EP3774024A1 - Préparation de matière composite microporeuse à base de chitosane et ses applications - Google Patents

Préparation de matière composite microporeuse à base de chitosane et ses applications

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Publication number
EP3774024A1
EP3774024A1 EP19718201.7A EP19718201A EP3774024A1 EP 3774024 A1 EP3774024 A1 EP 3774024A1 EP 19718201 A EP19718201 A EP 19718201A EP 3774024 A1 EP3774024 A1 EP 3774024A1
Authority
EP
European Patent Office
Prior art keywords
mpcm
solution
chitosan
sorbent
molybdenum
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP19718201.7A
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German (de)
English (en)
Inventor
Shameem Hasan
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Perma Fix Environmental Services Inc
Original Assignee
Perma Fix Environmental Services Inc
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Filing date
Publication date
Priority claimed from US15/935,398 external-priority patent/US10500564B2/en
Application filed by Perma Fix Environmental Services Inc filed Critical Perma Fix Environmental Services Inc
Publication of EP3774024A1 publication Critical patent/EP3774024A1/fr
Pending legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/06—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
    • B01J20/24—Naturally occurring macromolecular compounds, e.g. humic acids or their derivatives
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28002—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their physical properties
    • B01J20/28004—Sorbent size or size distribution, e.g. particle size
    • B01J20/28007—Sorbent size or size distribution, e.g. particle size with size in the range 1-100 nanometers, e.g. nanosized particles, nanofibers, nanotubes, nanowires or the like
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
    • B01J20/28026—Particles within, immobilised, dispersed, entrapped in or on a matrix, e.g. a resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/30—Processes for preparing, regenerating, or reactivating
    • B01J20/3085—Chemical treatments not covered by groups B01J20/3007 - B01J20/3078
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/30—Processes for preparing, regenerating, or reactivating
    • B01J20/32—Impregnating or coating ; Solid sorbent compositions obtained from processes involving impregnating or coating
    • B01J20/3202—Impregnating or coating ; Solid sorbent compositions obtained from processes involving impregnating or coating characterised by the carrier, support or substrate used for impregnation or coating
    • B01J20/3206—Organic carriers, supports or substrates
    • B01J20/3208—Polymeric carriers, supports or substrates
    • B01J20/3212—Polymeric carriers, supports or substrates consisting of a polymer obtained by reactions otherwise than involving only carbon to carbon unsaturated bonds
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
    • G21F9/04—Treating liquids
    • G21F9/06—Processing
    • G21F9/12—Processing by absorption; by adsorption; by ion-exchange
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
    • G21F9/04—Treating liquids
    • G21F9/06—Processing
    • G21F9/16—Processing by fixation in stable solid media

Definitions

  • fSM82J Disclosed herein are methods for modification of chitosan that increases their versatility as sorbents, particularly as sorbents of radioisotopes, as well the ability of these materials to function in environments where radioactivity is present. Also disclosed are the materials themselves, as well as methods of using them to separate and purify ⁇ radioisotopes, and to separate and purify contaminated materials, in particular those radioactive and nonradioaetive streams contaminated by metal ions, particularly those of heavy metals,
  • Radioactive isotopes are widely used, particularly in the field of nuclear medicine, both for therapy and imaging.
  • these materials can present production, storage, and disposal challenges due to their radioactivity, as vveii as their often significant half-lives,
  • w3 ⁇ 4 Te (having a half-life n TM 6h), is one of the most widely used radioisotopes in diagnostic medicine, obtained from the decay product of parent "Mo ft:.; ⁇ 66 h). is a pure gamma emitter
  • the parent w Mo can be produced by the irradiation of 98 Mo with thermal/epithermal neutrons in a nuclear reactor, but much of the world supply of "Mo comes from the fission product of highly enriched uranium (HEU) in a reactor.
  • HEU highly enriched uranium
  • the HEU process generates large quantities of radioactive waste and does not permit reprocessing of the unused uranium targets due to weapons prol feration concerns,
  • a sorbent that is readily available, or producible from readily available materials, and that is customizable by modification to have one or more functional groups (which may be the same or different) allowing the material to remove constituents from a process stream requiring such purification, and that is resistant to degradation by ionizing radiation,
  • Chhosan is a partially acety Sated glucosamine polymer encountered in the cell wails of fungi, it results from the deacetylation of chitin, which is a major component of crustacean shells and available in abundance in nature.
  • This biopolymer is very effective in adsorbing metal ions because of its ability' for complexation due to high content of amino and hydroxyl functional groups, in their natural form, chhosan is soft and has a tendency to agglomerate or form gels in acidic medium.
  • chitosan, in its natural form, is non-porous and the specific binding sites of this biopolymer arc not readily available for sorption.
  • Chitosan is a non-toxic, biodegradable material. It has been investigated for many new applications because of its availability, poiycationic character, membrane effect, etc.
