Nano Structured Metal Oxides as Potential Sorbents for 188W/188Re Generator: A Comparative Study

Nanostructured oxides of Ti, Zr, and Al were synthesized to evaluate their efficacy as sorbent matrices for the preparation of ¹⁸⁸W/¹⁸⁸Re generator. These oxides, in many respects, can improve the efficiency of the generator by providing better selectivity and enhanced capacity for ¹⁸⁸W, which arises from a higher surface area, surface energy, and surface charge, compared to the attributes of conventionally used bulk alumina. The performance of these materials, in the context of preparation of ¹⁸⁸W/¹⁸⁸Re generators, were compared with respect to sorption capacity for ¹⁸⁸W, shelf-life of the generator, purity, and quality of ¹⁸⁸Re for radiopharmaceutical applications.     

Tungsten and Rhenium Sorption Study on Alumina to Prepare 188W/188Re Generators

Abstract

Rhenium-188 is a radionuclide with favorable physical characteristics suitable for radiotherapeutic purposes (T_1/2 16.9 h, E_βmax 2.12 MeV; E_γ 155 keV (15%)) for radiotherapeutic purposes and can be continually obtained from ¹⁸⁸W/¹⁸⁸Re generator systems. The preparation conditions of an alumina based ¹⁸⁸W/¹⁸⁸Re generator are reported. Initially, the W and Re sorption behavior on alumina in NaCl and HCl medium was performed evaluating the following parameters: medium pH, alumina size particle, sorption capacity, and kinetic. Re-188 is not adsorbed in HCl and NaCl medium whereas W-188 is strongly adsorbed in both media at pH < 5. The strongest sorption of W was obtained in alumina with a particle size of 0.075–0.048 mm. The weight capacity of alumina is approximately 0.337 meq/g and the sorption equilibrium in static conditions is attained after 18 hours. This data was used to construct and evaluate alumina ¹⁸⁸W/¹⁸⁸Re-generators for a period of six months.     

Separation of No-Carrier-Added 188Re from Neutron-Irradiated Natural Tungsten

Abstract

Rhenium-188 has been determined to be a suitable therapy radiolable due to its unique half-life and β^? emission associated with 155 keV photons and chelation properties. ¹⁸⁸Re is obtained from the decay of parent ¹⁸⁸W in the form of a generator system while ¹⁸⁸W is produced by double neutron capture of ¹⁸⁶W. The yield of generators using alumina for separation is limited due to the low sorption capacity of sorbent. We have exploited precipitation as hydrous tungsten oxide in acid media and redissolution in alkaline media to separate ¹⁸⁸Re from tungsten. The optimized experimental conditions indicate the feasibility of a generator system based on this method.     

Preparation and evaluation of nano-crystalline titania as sorbent for 99Mo/99mTc generator

In the presented work, nano-crystalline titania (TiO₂) was synthesized and evaluated as a novel chromatographic sorbent for the preparation of the medical ⁹⁹Mo/^99mTc generator. TiO₂ was synthesized by dissolving TiCl₄.6H₂O with isopropyl alcohol to form a semisolid mass that was extensively dried and washed. The physicochemical parameters and surface area of the synthesized nano-crystalline TiO₂ were evaluated. TiO₂ was packed as a chromatographic column to study the sorption of ⁹⁹Mo-polymolybdate (VI) anionic solution by dynamic equilibrium. The maximum sorption capacity of ⁹⁹Mo was ~141±2mg Mo/g TiO₂, thereby confirming its suitability for using low specific activity ⁹⁹Mo for the preparation of ⁹⁹Mo/^99mTc generator. The elution performance of the prepared ⁹⁹Mo/^99mTc generator based on Ti-⁹⁹Mo was evaluated. It showed high radiochemical purity (≥ 97% TcO₄^?), high radionuclidic purity (≥ 99.99%^99mTc) and high chemical purity; all of these specifications show the suitability for use in nuclear medicine applications.     

