Mo Extraction Research Articles

Substitution influence of halo polyurethane foam on the removal of bismuth, cobalt, iron and molybdenum ions from environmental samples

Abstract Polyurethane foam was modified by the addition of halogen atoms and amino groups into the foam matrix in order to increase its polarity for the sorption of ionic species. The halo-modified sorbents (X-PUFs, X = Cl, Br or I) were characterized using FTIR, UV/Vis and Raman spectroscopy, EA, XRD and SEM. The average values of pHZCP, maximum value of ∆pH (pH 9) and bulk DC conductivity for X-PUFs are 3.8, −1.9 and 2.6 × 10−5 Ω−1 cm−1, respectively. The activity of the surface functional groups of X-PUFs were evaluated by the extraction of Bi(III), Co(II), Fe(III) and Mo(III) ions and extraction conditions including pH, shaking time, flow rate, temperature and initial metal concentration were optimized. Maximum extraction of those ions was achieved as their thiocyanate complexes in acidic medium (pH 1–3, 5–6 and 1.5–2 mol L−1 H2SO4) within 1–30 min. A perfect isotherm curve with almost zero intercept (0.008), good correlation coefficient R2 (0.973) was obtained. The values of LOD, LOQ and RSD (n = 6) for the determination of Bi(III), Co(II), Fe(III) and Mo(III) ions are 2 ng L−1, 7 ng L−1 and 0.75%, respectively. The sorption capacities of the tested metal ions onto Cl-PUF, Br-PUF and I-PUF are 0.16, 0.14 and 0.14 mmol g−1, respectively. The accuracy of the procedure was verified by the analysis of food, ground water and pharmaceutical samples with recovery and average RSD values of 99–100% and 2.39%, respectively.

Optimization of Callus Induction and Cell Suspension Culture of Betula pendula Roth for Improved Production of Betulin, Betulinic Acid, and Antioxidant Activity

This study aimed to establish an in vitro protocol for callus induction and cell suspension cultures of silver birch (Betula pendula Roth) and to assess the antioxidant activity of cell extract and the accumulation of betulin (B) and betulinic acid (BA). Callus was induced from the inner bark of stems on Gamborg (B5) and Nagata-Takebe (NT) media, and 23 different concentrations of growth regulators were tested. NT medium with 2.5 mg L−1 2,4-dichlorophenoxyacetic acid and 0.5 mg L−1 6-benzylaminopurine was optimal for callus induction. Cell suspension cultures were developed to improve cell growth and metabolite production under different concentrations of NT vitamins. Methanolic cell extracts indicated that the BA content of callus increased from 1 to 9 mo, with a maximum 2.01 mg g−1 (dry weight [DW]) at 9 mo. The highest level of B observed in cell suspension cultures (0.96 mg g−1 DW) was obtained on medium supplemented with 4× NT vitamins. The highest antioxidant activities of the 1,1-diphenyl-2-picrylhydrazyl free radical, 77 and 76%, were found in callus extract at 9 mo and cell extract in the 4× NT vitamin treatment, respectively. In conclusion, the use of NT medium supplemented with 4× NT vitamins effectively increased cell growth and the accumulation of B, BA, and antioxidant activity in cell suspension cultures of B. pendula.

Sequential biological process for molybdenum extraction from hydrodesulphurization spent catalyst

Spent catalyst bioleaching with Acidithiobacillus ferrooxidans has been widely studied and low Mo leaching has often been reported. This work describes an enhanced extraction of Mo via a two stage sequential process for the bioleaching of hydrodesulphurization spent catalyst containing Molybdenum, Nickel and, Aluminium. In the first stage, two-step bioleaching was performed using Acidithiobacillus ferrooxidans, and achieved 89.4% Ni, 20.9% Mo and 12.7% Al extraction in 15 days. To increase Mo extraction, the bioleached catalyst was subjected to a second stage bioleaching using Escherichia coli, during which 99% of the remaining Mo was extracted in 25 days. This sequential bioleaching strategy selectively extracted Ni in the first stage and Mo in the second stage, and is a more environmentally friendly alternative to sequential chemical leaching with alkaline reagents for improved Mo extraction. Kinetic modelling to establish the rate determining step in both stages of bioleaching showed that in the first stage, Mo extraction was chemical reaction controlled whereas in the subsequent stage, product layer diffusion model provided the best fit.