  • the amino group present in the chitosan structure is the active metal binding site, but It also renders chitosan soluble in weak add. In addle media, chitosan tends to form a gel which is not suitable for adsorption of metal ions in a continuous process.
  • Crosslinking of ehhosan with different functional groups is thought to depend mainly on the crosslinking reaction conditions, such as pH, temperature, ionic concentration, and the surface charge of the materials,
  • the surface charge of the chitosan that determines the type of bond that will form between the cross-linking agent and chitosan depends on the pH of the solution. Hasan, S., Krishnaiah, A., Ghosh, T. ., Viswanath, D.S., Boddu, V.M., and Smith, E. D,“Adsorption of divalent cadmium from aqueous solutions onto chitosan-e solvedd perlite beads, ind, Eng, Chem, Res., 45, 5066-5077, 2006.
  • the point of zero charge (FZC) value of pure chitosan is in the pH range of 6.2-6.8.
  • Chitosan is not soluble in alkaline pH, but at acidic pH, the amine groups present in the chitosan can undergo protonation to NiTY or (NHb-HsO)*.
  • the active surface of the resin is considered to be the critical structures of MPCM resin.
  • the critical structure of the resin which will primarily interact with the imparted energy from the ionizing radiation, needs to be protected. It is evident from SR and XPS analysis that MPCM resin may undergoes radiation induced cross-1 hiking reaction under high radiation field but the performance for metal ion uptake before and after the irradiation reported to he remained same.
  • the main constituents of MPCM resin are low Z elements (with less stopping power), therefore, the negative impact of high energy particles on MPCM surface can be minimized by maintaining proper aspect ratio of the column. Furthermore, the critical
  • I w structure of the resin which is also porous in nature, is assumed to be thin, due to range consideration; it should he protected also front interaction of radiation.
  • TO2 J One embodiment disclosed herein relates to a radiation-resistant sorbent comprising giutara!dehyde-crosslinked chitosan.
  • a sorbent containing a mieroporous materia! of chitosan that has been crosslinked with glutaraldehyde in the presence of a catalyst, such as an acid (e,g., HCl) to a giuiaraldehyde concentration of about 2 to 4 wt%, and which is resistant to degradation from exposure to beta and gamma radiation, and to degradation from exposure to adds or alkaline solutions,
  • a catalyst such as an acid (e,g., HCl) to a giuiaraldehyde concentration of about 2 to 4 wt%
  • the cross- linked mieroporous chitosan matrix enhances the add resistance and mechanical strength of the chitosan parfide.
  • the uptake capacity of the cross-linked particles increases for metal ions from acidic or alkaline radioactive solution in comparison to available commercial resins and commercial aluminas. This Increased uptake can result in efficiencies for molybdenum as high as 500-700 mg/g of sorbent, more particularly, about 600 mg/g of sorbent.
  • chitosan was cross-linked with gluteraidehyde in the presence of add as a catalyst at temperatures of around 70"C under continuous stirring.
  • gluteraidehyde it is believed that amino groups present in the chiiosan structure are protonated, and thus shielded from the reaction with gluteraldehyde, it is also believed that at temperatures of around ?0 t! C, more aldehyde groups are available for reaction than are available at room temperature.
  • the crosslirsked material can be further processed by, washing to remove excess giutaraldehyde, drying, wet or dry milling, and additional chemical processing.
  • additional chemical processing that has been found to be particularly suitable is at least partial oxidation with an oxidizer, In particular, oxidation with one of more of a permanganate (e,g.
  • a peroxide, a chlorite, a hypochlorite, a dichromate, or a metal oxide, or other ambiphilte oxidizer is especially suitable for increasing the selectivity of the sorbent for o(Yl) with respect to Tc(VIl), and for the efficient and rapid elution and recovery of technetium from loaded sorbent.
  • an oxidizer comprising one or more of an alkali metal chlorite, an alkali metal hypochlorite, an alkali metal diehromate, or a transition metal oxide is desirably used.
  • an oxidizer comprising one or more of sodium chlorite, sodium hypochlorite, polassium diehromate, or cerium oxide is desirably used.
  • these oxidizers can desirably be Included in an eluent solution used to release technetium from the sorbent.
  • such oxidizers are included in a saline-containing eluent solution in concentrations ranging from about 5 to about 40 m for chlorites or hypochlorites.
  • the sorbent has a surface area that ranges between about 10 and about 100 m3 ⁇ 4 and more particularly is about 25 m 2 /g, Also desirably, the sorbent has a point of zero charge ranges from about 7.5 to about 8.8, and more particularly is about 8.8,
  • Embodiments of the sorbents described herein have an excellent holding capacity for molybdenum, and can sorb molybdenum in amounts of around 60 wt%, based on the dry weight of the sorbent, or higher. This holding capacity can be around 6,25 mmoi/g of sorbent, or higher.