Development of a 68Ge/68Ga Generator to Avail 68Ga in Organic Medium for Industrial Radiotracer Applications

A chromatographic ⁶⁸Ge/⁶⁸Ga generator using nano zirconia as the sorbent matrix was developed to avail ⁶⁸Ga in an organic medium for industrial radiotracer applications. Acetylacetone was used as the eluent for the extractive desorption of ⁶⁸Ga ions from the sorbent phase. The effect of varying the amount of acetylacetone on ⁶⁸Ga yield and achieving ideal experimental conditions were studied. The major advantage of this generator is its ability to deliver ready to use “industrial ⁶⁸Ga tracer” with > 90% yield and high radionuclidic and radiochemical purity. The performance of the generator remained consistent on repeated elutions over a period of 1 year.     

Bi-Functional Radiotheranostics of 188Re-Liposome-Fcy-hEGF for Radio- and Chemo-Therapy of EGFR-Overexpressing Cancer Cells

Epidermal growth factor receptor (EGFR) specific therapeutics is of great importance in cancer treatment. Fcy-hEGF fusion protein, composed of yeast cytosine deaminase (Fcy) and human EGF (hEGF), is capable of binding to EGFR and enzymatically convert 5-fluorocytosine (5-FC) to 1000-fold toxic 5-fluorocuracil (5-FU), thereby inhibiting the growth of EGFR-expressing tumor cells. To develop EGFR-specific therapy, ¹⁸⁸Re-liposome-Fcy-hEGF was constructed by insertion of Fcy-hEGF fusion protein onto the surface of liposomes encapsulating of ¹⁸⁸Re. Western blotting, MALDI-TOF, column size exclusion and flow cytometry were used to confirm the conjugation and bio-activity of ¹⁸⁸Re-liposome-Fcy-hEGF. Cell lines with EGFR expression were subjected to treat with ¹⁸⁸Re-liposome-Fcy-hEGF/5-FC in the presence of 5-FC. The ¹⁸⁸Re-liposome-Fcy-hEGF/5-FC revealed a better cytotoxic effect for cancer cells than the treatment of liposome-Fcy-hEGF/5-FC or ¹⁸⁸Re-liposome-Fcy-hEGF alone. The therapeutics has radio- and chemo-toxicity simultaneously and specifically target to EGFR-expression tumor cells, thereby achieving synergistic anticancer activity.     

Study of Chromatographic Separation of Cesium,Europium, and Cobalt on Different Types of Tungstocerate Column Matrices

Interactions of ¹³⁴Cs(I), ^152,154Eu(III), and ⁶⁰Co(II) ions from HCl acid solutions with tungstocerate(IV) gel matrices, dried at 50°C, have been individually investigated by the batch equilibration method. The selectivity sequence was found to be in the order: Cs(I) >Eu(III) >Co(II). The breakthrough capacities of 12‐tungstocerate(IV) for Cs(I), Eu(III), and Co(II) were found to be 1.00, 0.55, and 0.26 mmol/g of the sorbent, respectively. In addition, a mixture of these radionuclides [6.20 × 10^?3 M Cs(I), 3.53 × 10^?3 M Eu(III), and 1.4 × 10^?3 M Co(II)], in 150 ml of 0.02 M HCl solution was passed through 1‐g 12‐tungstocerate(IV) chromatographic column. Quantitative uptake of both ¹³⁴Cs(I) and ^152,154Eu(III) has been achieved, while only ?22% of ⁶⁰Co(II) has been retained. Then, quantitative elution of the retained fraction of Co(II) was achieved with 14 ml of 0.1 M HCl acid solution leaving Eu(III) and Cs(I) strongly retained onto the column. Quantitative elutions of Eu(III) and Cs(I) were achieved by passing 20 ml of 0.3 M HCl and 16 ml of 2 M HCl acid solutions, respectively.     

Adjusted pH for the Selective Separation of Cadmium from Lead by Nano-Active Silica-Functionalized-[Bmim+Tf2 N−] Ionic Liquid

A method is described for the selective separation and extraction of cadmium-lead from aqueous solutions by tuning the pH value between 1.0 and 7.0. A modified nano-active silica sorbent was loaded with 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide hydrophobic ionic liquid, [Bmim⁺Tf₂N^?] and used in this work. The pH value was found to play a significant role in the sorption capacity of Cd(II) and Pb(II). In pH 1.0, the metal capacity values were characterized as 1.40 and 0.30 mmol g^?1 for Cd(II) and Pb(II), respectively. In pH 7.0, Cd(II) and Pb(II) switched their capacity values to 0.65 and 1.00 mmol g^?1, respectively. An anion exchange mechanism was proposed in solution with pH 1.0 for exchange of chloroanionic cadmium species by [Tf₂N^?]. The sorptive separation processes of Cd(II) and Pb(II) were studied and evaluated under the influence of various controlling factors. The potential applications of modified nano-silica sorbent for selective sorptive removal and separation of Cd(II) from Pb(II) in water samples was successfully accomplished by adjusting the pH value of the contact solution between 1.0 and 7.0. The results of this study indicated an efficient extraction behavior of the two examined metal ions.     

