Pectin based cerium (IV) and thorium (IV) phosphates as novel hybrid fibrous ion exchangers synthesis,characterization and thermal behaviour

Summary Pectin based cerium (IV) and thorium (IV) phosphates have been synthesized as new phases of hybrid fibrous ion exchangers. Both materials were characterized using X-ray diffraction, infrared (IR) spectra, thermogravimetric analysis (TG), differntial thermogravimetry (DTG), differntial thermal analysis (DTA) and scanning electron microscopy (SEM), as well as the determination of their ion exchange capacity, elution and pH titration. The X-ray study reveals the amorphous nature of the materials, while SEM studies confirm the fibrous nature of the materials. The thermal studies of these materials indicate that both of them are highly stable on heating as they retain about 97% of their ion-exchange capacity (i.e.c.) on heating up to 100°C and about 81% on heating up to 200°C.     

Synthesis,characterization and adsorption behaviour of TX-100 based Sn(IV) phosphate,a new hybrid ion exchanger

A new hybrid ion exchanger, Triton X-100 based tin(IV) phosphate (TX-100SnP) has been synthesized and characterized by ion exchange and physico-chemical methods such as ion exchange capacity, elution and concentration behaviour, IR, X-ray, TG/DTA and elemental analysis. Its adsorption behaviour has also been studied for some alkaline earths and heavy metal ions in different acidic media. It has been found generally more selective for metal ions as compared to tin(IV) phosphate prepared earlier. For Pb(II), Hg(II) and Fe(III) its selectivity has been found to be exceptionally good. On this basis, some binary separations have been performed involving these metal ions. Thermal studies show a high thermal stability of the material. It retains 54.54% of its i.e.c. at 200°C and 27.27% at 300°C.     

乙炔在钍配合物催化体系下的聚合

<正> 聚乙炔掺入杂质后,做为高分子导电材料已引起人们的极大关注。有关聚乙炔(下称PA)的合成、结构及性能测试,以及电池研究已有很多报道,其催化剂体系已有关于Ti、V、Cr、W、Fe、Mo、Ni和Co等过渡金属化合物,稀土化合物合成PA的报道。本文进行了应用重元素钍的高配合物[Th(P_(204))_8Cl_4]与三乙基铝组合作为催化剂、使乙炔在常温下定向聚合的研究,得到具有余属光泽银白色的PA,顺式含量为80％,并对PA薄     

Synthesis and characterization of nano-structured Th1?x Ce x O2 mixed oxide

GEL combustion technique was applied to obtain oxides of thorium and cerium from their respective nitrate solutions using citric acid as the gelating agent. The dried samples were characterized by IR and TG studies. Intermediate and final products during TG studies have been isolated and characterized by XRD studies. All the TG runs during heating of thorium and cerium nitrate with citric acid dried Gels showed a two step process. The weight loss at each step and the X-ray data of the product at each step, helped in suggesting a possible mechanism. Kinetic study was carried out independently for each step. The reaction mechanism as observed during interactive procedure was found to be diffusion controlled. The kinetic parameters (activation energy and pre-exponential factor) for each step in all reactions have been calculated. Observations from XRD studies show that with increase in cerium concentration in the oxides, the lattice parameter values have shown a decreasing trend for all the five compositions studied. It was observed that in TG studies with increase in cerium concentration, the final temperature of the reactions have shown a decreasing trend. SEM studies of the powders reveal that synthesized oxides have a tendency to form agglomerate of varying size ranging from 50 to 100 μm in case of mixed oxides but the size of thorium oxide powder so synthesized have pore size 10–100 μm. SEM images shows that GEL combustion may result in agglomeration, if the temperature is not properly controlled to the desired value. SEM studies also reveal that each agglomerate contains approximately 10–100 individual particles. Surface area of the mixed oxide powders were determined using Gas adsorption technique. The surface area was found to be in the range of 3–17 m²/g in all cases. Specific surface area of thorium oxide was found to be lesser than cerium oxide but in case of mixed oxides surface area decreases with increase in cerium content. Majority of pores, indicating the particle size are in the range of 0.01–0.04 cm³/g.     