  • the sorbents also have excellent selectivity for molybdenum with respect to technetium, and are able to hold molybdenum while passing pertechnale ion in saline solution with an efficiency of at least about 80%, Embodiments of the sorbents disclosed herein also provide excellent capacity to sorb heavy metals, including, e.g., the ability to sorb Hg in amounts of 2,96 mmo!/g dry sorbent or higher front aqueous solution at pH 6,
  • titanium oxide was incorporated into the chitosan gluteraldehyde composite polymer matrix
  • CST crystalline silica tltanate
  • titanium-based oxide materials have paved the way for metal ions adsorption studies onto hydrous titanium oxide from the radioactive and non-rad I oac live waste streams. See Anthony, R. G,, Doseh, R.G,, Gu, D. s and Philip, C.V. "‘Use of siSicotitarsates for removing cesium and strontium from defense waste” Ind. Eng, Chem.
  • titanium oxide can form surface complex with metal ion resulting from a bidenate bonding mode to surface oxygen atoms
  • Another embodiment relates to such a method further comprising:
  • the chhosan-based microporous composite material was then suspended in a solution with pH 3 and irradiated at 50,000 krad using ⁇ Coirradiatior.
  • the specific objectives of this work were to 1) prepare eh tosan-based microporous composite particles to adsorb metal ions from highly acidic or alkaline radioactive waste solutions; and 2) optimize the cross-linking process to obtain maximum metal binding sites.
  • Another embodiment relates to a method of separating isotopes from mixtures thereof, comprising:
  • fCNDSdJ Chltosan cross-linked composite is an excellent low cost alternative adsorption materia! compare to available resins, and thus a desirable adsorbent material to remove metal ions from radioactive and nonradioaetive aqueous solutions, it has been found that the success of adsorption processes in the w Mo/" m Te generator systems depends largely on the cost and capacity of the adsorbents and the ease of " ⁇ Tc release from the generator.
  • the sorbent includes a microporous materia! Including chitosan which has been erosslinked with glutaraldehyde in the presence of a catalyst to a glutaraldehyde concentration of about 2 to about 4 wt% to produce a cross-linked chitosan-gluteraldehyde composite matrix.
  • the cross-linked chitosan-gluteraldehyde composite matrix Is resistant to degradation from exposure to beta and gamma radiation and from exposure to acids.
  • a plurality of nanoparticles of a high Z element is disposed in the cross-linked chitosan- gluteraldehyde composite matrix and is integrated with the cross-linked chitosan- gluteraldehyde composite matrix.
  • the method includes the steps of combining chitosan with water in the presence of an acid to form a chitosan get, The method also includes a step of adding glutaraldehyde to the gel to form a semi-solid mass in the presence of catalyst at 70*0, in w'here condensation polymerization of reaction mass occurs. The method further includes a step of washing the semi-solid mass to remove unreaeied glutaraldehyde and form a washed
  • the next step of the method is suspending the washed mass in aqueous base to form a neutralized crosslinked mass. Then, a plurality of nanoparticles of a high Z element is disposed on the neutralized crosslinked mass. Next, the neutralized crosslinked mass including the plurality of nanoparticles is dried under vacuum to form the radiation-resistant sorbent.
  • the method includes a first step of grinding a salt of a high Z element with a surfactant under an inert atmosphere.
  • the method also includes a step of adding deionized water of between 5ml to 10ml during the step of grinding to form a homogenous mixture.
  • the method further includes a step of adding an alkaline solution to the homogenous mixture under sonicaiion to nucleate and grow the nanoparticles under an inert atmosphere.
  • the surfactant of the homogenous mixture is transferred into an alcohol solution containing the nanoparticles, Then, the alcohol solution is sonicated to obtain a uniform intermediate stage of the nanoparticles.
  • the precipitates, e.g. intermediate stage of nanoparticles, are then sonicated and washed thoroughly wit ethanol and deionized water to remove surfactant and impurities, respectively.
  • embodiments of the chitosan crosslinked composites disclosed herein can be used in a method for separating or concentrating or both one or more heavy metals from a liquid stream, such as a waste stream or a process stream, by contacting a liquid stream containing one or more heavy metals with the chitosan crosslinked composite and sorbing one or more of said heavy metals thereon,
  • FIG, 1 Is a scanning electron microscope photomicrograph that shows chitosan and embodiments of modified chitosan ⁇ MPCM ⁇ disclosed herein, FSG la shows unmodified chitosan; FIG. lb shows an embodiment of MPCM material.
  • FIG 2 is a graph showing the results of a ther ogravi etric analysis
  • FIG, 3 is a graph showing an X-ray diffraction pattern of chitosan and an embodiment of MPCM material.