Effect of Mass Transfer Resistance of Polymeric Surfactant on Transport of Metal through Bulk Liquid Membrane Interface

This research work deals with an investigation on the reduction of mass transfer coefficient due to the presence of polymeric surfactant/ polycondensate layer in the liquid membrane. Mo(VI) is chosen as target species which are to be removed from feed solution using Bulk Liquid membrane (BLM) in presence of polymeric surfactant and extractant. Mathematical model is developed for simulation of kinetics of Mo(VI) extraction using BLM. Study reveals that for efficient Mo(VI) extraction, reduction of stripping rate is not at all desirable. Abil EM 90 is found best suitable polymeric surfactant as it has least mass transfer resistance of Mo(VI) transport in strip phase. This study is very useful for selecting suitable polymeric surfactant/ polycondensate layer for stabilising liquid emulsion membrane for metal extraction/recovery purpose.

Groundwater nitrate contamination: Assessment and treatment using Moringa oleifera Lam. seed extract and activated carbon filtration

The present research evaluates the groundwater nitrate concentration of the Maringá region (Paraná State, Brazil) aiming at nitrate removal by coagulation/flocculation using a natural coagulant obtained from the seeds of the Moringa oleifera Lam. plant (MO) combined with an activated carbon filter. Groundwater samples were collected in Maringá City metropolitan area and characterized by physicochemical analyses. The results showed groundwater NO3− concentrations ranging from 0–60 mg NO3− L−1. Thus, the nitrate variation in the water used in the coagulation/flocculation assays lay between 10–60 mg · L−1 of NO3−. In these assays both aqueous and saline MO raw extracts were added (concentrations between 0.25–11 g · L−1). Coagulation/flocculation treatment with aqueous MO extract presents nitrate removal of 73.3 %, and saline MO extract presents 85.4 %. The source that presented the highest nitrate concentration along with the ideal MO concentration in the coagulation/flocculation process was used for the coagulation/flocculation process followed by activated carbon filtration. The treatment with MO combined with the filter met Brazilian, American, and international potability standards for nitrate and turbidity. The present study reveals the presence of nitrate in the groundwater of the area and also enables new procedures for treating this kind of water in small rural properties and needy communities.

Anti Proliferative Properties of Melissa officinalis in Different Human Cancer Cells.

Medicinal plants, especially examples rich in polyphenolic compounds, have been suggested to be chemopreventive on account of their antioxidative properties. Melissa officinalis L. (MO), an aromatic and medicinal plant, is well known in thios context. However, toxicity against cancer cells has not been fully studied. Here, we investigated the selective anticancer effects of an MO extract (MOE) in different human cancer cells. a hydro-alcoholic extract of MO was prepared and total phenolic content (TPC) and total flavonoid content (TFC) were determined by colorimetric assays. Antioxidant activity was determined by DPPH radical scavenging activity. MTT assays were used to evaluate cytotoxicity of different doses of MOE (0, 5, 20, 100, 250, 500, 1000 μg/ml) towards A549 (lung non small cell cancer cells), MCF-7 (breast adenocarcinoma), SKOV3 (ovarian cancer cells), and PC-3 (prostate adenocarcinoma) cells. Significant (P<0.01) or very significant (P<0.0001) differences were observed in comparison to negative controls at all tested doses (5-1000 μg/ml). In all cancer cells, MOE reduced the cell viability to values below 33%, even at the lowest doses. In all cases, IC50 values were below 5μg/ml. The mean growth inhibition was 73.1%, 86.7%, 79.9% and 77.8% in SKOV3, MCF-7 and PC-3 and A549 cells, respectively. Our results indicate that a hydro-alcoholic extract of MO possess a high potency to inhibit proliferation of different tumor cells in a dose independent manner, suggesting that an optimal biological dose is more important than a maximally tolerated one. Moreover, the antiprolifreative effect of MO seems to be tumor type specific, as hormone dependant cancers were more sensitive to antitumoral effects of MOE.