Pyridine based zirconium(IV) and tin(IV) phosphates as new and novel intercalated ion exchangers

Pyridine based zirconium(IV) phosphate (PyZrP) and tin(IV) phosphate (PySnP) have been synthesized as new and novel intercalated ion exchangers. These materials have been characterized using X-ray, IR spectra, TG, DTG and DTA studies in addition to their ion exchange capacity, elution, pH titration, concentration and distribution behaviour. The distribution studies towards several metal ions in different media/concentrations have suggested that PyZrP and PySnP are selective for Hg(II) and Pb(II), respectively. As a consequence some binary separations of metal ions involving Hg(II) and Pb(II) ions have been performed on a column of these materials, demonstrating their analytical and environmental potential.     

3,6-二-〔二甲氨基〕二苯并碘六环六硝酸钍配合物的研究

本文报道了在甲醇介质中以硝酸钍和碘杂环硝酸盐为原料合成了3,6—二—〔二甲氨基〕二苯并碘六环六硝酸钍配合物,组成为:     

Synthesis and ion exchange behaviour of polyaniline Sn(IV) arsenophosphate: a polymeric inorganic ion exchanger

Incorporation of a polymer material into an inorganic ion exchanger provides a class of hybrid ion exchangers with a good ion exchange capacity, high stability, reproducibility and selectivity for heavy metals. Such a type of ion exchanger ‘polyaniline Sn(IV) arsenophosphate’ has been synthesized by mixing polyaniline into inorganic material. This material is characterized using X-ray, IR, TGA studies in addition to ion exchange capacity, pH-titration, elution and distribution behaviour. On the basis of distribution studies, the material has been found to be highly selective for Pb(II). Kinetic study of exchange for the metal ions has been performed and some physical parameters such as self diffusion coefficient D₀, energy E_a and entropy ΔS* of activation have been determined.     

Thermogravimetric studies of dipyridinium complexes of cerium(IV), thorium(IV) and zirconium(IV)

The TG curves of dipyridinium complexes of Ce(IV), Th(IV) and Zr(IV) have been reported. The mode of decomposition of the cerium and thorium complexes is broadly comparable but the decomposition of Zr complex shows some variation.     

Highly efficient elimination of thorium(IV) from aqueous solution using poly(cyclotriphosphazene-co-melamine) microspheres

Highly crosslinked organic–inorganic hybrid polymer poly(cyclotriphosphazene-co-melamine) microspheres (PZM) were synthesized by a simple method. The microspheres was characterized by FTIR, SEM and EDX. It was applied to eliminate thorium(IV) from aqueous solution under various conditions, i.e., pH, initial concentration, dosage and contact time. The experimental data were well-imitated via the pseudo-second-order kinetic model and its adsorption processes comply with the Langmuir isotherm model. Adsorption thermodynamic studies demonstrated that the adsorption process, in essence, was spontaneous and endothermic. Furthermore, the maximum experimental adsorption capacity was 98.6 mg g^?1 for initial thorium(IV) concentration 50 mg L^?1. When pH?=?0.0, the thorium(IV) removal efficiency reached at 76.9%, which indicates that the adsorbent can also was used in a peracid environment. Adsorption behavior of thorium(IV) onto the microspheres were weakly affected via temperature, implying that adsorption would be done at room temperature.

     

Kinetic and thermodynamic stability of cluster compounds under heating

A new polymorphic form of Norfloxacin has been identified and fully characterized by a variety of methods including powder X-ray diffraction, vibrational spectroscopy (IR and Raman), thermal analysis (DSC and TG), SEM and solid-state NMR spectroscopy. The relationship between the new form C and the previously known forms A and B have been studied. Moreover, the crystal structure of the known form A has been solved by single-crystal methods.     

以四价锰为引发剂纤维素与丙烯腈接枝共聚的研究

<正> 对天然高分子纤维素进行接枝改性可以获得一系列新型高分子材料。但是,在接枝共聚过程中往往产生大量的均聚物,阻碍了该法的工业应用。此外,对接枝共聚产物的结构尚缺乏深入的研究,因此寻找不形成或少形成均聚物的简便接枝共聚方法,及研究纤     

Semiorganic nonlinear optical material for frequency doubling: preparation and properties of sodium p-nitrophenolate dihydrate (SPNP)