  • FIG. 4 is a graph showing Fourier Transform Infrared (FT!R) spectra of chitosan and an embodiment of MPCM material disclosed herein,
  • FIG, 5 is a graph showing X-ray photoelectron spectroscopy (XPS) survey scans for chitosan and an embodiment of MPCM,
  • FIG, 6 is a graph showing X-ray photo ectron spectroscopy (XPS) spectra for chitosan and an embodiment of MPCM.
  • FIG. 7 is a graph of energy-dispersive X-ray spectrometry (EDS) mlcroarsalysis spectra of an embodiment of MPCM herein
  • FSG 7a shows speetra of chitosan and an embodiment of MPCM before and after Irradiation
  • FIG 7b shows comparison of chitosan and an embodiment of MPCM
  • FIG 7e shows comparison of an embodiment of MPCM before and after irradiation
  • FIG 8 is a schematic diagram showing a reaction pathway for the preparation of an embodiment of MPCM described herein.
  • FIG. 9 Is a graph showing FT5R spectra of an embodiment of modified ehitosan disclosed herein before and after irradiation.
  • FIG. 10 is a graph showing X-ray photoeiectron spectroscopy (XPS) spectra for an embodiment of MPCM before an after radiation
  • FIG. 10a, 10b, and 10c show the C I s, O 1 s, and N 1 s positions, respectively,
  • FIG. 12 is a graph showing the effect of pH on molybdate sorption on an embodiment of MPCM, with initial conditions of a concentration of 5.21 moi/L and temperature 298 K.
  • FIG. 13 Is a schematic diagram showing reaction mechanisms for sorption of Mo (VI) onto an embodiment of MPCM from aqueous solution
  • F1C, 14 is a graph showing equilibrium sorption isotherms for Mo (VI) uptake on an embodiment of MPCM, showing experimental data (*) correlated with the Langmuir isotherm model (solid line) under conditions where the concentration of Mo(Vi) in solution is in the range of i mmoi/L to 94 mmoi/L, temperature 298 K, pH ⁇ 3.
  • FIG. 15a is a graph showing a breakthrough curve for Mo (Vi) sorption on a bed of MPCM, the inlet influent concentration was 5.21 mmole Mo (Vi)/L at the pH of 3.
  • FiG. 15b is a graph showing the effect of influent solution pH on the breakthrough curve for Mo (VI) from a column packed with an embodiment of MPCM, The inlet influent concentration was 5.21 mmole Mo (Vi)/L with 153,8 mmole NaC!/L at the pH of 4 to 7, respectively.
  • the bed height of the column was 3.2 cm.
  • the inlet influent flow rate was 1 mL min.
  • FIG, 16 is a graph showing breakthrough curves for pestechreale from a column packed with an embodiment of MPCM without oxidation which was loaded with 6.25 mM of Mo (VT)/gram of MPCM.
  • the volume of the column was 2,5 cm 3 .
  • the inlet Slow rate was 1 mb' min.
  • the inlet influent concentration was 0,25 mM pertechnetate /L in saline (0.9% aCS) solution.
  • FIG. 17 is a graph showing the surface charge of oxidized and non- oxidized MPCM exposed to 1 % Mo (VS) In aqueous solution in the presence of IN NsNOj.
  • FIG, I S is a graph showing an elution profile for 93 ⁇ 4 Tc from an embodiment of MPCM loaded with Mo (VI) spiked with "Mo,
  • FIG. 19 is a graph showing the relationship between number of eiution(s) and the percentages of 93 ⁇ 4n Tc and Mo (VI) release from an embodiment of MPCM as sorbent.
  • FIG, 20 is a flow diagram for a process using a 99m Te/"Mo generator systems and a "Mo production using neutrons capture method, using an embodiment of MPCM as the sorbent,
  • FIG. 2 N s a graph showing the effect of temperature on molybdenum uptake onto MPCM-CiCh resin under conditions of initial solution concentration of 1% Mo solution with 25 mM NaOCl, pH of 3,0, and solid to liquid ratio of 1 : 100 with a contact time of 0.5 hour,
  • FIG, 22 is a graph showing heat of adsorption at different loading and temperature (24°C to 50° €) of the resin of FIG, 21 ,
  • FIG. 23 Is a graph showing the projected specific activity of a proposed MPCM based generator with a column volume of 6- mL
  • FIG. 24 is a graph showing FT!R spectra of chitosan and another embodiment of modified chitosan disclosed herein.
  • FIG, 25 is asi 1R spectra of unirradiated molybdenum loaded MPCM-Z resin and the molybdenum loaded MPCM-Z resin irradiated at 250 kGy.
  • FIG, 26 is an IR spectra of unirradiated molybdenum loaded MPCM-Z resin and the molybdenum loaded MPCM-Z resin irradiated at 250 kGy
  • FIG, 27 is a graph illustrating the relationship between intensity ratios from C-O-C group ⁇ 13 oso/l ⁇ & 2Q) and hydroxy! group i asidinoo) and radiation doses (kGy).
