The dominant oxidation state for lanthanide ions is+3 due to the loss of 5d and 6s electrons from their shared configuration of[Xe]4f^(0-14)5d^(0-16)s(2).There are however several exceptions because of the completely ...The dominant oxidation state for lanthanide ions is+3 due to the loss of 5d and 6s electrons from their shared configuration of[Xe]4f^(0-14)5d^(0-16)s(2).There are however several exceptions because of the completely empty(Ce(Ⅳ)),half-filled(Eu(Ⅱ)),or fully filled(Yb(Ⅱ))4f subshell.As such,stable complexes are formed primarily with Ln(Ⅲ)ions[1].展开更多
This paper investigated the antibacterial mechanism of the Ag-Pr-antibacterial white carbon black.The sol-gel method was used to prepare the carrier:white carbon black.Silver ion was selected to be the antibacterial i...This paper investigated the antibacterial mechanism of the Ag-Pr-antibacterial white carbon black.The sol-gel method was used to prepare the carrier:white carbon black.Silver ion was selected to be the antibacterial ion,and praseodymium nitrate was selected to be the additive.The structure and antibacterial mechanism of this new inorganic antibacterial material were characterized by laser particle size analyzer,scanning electron microscope(SEM) techniques,energy dispersive spectrum(EDS) analysis,and antibacterial activity test(Escherichia coli as experimental bacterium).Results showed that the particle size of Ag-Pr-antibacterial White carbon black was less than 30 μm with a narrow size distribution.Ag+ is combined into the white carbon black by both the mode of ion exchange and the mode of adsorption process.The bacteriostasis rate of the Ag-Pr-antibacterial white carbon black was higher than that of the general Ag-antibacterial white carbon black.The antibacterial activity of Ag-Pr-antibacterial white carbon black was caused by the combination of contact and stripping antibacterial mechanism.The result also indicated that this new inorganic antibacterial material had good thermal and light stability.展开更多
The solvent extraction of Pr(Ⅲ) and Sm(Ⅲ) with trialkyl phosphine oxide(Cyanex 923) in chloroform,carbon tetrachloride,n-octane,cyclohexane,1,2-dichloroethane,benzene,toluene,xylene and nitrobenzene from acidic nitr...The solvent extraction of Pr(Ⅲ) and Sm(Ⅲ) with trialkyl phosphine oxide(Cyanex 923) in chloroform,carbon tetrachloride,n-octane,cyclohexane,1,2-dichloroethane,benzene,toluene,xylene and nitrobenzene from acidic nitrate medium was investigated.On the basis of slope analysis data,the composition of the extracted species was determined as(M(NO3)3?2CY923),CY923 refers to Cyanex 923.The values of the equilibrium constants and the separation factors were calculated.The effect of the diluents on the metal extracti...展开更多
A new approach was suggested in present work for improving the separation between Pr(Ⅲ) and Nd(Ⅲ)by a so-called kinetic "push and pull" system consisting of [A336][NO3] and DTPA in a column extractor.It is...A new approach was suggested in present work for improving the separation between Pr(Ⅲ) and Nd(Ⅲ)by a so-called kinetic "push and pull" system consisting of [A336][NO3] and DTPA in a column extractor.It is revealed that,when organic extractant [A336][NO3] is continuously pumped into the column extractor in the form of dispersed oil droplets and at the same time DTPA was injected into the aqueous feed solution whet the extraction was just started,the separatiot factor of Pr(Ⅲ) to Nd(Ⅲ),βPr/Nd,increased obviously with the time,and could even achieve 21.7.Such an amazing increase in βPr/Nd value might be due to the extraction rate of Pr(Ⅲ) by [A336][NO3] oil droplets being faster than that of Nd(Ⅲ),while the complexing rate of Nd(Ⅲ) with DTPA in the aqueous solutions being faster than that of Pr(III).The opposite order of the two rates for Pr(Ⅲ) and Nd(Ⅲ) result in their kinetic "push and pull" separation.In contrast,the βPr/Nd value in traditional thermodynamic separation reported in previous literatures is only around 5 or even less,even though using the same extractant [A336][NO3] and DTPA but by previously adding DTPA into the aqueous feed solutions for pre-complexing of Pr(Ⅲ) and Nd(Ⅲ).Various effects from the pH and addition amount of DTPA aqueous solutions,LiNO3 concentrations in initial aqueous feed solutions,the initial concentration ratios of Pr(Ⅲ) to Nd(Ⅲ) ions,the initial pH of aqueous feed solutions,and the concentrations of [A336][NO3] in organic phases,on the kinetic separatiot of Pr(Ⅲ) and Nd(Ⅲ) are discussed.The present work highlights a promising approach for separation of rare earths or other targets with extreme similarity in physicochemical properties.展开更多
We introduced a new catalyst,rare earth element praseodymium,for the catalytic graphitization of furan resin carbon.The extent of graphitization of the furan resin carbon was examined by X-ray diffraction and Raman sp...We introduced a new catalyst,rare earth element praseodymium,for the catalytic graphitization of furan resin carbon.The extent of graphitization of the furan resin carbon was examined by X-ray diffraction and Raman spectroscopy.The morphology of furan resin carbon was characterized by scanning electron microscopy.The effects of the praseodymium content and the heat-treatment temperature on the catalytic graphitization of furan resin carbon were also investigated.The results indicated that the praseodymium c...展开更多
