Ammonium Molybdophosphate Research Articles

Selectivity of 90Sr urine bioassay technique over 241Am, 238/239PU, 210PO, 137CS and 60CO

The selectivity of a rapid (90)Sr bioassay technique over (241)Am, (238/239)Pu, (210)Po, (137)Cs and (60)Co has been investigated. Similar to (90)Sr, these radionuclides are likely to be used in radiological dispersive devices. The purpose of this study was to demonstrate the degree to which the (90)Sr bioassay technique is free from interference by these radionuclides if present in a urine matrix. The interfering radionuclides were removed (from (90)Sr) by their retention on an anion exchange column. While, recovery of the target radionuclide ((90)Sr) was found to be >or= 90 %, contributions from (241)Am, (242)Pu and (208)Po were found to be <or= 3 % indicating minimal interference from these radionuclides. The breakthrough for (60)Co, however, was found to be <or=19 % indicating that it will have some interference contribution to the (90)Sr measurement if present in the urine sample. As (137)Cs was not retained at all by the anion exchange column, the method as such was not selective over (137)Cs. However, a slight modification of the method through the ammonium molybdophosphate treatment quantitatively removed Cs from the urine sample, thereby; making it selective for (90)Sr despite any (137)Cs that is present.

Nitration of benzene catalyzed by supported ammonium molybdophosphat catalyst

A series of supported ammonium molybdophosphat catalysts(AMPA/SiO_2) with different loading was prepared from tetraethyl orthosilicate,ammonium molybdate and ammonium dihydrogen phosphate by sol-gel method.The samples were characterized by X-ray diffraction(XRD) and IR spectrometry.The catalytic activities of these catalysts were evaluated for the liquid phase nitration of benzene in 65% nitric acid without solvent at 70 ℃.Results indicate that supported catalyst still maintained the Keggin structure of ammonium molybdophosphate catalyst and exhibited high nitration reaction catalytic activity and high selectivity of mononitrobenzene.Among these catalysts,the catalyst with 10% loading showed maximum activity(96%),with 100% selectivity towards mononitrobenzene.The reusability of the catalysts was also studied,and it was found that there was no obvious change for catalyst phase and structure after being reused four times,although the active component had somewhat been lost in the reaction process.

Synthesis and characterization of a new activated carbon supported ammonium molybdophosphate composite and its cesium-selective adsorption properties

A new Cs + adsorbent, activated carbon loaded ammonium molybdophosphate (AMP-AC) was prepared by repeating batch reaction of H 3 PO 4 and (NH 4 ) 6 Mo 7 O 24 . The surface of the activated carbon particles was coated with AMP microcrystals through a controlled crystallization process. The X-ray diffraction (XRD) analysis identified the AMP loaded on AC with the formula of (NH 4 ) 3 PO 4 (MoO 3 ) 12 ·4H 2 O. Scanning electron microscope images demonstrated that the fine AMP crystals was successfully immobilized and uniformly distributed on the porous carbon substrate. The effects of medium acidity, contact time, temperature and competing ions on Cs + uptake by the composite were investigated. The results show that the as-prepared adsorbent keeps high selectivity and adsorption capacity (∼0.75 mmol/g) for Cs + in acidic feed solution (0.1 M HN0 3 ), even in the presence of plentiful competing cations, Na + , Zn 2+ , Sr 2+ , Cr 3+ and La 3+ , while activated carbon itself has no specific affinity for Cs + . The adsorption process could be described by Langmuir adsorption equations. There is no significant difference (9.4%) on Cs + adsorption by the composite during system temperature changing from 298 to 348 K.