  • the modified chitosan disclosed herein can be prepared according to the reactions shown schematically in FIG, 7, by crosslinking with giuiaraidehyde under addle conditions at temperature conditions set forth below. While the amount of giuiaraidehyde used may vary somewhat, it has been found effective to use from about 2 ml to about 10 ml, more particularly from about 2 ml to about 8 ml, even more particularly, about 6 ml, of giuiaraidehyde per 4 g of chitosan.
  • the inking reaction between giuiaraidehyde and chitosan may also vary somewhat, but it has been found effective to use a pH of between about 0.7 and about 3, more particularly between about 0,7 and 2, even more particularly, of about 1.0.
  • the temperature of the erosslink g reaction may also vary, but is desirably between about 50 °C and about 80 °C, more particularly, around 70 e C, j009t
  • the sorbent comprises a microporous material including chitosan which has been crosslinked with glutaraldehyde in the presence of a catalyst to a glutaraldehyde concentration of about 2 to about 4 w % to produce a cross-linked chitosan-glutera!dehyde composite matrix.
  • the cross-linked chitosan- gluteraldehyde composite matrix is resistant to degradation from exposure to beta and gamma radiation and from exposure to adds.
  • the cross-linked chitosan-g!uteraldehyde composite matrix includes a plurality of nanoparticles, made from a high Z element, disposed in the cross-linked ehitosan-gluteraldehyde composite matrix and integrated with the cross-linked chitosan-gluteraidehyde composite matri to reduce primary impact of high radiation flux and minimize radiolytie effect on said cross-linked chitosan-gluteraidehyde composite matrix,
  • the high Z element with higher stopping power will have affinity for certain isotopes can be crosslinked with MPCM resin matrix. It is also believed that the radiation tolerance limit and selectivity of the MPCM resin for certain isotopes, can be further enhanced by the high Z element crosslinked MPCM resin as it will not be limited fey the radiofytie driven reaction. Therefore, it is the inclusion of the high Z element will reduce the primary impact of high radiation flux and minimize the radiolytie effect on to the MPCM’s porous critical structure compared to regular organic based resin such as MPCM resin,
  • Molybdenum (Mo) into the cross-linked chitosan-gluteraidehyde composite matrix is to protect the structure of the matrix from the Mo-99 related radiolytie impact.
  • the plurality of nanoparticles is made from the high Z element of Hafnium (HI). Hf is a
  • ‘>7 preferable high Z element for use connection with the cross-linked chitosan-gksteraldehyde composite matrix because Hf has no known toxicity and, therefore, can be qualified to use in medical applications. More preferably, Hf is present in the cross-linked ehitosan- gluieraldehyde composite matrix at a range of between 0, 15g to 0 35 g per grams of the cross-linked ehitosan-gluteraldehyde composite matrix H should be appreciated that the amount of Hf added to the composite matrix directly corresponds to the amount of activity of Molybdenum.
  • the composite matrix with lower amount of Hf is suitable for lower specific activity, e.g natural Mo, while the composite matrix with higher amount of Hf is suitable for higher activity enriched Mo.
  • excess amount of Hf also reduce resin capacity for molybdenum.
  • the method includes a first step of combining chitosan with water in the presence of an acid to form a chitosan gel.
  • the next step of the method is to add giuiaraidehyde to the gel to form a semi-solid mass in the presence of catalyst at ?G & C, in where condensation polymerization of reaction mass occurs.
  • the semi-solid mass is then washed to remove unreacled giutaraldehyde and form a washed mass
  • the washed mass is suspended in aqueous base to form a neutralized crosslinked mass
  • a plurality of nanopartic!es of a high 2 dement is disposed on the neutralized crosslinked mass.
  • the high Z element being used is for the step of disposing is made from hafnium (Hi) between 0 15g and 0,3Sg per grams of the neutralized crosslinked mass.
  • the neutralized crosslinked mass including the plurality of nanopartides is dried under vacuum to form the radiation-resistant sorbent
  • the high Z element such as hafnium can be integrated in to the neutralized crosslinked mass either self-asse bles or radiation induced cross-linking process.
  • f(HI95] It is another aspect to provide a method for preparing a plurality of mmopartieies for use in a radiation-resistant sorbent.
  • the method includes a first step of grinding a salt of a high Z element with a surfactant under an inert atmosphere
  • the salt of the high Z element is an aqueous salt that cars be soluble in water such as Hafnium Chloride of HfCbO®SI-bO
  • the amount of surfactant used for making the nanopartides ranges between 4 wL to 20 wt%.
  • the next step of the method is adding deionized water of between 5 mi to lOtnl during the step of grinding to form a homogenous mixture. The deionized water is added to the surfactant and the high Z dement under continuous grinding.