A series of praseodymium added CeO2（ZrO2）/TiO2 catalysts separately prepared by methods of sol-gel and impregnation were tested for selective catalytic reduction of NO, and characterized by X-ray diffraction （XRD）...A series of praseodymium added CeO2（ZrO2）/TiO2 catalysts separately prepared by methods of sol-gel and impregnation were tested for selective catalytic reduction of NO, and characterized by X-ray diffraction （XRD）, N2-brumauer-emmett-teller （N2-BET）, NH3-temperature programmed desorption （NH3-TPD）, H2-temperature programmed reduction （H2-TPR）, PL spectra, Ra-man spectra, electron paramagnetic resonance （EPR） and X-ray photoelectron spectroscopy （XPS）, respectively. Influence of prepara-tion method on catalytic performance was studied. Results showed that the influence of Pr addition on catalytic performance of the CeO2（ZrO2）/TiO2 catalysts was different between the sol-gel method and the impregnation method. The Pr addition tended to interact with TiO2 and formed the structure of Ti-O-Pr in the sol-gel method while it was more likely to interact with CeO2 forming the struc-ture of Ce-O-Pr in the impregnation method. The total acid amount and redox properties of the catalysts prepared by sol-gel method decreased with the addition of Pr element, which resulted in decrease of catalytic activity. In contrast, the Pr-added catalyst prepared by impregnation method was found to possess easier reducibility, more total acid amount and higher proportion of Ce3＋ species, which was favourable for higher catalytic activity.展开更多
Engineering of chitosan by praseodymium has been investigated to improve the adsorption properties as well as physical characteristics of chitosan. Modification of chitosan changes the original properties of chitosan ...Engineering of chitosan by praseodymium has been investigated to improve the adsorption properties as well as physical characteristics of chitosan. Modification of chitosan changes the original properties of chitosan so that it can be more suitable for adsorption of fluoride ions. In this study, chitosan-praseodymium （Chi-Pr） was synthesized by impregnation method. The Chi-Pr complex was characterized by scanning electron microscopic-energy dispersive X-ray spectroscopy （SEM-EDX）, Fourier transform infrared （FTIR） and employed as an adsorbent for removal of fluorides ions from water in the batch system. The variables such as contact time, concentration of Pr, adsorbent dose, initial concentration of fluoride ions, and competitor anions were studied. The adsorption efficiency of fluoride ions （n） with increasing Pr loading into chitosan （5 wt.%, 10 wt.%, 15 wt.%, 20 wt.% and 25 wt.%） were 35.5%, 56.1%, 72.0%, 68.5% and 62.5%, respectively. The Chi-Pr （15 wt.%） complex had the highest fluoride removal efficiency （72.0%）. The experimental data fitted well to the Langmuir isotherm with maximum adsorption capacity （qmax） of 15.87 mg/g and an equilibrium constant （kL） of 0.15 mg. Kinetic study revealed that the adsorption of fluoride ions from water followed pseudo-second-order model with a maximum adsorption capacity （q2） of 8.20 mg/g and a rate constant （k2） of 0.01 g/mg.min. Adsorption efficiency of fluoride ions in the simulated drinking water was diminished with the changes in pH levels. The presence of Pr3＋ in chitosan increased chitosan＇s performance as an adsorbent for adsorption of fluoride ions.展开更多
<正>The influence of Yb_2O_3 and Pr_2O_3 doping on electrical and gas sensing properties of tin dioxide was studied.A doping content of 0.5wt%～5wt% was investigated by mechanical mixing.The significant improvem...<正>The influence of Yb_2O_3 and Pr_2O_3 doping on electrical and gas sensing properties of tin dioxide was studied.A doping content of 0.5wt%～5wt% was investigated by mechanical mixing.The significant improvement on sensitivity and selectivity to 200μg/g hydrogen sulphide gas has been achieved by 3wt% Pr_2O_3 and 5wt% Yb_2O_3 adding.The better response and revovery properties of Pr or Yb doped tin dioxide sensor for 200μg/g hydrogen sulphide gas were found.The maximum sensitivity to H_2S gas is observed at about 120℃.Pr has stronger catalysis than Yb for H_2S reaction on SnO_2 surface.S~ 2-) was oxidized to S~ 6+) on the SnO_2 surface according to XPS.展开更多
Sulfation treatment has been widely used to promote the catalytic performance of ceria(CeO_(2))based catalysts for the selective catalytic reduction of NO by NH_(3)(NH_(3)-SCR of NO).Praseodymium oxide(PrO_(x)),anothe...Sulfation treatment has been widely used to promote the catalytic performance of ceria(CeO_(2))based catalysts for the selective catalytic reduction of NO by NH_(3)(NH_(3)-SCR of NO).Praseodymium oxide(PrO_(x)),another commonly used rare earth material with similar structural properties as CeO_(2),also shows satistactory redox properties due to the facile redox cycle of Pr^(3+)■Pr^(4+).In this work,gas phase sulfation treatment with varied duration was performed on PrO_(x) at 200℃,and the NH_(3)-SCR activity of sulfated PrO_(x) was evaluated.Based on the results of systematic characterizations(e.g.,N_(2)-physisorption,NH_(3) oxidation,NO oxidation,in situ diffuse Fourier transform infrared spectroscopy),it is revealed that the catalytic performance of sulfated PrO_(x)is highly dependent on the sulfation time(or the amount of sulfate species deposited on PrO_(x)),which has a significant impact on the competitive reaction between NH_(3) oxidation and NH_(3)-SCR of NO,thus determining the NH_(3)-SCR activity of PrO_(x).This work provides new insight into tuning the interaction between PrO_(x) surface and reactants(NO,NH_(3))via sulfation treatment,which cam guide the design and application of PrO_(x)based catalysts for NH_(3)-SCR of NO in the future.展开更多
