amount of polycarbazole present in the composite found to be (2.15 % in wt.). Polycarbazole is considered as one of modern material used in solar cells, furthermore it has become an important material for optoelectronic applications in recent years. The dc conductivity of polycarbazole nanocomposite membrane at 280C (using RC-Circuit) found to be equal to 3x10-5 Scm-1, range of semi-conductors. We suggest self-doping occurred on polymerization, which is due to H+ present in (O3POH)2 groups of [g-Zr0.64 Sn0.36 (HPO4)2]0.25. The electrochemistry of resultant polycarbazole in acetonitrile solution for a range of concentrations from 1.06 x10-4 to 2.19 x 10–3 mol dm-3 was carried out using CV techniques. Investigation of its electrochemical properties affords insight into the mechanisms for their oxidation and reduction, therefore provides the basis for evaluating the stabilities of the material and for designing novel polycarbazole-derived materials with desired properties as well as new devices. That will be discussed.

Adsorption of UO 22+ on Fibrous Cerium Phosphate and its Alanine and Arginine Intercalated Materials

Amorphous fibrous cerium (IV) phosphate (f-CeP) was prepared and characterized. Batch sorption method was performed to investigate uptake of uranyl ion (UO2)2+ aqueous solution by amorphous fibrous cerium phosphate f-CeP, using different variables in order to elucidate its applicability as a uranium sorption medium. Sorption of Uranyl ions was measured spectrophotometically after its extraction by 8-hydroxy quinoline, implementing best adsorption conditions (pH, contact time, ionic strength, amount of adsorbent, and initial uranyl ion concentration) for estimation. Exchange capacity of f-CeP was 4.25meq/g. Its x-ray powder diffraction pattern showed an amorphous material with d001 spacing value of 10.76 Å. While its amino acid intercalates showed a significant increase in the d001 to 11.33Å for f-CeP / alanine and 14.19Å for f-CeP / arginine. From spectrophotometric analysis, the results showed that the maximum uranyl ion adsorption capacity reached the initial concentration of 50ppm, pH 4.5, contact time 3hrs and adsorption dosage of 2 g/L. However, amino acid intercalates showed less adsorption efficiency than their parent analogue.

γ-Zirconium Titanium-Phosphates – Fibrous Cerium Phosphate / Polyaniline, Polyindole, Polycarbazole and Polyimidazole Nanocomposite Membranes

Layered nanosized mixed γ-zirconium titanium phosphates and fibrous cerium phosphate, γ-ZrxTi(1-x)..PO4.H2PO4.2H2O (γ-ZTP), Ce(HPO4)2.2.9H2O(nCePf), respectively, (x= 0.95, 0.89), and their [γ-ZrxTi(1-x).PO4. H2PO4]0.3 [Ce(HPO4)2]0.70. 2H2O nanocomposite membranes were prepared and characterized by chemical, x-ray diffraction (XRD), thermogravimetric analysis (TGA) and Fourier transform spectroscopy (FT-IR). Novel [γ-ZrxTi(1-x).PO4.H2PO4]0.3[Ce(HPO4)2]0.70 /polyaniline, polyindole, polycarbazole, and polyimidazole nanocomposite membranes were prepared via in-situ chemical oxidation of the monomers aniline, indole, carbazole and imidazole, respectively, that was promoted by the reduction of Ce(IV) ions present on the surface of the inorganic matrix composite. A possible explanation is nCePf occurs at the surface of the composite was attacked by the monomers, respectively, converted to cerium (III) orthophosphate (CePO4). The resultant novel composites were characterized by elemental (C,H,N) analysis and FT-IR. From elemental (C,H,N) analysis the % in weight of the resultant conducting polymers present in [γ-Zr0.95Ti0.05.PO4.H2PO4]0.3 [Ce(HPO4)2]0.70 composite were [ Pani 19.35, PIn 5,72. PCz 5.8, PIm 23.7]%. The % in weight of the conducting polymers in the composite [γ-Zr0.9Ti0.11.PO4.H2PO4]0.3[[Ce(HPO4)2]0.70 were [Pani 8.54, PIn 8.02, PCz 7.72, PIm 22.27]%. The conductivity of the resultant conducting polymers found to be in the range of semiconductors.