  • the homogenous mixture of the surfactant and the high Z element is formed.
  • the next step of the method is to add an alkaline solution to the homogenous mixture to nucleate and grow the nanopartides.
  • the addition of the alkaline solution to the homogenous mixture of the surfactant and the salt of a high Z element can be conducted under sonication to obtain a homogenously dispersed solution.
  • the alkaline solution added to the homogenous mixture is selected from NaOH or NRtOH.
  • the steps of grinding, adding the deionized water, and adding the alkaline solution are conducted in an inert atmosphere, e.g. under Nitrogen.
  • the growth of the nanopartides can be further facilitated with the addition of excess amount of ethanol in the final solution obtain a uniform intermediate stage of the nanopartides.
  • the precipitates, e.g, the intermediate stage of Hafnium oxide nanoparticles, are then sonicated and washed thoroughly with ethanol and deionized water to remove the surfactant and impurities, respectively,
  • the mass of the hafnium nanopartides are mixed with chitosan gel before adding glutaraldehyde in the final step of MPCM preparation process.
  • the hafnium nanopartides can be deposited onto the MPCM resin matrix and the MPCM resin matrix can be dried under vacuum and at 120°C for 12 hours.
  • the reaction with gluteraldehyde was performed by drop-wise addition of approximately 6 ml. g!uieraidehyde solution, having a concentration of 50%, to the acidic chitosan gci under continuous stirring (established based on trial and error, but generally from 200 rpm to 500 rpm) at 7Cf € The final pH of the the mixture was approximately l ,0. The amount of gluteraldehyde was used in this study was established based on trial and error basis. The mixture was kept under continuous vigorous stirring (500 rpm) at 70*0 for another i hr to obtain semi-solid gel.
  • the amino groups present in the chitosan are much more reactive with aldehyde through Schiff s reaction than the hydroxyl groups of chitosan, it was envisaged that, at 70°C, more free aldehyde groups will be present in the solution than would be present at room temperature. In acidic solution, the protonation of the amine group will inhibit the formation of complexes of aldehyde and amino groups. Moreover, gluteraldehyde may undergo aldo! condensation and the reaction of hydroxyl groups of chitosan with free aldehyde can be catalyzed by acid at 7CPC.
  • the MPCM was ground using a laboratory jar mill to a particle size in the range of about 50 to 200 pm, An amount of these MPCM particles was suspended overnight in aqueous solution having pH 3, The pH of the solution was maintained using 0. I M HN(3 ⁇ 4. The suspended MPCM particles were irradiated using 6 Co as a y source, The characterizations of the MPCM sample were performed using SEM, EDS X-ray mieroanalysis, FT1R, and XPS spectroscopic analysis,
  • FIG. i A scanning electron micrograph (SEM) of chitosan and MPCM material was taken to study the surface morphology and is shown in FIG. i .
  • SEM scanning electron micrograph
  • the SEM micrograph of the cross-section of chitosan and MPCM sample is shown In FIG. l a and l b, respectively, It appears from FIG. la that chitosan Is nonporous, and from PIG, l b the MPCM appears to be mieroporous in nature,
  • ⁇ s is the volume of swollen MPCM and Y ⁇ i is the volume of dry sample, in deionized water it was observed that the ehitosan swelled by approximately 105% of its original volume at 24 hours of equilibrium lime.
  • MPCM shows very fast swelling behavior reaching approximately 200% increase within five minutes and reaching equilibrium at 24 hours, The swelling studies with deionized water were performed within the pH range of 3 to 6. At equilibrium, the maximum volume of the MPCM was almost 219% more than its dry volume.
  • Table 1 shows she results for the acid tolerance capacity of MPCM. It was observed that MPCM material shows better HCI tolerance capacity than it does tolerance for HNC3 ⁇ 4 and PbS(3 ⁇ 4. The physical size and shape of MPCM did not show any sign! (leant change op to !2M HCI, I2M H 2 SO and 3,9 M HNOj solution hoi the MPCM appeared to be dissolved completely in 7.8 M HNCh solution, it is evident that the MPCM Is more acid resistant compared to chitosan.
  • Figure 3 shows the XRD pattern for pure chitosan and MPCM beads.
  • the chitosan sample showed a diffraction peak near 20 s , indicative of the relatively regular crystal lattices (1 10, 040) of chitosan. See Wan et ah, "Biodegradable PolySaetk /Chhosan Blend Membranes,” Blomacromolecules 7(4): 1362-1372 (2006).
  • the peak observed for MPCM Is appeared to be broadened suggesting that the MPCM sample is amorphous in nature.
  • St also indicates that chitosan and glntaraidehyde formed a complex in the presence of acid; therefore the crystalline structure of the chitosan was disrupted by the chemical bonding between chitosan and g!utaraldehyde.