The crystal structures, electronic structures and optical properties of nitrogen or/and praseodymium doped anatase TiO2 were calculated by first principles with the plane-wave ultrasoft pseudopotential method based on...The crystal structures, electronic structures and optical properties of nitrogen or/and praseodymium doped anatase TiO2 were calculated by first principles with the plane-wave ultrasoft pseudopotential method based on density functional theory. Highly efficient visible-light-induced nitrogen or/and praseodymium doped anatase TiO2 nanocrystal photocatalyst were synthesized by a microwave chemical method. The calculated results show that the photocatalytic activity of TiO2 can be enhanced by N doping or Pr doping, and can be further enhanced by N＋Pr codoping. The band gap change of the codoping TiO2 is more obvious than that of the single ion doping, which results in the red shift of the optical absorption edges. The results are of great significance for the understanding and further development of visible-light response high activity modified TiO2 photocatalyst. The photocatalytic activity of the samples for methyl blue degradation was investigated under the irradiation of fluorescent light. The experimental results show that the codoping TiO2 photocatalytic activity is obviously higher than that of the single ion doping. The experimental results accord with the calculated results.展开更多
Luminescent properties of Y2O3 and LaAlO3 nanopowders doped with Pr^3＋ ions and PMMA-based composite materials doped with these powders were reported. The set of active nanopowders differing in praseodymium ions conc...Luminescent properties of Y2O3 and LaAlO3 nanopowders doped with Pr^3＋ ions and PMMA-based composite materials doped with these powders were reported. The set of active nanopowders differing in praseodymium ions concentration was prepared using sol-gel method and carefully characterized with respect to emission properties in the visible spectral range. In particular, the excitation and emission spectra were measured together with fluorescence decay profiles and the differences between optical properties of these materials were discussed and compared with data available for bulk materials. Finally, the PMMA-based composite materials doped with Pr^3＋：Y2O3 and Pr^3＋：LaAlO3 nanopowders were manufactured and characterized. The obtained results showed that polymer composites doped with active nanopowders in general tended to keep the luminescent properties of the original nanopowders.展开更多
Reaction of Na2CO3, Pr6O11 and H3PO4 gave the sodium praseodymium polyphosphate NaPr（PO3）4.The title compound crystallized in the monoclinic P21/n space group with a=0.9965（4） nm, b=1.31437（4） nm, c=0.72271（3）...Reaction of Na2CO3, Pr6O11 and H3PO4 gave the sodium praseodymium polyphosphate NaPr（PO3）4.The title compound crystallized in the monoclinic P21/n space group with a=0.9965（4） nm, b=1.31437（4） nm, c=0.72271（3） nm, β=90.429（3）°, V=0.9465（4） nm3, Z=4, R=0.0493 and wR=0.1266 for 1855 independent reflections.The structure of NaPr（PO3）4 consisted of PrO8 polyhedra sharing oxygen atoms with phosphoric group PO4 to form a three-dimensional framework, delimiting intersecting tunnels in which the sodium ion was located.Each Na＋ ion was bonded to seven oxygen atoms.展开更多
The effects of lanthanum-praseodymium-cerium mischmetal （LPC） on the microstructure and mechanical properties of Mg-Al alloy were investigated. With the addition of LPC, an additional rod-like Al11La3 phase was depo...The effects of lanthanum-praseodymium-cerium mischmetal （LPC） on the microstructure and mechanical properties of Mg-Al alloy were investigated. With the addition of LPC, an additional rod-like Al11La3 phase was deposited in the alloy. LPC greatly improves the tensile strength of cast Mg-Al alloys but negatively affects the elongation of cast alloys above 473 K. Cast alloys are strengthened by both precipitation strengthening and dispersion strengthening at ambient temperature. When the temperature exceeds 473 K, only the dispersion operates as a strengthening mechanism.展开更多
The electrochemical behaviour of Pr(III) on iron electrode in molten PrCl3-KCl-NaCl was studied by means of cyclic voltammetry and potential-time curve method. The results show that the reduction of Pr(III) to Pr on t...The electrochemical behaviour of Pr(III) on iron electrode in molten PrCl3-KCl-NaCl was studied by means of cyclic voltammetry and potential-time curve method. The results show that the reduction of Pr(III) to Pr on the iron electrode proceeds reversibly in one step and forms Pr-Fe alloys. The Pr-Fe alloys are obtained by molten salt electrolysis with molten KCl-NaCl as electrolyte and PrCl3 as raw materials. The composition of electrolytic product is PrFe2 and Pr analysed by X-ray diffraction. Pr recovery efficiency is 90% and the current efficiency is 85%.展开更多
Two new coordination complexes, [Pr（1,3-pda）0.5（nbca）2（H2O）2]（1） and [Pr2（1,3-pda）3（2,2ˊ-bpy）2（H2O）2]（2）（H2pda = 1,3-phenylenediacetic acid, Hnbca = 5-nitro [1,1ˊ-biphenyl]-3-carboxylic acid, 2,2ˊ-...Two new coordination complexes, [Pr（1,3-pda）0.5（nbca）2（H2O）2]（1） and [Pr2（1,3-pda）3（2,2ˊ-bpy）2（H2O）2]（2）（H2pda = 1,3-phenylenediacetic acid, Hnbca = 5-nitro [1,1ˊ-biphenyl]-3-carboxylic acid, 2,2ˊ-bpy = 2,2ˊ-bipyridine）, have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectra, and single-crystal X-ray diffraction. In 1, the nbca ligands bridge the Pr3＋ ions to form a 1D chain. Moreover, these 1D chains are united together through the 1,3-pda ligands to afford a 2D layer. In contrast, due to a different auxiliary ligand, complex 2 is a 2D layer linked through only bridging deprotonated 1,3-pda. Thermal stabilities and solid fluorescence properties of 1 and 2 were also studied.展开更多