An electroamalgamation approach to separate 47Sc from neutron-activated 46Ca target for use in cancer theranostics

Scandium-47 [T_½ = 3.35 d, E_β-(max.) = 600 keV, Eγ = 159 keV] is a relatively new radioisotope that holds tremendous potential for use in cancer theranostics. The radioisotope was produced by thermal neutron irradiation of enriched ⁴⁶Ca producing ⁴⁷Ca, which decays by β^? emission to ⁴⁷Sc. A viable method based on the selective electroamalgamation of Ca²⁺ ions has been developed for the clinical-scale separation of ⁴⁷Sc from ⁴⁷Ca. The overall yield of ⁴⁷Sc after the separation process was >80% and it was obtained with >99.9% radionuclidic purity in a form suitable for radiopharmaceutical preparation. This strategy holds promise for future clinical translation of this radioisotope.     

Comparative Assessment of Nanostructured Metal Oxides: A Potential Step Forward to Develop Clinically Useful 99Mo/99mTc Generators using (n,γ)99Mo

While the use of nanostructured metal oxides such as nanotitania, nanozirconia, nanoalumina, and mesoporous alumina, as column matrices constitutes a successful paradigm in the development of chromatographic ⁹⁹Mo/^99mTc generators using (n,γ)⁹⁹Mo, a comparative assessment of their properties is essential not only to determine the merits and bottlenecks of each sorbent but also to evaluate their usefulness commensurate with the specific activity of (n,γ)⁹⁹Mo obtained from different sources. Characteristics which were compared included the sorption capacity, zeta potential, shelf-life of the generator, radioactive concentration and purity of ^99mTc for radiopharmaceutical applications, and recovery of decayed Mo from spent generators. Mesoporous alumina was identified as the most suitable sorbent for ensuring sustainable production of clinical grade ⁹⁹Mo/^99mTc generators using low specific activity ⁹⁹Mo.     

Foamability of Detergent Solutions Prepared with Different Types of Surfactants and Waters

In the development of new detergent products, it is important to test the foaming behavior of different types of surfactants. Different types and concentrations of surfactant solutions prepared with three types of water are expected to present differences in their foamability. In this study, foam volumes produced by cetyl trimethyl ammonium bromide (CTAB; C₁₉H₄₂BrN), Tween 80^® (T80; C₆₄H₁₂₄O₂₆) and sodium dodecylsulfate (SDS; C₁₂H₂₅NaO₄S) aqueous solutions (0.5, 1.0 and 1.5%, w/v) were compared using a stirring system, rotating at 8,000, 9,500 and 13,500 rpm. The foamability produced by CTAB, SDS and T80 solutions, in a concentration range between 0.2 and 1.0% (w/v), prepared using deionized, hard and hypersaline water were also compared. Foam volumes were higher at a stirring speed of 9,500 rpm than at 8,000 rpm. However, the results obtained at 9,500 and 13,500 rpm were not significantly different. In general, SDS solutions produced higher foam volumes than CTAB and T80 solutions. Water characteristics did not seem to influence significantly the foamability of the three types of surfactants in the studied concentrations. These studies related with foaming behavior appear to be an important step in the pre-formulation of detergent products, particularly in cosmetics and pharmaceutics.     