Extraction of metal thiocyanate complexes in a water-potassium bis (alkylpolyoxyethylene) phosphate-ammonium sulfate segregating system

Dependence of Fe(III), Zn(II), Co(II), Cu(II), Cd(II), and Mo(VI) extraction at concentration of 0.01 mol/L in a water-potassium bis-(alkylpolyoxyethylene) phosphate (Oxyphos B)-ammonium sulfate system on NH4SCN and H2SO4 concentration was studied. Conditions for the quantitative recovery of Fe(III), Zn(II), Cu(II), Co(II), and Mo(VI) were found. Spectrophotometric characteristics of extracted Cu(II), Co(II), and Fe(III) thiocyanate complexes were studied.

Purification of bismuthinite concentrate by selective electro-oxidation of molybdenite

The flotation separation is the general method to recover molybdenite from a concentration containing molybdenite and bismuthinite, although the whole circuit could be long and complicated. In this paper, a novel selective electro-oxidation of molybdenite process has been introduced and systematically investigated for bismuthinite purification. It was found that Mo could be selectively separated by the electro-oxidation method under the conditions of pH not less than 9.0 and the applied potential at between 3.0V and 4.0V, by this circumstance Bi was hard to extract. The effects of NaCl concentration, liquid/solid ratio and stirring speed on electro-oxidation leaching were investigated. Optimum leaching conditions were found as follows: operated at room temperature, leaching time=2.5h, NaCl concentration=4mol/L, pH=9–10, applied potential=3.4V, liquid/solid ratio=30mL/g, stirring speed=400rpm. Under these conditions, Mo extraction yield was obtained at 98.4% and 99.3% of Bi remained in the residue. The chlorine evolution reaction at the anode which was effected by leaching pH was studied by linear scan voltammetry. Mechanism of electro-oxidation leaching of Mo was studied by cyclic voltammetry. Furthermore, the mass transfer of Mo from leachate to organic phase was introduced, and the two phase transfer could obtain as high as 99.6%.

Selective extraction of Mo from a Ni–Mo ore using pressure alkaline leaching

Pressure alkaline leaching of a Ni–Mo ore for selective extraction of Mo was investigated. Thermodynamic analysis of Mo–S–H2O and Ni–S–H2O indicated that pressure alkaline leaching of Ni–Mo ore is technically feasible for selective extraction of Mo. The effects of NaOH concentration, temperature, leaching duration, liquid/solid ratio and particle size on the leaching of Mo and Ni were studied. The results showed that Mo extraction was improved significantly by NaOH concentration, temperature or leaching duration, but not by liquid/solid ratio or particle size. The optimum parameters were: NaOH concentration of 100g/L, temperature of 120°C, leaching duration of 5h, liquid/solid ratio of 3mL/g and particle size of 74–98μm. Under these conditions, about 95.7% of Mo and 1.3% of Ni could be extracted.

English

The study evaluated the effect of Moringa oleifera aqueous leaf extracts on follicle stimulating hormone and serum cholesterol in Wistar rats. Thirty six (36) mature Wistar rats (20 male and 16 female rats) were used. The male rats were grouped into four groups with five animals each, while the female animals were grouped into four made up of four animals per group, on the basis of their body weights. Graded doses (1, 5 and 10 g) aqueous extract were prepared from the Mo leaves as the test samples. In the first phase: The test extract was administered orally after acclimatization to individual groups: A-male and E-female rats, 1%; groups B-male and F-female rats, 5%; and groups C-male and F-female rats, 10%. These test groups also had rat chow and water ad libitum. The second phase of the experiment involved mating the male and female animals that had the same dose of M. oleifera extract. The results show that the mean body weights of the male rats increased significantly after treatment (p&lt;0.05). The study also reveals that the administration of M. oleifera extract at different doses for the male and female rats differed significantly (p&lt;0.05) with that of the control in raising the level of follicle stimulating hormone (FSH). A-1% increased by 38.52% while B-5% decreased (-21.20%); E-1% decreased (-12.96%) and F-5% (-25.64%). After mating, the % increase in FSH concentration was observed to be significantly (p&lt;0.05) difference. Administration of Mo extract at different levels for the male and female rats differed significantly (p&lt;0.05) in this study as compared with the control in lowering the total serum cholesterol of the rats. A-1% increased total cholesterol by 1.10%, while B-5% revealed a decrease of (-10.99%). &nbsp; Key words: Moringa oleifera, follicle stimulating hormone, serum cholesterol, Wistar rats.