The kinetics and the difference for Pr(Ⅲ)and Nd(Ⅲ)extraction from nitrate aqueous solution using trialkylmethylammonium nitrate([A336][NO3])as extractant were investigated by the single drop technique.The dependence...The kinetics and the difference for Pr(Ⅲ)and Nd(Ⅲ)extraction from nitrate aqueous solution using trialkylmethylammonium nitrate([A336][NO3])as extractant were investigated by the single drop technique.The dependence of the extraction rate of Pr(Ⅲ)and Nd(Ⅲ)on the concentrations of free Pr(Ⅲ)and Nd(Ⅲ)ions,the concentrations of Na NO3 and H+in aqueous solutions,and the concentrations of[A336][NO3]in kerosene solutions were discussed and the corresponding extraction rate equations for Pr(Ⅲ)and Nd(Ⅲ)were obtained.These equations demonstrated that the reaction rate constant of Pr(Ⅲ)with[A336][NO3]was double than that of Nd(Ⅲ).The effect of the addition of diethylenetriaminepentaacetic acid(DTPA)on the difference in the extraction rate of Pr(Ⅲ)and Nd(Ⅲ)by[A336][NO3]was also investigated.It was revealed that the difference in the complex formation rates of Pr(Ⅲ)and Nd(Ⅲ)with DTPA made a significant impact on the difference in the extraction rates of Pr(Ⅲ)and Nd(Ⅲ)with[A336][NO3].The ratio of extraction rates of Pr(Ⅲ)to Nd(Ⅲ)with[A336][NO3]was in proportion to the ratio of complex formation rates of Pr(Ⅲ)to Nd(Ⅲ)with DTPA.The extraction rate difference for Pr(Ⅲ)and Nd(Ⅲ)with[A336][NO3]increased due to a higher complex formation rate constant of DTPA with the free and un-complexed Nd(Ⅲ)ions in the aqueous nitrate solution than that with Pr(Ⅲ)ions.Therefore,the addition of DTPA in the aqueous nitrate solution is an effective method to intensify the separation of Pr(Ⅲ)and Nd(Ⅲ)in kinetics.The study on the extraction mechanism indicated that both the extraction of Pr(Ⅲ)and Nd(Ⅲ)by[A336][NO3]were diffusion controlled,and the reactions obeyed SN2 mechanism.The present work highlights a possible approach to strengthen the kinetic separation of Pr(Ⅲ)and Nd(Ⅲ).展开更多
The synergistic extraction of Pr^3＋ from hydrochloric medium using mixture of 2-ethylhexyl phosphonic acid mono- 2-ethylhexyl ester （P507, HL） and 8-Hydroxyquinoline （HQ） in heptane was investigated. The effect o...The synergistic extraction of Pr^3＋ from hydrochloric medium using mixture of 2-ethylhexyl phosphonic acid mono- 2-ethylhexyl ester （P507, HL） and 8-Hydroxyquinoline （HQ） in heptane was investigated. The effect of equilibrium of aqueous acidity on extraction of Pr^3＋ was discussed. The effect of extractant concentraction, different diluents, equilibrium time and acetate ion concentration oil extraction reaction were also studied. With a method of double-logarithmic slope, composition of the extracted species on 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester and 8-Hydroxyquinoline was derived. The result shows that the synergistic extraction system not only overcomes emulsification of 8-Hydroxyquinoline, but also shows perfect capacity of synergistic extraction. The largest synergistic enhancement factor can be calculated to be 5.49 at pH 3.6 for Pr^3＋.展开更多
A Pr-doped TiO2-NTs/SnO2-Sb electrode was prepared by a simple method, cyclic voltarnmetry （CV）. The methyl orange （MO）aqueous solution was selected as a simulated wastewater. The ordered microstructural TiO2-NTs ...A Pr-doped TiO2-NTs/SnO2-Sb electrode was prepared by a simple method, cyclic voltarnmetry （CV）. The methyl orange （MO）aqueous solution was selected as a simulated wastewater. The ordered microstructural TiO2-NTs substrate was synthesized by an electrochemical method to obtain large specific surface area and high space utilization. The phase structure, electrode surface morphology and electrochemical properties of electrodes were characterized by XRD, SEM and electrochemical technology, respectively. The results showed that praseo- dymium oxide was successfully doped into the SnOz-Sb film by CV method. Due to the doped Pr, the oxygen evo- lution potential increased from 2.25 V to 2.40 V. The degradation of MO was investigated by UV-vis. The Ct/C0（φ） was studied as a function to obtain the optimal parameters, such as the amount of doped Pr, current density and initial dye concentration. In addition, the degradation process followed pseudo-first-order reaction kinetics and the rate constant was 0.099 3 min-1. The result indicated that the introduction of Pr reduced the formation of oxygen vacancies or enhanced the formation of adsorbed hydroxyl radical groups on the surface, thus leading to better activity and stability.展开更多
Oxygen storage and adsorptive properties of praseodymium oxides were investigated by pulse experiments and temperature - programmed desportion/reduction (TPD/TPR) experiments. Pr2O3 possesses the similar oxygen storag...Oxygen storage and adsorptive properties of praseodymium oxides were investigated by pulse experiments and temperature - programmed desportion/reduction (TPD/TPR) experiments. Pr2O3 possesses the similar oxygen storage properties to CeO2, and its dynamic oxygen storage capacity is 14.9 mumol.g(-1). The studies on TPD Of O-2, H2O and CO and TPR show that Pr2O3 provides more active surface oxygen species and at a lower temperature than CeO2. It is suggested that Pr2O3 can be a well candidate as an oxygen storage component in automobile three-way catalyst.展开更多
The new lanthanum (Ⅲ) and praseodymium (Ⅲ) complexes of the general formula [Ln(L)3] (Ln=La(Ⅲ) or Pr(Ⅲ); LK=potassium salt of dithiocarbazinates) were prepared by both, conventional thermal and by the use of micro...The new lanthanum (Ⅲ) and praseodymium (Ⅲ) complexes of the general formula [Ln(L)3] (Ln=La(Ⅲ) or Pr(Ⅲ); LK=potassium salt of dithiocarbazinates) were prepared by both, conventional thermal and by the use of microwave technology. Elemental analyses, electrical conductance, magnetic moment and electronic, infrared, far-infrared, 1H and 13C NMR spectral studies were used to characterize the complexes. The molecular weights of few complexes were determined by FAB-mass spectra. Nephelauxetic ratio, covalency parameter and bonding parameter for these complexes were also calculated. The probable structures of the complexes were proposed. The antifungal and antibacterial activities of the complexes were evaluated. The activities were correlated with the structures of the compounds.展开更多
基金supported by the National Natural Science Foundation of China(22101116,92261203,21971106)Shenzhen Fundamental Research Program(JCYJ20220530115001002 and JCYJ20220818100417037).