Preparation of the Sulfonamide Containing Block Copolymer as Polymeric Sorbent for Removal of Mercury from Aqueous Solutions

A new sulfonamide containing polymeric sorbent for the removal of mercury ions from waste waters was prepared starting from poly(glycidyl methacrylate)-b-poly(ethylene glycol)-b-poly(glycidyl methacrylate) (PGMA- b -PEG- b -PGMA) triblock copolymer prepared by using the ATRP method. Epoxy groups on the block copolymer were functionalized with amino groups. Ammonia-functionalized PGMA- b -PEG- b -PGMA was treated with excess of benzenesulfonyl chloride to obtain a sulfonamide-based polymeric sorbent. The sulfonamide containing the polymeric sorbent with a 3.5 mmol · g^?1 total nitrogen content is able to selectively sorb mercury from aqueous solutions. The mercury sorption capacity of the resin is around 3.12 mmol g^?1 under non-buffered conditions. Experiments performed in identical conditions with several metal ions revealed that Cd(II), Pb(II), Zn(II), Fe(III), and Fe(II) also were extractable in quantities (0–0.45 mmol/g). The sorbed mercury can be eluted by repeated treatment with 4 M HNO₃ without hydrolysis of the sulfonamide groups.     

Fractional Separation of Hemicelluloses and Lignin in High Yield and Purity from Mild Ball-Milled Periploca sepium

Abstract

A novel three-step procedure for separation of hemicelluloses and lignin with high yield and purity was proposed in this study, where wood is mildly milled and successively extracted to produce three hemicellulosic and lignin fractions representing the total hemicelluloses and lignin in wood. The sequential treatments of the mild ball-milled Periploca sepium with 80% aqueous dioxane containing 0.05 M HCl at 85°C for 4 h, DMSO at 85°C for 4 h, and 8% NaOH at 50°C for 3 h resulted in a total release of over 85% of the original hemicelluloses and 86% of the original lignin. In particular, approximately 36% of the original hemicelluloses and 50% of the original lignin were separated during the first mild acidolytic hydrolysis process after low intensity milling. The structure of the acidic dioxane-, DMSO-, and alkali-soluble hemicellulosic and lignin fractions were elucidated using wet chemical analysis, FT-IR, and solution-state ¹H, ¹³C, and ³¹P NMR techniques. Results showed that both the mild ball milling and the mild acidolysis under the conditions given did not affect the separated lignin macromolecular structure. On the other hand, the mild acidolytic hydrolysis condition did cause substantial hemicellulosic depolymerization exception for a significant cleavage the ether linkages between lignin and hemicelluloses. The acidic dioxane-soluble lignin fraction was structurally different from the DMSO- and alkali-soluble lignin preparations and may originate mainly from the primary wall, while the alkali-soluble lignin preparation was mainly released from the secondary wall of Periploca sepium. Furthermore, it was found that the acidic dioxane-soluble hemicelluloses mainly contained more branched and less acidic arabinoxylans, and the 8% NaOH-soluble hemicellulosic fraction H₃ was both less branched and less acidic in structure, whereas the DMSO-soluble hemicelluloses were more acidic but less branched and consisted mainly of 4-O-methylglucuronoarabinoxylan.     

Characterization of Copper–Cobalt Ores and Quantification of Cu2+, Co2+, Co3+, and Fe3+ in Aqueous Leachates Using UV/Visible Spectrophotometry

Ultraviolet/visible (UV/vis) spectroscopy was used to determine qualitatively and quantitatively Cu²⁺, Co²⁺, Co³⁺, and Fe³⁺ in oxidized Cu–Co ore leachates. The mineralogical and chemical characteristics of the three oxidized Cu–Co ore samples considered were determined using Fourier transform infrared spectroscopy (FTIR), X-ray powder diffractometry (XRD), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), and X-ray fluorescence spectrometry (XRF). The results showed that Cu and Co in the samples were in the form of carrollite (Co₂CuS₄), malachite (Cu₂CO₃(OH)₂, and heterogenite (CoO(OH)). The samples contained (2.73% Cu and 0.19% Co), (2.82% Cu and 0.07% Co), and (0.03% Cu and 0.05% Co), respectively. Gangues were mainly constituted of quartz, goethite, and hematite. The ultraviolet/visible (UV/vis) results indicated that the wavelengths of absorbance of the metal ions in dilute ethylenediaminetetraacetic acid aqueous solution (pH ≈ 3.5) were Fe³⁺ (293 nm), Cu²⁺ (821 nm), Co³⁺ (344 nm), and Co²⁺ (512 nm). The molar concentrations of the metal ions obtained using the UV/vis method compared well with the results obtained using the atomic absorption spectroscopy (AAS) method. UV/vis spectroscopy was also used to monitor the conversion of Co³⁺ into Co²⁺ using different reducing agents. The results showed that the molar concentration of Co²⁺ in the aqueous solutions increased with the addition of reducing agents, of about 80.95% (copper foil), 61.22% (ferrous sulfate), and 20.35% (sodium sulfite), respectively.     