Rubidium and cesium ion adsorption by an ammonium molybdophosphate–calcium alginate composite adsorbent

A composite spherical adsorbent was prepared with ammonium molybdophosphate (AMP), sodium alginate (NaALG), and calcium chloride. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to characterize the composite adsorbent. The adsorption of rubidium and cesium ions onto the composite adsorbent in aqueous solutions was investigated comprehensively by varying the initial metal ion concentration, pH, ionic strength, and temperature. The adsorption kinetics of both rubidium and cesium was described by the first-order and second-order kinetic models. The second-order rate constant and the initial adsorption rate increase with increasing temperature. In general, the equilibrium adsorption amount of both rubidium and cesium increases with the increase in initial metal ion concentration, but decreases with increasing ionic strength and temperature. Maximum adsorption of rubidium and cesium occurs in the solution with an equilibrium pH value of 3.5–4.5. Under similar conditions, cesium shows a higher adsorption amount than rubidium. The composite adsorbent is easy to prepare and highly porous. It has a fast adsorption rate and an adsorption capacity of 0.58 and 0.69 mmol g −1 for rubidium and cesium, respectively. The composite adsorbent is effective for the adsorption of rubidium or cesium ions from solutions containing some other alkali metal ions, such as sodium ions.

An Inorganic Microsphere Composite for the Selective Removal of 137Cesium from Acidic Nuclear Waste Solutions. 1: Equilibrium Capacity and Kinetic Properties of the Sorbent

A new inorganic ion exchange composite consisting of ammonium molybdophosphate, (NH4)3P(Mo3O10)4·3H2O (AMP), synthesized within hollow aluminosilicate microspheres (AMP‐C) has been developed. Two different batches of the sorbent were produced resulting in 20% and 25% AMP loading for two and three loading cycles, respectively. The selective cesium exchange capacity of this inorganic composite was evaluated using simulated sodium bearing waste solution as a surrogate for the acidic tank waste currently stored at the Idaho National Laboratory (INL). Equilibrium isotherms obtained from these experiments were very favorable for cesium uptake and indicated maximum cesium loading of approximately 9% by weight of dry AMP. Batch kinetic experiments were also performed to obtain the necessary data to estimate the effective diffusion coefficient for cesium in the sorbent particle. These experiments resulted in effective intraparticle cesium diffusivity coefficients of 4.99 × 10−8 cm2/min and 4.72 × 10−8 cm2/min for the 20% and 25% AMP‐C material, respectively.

An Inorganic Microsphere Composite for the Selective Removal of 137Cesium from Acidic Nuclear Waste Solutions. 2: Bench‐Scale Column Experiments, Modeling, and Preliminary Process Design

A new inorganic ion exchange composite for removing radioactive cesium from acidic waste streams has been developed. The new material consists of ammonium molybdophosphate, (NH4)3P(Mo3O10)4·3H2O (AMP), synthesized within hollow aluminosilicate microspheres (AMP‐C), which are produced as a by‐product from coal combustion. The selective cesium exchange capacity of this inorganic composite was evaluated in bench‐scale column tests using simulated sodium bearing waste solution as a surrogate for the acidic tank waste currently stored at the Idaho National Laboratory (INL). Total cesium loading on the columns at saturation agreed very well with equilibrium values predicted from isotherm experiments performed previously. A numerical algorithm for solving the governing partial differential equations (PDE) for cesium uptake was developed using the intraparticle mass transfer coefficient obtained from previous batch kinetic experiments. Solutions to the governing equations were generated to obtain the cesium concentration at the column effluent as a function of throughput volume using the same conditions as those used for the actual column experiments. The numerical solutions of the PDE fit the column break through data quite well for all the experimental conditions in the study. The model should therefore provide a reliable prediction of column performance at larger scales.

Studies on the adsorption behavior of trace amounts of 90Sr 2+, 140La 3+, 60Co 2+, Ni 2+and Zr 4+ cations on synthesized inorganic ion exchangers

Three inorganic ion exchangers namely potassium zinc hexacyanoferrate(II) (PZF), magnesium oxide–polyacrylonitrile composite (MgO–PAN) and ammonium molybdophosphate (AMP) were synthesized. The physicochemical properties of these ion exchangers were determined using different techniques including inductively coupled plasma (ICP), CHNSO elemental analysis, infrared spectroscopy (IR), X-ray diffraction (XRD), thermogravimetric (TGA) and pH – titration curve analysis. The solubility of the synthesized ion exchangers in different acidic and alkaline media, their thermal stability and the effect of gamma irradiation were investigated. It was observed that the exchange capacity of the ion exchangers depend upon the pH value of the solution used. Furthermore, the adsorption of 90Sr 2+, 140La 3+, 60Co 2+ and the distribution coefficient of these ion exchangers for Ni 2+and Zr 4+ were studied. The effect of parameters such as pH and contact time on the adsorption was also investigated and the optimum conditions for separation of these ions were determined.