文摘The dominant oxidation state for lanthanide ions is+3 due to the loss of 5d and 6s electrons from their shared configuration of[Xe]4f^(0-14)5d^(0-16)s(2).There are however several exceptions because of the completely empty(Ce(Ⅳ)),half-filled(Eu(Ⅱ)),or fully filled(Yb(Ⅱ))4f subshell.As such,stable complexes are formed primarily with Ln(Ⅲ)ions[1].
基金Project supported by the Natural Science Foundation of Yunnan Province (2009ZC040M)the Science Research Fund of Yunnan Provincial De-partment of Education (07Y41398)the National College Students Innovative Experimental Foundation of China (091067437)
文摘This paper investigated the antibacterial mechanism of the Ag-Pr-antibacterial white carbon black.The sol-gel method was used to prepare the carrier:white carbon black.Silver ion was selected to be the antibacterial ion,and praseodymium nitrate was selected to be the additive.The structure and antibacterial mechanism of this new inorganic antibacterial material were characterized by laser particle size analyzer,scanning electron microscope(SEM) techniques,energy dispersive spectrum(EDS) analysis,and antibacterial activity test(Escherichia coli as experimental bacterium).Results showed that the particle size of Ag-Pr-antibacterial White carbon black was less than 30 μm with a narrow size distribution.Ag+ is combined into the white carbon black by both the mode of ion exchange and the mode of adsorption process.The bacteriostasis rate of the Ag-Pr-antibacterial white carbon black was higher than that of the general Ag-antibacterial white carbon black.The antibacterial activity of Ag-Pr-antibacterial white carbon black was caused by the combination of contact and stripping antibacterial mechanism.The result also indicated that this new inorganic antibacterial material had good thermal and light stability.
文摘The solvent extraction of Pr(Ⅲ) and Sm(Ⅲ) with trialkyl phosphine oxide(Cyanex 923) in chloroform,carbon tetrachloride,n-octane,cyclohexane,1,2-dichloroethane,benzene,toluene,xylene and nitrobenzene from acidic nitrate medium was investigated.On the basis of slope analysis data,the composition of the extracted species was determined as(M(NO3)3?2CY923),CY923 refers to Cyanex 923.The values of the equilibrium constants and the separation factors were calculated.The effect of the diluents on the metal extracti...
基金supported by the National Natural Science Foundation of China(51574213,51074150)the Key Project of Chinese National Programs for Fundamental Research and Development(973 Program)(2012CBA01203).
文摘A new approach was suggested in present work for improving the separation between Pr(Ⅲ) and Nd(Ⅲ)by a so-called kinetic "push and pull" system consisting of [A336][NO3] and DTPA in a column extractor.It is revealed that,when organic extractant [A336][NO3] is continuously pumped into the column extractor in the form of dispersed oil droplets and at the same time DTPA was injected into the aqueous feed solution whet the extraction was just started,the separatiot factor of Pr(Ⅲ) to Nd(Ⅲ),βPr/Nd,increased obviously with the time,and could even achieve 21.7.Such an amazing increase in βPr/Nd value might be due to the extraction rate of Pr(Ⅲ) by [A336][NO3] oil droplets being faster than that of Nd(Ⅲ),while the complexing rate of Nd(Ⅲ) with DTPA in the aqueous solutions being faster than that of Pr(III).The opposite order of the two rates for Pr(Ⅲ) and Nd(Ⅲ) result in their kinetic "push and pull" separation.In contrast,the βPr/Nd value in traditional thermodynamic separation reported in previous literatures is only around 5 or even less,even though using the same extractant [A336][NO3] and DTPA but by previously adding DTPA into the aqueous feed solutions for pre-complexing of Pr(Ⅲ) and Nd(Ⅲ).Various effects from the pH and addition amount of DTPA aqueous solutions,LiNO3 concentrations in initial aqueous feed solutions,the initial concentration ratios of Pr(Ⅲ) to Nd(Ⅲ) ions,the initial pH of aqueous feed solutions,and the concentrations of [A336][NO3] in organic phases,on the kinetic separatiot of Pr(Ⅲ) and Nd(Ⅲ) are discussed.The present work highlights a promising approach for separation of rare earths or other targets with extreme similarity in physicochemical properties.