Separation of Carrier Free 90Y from 90Sr by Hollow Fiber Supported Liquid Membrane Containing Bis(2-ethylhexyl) Phosphonic Acid

The present article gives a comparative account of the efficiency of carrier-free ⁹⁰Y separation from ⁹⁰Sr by solvent extraction, flat sheet-supported liquid membrane (FSSLM) and hollow fiber-supported liquid membrane (HFSLM) methods using bis(2-ethylhexyl) phosphonic acid (PC88A) as the carrier extractant. The major focus of this work has been to develop the HFSLM method for the separation of Y(III) on a relatively large scale. The feed and receiver phase conditions were optimized by carrying out batch solvent-extraction studies. The extraction of Sr(II) by PC88A was negligible in the acidity range of 0.01–3 M HNO₃, whereas the extraction of Y(III) was significantly large at lower acidity (≤0.1 M HNO₃) with a separation factor (SF = D_Y/D_Sr) of 8.5 × 10⁴. HFSLM studies suggested selective and efficient transport of Y(III) into 3 M HNO₃ from a feed solution containing a mixture of Y(III) and Sr(II) at 0.1 M HNO₃. On the other hand, transport of Sr(II) was negligible in the receiver phase. The purity of the separated ⁹⁰Y was ascertained by paper chromatography and by half-life measurement. The radiation stability of the carrier was excellent as studied up to 1000 KGy dose.     

Heavy Metal Adsorption by Magnetic Hybrid-Sorbent: An Experimental and Theoretical Approach

This study examined the sorption and desorption behaviors of Cu²⁺ and Pb²⁺ ions, which were adsorbed on the vinyl benzene chloride divinylbenzene (VBC-DVB-OH) polymer and magnetic hybrid adsorbent (VBC-DVB-OH-Fe) at pH 5. Batch and fixed bed column experiments were performed to study practical applicability and the breakthrough curves were obtained. The experimental equilibrium data, suitably fitted by the Langmuir and Freundlich isotherms, have shown that ferric oxide loaded magnetic hybrid sorbent (VBC-DVB-OH-Fe) exhibits higher adsorption capacity than vinyl benzene chloride divinylbenzene (VBC-DVB-OH) polymer. The results indicate the following order to fit the isotherms for both metal ions: Langmuir > Freundlich for polymeric sorbent and Freundlich > Langmuir for VBC-DVB-OH-Fe. The maximum adsorption capacity of VBC-DVB-OH adsorbent is 26.39 mg/g for Pb²⁺ and 7.93 mg/g for Cu²⁺ whereas it is increased to 45.81 mg/g for Pb²⁺and 25.64 mg/g for Cu²⁺ by using VBC-DVB-OH-Fe adsorbent. A series of column experiments were carried out to determine the breakthrough curves. The regeneration efficiency of the column runs was determined using HCl (10% v/v). The elution efficiency was 90% for each adsorbent.     

Extraction relationship of Li+ and H+ using tributyl phosphate in the presence of Fe(III)

ABSTRACT

During the extraction of lithium from high Mg-containing salt lake brines by tributyl phosphate (TBP) in the presence of Fe(III), H⁺ is used to stabilize Fe(III). However, the distribution ratio of H⁺ (D_H) is 4–6 times higher than that of Li⁺ (D_Li), which affects the extraction of Li⁺ significantly. In this study, the competition mechanism between H⁺ and Li⁺ was investigated by spectral analysis and thermodynamic equilibrium. The extracted species are determined as HFeCl₄ · 2TBP and LiFeCl₄ · 2TBP for H⁺ and Li⁺, respectively. The apparent equilibrium constants are K_H = 799.8 and K_Li = 120.6, respectively. Both equilibrium constants and the distribution ratios for H⁺ and Li⁺ extraction show that extraction of H⁺ is stronger than Li⁺.     

