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.     

The production of higher alcohols from syngas using potassium promoted Co/Mo/A12O3 and Rh/Co/Mo/A12O3

The optimized compositions K(4.9)/Co(2.7)/Mo(6.4)/A1₂0₃(gamma) and K(1.2)/ Rh(1.1)/Co(0.6)/Mo(5.7)/A1₂0₃(gamma) are both productive catalysts for higher alcohols. The incorporation of rhodium into the K/Co/Mo/A1₂0₃-system allows the space-time-yield for alcohols to be increased from 0.37 g alcohols (g catalyst)^–1 h^–1 to 1.1 g alcohols (g catalyst)–1 h–1. In addition, the higher productivity can be achieved with the rhodium-type catalyst at a lower reaction temperature (45°C lower), and so a higher selectivity to alcohols is observed. Potassium is a key promoter in both catalyst systems, and shifts the distribution of oxygenates towards higher alcohols. In IR measurements it is found that potassium stimulates bands for adsorbed CO around 1885 cm–. These bands are small for the K/Co/Mo/A1₂0₃ system, but are greatly stimulated by the incorporation of rhodium. It is suggested that these bands are indicative of the sites used to catalyze higher alcohols, thereby explaining the promotional effect of rhodium in the K/Co/Mo/A1₂0₃ catalyst system. Previous workers have suggested that the less-electron-rich sites (ionic) are important for methanol synthesis, while the more electron-rich sites (metallic) are important for higher alcohols and hydrocarbons synthesis. The IR measurements and reactivity data support these suggestions.     

Photoanodic response of iron oxide electrode in aqueous solution and its application to Pb removal under visible light irradiation

The iron oxide electrode was prepared from thermal oxidation of iron at 600 °C for 3 h in air atmosphere. This electrode with the structure of Fe₃O₄ and α-Fe₂O₃ showed the response of photoanodic current to the light with wavelength shorter than 600 nm. The band gap energy of this electrode was 1.99 eV. The onset potential of distinct steady photocurrent and also the flatband potential were 0.80 and 0.09 V vs. Ag/AgCl, respectively, in 0.1 M HNO₃ aqueous solution. The cell consisting of the iron oxide photoanode in HNO₃-Pb(NO₃)₂ and the graphite cathode in H₂SO₄-Ce(SO₄)₂ caused the PbO₂ deposit on the surface of the former electrode due to visible light irradiation without application of voltage. By holding the potential of this electrode at more positive value than 0.90 V, the photoanodic removal rate of Pb²⁺ in HNO₃-Pb(NO₃)₂ solution was higher than that observed when Ce⁴⁺ was used as electron acceptor.     

A study of active sites for alkene and alkane oxidation over Mo and V mixed oxide catalysts using 18O tracer and Raman spectroscopy

The oxygen ions of MoO₃, V₂O₅, -VOPO₄, -Mg₂V₂O₇, -CoMoO₄and -Bi₂Mo₃O₁₂were exchanged with ¹⁸O via a reduction–oxidation method and the catalytic oxidation of alkene or alkane using ¹⁸O₂. The Raman bands of the catalysts shifted to lower frequencies by the exchange with ¹⁸O tracer. With MoO₃, V₂O₅, -VOPO₄and -Mg₂V₂O₇, the weak oxygen bonds were active to exchange, i.e., to be active for the oxygen insertion and oxidation reactions, but the strong bonds were less active. The results of exchange features on -Bi₂Mo₃O₁₂catalyst indicate that some sets of two lattice oxygen ions in a twin tetrahedra seem to be good for fitting and bonding with allyl intermediates.     