基金supported by the National Basic Research Program of China (2006CB600903)
文摘We introduced a new catalyst,rare earth element praseodymium,for the catalytic graphitization of furan resin carbon.The extent of graphitization of the furan resin carbon was examined by X-ray diffraction and Raman spectroscopy.The morphology of furan resin carbon was characterized by scanning electron microscopy.The effects of the praseodymium content and the heat-treatment temperature on the catalytic graphitization of furan resin carbon were also investigated.The results indicated that the praseodymium c...
基金supported by National Key Research and Development Program of China(2016YFC0205500)National Natural Science Foundation of China(51272105)+1 种基金Jiangsu Provincial Science and Technology Supporting Program(BE2013718)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘A series of praseodymium added CeO2（ZrO2）/TiO2 catalysts separately prepared by methods of sol-gel and impregnation were tested for selective catalytic reduction of NO, and characterized by X-ray diffraction （XRD）, N2-brumauer-emmett-teller （N2-BET）, NH3-temperature programmed desorption （NH3-TPD）, H2-temperature programmed reduction （H2-TPR）, PL spectra, Ra-man spectra, electron paramagnetic resonance （EPR） and X-ray photoelectron spectroscopy （XPS）, respectively. Influence of prepara-tion method on catalytic performance was studied. Results showed that the influence of Pr addition on catalytic performance of the CeO2（ZrO2）/TiO2 catalysts was different between the sol-gel method and the impregnation method. The Pr addition tended to interact with TiO2 and formed the structure of Ti-O-Pr in the sol-gel method while it was more likely to interact with CeO2 forming the struc-ture of Ce-O-Pr in the impregnation method. The total acid amount and redox properties of the catalysts prepared by sol-gel method decreased with the addition of Pr element, which resulted in decrease of catalytic activity. In contrast, the Pr-added catalyst prepared by impregnation method was found to possess easier reducibility, more total acid amount and higher proportion of Ce3＋ species, which was favourable for higher catalytic activity.
基金Project supported by the Hibah Kompetensi(2476/H2.R12/HKP.05.00/2013)a project funded by the DIKTI Republic of Indonesia
文摘Engineering of chitosan by praseodymium has been investigated to improve the adsorption properties as well as physical characteristics of chitosan. Modification of chitosan changes the original properties of chitosan so that it can be more suitable for adsorption of fluoride ions. In this study, chitosan-praseodymium （Chi-Pr） was synthesized by impregnation method. The Chi-Pr complex was characterized by scanning electron microscopic-energy dispersive X-ray spectroscopy （SEM-EDX）, Fourier transform infrared （FTIR） and employed as an adsorbent for removal of fluorides ions from water in the batch system. The variables such as contact time, concentration of Pr, adsorbent dose, initial concentration of fluoride ions, and competitor anions were studied. The adsorption efficiency of fluoride ions （n） with increasing Pr loading into chitosan （5 wt.%, 10 wt.%, 15 wt.%, 20 wt.% and 25 wt.%） were 35.5%, 56.1%, 72.0%, 68.5% and 62.5%, respectively. The Chi-Pr （15 wt.%） complex had the highest fluoride removal efficiency （72.0%）. The experimental data fitted well to the Langmuir isotherm with maximum adsorption capacity （qmax） of 15.87 mg/g and an equilibrium constant （kL） of 0.15 mg. Kinetic study revealed that the adsorption of fluoride ions from water followed pseudo-second-order model with a maximum adsorption capacity （q2） of 8.20 mg/g and a rate constant （k2） of 0.01 g/mg.min. Adsorption efficiency of fluoride ions in the simulated drinking water was diminished with the changes in pH levels. The presence of Pr3＋ in chitosan increased chitosan＇s performance as an adsorbent for adsorption of fluoride ions.
文摘<正>The influence of Yb_2O_3 and Pr_2O_3 doping on electrical and gas sensing properties of tin dioxide was studied.A doping content of 0.5wt%～5wt% was investigated by mechanical mixing.The significant improvement on sensitivity and selectivity to 200μg/g hydrogen sulphide gas has been achieved by 3wt% Pr_2O_3 and 5wt% Yb_2O_3 adding.The better response and revovery properties of Pr or Yb doped tin dioxide sensor for 200μg/g hydrogen sulphide gas were found.The maximum sensitivity to H_2S gas is observed at about 120℃.Pr has stronger catalysis than Yb for H_2S reaction on SnO_2 surface.S~ 2-) was oxidized to S~ 6+) on the SnO_2 surface according to XPS.
基金Project supported by the National Natural Science Foundation of China(21972063)the Natural Science Foundation of Jiangsu Province(BK20200012).
文摘Sulfation treatment has been widely used to promote the catalytic performance of ceria(CeO_(2))based catalysts for the selective catalytic reduction of NO by NH_(3)(NH_(3)-SCR of NO).Praseodymium oxide(PrO_(x)),another commonly used rare earth material with similar structural properties as CeO_(2),also shows satistactory redox properties due to the facile redox cycle of Pr^(3+)■Pr^(4+).In this work,gas phase sulfation treatment with varied duration was performed on PrO_(x) at 200℃,and the NH_(3)-SCR activity of sulfated PrO_(x) was evaluated.Based on the results of systematic characterizations(e.g.,N_(2)-physisorption,NH_(3) oxidation,NO oxidation,in situ diffuse Fourier transform infrared spectroscopy),it is revealed that the catalytic performance of sulfated PrO_(x)is highly dependent on the sulfation time(or the amount of sulfate species deposited on PrO_(x)),which has a significant impact on the competitive reaction between NH_(3) oxidation and NH_(3)-SCR of NO,thus determining the NH_(3)-SCR activity of PrO_(x).This work provides new insight into tuning the interaction between PrO_(x) surface and reactants(NO,NH_(3))via sulfation treatment,which cam guide the design and application of PrO_(x)based catalysts for NH_(3)-SCR of NO in the future.