Determination of low 137Cs concentration in seawater using ammonium 12-molybdophosphate adsorption and chemical separation method

A new method has been developed for analyzing 137Cs in a small volume of seawater. Ammonium 12-molybdophosphate (AMP) was used two times during pretreatment procedure. The first step was to adsorb 137Cs in seawater samples into AMP in order to reduce sample volume, and the second was to remove 87Rb, interference nuclide for β counting. The AMP adsorbing 137Cs was dissolved by sodium hydroxide solution, and then 137Cs was finally formed to be cesium chloroplatinate precipitate by adding 10% hexachloroplatinic acid. The beta rays emitted from 137Cs were measured with a low background gas-proportional α/β counter. This method was applied to several seawater samples taken in the East Sea of Korea. Compared to the routinely used γ-spectrometry method, this new AMP method was reliable and suitable for analyzing 137Cs in deep seawater.

Recovery of purified radiocesium from acidic solution using ammonium molybdophosphate and resorcinol formaldehyde polycondensate resin

Separation of Cs + from acidic solution was investigated using ammonium molybdo- phosphate (AMP) based sorbents. Four sorbents including two AMP powders and two composites prepared by coating of AMP powder on polymethylmethacrylate (PMMA) beads were used in this study. Equilibrium sorption isotherms for Cs + on AMP sorbents were determined. The effect of H + concentration on Cs + uptake by AMP–PMMA beads was examined. Two column runs were carried out to establish the Cs + separation performance of AMP–PMMA beads from 1.0 M nitric acid having Cs + concentration equivalent to 10 Ci of 137Cs per litre. Recovery of Cs + from loaded AMP–PMMA column was carried out by dissolution of AMP using NaOH solution. The feasibility of ion exchange purification of the recovered Cs + solution was examined using resorcinol formaldehyde polycondensate resin (RFPR). The Cs + sorption isotherm on RFPR from Cs-bearing dissolved AMP solution was determined. Purification of Cs + from dissolved AMP solution was studied in two column runs using RFPR in loading-elution cycles. The results of these studies are useful in formulating a scheme for the recovery of purified 137Cs product from high level waste for large-scale utilization as a radiation source in industrial irradiators.

A new back-end cycle strategy for enhancing separation, transmutation and utilization of materials (Adv.-ORIENT cycle)

To minimize the ecological burden originating in nuclear fuel recycling, a new R&D strategy, the Adv.-ORIENT ( Advanced Optimization by Recycling Instructive Eleme nts) cycle was set forth. In this context, mutual separation of f-elements, such as minor actinide (MA)/lanthanide (Ln) and Am/Cm, are essential to enhance the MA (particularly 241Am) burning. Isotope separation before transmutation is also inevitably required in the case of some long-lived fission products (LLFPs) like 126Sn, 135Cs, etc. The separation and utilization of rare metal fission products (RMFPs: Ru, Rh, Pd, Tc, Se, Te, etc.) are offering a new direction in the partitioning and transmutation (P&T) field. 99Tc and 106Ru, well-known interfering nuclides in reprocessing, should be removed prior to the actinide stream. Separation of exothermic nuclides 90Sr, 137Cs as well as MA will significantly help to mitigate the repository tasks. A key separation tool is ion exchange chromatography (IXC) by a tertiary pyridine resin having soft donor nitrogen atoms. This method has provided individual recovery of pure Am and Cm products with a Pu/U/Np fraction from irradiated fuel in just a 3-step separation. A catalytic electrolytic extraction (CEE) method by Pd adatom has been employed to separate, purify and fabricate RMFP catalysts. Differently functioned ion exchangers, e.g., ammonium molybdophosphate (AMP), have been investigated for the separation of Cs +. Theoretical and laboratory studies on the isotope separation of LLFPs were begun for 79Se, 126Sn and 135Cs.