99mTc-HDP Labeling—A Non-Destructive Method for Real-Time Surveillance of the Osteogenic Differentiation Potential of hMSC during Ongoing Cell Cultures

99-Metastabil Technetium (^99mTc) is a radiopharmaceutical widely used in skeletal scintigraphy. Recent publications show it can also be used to determine the osteogenic potential of human mesenchymal stem cells (hMSCs) by binding to hydroxyapatite formed during bone tissue engineering. This field lacks non-destructive methods to track live osteogenic differentiation of hMSCs. However, no data about the uptake kinetics of ^99mTc and its effect on osteogenesis of hMSCs have been published yet. We therefore evaluated the saturation time of ^99mTc by incubating hMSC cultures for different periods, and the saturation concentration by using different amounts of ^99mTc activity for incubation. The influence of ^99mTc on osteogenic potential of hMSCs was then evaluated by labeling a continuous hMSC culture three times over the course of 3 weeks, and comparing the findings to cultures labeled once. Our findings show that ^99mTc saturation time is less than 0.25 h, and saturation concentration is between 750 and 1000 MBq. Repeated exposure to γ-radiation emitted by ^99mTc had no negative effects on hMSC cultures. These new insights can be used to make this highly promising method broadly available to support researchers in the field of bone tissue engineering using this method to track and evaluate, in real-time, the osteogenic differentiation of hMSC, without any negative influence on the cell viability, or their osteogenic differentiation potential.     

Comparative Preclinical Evaluation of Peptide-Based Chelators for the Labeling of DARPin G3 with 99mTc for Radionuclide Imaging of HER2 Expression in Cancer

Non-invasive radionuclide imaging of human epidermal growth factor receptor type 2 (HER2) expression in breast, gastroesophageal, and ovarian cancers may stratify patients for treatment using HER2-targeted therapeutics. Designed ankyrin repeat proteins (DARPins) are a promising type of targeting probe for radionuclide imaging. In clinical studies, the DARPin [^99mTc]Tc-(HE)₃-G3 labeled using a peptide-based chelator His-Glu-His-Glu-His-Glu ((HE)₃), provided clear imaging of HER2 expressing breast cancer 2–4 h after injection. The goal of this study was to evaluate if the use of cysteine-containing peptide-based chelators Glu-Glu-Glu-Cys (E₃C), Gly-Gly-Gly-Cys (G₃C), and Gly-Gly-Gly-Ser-Cys connected via a (Gly-Gly-Gly-Ser)₃-linker (designated as G3-(G₃S)₃C) would further improve the contrast of imaging using ^99mTc-labeled derivatives of G3. The labeling of the new variants of G3 provided a radiochemical yield of over 95%. Labeled G3 variants bound specifically to human HER2-expressing cancer cell lines with affinities in the range of 1.9–5 nM. Biodistribution of [^99mTc]Tc-G3-G₃C, [^99mTc]Tc-G3-(G₃S)₃C, and [^99mTc]Tc-G3-E₃C in mice was compared with the biodistribution of [^99mTc]Tc-(HE)₃-G3. It was found that the novel variants provide specific accumulation in HER2-expressing human xenografts and enable discrimination between tumors with high and low HER2 expression. However, [^99mTc]Tc-(HE)₃-G3 provided better contrast between tumors and the most frequent metastatic sites of HER2-expressing cancers and is therefore more suitable for clinical applications.     

Effect of thermal treatment on states of molybdenum in Mo/H–ZSM-5 catalyst for methane dehydroaromatization: ESR and UV–VIS study

Valence and coordination states of molybdenum ions formed upon thermal treatment of Mo/H–ZSM-5 catalyst for methane dehydroaromatization in Ar and Ar/CH₄ media at 573–973 K have been studied by ESR and UV–VIS spectroscopy. For comparison, the characteristic ESR spectra of thermolyzed bulk ammonium heptamolybdate have been studied and analyzed in detail. The nature of earlier observed Mo⁵⁺ ions has been verified, and new paramagnetic states of molybdenum in Mo/H–ZSM-5 catalysts have been detected: Mo³⁺ ions, and Mo⁵⁺ ions in tetrahedral coordination with delocalization of unpaired electron to Al and H or Al and N atoms.     