基金Project supported by the National Natural Science Foundation of China(Grant No.50862009)the New Century Excellent Talents in University of the Ministry of Education,China(Grant No.NCET-04-0915)the Natural Science Foundation of Yunnan Province of China(Grant No.2005E007M)
文摘The crystal structures, electronic structures and optical properties of nitrogen or/and praseodymium doped anatase TiO2 were calculated by first principles with the plane-wave ultrasoft pseudopotential method based on density functional theory. Highly efficient visible-light-induced nitrogen or/and praseodymium doped anatase TiO2 nanocrystal photocatalyst were synthesized by a microwave chemical method. The calculated results show that the photocatalytic activity of TiO2 can be enhanced by N doping or Pr doping, and can be further enhanced by N＋Pr codoping. The band gap change of the codoping TiO2 is more obvious than that of the single ion doping, which results in the red shift of the optical absorption edges. The results are of great significance for the understanding and further development of visible-light response high activity modified TiO2 photocatalyst. The photocatalytic activity of the samples for methyl blue degradation was investigated under the irradiation of fluorescent light. The experimental results show that the codoping TiO2 photocatalytic activity is obviously higher than that of the single ion doping. The experimental results accord with the calculated results.
基金Project supported by Ministry of Science and Higher Education (N N515 518538)
文摘Luminescent properties of Y2O3 and LaAlO3 nanopowders doped with Pr^3＋ ions and PMMA-based composite materials doped with these powders were reported. The set of active nanopowders differing in praseodymium ions concentration was prepared using sol-gel method and carefully characterized with respect to emission properties in the visible spectral range. In particular, the excitation and emission spectra were measured together with fluorescence decay profiles and the differences between optical properties of these materials were discussed and compared with data available for bulk materials. Finally, the PMMA-based composite materials doped with Pr^3＋：Y2O3 and Pr^3＋：LaAlO3 nanopowders were manufactured and characterized. The obtained results showed that polymer composites doped with active nanopowders in general tended to keep the luminescent properties of the original nanopowders.
基金supported by the Ministry of Higher Education,Scientific Research and Technology of Tunisia
文摘Reaction of Na2CO3, Pr6O11 and H3PO4 gave the sodium praseodymium polyphosphate NaPr（PO3）4.The title compound crystallized in the monoclinic P21/n space group with a=0.9965（4） nm, b=1.31437（4） nm, c=0.72271（3） nm, β=90.429（3）°, V=0.9465（4） nm3, Z=4, R=0.0493 and wR=0.1266 for 1855 independent reflections.The structure of NaPr（PO3）4 consisted of PrO8 polyhedra sharing oxygen atoms with phosphoric group PO4 to form a three-dimensional framework, delimiting intersecting tunnels in which the sodium ion was located.Each Na＋ ion was bonded to seven oxygen atoms.
文摘The effects of lanthanum-praseodymium-cerium mischmetal （LPC） on the microstructure and mechanical properties of Mg-Al alloy were investigated. With the addition of LPC, an additional rod-like Al11La3 phase was deposited in the alloy. LPC greatly improves the tensile strength of cast Mg-Al alloys but negatively affects the elongation of cast alloys above 473 K. Cast alloys are strengthened by both precipitation strengthening and dispersion strengthening at ambient temperature. When the temperature exceeds 473 K, only the dispersion operates as a strengthening mechanism.
文摘The electrochemical behaviour of Pr(III) on iron electrode in molten PrCl3-KCl-NaCl was studied by means of cyclic voltammetry and potential-time curve method. The results show that the reduction of Pr(III) to Pr on the iron electrode proceeds reversibly in one step and forms Pr-Fe alloys. The Pr-Fe alloys are obtained by molten salt electrolysis with molten KCl-NaCl as electrolyte and PrCl3 as raw materials. The composition of electrolytic product is PrFe2 and Pr analysed by X-ray diffraction. Pr recovery efficiency is 90% and the current efficiency is 85%.
基金supported by the National Natural Science Foundation of China(21373178)the Provincial College Students’Innovation and Entrepreneurship Training Program(1238)the Natural Science Foundation of Yan’an University(YDZ2013-09)
文摘Two new coordination complexes, [Pr（1,3-pda）0.5（nbca）2（H2O）2]（1） and [Pr2（1,3-pda）3（2,2ˊ-bpy）2（H2O）2]（2）（H2pda = 1,3-phenylenediacetic acid, Hnbca = 5-nitro [1,1ˊ-biphenyl]-3-carboxylic acid, 2,2ˊ-bpy = 2,2ˊ-bipyridine）, have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectra, and single-crystal X-ray diffraction. In 1, the nbca ligands bridge the Pr3＋ ions to form a 1D chain. Moreover, these 1D chains are united together through the 1,3-pda ligands to afford a 2D layer. In contrast, due to a different auxiliary ligand, complex 2 is a 2D layer linked through only bridging deprotonated 1,3-pda. Thermal stabilities and solid fluorescence properties of 1 and 2 were also studied.