Selective Uptake of Cesium Ions on AMP-loaded Silica Gels

Ammonium molybdophosphate (AMP) was incorporated in the porous silica gels by successive impregnation with H3Mo12O40P and NH4NO3. The selective uptake properties of Cs+ on AMP-loaded silica gels (SCAMP) and the recovery of Cs+ have been studied by batch and column methods, respectively. The uniform incorporation of AMP in matrices was confirmed by the characterization with SEM/EPMA. The loading percentage of AMP crystals on silica gels increased with the repetition times of impregnation. The distribution coefficient of Cs+ on SGAMP was above 500 cm3/g even in the presence of 5 M (= mol/dm3) HNO3, while other nuclides were less than 20, indicating high selectivity of SGAMP toward Cs+. This ion exchanger is effective for the selective isolation of Cs+ from simulated high-level liquid wastes.

A facile regio- and stereoselective synthesis of β-aminosulfides from aziridines using ammonium-12-molybdophosphate

An efficient regio- and stereoselective synthesis of β-aminosulfides has been achived by treatment of aziridines with thiols in the presence of ammonium-12-molybdophosphate (AMP) as a heterogeneous catalyst.

A rapid and high-yielding synthesis of β-hydroxyselenides by regio- and stereoselective ring-opening of epoxides with benzeneselenol using ammonium-12-molybdophosphate

β-Hydroxyselenides have conveniently been synthesized within a short period of time and in excellent yields by regio- and stereoselective ring-opening of epoxides with benzeneselenol at room temperature in the presence of ammonium-12-molybdophosphate (AMP) as a heterogeneous catalyst.

A mild, rapid and highly regioselective ring-opening of epoxides and aziridines with acetic anhydride under solvent-free conditions using ammonium-12-molybdophosphate

A highly regioselective ring opening of epoxides and aziridines can be carried out efficiently with acetic anhydride to form the acetates of the corresponding 1,2-diols and 2-amino-alcohols, respectively, using ammonium-12-molybdophosphate (AMP) as a heterogeneous catalyst, at room temperature, in the absence of solvent.

Radiochemical Separation and Purification of 144Ce from Purex High-Level Waste

ABSTRACTA solvent extraction technique has been developed for the radiochemical separation and purification of 144Ce from Purex high-level waste (HLW). The feed solution initially was in contact with granulated ammonium molybdophosphate for the selective removal of cesium to reduce the gamma dose during the subsequent process. In the next step, uranium and plutonium were removed quantitatively by using 20% 2-ethylhexyl hydrogen 2-ethylhexyl phosphonate (KSM-17) in dodecane. The trivalent cerium present in the cesium-, uranium-, and plutonium-depleted raffinate was oxidized to its tetravalent state by using K2Cr2O7 and was extracted into KSM-17. The loaded cerium from the organic phase was stripped with 0.5 M nitric acid. Final decontamination from trace impurities such as 106Ru and 125Sb could be achieved by an additional cerium-extraction step with KSM-17 at pH 2, followed by its stripping with 0.5 M HNO3. About 10 mCi of cerium was separated from Purex HLW by using this technique. This method is amenable for automation and scale up.

Adsorption of cesium on a composite inorganic exchanger zirconium phosphate - ammonium molybdophosphate

The applicability of zirconium phosphate-ammonium molybdophosphate (ZrP-AMP) for the efficient removal of cesium from aqueous acidic solutions by adsorption has been investigated. The adsorption data analysis was carried out using the Freundlich, Dubinin-Raduskevich (D-R) and Langmuir isotherms for the uptake of Cs in the initial concentration range of 3.75.10-5-7.52.10-3 mol.dm-3 on the ZrP-AMP exchanger from nitric acid medium. The mean free energy (E) values for the adsorption of Cs were obtained from the D-R isotherm. Equilibrium adsorption values at different temperatures have been utilized to evaluate the change in enthalpy, entropy and free energy (ΔH°, ΔS°, ΔG°). The adsorption of cesium on the ZrP-AMP exchanger was found to be endothermic.

Separation of 137Cs from Acidic Nuclear Waste Simulant via an Engineered Inorganic Ion Exchanger

AbstractAn engineered ion exchange material has been prepared for the specific purpose of removing radioactive cesium from acidic waste. Separating the fission product 137Cs from the bulk of the nuclear waste stream is often advantageous because, after typical cooling times, this isotope is usually the primary source of gamma radiation dose. The engineered ion exchanger was prepared using ammonium molybdophosphate impregnated into hollow glass crystalline microspheres. The microspheres or cenospheres, are refractory compounds of silica and alumina that are derived from the fly ash produced in coal combustion. This paper describes equilibrium experiments that were conducted with the engineered ion exchanger and a simulated acidic waste solution. These tests indicate that the new material has a high capacity and selectivity for cesium in these matrices.