Study on relationship between the concentration of hydrocarbon groups in heavy oils and their structural parameter from H NMR spectra

More than 60 heavy oils samples, belonging to the hydrogen adding tail oil, catalytic oil slurry, catalytic heavy oil slurry and catalytic heavy tar waxy oil, which taken from different processing units in Nanjing Refinery, are analysed by ¹H NMR and column chromatography. The analytical data of the heavy oils by two methods are compared and correlated, while good relationships between the specific area proton's percentage in ¹H NMR spectra and the contents of paraffinic and alicyclic hydrocarbons ((P+N)%), aromatic hydrocarbons (A%) are found. Our ¹H NMR method in calculating the amount of (P+N) and A in heavy oils proved fast, convenient and reliable.     

Silkworms’ feces-based activated carbons as cheap adsorbents for removal of cadmium and methylene blue from aqueous solutions

Activated carbon samples, ACs, were obtained from silkworms’ feces via chemical activation method. Many activating agents including the new ones KCl, CrCl₃ and TiCl₄ were compared. Acidic and basic oxidic groups in addition to aromatic tertiary and secondary amines have been detected on the surface of produced ACs. Furthermore, microporous solids furnishing high internal specific surface area, ranging between 1000 and 2000 m²/g, and total pore volume up to 0.85 cm³/g were obtained. TiCl₄ resulted in the solid possessing the highest area and pore volume. The obtained solids showed high efficiency in removing methylene blue and cadmium from their aqueous solutions. Adsorption capacity of sample AC/TiCl₄ is 461 mg/g of MB at pH = 10, and 62.6 mg/g of Cd²⁺ at pH = 8. The nature of the formed microporous texture and the prevailing surface oxidic groups are the main controlling parameters for the observed high efficiency toward both adsorbates.     

Modification and magnetization of MOF (HKUST-1) for the removal of Sr2+ from aqueous solutions. Equilibrium,kinetic and thermodynamic modeling studies

In this research, metal-organic framework MOF(HKUST-1) was synthesized, magnetized and modified by hexacyanoferrate in order to prepare an efficient adsorbent for the removal of Sr²⁺ from aqueous solutions. The synthesized adsorbent was characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy, thermal methods (TG-DTG[Themogravimetry- Derivative Theromogravimetry]), Fourier transform infrared (FTIR) spectroscopy, Brunauer–Emmett–Teller (BET) surface area and scanning electron microscopy (SEM). The non-magnetized (MOF/KNiFC[potassium nickel hexacyanoferrate]) and magnetized (MOF/Fe₃O₄/KNiFC) adsorbents were then employed for the removal of Sr²⁺ from aqueous solutions. The adsorption capacity of 110 and 90 mg.g^?1 was obtained, respectively, for MOF/KNiFC and MOF/Fe₃O₄/KNiFC. The adsorption process was kinetically fast and the equilibration was established within 45 min. The magnetic capability of the adsorbent examined by the vibrating sample magnetometer (VSM) technique indicated that the used adsorbent was capable of separating from the solution by applying an external magnetic field. The adsorbent showed good selectivity toward Sr²⁺ in the presence of Cs⁺, Na⁺, Mg²⁺, Ca²⁺ and Ba²⁺. The regenerated adsorbent retained more than 90% of its initial capacity. Different isotherm models including Langmuir, Freundlich, Tempkin, Sips and Redlich–Peterson were employed to examine the applicability of the isotherms to the experimental data. It was concluded that the data was best fitted to the Langmuir isotherm model. The thermodynamic parameters showed that the process was endothermic.     