基金financially supported by the National Natural Science Foundation of China(Nos.51574213,51074150)the Key Project of Chinese National Programs for Fundamental Research and Development(973 Program No.2012CBA01203)。
文摘The kinetics and the difference for Pr(Ⅲ)and Nd(Ⅲ)extraction from nitrate aqueous solution using trialkylmethylammonium nitrate([A336][NO3])as extractant were investigated by the single drop technique.The dependence of the extraction rate of Pr(Ⅲ)and Nd(Ⅲ)on the concentrations of free Pr(Ⅲ)and Nd(Ⅲ)ions,the concentrations of Na NO3 and H+in aqueous solutions,and the concentrations of[A336][NO3]in kerosene solutions were discussed and the corresponding extraction rate equations for Pr(Ⅲ)and Nd(Ⅲ)were obtained.These equations demonstrated that the reaction rate constant of Pr(Ⅲ)with[A336][NO3]was double than that of Nd(Ⅲ).The effect of the addition of diethylenetriaminepentaacetic acid(DTPA)on the difference in the extraction rate of Pr(Ⅲ)and Nd(Ⅲ)by[A336][NO3]was also investigated.It was revealed that the difference in the complex formation rates of Pr(Ⅲ)and Nd(Ⅲ)with DTPA made a significant impact on the difference in the extraction rates of Pr(Ⅲ)and Nd(Ⅲ)with[A336][NO3].The ratio of extraction rates of Pr(Ⅲ)to Nd(Ⅲ)with[A336][NO3]was in proportion to the ratio of complex formation rates of Pr(Ⅲ)to Nd(Ⅲ)with DTPA.The extraction rate difference for Pr(Ⅲ)and Nd(Ⅲ)with[A336][NO3]increased due to a higher complex formation rate constant of DTPA with the free and un-complexed Nd(Ⅲ)ions in the aqueous nitrate solution than that with Pr(Ⅲ)ions.Therefore,the addition of DTPA in the aqueous nitrate solution is an effective method to intensify the separation of Pr(Ⅲ)and Nd(Ⅲ)in kinetics.The study on the extraction mechanism indicated that both the extraction of Pr(Ⅲ)and Nd(Ⅲ)by[A336][NO3]were diffusion controlled,and the reactions obeyed SN2 mechanism.The present work highlights a possible approach to strengthen the kinetic separation of Pr(Ⅲ)and Nd(Ⅲ).
文摘The synergistic extraction of Pr^3＋ from hydrochloric medium using mixture of 2-ethylhexyl phosphonic acid mono- 2-ethylhexyl ester （P507, HL） and 8-Hydroxyquinoline （HQ） in heptane was investigated. The effect of equilibrium of aqueous acidity on extraction of Pr^3＋ was discussed. The effect of extractant concentraction, different diluents, equilibrium time and acetate ion concentration oil extraction reaction were also studied. With a method of double-logarithmic slope, composition of the extracted species on 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester and 8-Hydroxyquinoline was derived. The result shows that the synergistic extraction system not only overcomes emulsification of 8-Hydroxyquinoline, but also shows perfect capacity of synergistic extraction. The largest synergistic enhancement factor can be calculated to be 5.49 at pH 3.6 for Pr^3＋.
基金Supported by the National Natural Science Foundation of China(No.20706041)the Natural Science Foundation of Tianjin(No.09JCYBJC06500)
文摘A Pr-doped TiO2-NTs/SnO2-Sb electrode was prepared by a simple method, cyclic voltarnmetry （CV）. The methyl orange （MO）aqueous solution was selected as a simulated wastewater. The ordered microstructural TiO2-NTs substrate was synthesized by an electrochemical method to obtain large specific surface area and high space utilization. The phase structure, electrode surface morphology and electrochemical properties of electrodes were characterized by XRD, SEM and electrochemical technology, respectively. The results showed that praseo- dymium oxide was successfully doped into the SnOz-Sb film by CV method. Due to the doped Pr, the oxygen evo- lution potential increased from 2.25 V to 2.40 V. The degradation of MO was investigated by UV-vis. The Ct/C0（φ） was studied as a function to obtain the optimal parameters, such as the amount of doped Pr, current density and initial dye concentration. In addition, the degradation process followed pseudo-first-order reaction kinetics and the rate constant was 0.099 3 min-1. The result indicated that the introduction of Pr reduced the formation of oxygen vacancies or enhanced the formation of adsorbed hydroxyl radical groups on the surface, thus leading to better activity and stability.
文摘Oxygen storage and adsorptive properties of praseodymium oxides were investigated by pulse experiments and temperature - programmed desportion/reduction (TPD/TPR) experiments. Pr2O3 possesses the similar oxygen storage properties to CeO2, and its dynamic oxygen storage capacity is 14.9 mumol.g(-1). The studies on TPD Of O-2, H2O and CO and TPR show that Pr2O3 provides more active surface oxygen species and at a lower temperature than CeO2. It is suggested that Pr2O3 can be a well candidate as an oxygen storage component in automobile three-way catalyst.
文摘The new lanthanum (Ⅲ) and praseodymium (Ⅲ) complexes of the general formula [Ln(L)3] (Ln=La(Ⅲ) or Pr(Ⅲ); LK=potassium salt of dithiocarbazinates) were prepared by both, conventional thermal and by the use of microwave technology. Elemental analyses, electrical conductance, magnetic moment and electronic, infrared, far-infrared, 1H and 13C NMR spectral studies were used to characterize the complexes. The molecular weights of few complexes were determined by FAB-mass spectra. Nephelauxetic ratio, covalency parameter and bonding parameter for these complexes were also calculated. The probable structures of the complexes were proposed. The antifungal and antibacterial activities of the complexes were evaluated. The activities were correlated with the structures of the compounds.