Extraction and determination of Cs in natural waters by ICP-MS after ion exchange separation

This article describes a novel and fast technique for the separation, preconcentration and determination of caesium in aqueous samples at sub-ppt levels using ion exchange separation and ICP-MS. The scheme is proposed for the extraction of radioactive caesium from the sample matrix. A new separation technique for the determination of caesium by inductively coupled plasma mass spectrometry is developed. Water samples with a pH less than 4 are loaded onto an ammonium molybdophosphate column at a flow rate of 8 mL min−1. Elution of Cs from the AMP is accomplished using sequential extraction by NH4OH (elutes AMP), H2O (elutes excess AMP) and finally HNO3 (elutes Cs). Preconcentration and separation of caesium from various sample matrices (sea-water and freshwater) was performed. Interferences (isobaric, polyatomic and matrix effects) were reduced using the developed protocol. Minimum detection limits for the determination of 133Cs in a 1 L sample of water were found to be 0.02 ng L−1 and 0.2 ng L−1 using an ELEMENT-2 and an ELAN-5000 ICP-MS, respectively.

Potassium hexacyanocobalt ferrate and ammonium molybdophosphate sorption bags for the removal of 137Cs from aqueous solutions and a simulated waste

AbstractIn the present study, the removal and immobilization of 137Cs from aqueous waste solutions and a simulated waste was investigated. Two inorganic ion‐exchange complexes: di‐potassium hexacyanocobalt(II)‐ferrate(II), K2CoFe(CN)6·xH2O (KCFC), and ammonium‐12‐molybdophosphate [(NH4)3PMo12O40·aq] (AMP), were charged separately into porous nylon bags (sorption bags) of 5 µm pore diameter. The first complex (KCFC) was prepared in our laboratory. The second (AMP) was used for comparison. Easy handling and increased potential for reuse characterize the sorption bag technique. The KCFC complex was investigated by thermal gravimetric analysis (TGA) and differential thermal analysis (DTA), porosity, infra‐red (IR) and X‐ray powder diffraction (XRD). The chemical and structural investigations revealed that the KCFC complex has adequate ion‐exchange capacity and high affinity for 137Cs. The sorption bag technique showed promising results for the removal of 137Cs from aqueous waste solutions. The KCFC bags showed the highest 137Cs removal (∼0.91 g g−1), at pH 8.5; AMP bags gave the highest 137Cs removal (∼0.97 g g−1) in 0.1 N HNO3 and 1.5 N HNO3, both with a waste: sorbent ratio of 80 cm3 g−1. Sorption data for both KCFC and AMP revealed a good fit to the Freundlich sorption isotherm. To assess the potential of sorption bags, the used bags were regenerated in different leachants and reused in further sorption investigations. 137Cs recovery from the used sorbents was ∼0.46 g g−1 using 6 N HCl as leachant for AMP, compared with ∼0.253 g g−1 for KCFC using 6 N NaCl. These results indicated stronger cesium immobilization in the KCFC complex. Copyright © 2003 Society of Chemical Industry

Application of a second order kinetic model for the preliminary design of an adsorption bed system using ammonium molybdophosphate–polyacrylonitrile for the removal of 137Cs from acidic nuclear waste solutions

Ammonium molybdophosphate (AMP) immobilized on polyacrylonitrile (PAN) is an engineered form of cesium selective sorbent material developed at the Czech Technical University in Prague. A form of a second order kinetic model is applied to experimental AMP–PAN breakthrough data. A system utilizing three fixed beds in series is described that allows for continuous nuclear waste processing at approximately 890 l/h. This process would yield a product stream that is below the NRC Class A low level waste limit for 137Cs, and would result in high activity waste volume reduction factors of approximately 2200 and 570 for liquid sodium bearing waste and dissolved calcine waste, respectively, which are currently stored at the Idaho National Engineering and Environmental Laboratory.