Process development and modeling of pyruvate recovery from a model solution and fermentation broth

The mono- and bi-polar electrodialysis processes for pyruvate recovery and pyruvic acid generation, respectively, were examined in order to determine their feasibility for application in the pyruvate production process. Under optimum process conditions (constant current mode i = 39.7 A m⁻², pyruvate model solution c_p = 50 g dm⁻³ in the monopolar electrodialysis experiment pyruvate flux reached 367 g m⁻² h⁻¹ and specific energy consumption was 1.4 kWh kg⁻¹. In the bi-polar electrodialysis experiment under optimum process conditions (constant current mode i = 9.6 A m⁻², pyruvate model solution c_p = 48 g dm⁻³, pyruvate flux reached 125 g m⁻² h⁻¹ and specific energy consumption was 1.5 kWh kg^-1. Generally speaking, performances of the bi-polar electrodialysis were equal to the best process conditions observed with mono-polar electrodialysis. On the other hand, current densities investigated in the bi-polar electrodialysis experiments were four-fold lower than those applied in the mono-polar electrodialysis experiments. Additionally, a mathematical model to represent the ion and water transport behavior of an electrodialysis process for concentrating pyruvic acid under the influence of different current density was developed. Estimation of both the model parameters and model validation were demonstrated in the work.     

Application of Tetraphenyl- and Ethyltriphenylphosphonium Salts for Separation of Reactive Dyes from Aqueous Solution

The decolorization efficiency of four anionic dyes dissolved in aqueous solution using two quaternary phosphonium salts, ethyltriphenylphosphonium bromide, and tetraphenylphosphonium bromide, has been investigated by spectroscopic measurements in neutral, acidic and basic media. The NMR studies suggest possible formation of ion pairs of tetrasubstituted phosphonium salts with the reactive dyes. According to the results, the tetraphenylphosphonium bromide, which contains a more hydrophobic and bulky cation, exhibited a stronger tendency to associate with the dyes.     

Development of novel adsorbent materials for recovery and enrichment of uranium from aqueous media

A new polymeric adsorbent bearing both hydrophilic groups providing swelling in water and amidoxime groups for chelating with uranyl ions (UO₂²⁺), has been developed and its adsorptive ability for recovering uranium from aqueous media has been investigated. The polymers obtained by irradiating the solution of polyethylene glycol (PEG) in acrylonitrile (AN) are defined as interpenetrating polymer networks (IPNs) and the adsorbent has been obtained by applying the amidoximation reaction to the IPNs with a conversion ratio of ∼ 60%. Kinetics of the conversion reaction of the cyano (CN) group to the amidoxime (HONCNH₂) group has been studied by reacting with hydroxylamine (NH₂OH) solution at a molar ratio of NH₂OH/CN = 1.25 in aqueous media at three different temperatures, 30, 40, and 50°C, for 3–4 days. The degree of amidoximation ratio was determined by UO₂²⁺ ion adsorption and FTIR spectrometry and the UO₂²⁺ ion adsorption values were found by both UV and gamma spectrometry and also by gravimetry. It was found that the polymeric adsorbent has a very high adsorption ability for uranium and quite a good stability in aqueous media. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2475–2480, 1997     

Nano-Mg(OH)2 platelets coated flexible polyurethane foam for fast and environment-friendly removal of Cu2+ from aqueous solution

In this study, flexible polyurethane foam (FPUF) was successfully coated with nano-Mg(OH)₂ platelets. Due to the strong interaction between chitosan and nano-Mg(OH)₂, it was possible to yield modified foam with a weight-gain of up to 15 wt% by depositing one chitosan layer and one nano-Mg(OH)₂ layer. Meanwhile, the adsorption isotherms of Cu²⁺ on FPUF covered with 10 wt% coating (FPUF-10) shows the Langmuir behavior. It was found that for the FPUF-10, the removal % for Cu²⁺ after 30 min and 50 min treatment were 86% and 90%, respectively. Moreover, the maximum removal % could reach up to 95%.     