Magnolia officinalis attenuates free fatty acid-induced lipogenesis via AMPK phosphorylation in hepatocytes

Ethnopharmacological relevanceMagnolia officinalis (MO) is a traditional Chinese herbal medicine that has been used in clinical practice to treat liver disease. The aim of this study is to examine the effects of MO on the development of nonalcoholic fatty liver in hepatocytes. Materials and methodsHuman hepatoma-derived HepG2 cells and mouse normal FL83B hepatocytes were exposed to 0.5mM free fatty acids (FFAs; oleate:palmitate, 2:1) for 24h to simulate conditions of nonalcoholic fatty liver in vitro. The cells were treated with a standardized MO extract 1h prior to FFA exposure. ResultsMO pretreatment attenuated the increases in intracellular lipid accumulation and triglyceride content in FFA-exposed hepatocytes in a dose-dependent manner. MO pretreatment significantly inhibited both sterol regulatory element-binding protein (SREBP)-1c activation and increases in fatty acid translocase, fatty acid synthase, and stearoyl CoA desaturase-1 protein expression in FFA-exposed hepatocytes in a dose-dependent manner. MO pretreatment markedly induced adenosine monophosphate-activated protein kinase (AMPK) phosphorylation in hepatocytes. Compound C, an AMPK inhibitor, blocked the inhibitory effect of MO on the increases in intracellular lipid accumulation and triglyceride content induced by FFAs. In hepatocytes pretreated with compound C, MO failed to inhibit SREBP-1c activation and the increases in fatty acid translocase, fatty acid synthase, and stearoyl-CoA desaturase-1 protein expression induced by FFAs. ConclusionsOur results indicate that MO attenuates triglyceride biosynthesis and accumulation induced by FFAs in hepatocytes, suggesting its pharmacological potential for the prevention of nonalcoholic fatty liver disease. These effects may be mediated by the inhibition of SREBP-1c via AMPK phosphorylation.

Alkali extraction of valuable metals from spent Mo–Ni/Al2O3 catalyst

Extraction of metal values from the spent Mo–Ni/Al2O3 catalyst containing complex oxides was investigated in this work. Aiming at studying selective extraction of metals, a sequential recycle process is conceived as follows: First, acidic oxide MoO3 is selectively extracted by alkali leaching. Then amphiprotic Al2O3 is dissolved by caustic soda autoclaving. Al(OH)3 is obtained by seeding precipitation and used to prepare the support of new catalysts. Besides, Ni(OH)2 remains in the digestion residue as “green mud” of the modified Bayer process. In the light of the idea, alkali leaching experiments were conducted, using several common basic leaching agents. The results show that caustic autoclaving at low NaOH/Mo ratio could selectively extract Mo without significant dissolution of the matrix. Under the optimum operating conditions of temperature 160°C, NaOH dosage 1.2 times the stoichiometric amount, solid/liquid ratio 1:4, retention time 120min and stirring rate 300rpm, over 96% of Mo was recovered while less than 0.2% of Al was dissolved. After leaching of Mo, the Al2O3 matrix was dissolved completely by caustic soda autoclaving at 160°C. Sodium aluminate solution was purified by CaO and Ba(OH)2. The overall Mo and Al extraction yields were up to 99%.