Sodium p-nitrophenolate (SPNP), a semiorganic nonlinear optical (NLO) material useful for frequency doubling in the IR region, has been synthesized. The solubility studies have been carried out in the temperature range 30-50 degrees C. Single crystals (size 12 mmx7 mmx4 mm) have been grown by slow evaporation of the saturated aqueous solution (methanol as solvent) at 30 degrees C. The lattice parameters of the grown crystals have been determined by single crystal X-ray diffraction technique. The UV-vis-NIR transmittance spectrum has been recorded in the range 200-1500 nm. The molecular structure was confirmed by FT-IR and FT-NMR. SPNP was thermally stable up to 103 degrees C as determined by TG/DTA curves. By a modified Kurtz and Perry method, the powder SHG efficiency was found to be five times that of KDP and its phase matching property was established. Laser damage threshold of SPNP was determined using a Nd:YAG laser.     

Coordination around thorium(IV) in aqueous perchlorate,chloride and nitrate solutions

The coordination around the thorium(IV) ion in aqueous perchlorate, chloride and nitrate solutions has been determined from large angle X-ray scattering measurements. In perchlorate solutions, where inner-sphere complexes are not formed, the first coordination sphere contains 8.0±0.5 water molecules with Th-H₂O bond lengths of 2.48₅ Å. In chloride solutions inner-sphere complexes are formed, which lead to an increase in the coordination number. In nitrate solutions the nitrate ions are bonded as bidentate ligands to the thorium ion. The bond lengths are similar to those found in crystalline hydrates of thorium nitrate. The coordination numbers found for thorium(IV) in solution are compared with previously reported values for lower charged ions of similar size.On leave from Department of Inorganic Chemistry Royal Institute of Technology S-10044 Stockholm Sweden     

Liquid–liquid extraction of thorium(IV) by fatty acids: a comparative study

In this paper, extractants that have the potential to be sustainably regenerated, are proposed for thorium(IV) removal from nitrate aqueous phases. These extractants are oleic (OA), palmitic (PA) and lauric (LA) acids. The advantages of using these acids are their sustainability, their biocompatibility and their non-toxicity, this makes these simpler and greener compared to other extractants (organophosphorus, azote derivatives, macrocyclic crown, etc…) used for metal extraction. These acids were applied as chelating agent for Th(IV) liquid–liquid extraction. The extractions were carried out in chloroform as an organic phase through the formation of thorium–OA, thorium–PA and thorium–LA complexes. The synergistic extraction of Th(IV) with these extractants in the presence of tributhylphosphine (TBP) has been investigated. The effect of different variables, such as time contact, pH of the aqueous phase, concentration of fatty acid, TBP addition on fatty acids, ionic strength and temperature, is reported. The results showed that the extraction kinetics using LA and OA were fast than with PA. The KNO₃ addition does not seem to highly influence the extraction yield, and no important synergy effect was noticed in the presence of TPB. Thermodynamic data for Th(IV) solvent extraction are also reported in this paper.     

以二甲基二乙基氢氧化铵为模板剂UZM-8沸石的合成与表征

以二甲基二乙基氢氧化铵(DEDMAOH)作为模板剂, 通过水热合成方法制备了新型层状沸石材料UZM-8, 并考查了DEDMAOH模板剂用量及投料硅铝比对UZM-8沸石结构的影响. 采用X衍射(XRD)、扫描电子显微镜(SEM)、傅立叶变换红外(FT-IR)、热重分析(TG, DTG)等方法对所得系列UZM-8沸石进行了表征. 该层状沸石具有与MCM-56相似的MWW结构, 但层间距及其堆积方式等有所不同. 当DEDMAOH/SiO2＜0.3时, 无法有效合成出UZM-8沸石. 随硅铝比的提高, UZM-8在2θ角6.6°和7.1°处的两个衍射峰转变为一个峰, 层间沿c轴方向收缩.     

Selective extraction, preconcentration and transport studies of thorium(IV) using octa-functionalized calix[4]resorcinarene-hydroxamic acid.