Sodium molybdate—a possible alternate additive for sodium dichromate in the electrolytic production of sodium chlorate

Sodium dichromate is commonly used in sodium chlorate production to maintain high current efficiency; however, it is also a well documented carcinogen. To reduce the environmental impact, identification of a suitable alternative with similar buffering characteristics to dichromate and without adverse effect on the electrolytic performance of sodium chlorate production is important; sodium molybdate is a good candidate. Molybdate ion and its conjugated acid work as a buffer pair at pH 5–6, a lower and slightly narrower pH window than the typical buffer region of dichromate. Nonetheless, the molybdate buffer works effectively during the electrolytic process by maintaining pH at 5.9. Although the use of molybdate buffer will lower the overpotential of hydrogen evolution reaction (HER) by 100 mV, the average off-gas oxygen content is noticeably compromised at 3.6–4.6%, measured using a pilot cell operated at 3 kA m⁻²and 80 °C during a 3-day trial. The resulting current efficiency of 91 92% is significantly lower than when dichromate is employed as the process additive (> 96%). Mixtures of different dichromate and molybdate ratio were also investigated in terms of the resulting cathode surface potential.     

高炉渣余热回收协同转化生物质制氢

高炉渣是钢铁生产过程的主要副产品,是一种多元金属熔体,具有大量显热并能促进焦油及甲烷等低分子碳氢化合物的催化转化。鉴于此本文提出通过干法离心粒化技术将液态炉渣制备成液-固过渡态的高温炉渣颗粒,作为生物质气化热载体,利用炉渣中多种金属矿物对大分子的解构、断键和分解的催化作用,提高气化反应的选择性,实现对炉渣显热的回收和转换,将低品位的液态炉渣余热转换成高品位的氢能。通过气化实验,对影响气化产物分布及气体组成的主要因素进行考察,结果表明：高炉渣在促进焦油分解和碳氢化合物重整方面表现出良好的催化性能,增加热载体炉渣颗粒温度,减小颗粒粒径能够减小炉渣表面积炭,降低气化产物中焦油产率和提升富氢气体品质,在最佳工况下（选用粒径小于2 mm,温度为1200℃的高炉渣颗粒作为热载体）,气化产物中焦油含量仅为2.52%,气体产率达到1.65 m³·kg^-1,富氢气体中H₂含量可达53.22%。     

Three-dimensional g-C3N4/MgO composites as a high-performance adsorbent for removal of Pb(II) from aqueous solution

ABSTRACT

A novel, three-dimensional material of g-C₃N₄/MgO was prepared by pyrolysis method. The adsorption behavior for Pb(II) onto g-C₃N₄/MgO was systematically investigated. The adsorption experiments confirmed that the g-C₃N₄/MgO exhibited remarkable adsorption performance owing to its rough morphology and abundant active sites on the surface. The maximum adsorption capacities for Pb(II) reached to 220.3, 226.2 and 235.1 mg/g at 308 K, 318 K and 328 K, respectively. The optimum adsorbent dosage was 1.0 g/L. The adsorption kinetics and isotherm could be well described by the pseudo-second-order model and Langmuir isotherm model, respectively. The adsorption process was spontaneous and endothermic.     

Lignocellulosic jute fiber as a bioadsorbent for the removal of azo dye from its aqueous solution: Batch and column studies

The feasibility of the use of jute fiber for the adsorption of azo dye from an aqueous solution was evaluated with batch and fixed‐bed column studies. The batch studies illustrated that dye uptake was highly dependent on different process variables, namely, the pH, initial dye concentration of the solution, adsorbent dosage, contact time, ionic strength, and temperature. The exothermic and spontaneous nature of adsorption was revealed from thermodynamic study. The equilibrium adsorption data were highly consistent with the Langmuir isotherm and yielded an R² value of 0.999. Kinetic studies divulged that the adsorption followed a pseudo‐second‐order model with regard to the intraparticle diffusion. In the column studies, the total amount of adsorbed dye and the adsorption capacity decreased with increasing flow rate and increased with increasing bed height and initial dye concentration. Also, the breakthrough time and exhaustion time increased with increasing bed depth but decreased with increasing flow rate and influent dye concentration. The column performances were predicted by the application of the bed‐depth service time model and Thomas model to the experimental data. The virgin and dye‐adsorbed jute fiber was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy analyses. The investigation suggested that jute fiber could be applied as a promising low‐cost adsorbent for dye removal. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013