Antioxidative properties of &lt;i&gt;Mallotus oppositifolium&lt;/i&gt; decoction leaves extract using &lt;i&gt;in vitro&lt;/i&gt; models

In an attempt to explain the scientific basis for the medicinal benefits of Mallotus oppositifolium (Euphorbiaceae), the phytochemical constituent and the antioxidative properties of the aqueous decoction leaves extract of the plant versus standard Vitamin C were assessed. The phytochemical analysis (screening and quantitative assay), the 1,1- Diphenyl-2-picrylhydrazyl (DPPH), Nitric oxide, and hydroxyl radicalscavenging, the reducing power, ferrous reducing antioxidant power (FRAP) and the β carotene bleaching of the extract were performed using colorimetric or spectrophotometric methods. Qualitative screening of the extract showed the presence of alkaloids, flavonoids, steroids, phenolic compounds, tannins, phlobatannins, saponins, lipids, carbohydrates, mucilages, and proteins. The phytochemical quantitative assay of the decoction extract revealed that the plant depicted flavonols (38.278 mg.g-1 catechin equivalent), tannins (23.13 mg.g-1 tannic acid equivalent), phenolics (13.73 mg.g-1 tannic acid content), flavonoids (10.62 mg.g-1 quercetin equivalent), proanthocyanidins (2.53 mg.g-1 quercetin equivalent) contents. Alkaloids and saponins content were 200 mg.g-1 and 285 mg.g-1, respectively. The ferric reducing antioxidant power (FRAP) of Mo extract and the IC50 of vitamin C were 228±0.4 mg.mL-1 and 592.0±0.8 mg.mL-1 , respectively. The DPPH radicalscavenging properties of IC50 of vitamin C was 480.0±0.8mg.mL-1 and that of Mo extract was 360.0±0.8 mg.mL-1. The IC50 of Mo’s reduce abilities was 39.2±0.8 mg.mL-1 and that of vitamin C was 320.0±0.8 mg.mL-1.The IC50 of the hydroxyl radical scavenging activity of Mo was 75.2±0,8 mg.mL-1 whereas that of IC50 of vitaminC was not defined. The nitric oxide radical scavenging activity of IC50 of Mo was 121.6±0.8 mg.mL-1 and that of the vitamin C was 130.4±0.8 mg.mL-1, respectively. The β carotene bleanching gives the IC50 of M. oppositifolium was 12,0±0,0 mg.mL-1 and for the vitamin C was 16.0±0,0 mg.mL-1. The decoction leaves of Mallotus oppositifolium (Mo) exhibited powerful antioxidative properties as vitamin C. The plant can be a source of antioxidative materials.Keywords: Traditional medicine, phytochemical analysis, antioxidant

Recovery of molybdenum from uranium bearing solution by solvent extraction with 5-Nonylsalicylaldoxime

5-Nonylsalicylaldoxime, LIX 622N was used to extract and recover Mo(VI) from sulfate leach liquor containing Mo(VI) and U(VI). The extraction parameters were optimized as 10%(v/v) LIX 622N diluted in kerosene at equilibrium pH1.0 and O/A phase ratio=1:1. Under these conditions, complete extraction of Mo(VI) was realized by a two-stage counter current extraction. The formed complex MoO2R2 is assessed by FTIR analysis. The molybdenum content in the organic phase was stripped using a mixture of 2M NH4OH+2M (NH4)2CO3. It was precipitated at pH value 2.0 as ammonium molybdate. After drying, thermal decomposition high purity (>99.9%) of MoO3 was produced. The effect of temperature on the Mo(VI) extraction process showed that, the extraction process is exothermic with enthalpy change −24.514kJmol−1.