A New Method for Removing and Binding Th(IV) and Other Radionuclides by In Situ Formation of a Sorbent Based on Fibrous Cerium(IV) Hydrogen Phosphate in Liquid Media

A novel method was suggested for removing Th(IV) and other radionuclides from liquid media. The method consists in formation of the sorbent, fibrous cerium(IV) hydrogen phosphate, directly in the aqueous solution. The sorbent shows the highest performance in the removal of Th(IV). The sorbent can also serve as a host material for the subsequent Th(IV) disposal.

Zirconium Phosphate/Fibrous Cerium Phosphate Nanocomposite Membrane Self Supported Benzimidazole, Its Co-Aniline, Co-Pyrrole and Co-Indole Polymerization Agent

Nanosized zirconium phosphate and nano fibrous cerium phosphate , Zr(HPO4)2.H2O(nZrP) , Ce(HPO4)2.2.9H2O (nCePf), respectively, were prepared and characterized.  Mixing slurry aqueous solution of (nZrP and nCePf ) in 25:75 wt/wt% mixing ratios) , respectively, lead to formation of novel zirconium phosphate- fibrous cerium phosphate nanocomposite membrane, [Zr(HPO4)2]0.25[Ce(HPO4)2]0.75.3.87H2O(nZrP-nCePf), was characterized. Zirconium phosphate-fibrous cerium phosphate/ polybenzimidazole-/polybenzimidazolee-co-polyaniline-/polybenzimidazole-co-polypyrrole-/polybenzimidazole-co-polyindole nanocomposite membranes were prepared via in-situ chemical oxidation polymerization of the benzimidazole, and its co-monomers in alcohol, that was promoted by the reduction of Ce(iv) ions present in the inorganic matrix of (nZrP-nCePf ) nanocomposite membrane. A possible explanation is  nCePf  , present on the surface of composite membrane, is attacked by benzimidazole and its co-monomers , converted to cerium(III) orthophosphate(CePO4). The resultant materials were characterized by elemental (C,H,N) analysis , FT-IR, and scanning electron microscopy(SEM) .. SEM images of the resulting nanocomposites reveal a uniform distribution of the polybenzimidazole and its co-polymers on the inorganic matrix. From elemental (C,H,N) analysis the amount of organic material (PBI) present in (nZrP-nCePf)/PBI composite found to be = 5.7% in wt.. T.he amount of organic materials present in copolymers found to be for (nZrP-nCePf)/PBI-co-PANI (PBI = 9.33%, PANI= 13.32% in wt)., for  (nZrP-nCePf) /PBI -co-PPy (PBI = 12.85%, PPy = 7.1% in wt) , and for (nZrP-nCePf) /PBI-co-PIn ( PBI = 16.47% , PIn = 8.81% in wt).

Nano Fibrous Cerium(IV) Hydrogen Phosphate Membrane Self Supported Indole Polymerization Agent

Nano Fibrous Cerium(IV) Hydrogen Phosphate Membrane Self Supported Indole Polymerization Agent

Fibrous Cerium (IV) Hydrogen Phosphate Membrane Self-Supported Benzimidazole Polymerization Agent

Nanosized fibrous cerium phosphates, Ce (HPO4)2.2.9H2O (nCePf), wa prepared. was characterized by chemical , XRD, TGA analysis, Scanning electron microscope (SEM) and transmission electron microscope (TEM). Novel supported polybenzimidazole/ fibrous cerium phosphate nanocomposite membrane was prepared via in-situ chemical oxidation of the monomer that was promoted by the reduction of Ce (iv) ions present in the inorganic matrix. The presence of Ce (iv) ions allows redox reactions necessary to oxidative polymerization to occur. The resultant material was characterized by XRD, TGA, elemental (C,H,N) analysis and by FT-IR spectroscopy. Image SEM of the resulting nanocomposite reveals a uniform distribution of the polymer on the inorganic matrix }. Amount of polymer present in the composites found to be 11%.