  • FIG, 4 shows the comparison of l spectra of ehitosan with MPCM .
  • ehitosan and MPCM exhibited peaks at 3498 cm 5 and 2950 cm 5 , respectively, corresponding to the stretching O-H and N-H groups and C ⁇ H stretching vibration in CH, and €H 3 ⁇ 4 .
  • the peaks at 1350 to 1450 em J indicate alkane C-H bending.
  • the XPS analysis of ehitosan and the MPCM sample prepared above was performed to gain a better understanding of mtermolecnlar interaction between ehitosan and gluteraidehyde.
  • a survey scan was used to ensure that the energy range was suitable to detect all the elements.
  • the XPS data were obtained using a &RATQS model AXIS 165 XPS spectrometer with monochromatic Mg X-rays (hv Si 1253.6 eV) t which were used as the excitation source at a power of 240 W.
  • the spectrometer was equipped with an eight-channel hemispherical detector, and the pass energy of 5-160 eV was used during the analysis of the samples. Each sample was exposed to X-rays for the same period of time and Intensity, The XPS system was calibrated using peaks of U0 3 (4f7/2), whose binding energy was 379,2 eV. A 0° probe angle was used for analysis of the samples, [001 ⁇ 3] FiG, 5 shows the peak positions of C Is, O is, and N i s obtained by the survey scan of chitosan and the MPCM sample prepared above, respectively, FiG. 6 shows the peak positions in detail for C Is, G is, and N i present in chitosan and MFC hi.
  • N Is peak for chitosan was at 397,5 eV (FWHM 1 ,87) for nitrogen in the -Nhb group of chitosan (FIG. 5c); for the MPCM the M Is peak appeared at 397.7 eV.
  • One of the objectives for investigating the N I peak was to Identify whether amine groups, which are active metal binding sites for chitosan, were Involved in cross-linking reactions
  • FIG. 6c shows a strong M is peak for MPCM at 397,7 eV, which can be assigned to ⁇ NHs groups * suggesting that the amine groups of chitosan were not affected by the cross-linking reaction with giutaraidehyde. This is also evident from the FTIR spectra (FIG. 4).
  • the EDS microanaiysis was used for elemental analysis of MPCM (FIG. 7), The peaks for carbon, oxygen, and nitrogen are shown at 0,3 keV, 0.36, and 0,5 keV, respectively, which are the main components of chitosan (F3G. 7a, 7b).
  • FIG, 7b shows that the nitrogen peak present in the MPCM sample shifted, due to protonation of amine groups (-N3 ⁇ 4) compared to the nitrogen peak in chitosan.
  • FIG. 7c shows EDS spectra of chitosan and MPCM particles before and after irradiation at 50.000 krad with a ® Co source.
  • FIG, 7c indicates that the intensity of carbon, oxygen, and nitrogen peaks did not change substantially after irradiation of the sample.
  • FIG. 10 shows the peak positions of carbon, oxygen, and nitrogen obtained by the XPS analysis of the MPCM sample before and after irradiation. It was observed that the magnitude of total C I s peak binding energy changed after irradiation as shown In Table 2.
  • the C I s peak for the MPCM sample was 283.5 eV, while for the MPCM sample after irradiation * two peaks were observed at 283.5 and 284,5 eV (PIG, SGa).
  • the N Is peak present in the MPCM sample after irradiation around 397,5 eV can be assigned to Nfb groups in the MPCM structure. No change was observed for O-l s peak of the irradiated MPCM sample.
  • the magnitude of the binding energy shift depends on the concentration of different atoms, in particular on the surface of a material. In comparison with the XPS (FIG.
  • the supernatant was then filtered through a 0.45-pm membrane filter and the filtrate was analyzed for molybdenum removal by an Inductively Coupled Plasma (ICP) (Agilent 7700X) that is equipped with mass spectroscopy for molybdenum detection.
  • ICP Inductively Coupled Plasma
  • the adsorption isotherm was obtained by varying the Initial concentration of molybdenum in the solution.
  • the amount of molybdenum adsorbed per unit mass of adsorbent (qv) was calculated using the equation,
  • the surface charge of a bead of MPCM sample was determined by a standard potentiometric titration method in the presence of a symmetric electrolyte, sodium nitrate, as per Hasan ef a!,, supra.
  • the magnitude and sign of the surface charge was measured with respect to the point of zero charge (PZC),
  • PZC point of zero charge
  • the pH at which the net surface charge of the solid is zero at all electrolyte concentrations is termed as the point of zero charge.