Ion‐Exchange Separation of Pu from Macro Concentration of Th in HNO3 Medium

Abstract

Sorption behavior of Th and Pu from anion‐ as well as cation‐exchange resin was investigated from nitric acid medium by both batch and column methods. The anion‐exchange studies involved anionic nitrate complexes of Pu⁴⁺ and Th⁴⁺ sorbed onto DOWEX 1x4 resin (50–100 mesh), and the cation‐exchange studies involved the sorption of Pu³⁺ and Th⁴⁺ onto BIORAD AG 50Wx8 (50–100 mesh) or DOWEX 50Wx4 (50–100 mesh) resin. The batch data gave a separation factor (K _d,Pu/K _d,Th) of 22 for the anion‐exchange method and 0.017 for the cation‐exchange method at 3 and 2 M HNO₃, respectively. A two‐stage ion‐exchange separation method was developed for the quantitative separation of Pu (8 g/L) from a macro amount of Th (200 g/L) in nitric acid medium. The first step involved the quantitative sorption of plutonium from the mixture while about 90% of Th could be washed in 6 column volumes. The plutonium, eluted (as Pu³⁺) using 0.5 M HNO₃ + 0.2 M hydrazinium nitrate (HN) + 0.2 M hydroxyl ammonium nitrate (HAN), and the residual (～10%) Th were subsequently loaded onto a cation‐exchange column in the second step. Greater than 99% Pu was recovered with 2 M HNO₃ (in ～8 column volumes) containing 0.2 M HN + 0.2 M HAN. The final elution of thorium from the cation‐exchange column was achieved in about 6 column volumes of 1 M α‐hydroxy isobutyric acid. A (Pu, Th)O₂ fuel scrap sample was dissolved in 16 M HNO₃ containing 0.005 M HF and was used subsequently as the feed for the anion‐exchange column. The eluted Pu was subsequently loaded onto a cation‐exchange column for final purification. The recovery of plutonium and thorium was found to be >99% and >98%, respectively, while the respective decontamination factors were estimated to be 215 and 292.     

Development of Mo recovery and concentration column processes for production of 99Mo from accelerator-driven irradiation of aqueous uranyl-sulfate solution

ABSTRACT

Recovery and concentration columns were designed for separation of Mo from highly concentrated uranyl–sulfate solution. Molybdenum uptake on titania sorbent, from concentrated uranium solutions, is superior to alumina and enables use of low-enriched uranium (LEU, <20% U-235) for ⁹⁹Mo production. Compared to highly enriched uranium (HEU), LEU requires five times more uranium to produce the same amount of Mo. Isotherm parameters were examined for Mo, Te, and Tc. The VERSE (VErsatile Reaction SEparation) model was used to generate profiles for metal ion concentrations in the columns and determine the minimum column length required for 99.9% Mo capture. Column designs were verified with an irradiated uranyl sulfate solution in a pilot-scale process, where 1.4 Ci of ⁹⁹Mo was produced, recovered, and purified. Partitioning of fission products on titania columns is also presented.     

Translating Research for the Radiotheranostics of Nanotargeted 188Re-Liposome

Nanoliposomes are one of the leading potential nano drug delivery systems capable of targeting chemotherapeutics to tumor sites because of their passive nano-targeting capability through the enhanced permeability and retention (EPR) effect for cancer patients. Recent advances in nano-delivery systems have inspired the development of a wide range of nanotargeted materials and strategies for applications in preclinical and clinical usage in the cancer field. Nanotargeted ¹⁸⁸Re-liposome is a unique internal passive radiotheranostic agent for nuclear imaging and radiotherapeutic applications in various types of cancer. This article reviews and summarizes our multi-institute, multidiscipline, and multi-functional studied results and achievements in the research and development of nanotargeted ¹⁸⁸Re-liposome from preclinical cells and animal models to translational clinical investigations, including radionuclide nanoliposome formulation, targeted nuclear imaging, biodistribution, pharmacokinetics, radiation dosimetry, radiation tumor killing effects in animal models, nanotargeted radionuclide and radio/chemo-combination therapeutic effects, and acute toxicity in various tumor animal models. The systemic preclinical and clinical studied results suggest ¹⁸⁸Re-liposome is feasible and promising for in vivo passive nanotargeted radionuclide theranostics in future cancer care applications.