Fibrous Cerium (IV) Acid Phosphates Host of Weak and Strong Lewis Bases

In this paper, we evaluated the behavior of fibrous cerium (IV) acid phosphate (CeP) in insertion procedures involving a strong Lewis base (ethylamine) and a weak one (ɛ-caprolactam). In the former case, the procedure was performed by exposing a sample of CeP to a saturated amine atmosphere. Insertion was shown to be independent of the crystallinity of CeP, and the products showed strong host–guest interactions of the Coulombic type. Conversely, ɛ-caprolactam insertion was achieved by immersing CeP samples into its fused form. This process was dependent on the crystallinity of the inorganic solid, and host–guest interactions were characterized as involving hydrogen bonds.

Preparation and Characterization of Fibrous Cerium Oxide Templated from Activated Carbon Fibers

AbstractHigh surface area cerium oxide has been prepared using a carbon templating method. Impregnation of a highly mesoporous activated carbon (Darco KB-B) with an aqueous solution of cerium nitrate, followed by carbon burn off, afforded ceria with surface area of up to 148 m2/g. According to thermogravimetric studies, ceria formation proceeds via decomposition of cerium nitrate at ca. 410 K; oxidation of the carbon template commences at the same temperature, being facilitated by the release of NO2 from the Ce compound. Use of activated carbon fibers (ACFs) as template was found to provide a simple route to fibrous cerium oxide. The lower surface areas (3 - 59 m2/g) of the resulting ceria fibers reflect the largely microporous nature of the ACFs; evidently the Ce nitrate solution is unable to penetrate their micropores. Consequently, the surface area of the ceria product is found to increase with increasing mesoporosity of the ACF template. Electron microscopy reveals that the ceria fibers are composed of highly crystalline primary particles of 5-10 nm diameter; further, the fibers display a number of interesting morphological features at the macro- and nano-scales.

Preparation of the conducting nanocomposites using molded inorganic matrix: fibrous cerium(iv) hydrogenphosphate as a self-supported pyrrole polymerization agent

New supported polypyrrole nanocomposites have been prepared and studied in this work. Self-supported sheets of fibrous cerium(IV) hydrogenphosphate (CePf) were used as the inorganic matrix, since the fibrous morphology presented by this material makes molding possible, giving a desired shape to the final polypyrrole/CePf conducting nanocomposites. The influence of pyrrole concentration on the nanocomposite preparation was studied, as well as the influence of CePf on the polypyrrole characteristics. XRD, Raman, SEM and conductivity measurement data show the conducting polypyrrole coating CePf fibers, yielding self-supported sheets of organic–inorganic conducting nanocomposites.

SORPTION OF TRIVALENT METAL ION ON FIBROUS CERIUM(IV) HYDROGENPHOSPHATE

ABSTRACT Thermodynamics of trivalent metal ions/hydrogen ions exchange on a fibrous cerium(IV) hydrogenphosphate have been investigated by the micro-amount uptake. Selectivities for trivalent metal ions increase in the order; La3+ <Y3+ <Eu3+ <<Sc3+. The standard enthalpy change and entropy change of the ion exchange reaction increase in the order of Eu3+ <La3+ <Y3+ <Sc3+ and Eu3+ < Sc3+ <La3+ <Y3+, respectively. An enthalpy - entropy compensation relation holds except for Sc3+ ion. X-ray diffractometry and thermal analyses were also conducted the ion-exchanger phase for the macro-amount uptake. The maximal interlayer spacings were observed around the metal loading of 0.5mmol/g and the weight loss for the adsorbed and interlayer water at the low metal loading increased in the order; Sc3+ <La3+ <Eu3+ <Y3+. In the case of scandium ion, the formation of insoluble scandium phosphate was confirmed by the DTA peak at 255°C and characteristic peaks to Sc(PO4) - 2H2O in the XRD pattern.