Liquid–liquid equilibria, excess molar volume and deviations of the refractive indices at 298.15 K for mixtures of solvents used in the molybdenum extraction process

A separation process is necessary for the recycling of the solvent and diluent from a molybdenum (Mo) acid leaching solution. Acetylacetone is a commercial Mo solvent and phosphonium-based ionic liquid (IL) that is a promising green selective solvent for Mo ions or dilutor based on the Mo extraction test. To develop a recycling process for the solvent, pseudo ternary liquid–liquid equilibria (LLE), a separation process design data set, was determined for several systems at 298.15K: {Aqueous acid solution (AS-solution)+acetylacetone+tri-hexyltetradecyl phosphonium chloride ([P666,14][Cl])}, {AS-solution+acetylacetone+tri-hexyltetradecyl phosphonium bis(2,2,4-trimethylpentyl) phosphinate ([P666,14][TMPP])} and {AS-solution+acetylacetone+tri-hexyltetradecylphosphonium dictanamide ([P666,14][DCA])}. The experiments were carried out at atmospheric pressure using stirred and thermo-regulated cells. The experimental LLE data for the aforementioned pseudo ternary systems were correlated using the non-random two liquid (NRTL) activity coefficient model. In addition, mixture properties, namely the excess molar volume (VE) and deviations of the refractive indices (ΔR), were determined for the following binary systems at 298.15K: {acetylacetone+[P666,14][Cl]}, {acetylacetone+[P666,14][TMPP]} and {acetylacetone+[P666,14][DCA]}. These binary data were correlated with the Redlich–Kister polynomial.

The Effect of Different Additives and Medium on the Bioleaching of Molybdenite for Cu and Mo Extraction Using Mix Mesophilic Microorganism

Bioleaching processes for extraction of Cu and Mo from molybdenite cons. are more environmentally friendly and consume less energy than conventional technologies, yet less economically efficient. One necessary step towards arriving at a cost-effective bioleaching process is using appropriate methodology to optimize pertinent factors in such processes. To this end, the present study employed Response Surface Methodology to optimize important factors in a molybdenite bioleaching process by mix mesophilic microorganism using shake flasks. The effect of change in the levels of molybdenite concentration, pyrite and silver ion concentration as additives - in the range 3-9%, 1-5%, and 0-1.2gr/l, respectively - on the rate of Cu and Mo bioleaching was studied using a Central Composite Design. The results showed a statistically significant effect of silver ion and molybdenite concentration, and to a lesser pyrite concentration, on the rate of bioleaching of Cu and Mo. Further, different mediums and additives were evaluated for copper and molybdenum extraction from molybdenite concentrate in bioleaching process. Small amounts of silver (100mgr/l AgSO4) dramatically accelerated the copper dissolution process. Addition of FeS2 and sulfur with ferrous sulfate accelerated the acidification and raised the oxidation-reduction potential of solution (medium) with an inoculation of 15% (v/v) of active and adapted indigenous mesophilic bacteria, thus resulting in an overall increase in Mo dissolution efficiency.

Separation of Simulated Mixed Mo(VI) and V(V) From HNO3 and HCl Solutions by Selective Extraction and Stripping with Tri-N-Butyl Phosphate as Extractant

Equilibrium study was carried out to determine the optimum conditions required for Mo(VI) extraction from HNO3 solutions and subsequently, simulated mixed Mo(VI), and V(V) were extracted from HNO3 (pH = 1.0) and 6.0 mol L−1 HCl solutions with TBP dissolved in n-hexane. The variation of pH (selective extraction) and selective stripping were investigated as methods of separation of Mo(VI) and V(V). The latter method was found inefficient for separations from HNO3 solutions (pH = 1.0) except supplemented with selective stripping (back-extraction with 2.0 mol L−1 H2SO4/14.5 mol L−1 NH4OH). While from 6.0 mol L−1 HCl, selective stripping was adequate to quantitatively strip in turns the Mo(VI) and V(V) co-extracted into the TBP phase. About 100% of the co-extracted V(V) from the HCl medium was stripped in a two-stage process, in contrast to a single-stage required for Mo(VI) of the same result. The selective stripping method was found to be better because an initial appreciable co-extraction had occurred prior to stripping separation. Based on analytical and spectra data, the extracted complexes from HNO3 and HCl media were formulated as ((MoO2)7–8n(VO2)2n · (NO3)16) (16–18)n- · m TBP (where n>m) and (MoO2Cl2 · VO2 Cl) · xTBP, respectively.