A new calix[4]resorcinarene bearing eight hydroxamic acid groups (C4RAHA) has been synthesized and characterized by FT-IR, 1H-NMR and elemental analysis. Its analytical properties were investigated, and showed high affinity and selectivity toward thorium(IV) in the presence of large quantities of associated metal ions. Thorium(IV) was extracted from an ethyl acetate solution of C4RAHA at pH 4.5. The lambdamax and molar absorptivity (epsilon) for thorium(IV) were 341 nm and 7120 l mol(-1) cm(-1). The complexation of thorium(IV) with C4RAHA has a 4:1 metal:ligand stoichiometry, which is relatively rare. The extracts were directly aspirated in the plasma for ICP-AES measurements for thorium(IV) in the presence of a diversified matrix. The system obeyed Beer's law over the range 0.1 - 6.5 microg ml(-1) of thorium(IV) with a Sandell sensitivity of 0.0325 microg cm(-2). The preconcentration factor and overall stability constant evaluated at 25 degrees C for thorium(IV) were 133 and 15.86, respectively. The complexation was characterized by a favorable enthalpy change. A liquid-membrane transport study of thorium(IV) was carried out from the source to the receiving phase under controlled conditions, and a mechanism of transport proposed. To check the validity of the proposed method, thorium(IV) was determined in monazite sand, rare earth sand and water samples.     

The synergistic extraction of thorium(IV) and uranium(VI) with mixtures of 3-phenyl-4-benzoyl-5-isoxazolone and crown ethers

The extraction of thorium(IV) and uranium(VI) from nitric acid solutions has been studied using mixtures of 3-phenyl-4-benzoyl-5-isoxazolone (HPBI) and dicyclohexano-18-crown-6, benzo-18-crown-6, dibenzo-18-crown-6 or benzo-15-crown-5. The results demonstrate that these metal ions are extracted into chloroform as Th(PBI)(4) and UO(2)(PBI)(2) with HPBI alone and as Th(PBI)(4) . CE and UO(2)(PBI)(2) . CE in the presence of crown ethers (CE). The equilibrium constants of the above species have been deduced by non-linear regression analysis. The addition of a CE to the metal chelate system enhances the extraction efficiency and also improves the selectivities between thorium and uranium. IR spectral data of the extracted complexes were used to further clarify the nature of the complexes. The binding to the CEs by Th(PBI)(4) and UO(2)(PBI)(2) follows the CE basicity sequence but with DC18C6 and DB18C6, steric effects become more important.     

Column chromatographic separation of thorium(IV) from ascorbic acid medium using poly-(dibenzo-18-crown-6)

A simple separation method has been developed for thorium(IV) using poly-(dibenzo-18-crown-6) and column chromatography. The separation was carried out from ascorbic acid medium. The adsorption of thorium(IV) was quantitative from 0.001-0.01M ascorbic acid. The elution of thorium(IV) was quantitative with 4.0-8.0M HCl, 3.0-6.0M HClO₄, 4.0-8.0M H₂SO₄ and 1.0-8.0M HBr. The capacity of poly-(dibenzo-18-crown-6) for thorium(IV) was found to be 1.379±0.01 m^.mol/g of crown polymer. Thorium(IV) was separated from a number of cations in binary as well as in multicomponent mixtures. The method was extended to the determination of thorium in monazite sand. It is possible to separate and determine 5 ppm of thorium(IV) by this method. The method is very simple, rapid, selective and has good reproducibility (approximately ±2%).     

A Spectroscopic Study of Thorium(IV) Complexes with bidentate SCHIFF Bases

The complexes of thorium(IV) chloride with bidentate SCHIFF bases have been prepared. The analytical data indicate 1:2 stoichiometry. The complexes are yellow in colour, non-electrolytes in DMF and appear to be octahedral. The UV, IR and NMR spectra of the ligands and the complexes are reported.     

Uptake of thorium ions from aqueous solutions by a molecular sieve (13X type) powder

The adsorption of thorium(IV) ions on molecular sieve (13X type) powder from aqueous solutions has been studied as a function of shaking time pH, thorium ion concentration and temperature. The conditions of maximum adsorption of thorium ions obeys Langmuir and D-R isotherms over the entire concentration range studied. Thermodynamic quantities such as H, G and S have been calculated fromK _D values determined at various temperatures. The results show endothermic heat of adsorption, but negative free energy value indicates that the process of thorium adsorption on molecular sieve powder is favored at high temperature. The influence of various cations and anions on thorium(IV) ion adsorption was examined. A wavelength dispersive X-ray fluorescence spectrometer was used for measuring the thorium ion concentration in solutions.