Strontium Immobilization by Fibrous Cerium(IV) Bis(monohydrogenphosphate) under Hydrothermal Conditions

Abstract The uptake of strontium ions from an aqueous solution by fibrous cerium(IV) bis(monohydrogenphosphate) has been studied from the viewpoints of the immobilization of strontium in radioactive waste by a batchwise operation in the temperature range from 25 to 250 °C. Strontium ions can be exchanged below 100 °C following an ion-exchange reaction between hydrogen ions of the phosphate groups. In contrast, strontium ions can be effectively immobilized under hydrothermal conditions accompanied by a structural change of the exchanger, where divalent strontium ions are incorporated into the monazite-like compound to compensate tetravalent cerium ions in trivalent cerium orthophosphate system. This phenomenon is peculiar to alkaline earth metal ions, since the monazite-like compounds were obtained in the presence of Ca2+ and Ba2+, while this phenomenon was absent in the presence of Cu2+ or Ni2+.

Preparation of Alkylamine Intercalated Fibrous Cerium Hydrogenphosphate Complexes and Their Cobalt Ion Adsorption Properties under Hydrothermal Conditions

Preparation of Alkylamine Intercalated Fibrous Cerium Hydrogenphosphate Complexes and Their Cobalt Ion Adsorption Properties under Hydrothermal Conditions

Hydrothermal treatment and strontium ion sorption properties of fibrous cerium(IV) hydrogenphosphate

Fibrous cerium hydrogenphosphate, CeP, has been treated hydrothermally in 1 mol dm -3 phosphoric acid solution. CEP and its hydrothermally treated product, CeP(HT), have been characterized by X-ray powder diffractometry, scanning electron microscopy, solid-state 31 P MAS NMR spectroscopy, FTIR spectroscopy, chemical and thermal analyses. A poorly crystalline fibrous CeP with a d-spacing of 1.1 nm converted into a highly crystalline CeP(HT) with platelet morphology by hydrothermal treatment. Solid-state 31 P MAS NMR and FTIR measurements confirmed that one kind of phosphate (H 2 PO 4 ) is present in CeP and two kinds of phosphate (HPO 4 , PO 4 ) are present in CeP(HT), in which the integrated intensity ratio of HPO 4 to PO 4 is 2:1. From chemical and thermal analyses, structural formulae for CeP and CeP(HT) are assumed to be CeO(H 2 PO 4 ) 2 2H 2 O and Ce(HPO 4 ) (PO 4 ) 0.5 (OH) 0.5 , respectively. The Na + exchange capacity of CeP amounted to 4.5 mmol g -1 at pH 11 while that of CeP(HT) was less than 1.0 mmol g -1 in the pH range 2–12. The pH dependence of the metal ion distribution coefficients exhibited ideal ion-exchange behaviour on CeP while metal ion distribution coefficients on CeP(HT) scarcely depended on pH. The metal ion selectivities of CeP and CeP(HT) increased in the order: Na + <Ca 2+ <Sr 2+ <K + , and Na + <K + <Ca 2+ <Sr 2+ , respectively. The distribution coefficient for the Sr 2+ ion of CeP(HT) was higher than that of CeP under hydrothermal conditions.