A novel sequential process of bioleaching and chemical leaching for dissolving Ni, V, and Mo from spent petroleum refinery catalyst

Two step leaching experiments were carried out to extract nickel, vanadium, and molybdenum present in spent refinery catalyst. A bioleaching process was applied in the first step. Pulp density, initial Fe(II) concentration, initial pH, particle size, and temperature were varied to optimize the bioleaching process. Ni, V, and Mo were leached out with maximum recoveries of 97%, 92% and 53%, respectively, at an optimized bioleaching condition of initial ferrous ion of 2g/L, initial pH of 2, pulp density of 10% (w/v), particle size of (−106+45) μm, and a temperature of 35°C. As the Mo leaching rate was very low, a second leaching step for the bioleached residue was applied with different concentrations of (NH4)2CO3, Na2CO3, or H2SO4. The second step leaching was optimum at a concentration of 30g/L (NH4)2CO3 with respect to Mo extraction. The rate of Mo dissolution with respect to concentration of lixiviant in the second leaching step was evaluated. The percentages of Ni, V, and Mo leached were 97%, 97% and 99%, respectively, by combining the first step under optimized conditions and the second step with 30g/L (NH4)2CO3.

Selective leaching of molybdenum from spent hydrodesulphurisation catalysts using ultrasound and microwave methods

Spent hydrodesulphurisation (HDS) catalysts from petroleum refineries, mostly constituted by aluminium (Al), molybdenum (Mo), nickel (Ni) and cobalt (Co), are classified as hazardous wastes and disposal is restricted by environmental regulations; thus, the recovery of valuable metals is the most attractive option in the processing of these residues. Selective Mo leaching from two spent HDS (Ni–Mo or Co–Mo) catalysts, roasted at 500°C, was studied using three different approaches: conventional, ultrasound- and microwave-assisted methods. For the Ni–Mo or Co–Mo catalysts, 77% and 84% of Mo extraction, respectively, was achieved when a conventional (10g/L NaOH, 80°C, 120min, S/L=50g/L) approach was used. For both catalysts, ultrasound-assisted leaching (pulse 0.5s and 20% amplitude) with 10g/L NaOH and S/L=50g/L led to 66% Mo dissolution after 10min. Under microwave-assisted (four cycles of 30s) conditions, Mo leaching reached 89% and 91% for Ni–Mo and Co–Mo catalysts, respectively. The latter conditions represent the best compromise between Mo extraction and selectivity, since Al dissolution was between 6% and 9%.

Actinide Partitioning with a Modified TODGA Solvent: Counter-Current Extraction Studies with Simulated High Level Waste

Actinide partitioning studies with improved N,N,N',N'-tetraoctyl diglycolamide (TODGA) solvent (0.05 M TODGA + 5% iso-decanol in n-dodecane) has been explored in order to achieve better decontamination from fission products. The distribution behavior of various metal ions, viz. Am, Pu, U, Eu, Sr, Pd, Cs, Tc, Fe, and Mo with improved TODGA solvent was investigated. Lower concentration of TODGA (0.05 M as compared to previously proposed 0.1 M or 0.2 M) exhibited required extraction properties for actinide partitioning from pressurized heavy water reactor high level waste (PHWR-HLW). Counter-current extraction studies with simulated PHWR-HLW spiked with different radio-tracers (viz. 241Am, 152Eu, 137Cs, 85,89Sr, 59Fe, 106Ru, 109Pd, 95Zr, and 99Mo) suggested that > 99.9% of the trivalent actinides and lanthanides could be extracted in six stages and stripped in four stages. The decontamination factor for various fission products with respect to Am was: 3918 (Cs), 2990 (Sr), 1150 (Zr), 1407 (Ru), 1185 (Pd), and 3250 (Mo). The counter-current extraction studies with the irradiated solvent (500 kGy) reflected a significant amount of Mo extraction.