THERMODYNAMICS OF ALKALI AND ALKALINE EARTH METAL ION - EXCHANGE ON CERIUM(IV) HYDROGEN PHOSPHATE

ABSTRACT Thermodynamics of alkali and alkaline earth metal ions/hydrogen ions exchange on a fibrous cerium(IV) hydrogen phosphate have been investigated. Selectivities for alkali and alkaline earth metal ions increase in the order; Na+<<K+<Rb+<Cs+ and Mg2+<Ca2+<Sr2+<Ba2+, respectively. The enthalpy changes for alkali metal and Ba2+ ions/H+ exchange are negative, those for the other alkaline earth metal ions/H+ exchange are positive, indicating that the enthalpy changes for monovalent ions are more favorable than those for divalent ions. In comparison with ions of the same valency, the enthalpy change decreases with the atomic number of the metal ion corresponding to a decrease in the entropy change of dehydration in response to enthalpy-entropy compensation.

Ionic conductivity in fibrous Ce(HPO 4) 2·(3+ x)H 2O

The ac conductivity of fibrous cerium phosphates Ce(HPO 4) 2·(3+ x)H 2O has been studied by the complex impedance method as a function of temperature and water pressure. Adsorption isotherms show that some water molecules are physically adsorbed at the surface of the fibers. Conductivity increases with this water content and follows an Arrhenius law σ(T)=σ 0 exp (− E a kT ) . Both the preexponential factor σ 0 and the activation energy E a depend on the water stoichiometry in such a way that the fibrous cerium phosphate can be considered as a “particle hydrate”.

Surface properties of fibrous cerium (IV) and thorium (IV) phosphates

The evolution of some properties of cerium (IV) phosphate and thorium (IV) phosphate with temperature (range 110°C–600°C) has been studied. The original samples as well as the thermally actived ones were characterized by TG, DSC, IR spectroscopy and X-ray diffraction. Surface properties (surface area accessible to N 2 at 77.4 K, acid surface centers and porosity) are also studied. Isosteric heats and differential entropies of the adsorption processes, for the samples dried at 110°C, were calculated from the N 2 adsorption istherms at 77.4 K and 90.1 K.

On the retention of n‐butylamine by crystalline and fibrous cerium(IV) phosphate

AbstractThe retention of n‐butylamine dissolved in cyclohexane on both crystalline and fibrous cerium(IV) hydrogen phosphate has been studied. The products involved were characterized by thermogravimetry, derivative thermogravimetry, differential scanning calorimetry, IR spectroscopy and X‐ray diffraction. The experimental results obtained reveal that the adsorption of n‐butylamine from cyclohexane solutions results in a net increase in the lattice space of the crystalline variety of the phosphate. Integral enthalpies and entropies, isosteric heats and differential entropies of retention were calculated from the adsorption isotherms run at 10, 15, 20, 25 and 30°C. The results show that variation of the different thermodynamic parameters with the degree of coverage for the two types of phosphate to be rather different.

Crystalline insoluble acid salts of tetravalent metals : XXIV. Ion-exchange behaviour of fibrous cerium(IV) phosphate

Titration curves of fibrous cerium(IV) phosphate with alkali and alkaline earth metal ions show that the ion-exchange processes occur without phase transition. The exchanger displays a wide range of acidities like an amorphous or semi-crystalline material. About 30% of exchangeable protons are much more acidic than the others. In these sites, the exchanger prefers counter ions that have a large ionic radius, while several inversions occur at high metal ion loadings. Furthermore, the shapes of the Na +/K + and Na +/Cs + isotherms also indicate that there are about 30% of sites where the counter ions that have the largest ionic radius are preferred. Separations factors and K d values for various cations at different concentrations have been determined and a marked selectivity for Pb 2+, Ba 2+, Ag + and Tl + has been found. The selectivity for Pb 2+ was investigated for the full range of composition of the exchanger and the H +/Pb 2+ isotherm was obtained. The unusual selectivity of fibrous cerium(IV) phosphate for certain cations should lead to some useful practical applications. The batch analytical separation of Ca 2+Pb 2+ at low pH values has shown that Pb 2+ is selectively exchanged also in presence of large amounts of Ca 2+.