  • the pH of the PZC for a given surface depends on the relative basic and acidic properties of the solid and allows an estimation of the net uptake of H and OH ions from the solution. The results are shown in FIG. 1 1 ,
  • the surface charge of MPCM was almost zero in the pH range of 7,5 to 8.8, The protonation of the MPCM sharply increased at the pH range of 7,5 to 2.5 making the surface positive, At pH below 2,5, the difference between the initial pH and the pH alter the equilibration time was not significant, suggesting complete protonalion of amine (-NH ) groups present in MPCM. At higher pH, 7.5 to 8,8. the surface charge of the MPCM slowly decreased, indicating slow protonation of MPCM. In ease of chitosan, the extent of protonation is reported to be as high as 97% at a pH of 4.3.
  • the amount of molybdenum uptake at the equilibrium solution concentration is shown for each different initial pH of the solution in FIG, 12,
  • the uptake of molybdenum by MPCM increased as the pH increased from 2 to 4, Although a maximum uptake was noted at a pH of 3, as the pH of the solution increased above 6, the uptake of molybdenum onto MPCM started to decrease. Accordingly, experiments were not conducted at a pH higher than the PZC of the MPCM sample.
  • the metal In order to adsorb a metal Ion on an adsorbent from a solution the metal should form an ion in the solution.
  • the types of ions formed in the solution and the degree of ionisation depends on the solution pH, In the case of MPCM, the main functional group responsible for metal son adsorption is the amine (-NI1 ⁇ 2) group. Depending on the solution pH, these amine groups can undergo profanation to NHb or (NFh-HbG) ⁇ , and the rate of protonation will depend on the solution pH.
  • the surface charge on the MPCM will determine the type of bond formed between the metal ion and the adsorbent surface,
  • molybdenum in an aqueous solution can be hydrolyzed with the formation of various species.
  • MoOf and various isopo!yanions mainly Mt3 ⁇ 4£3 ⁇ 4
  • the MoO i " anion undergoes formation of many different polyanions in acidic solutions. See Guibal et ah, ‘‘Molybdenum Sorption by Cross-linked Chitosa Beads: Dynamic Studies”.
  • the MPCM had a maximum adsorption capacity at a pH of around 3 front a solution of molybdenum Ions.
  • the amine group of the MPCM has a lone pair of electrons from nitrogen, which primarily act as an active site for the formation of a complex with a metal ion.
  • the amine group of MPCM undergoes protonallon, forming NH * leading to an Increased electrostatic attraction between NHs and sorbate anion.
  • the MPCM material contains amino groups that are available for characteristic coordination bonding with metal ions. Adsorption of etal ion, when pH dependent, may be described by the following one-site Langmuir equation. The effect of pH was incorporated by introducing a parameter "‘a” that is dependent on pH of the solution. The expression is given below:
  • Equation 5 was used to correlate the adsorption capacity of the MPCM.
  • the equilibrium data for molybdenum could be correlated with the Langmuir equation within ⁇ 5% of experimental valise.
  • the constants of Equation 5 are obtained by non-linear regression of the experimental data and are given in Table 3. It was noted that Equation 5 represented the adsorption behavior of molybdenum on the MPCM adequately ( Figure 14), The adsorption isotherm data obtained at pH 3 showed Type 1 behavior,
  • MPCM-I Sample after irradiation at 50,000 6i5 Co y-source.
  • a column was used to study the adsorption of Mo (VI) with or without the presence of ions in the solution under dynamic conditions. Approximately 1 .125 gram of MPCM was used to make a 2.5 cm 3 column with 0,5 cm inner diameter and 3.2 cm height. A flow rate of I mL/m snute was used during a run, The run was continued for 1 500 minutes, and samples at the bed out let were collected at a regular time intervals.
  • the long lived technetium ( 3 ⁇ 43 ⁇ 4 Tc) was used to evaluate the performance of MPCM to adsorb technetium with and without the presence of other ions from an aqueous solution in the pH range of 3 to 1 1.
  • Technetium is chemically inert and has multiple oxidation states ranging from I to VIS.
  • the most dominant species of technetium that is found in aqueous waste streams is pertechnetate (TcQ ⁇ ) See Gu et ah, Development of Novel Bifunctsonal Anion-Exchange Resin with improved Selectivity for Pertechnetate sorption from contaminated groundwater, Environ, Sci.
  • Table 4 shows that the adsorption of technetium onto MPCM is pH independent in the solution pH range of 3 to 1 1 , It was observed that approximately 95% of 1 mM technetium/L of solution was adsorbed onto PCM in the pH range of 3 to I I , whereas the technetium removal was reduced to 56% in present of 0,9% NaCI over the pH range of 3 to I I .
  • MPCM shows positive charge in the pH range of 3 to 7,5.
  • FUR spectrum of MPCM confirms the presence of --NH , CHQH, and CHbQH groups on PCM surface (FIG. 4).
  • MPCM was also used to adsorb Mo (VI) and Te ⁇ VlS) simultaneously from a mixed solution containing 1 mmole of Mo(Vl)/L and O.I i pmole of shoveehnetate/L with or without the presence of 0,9% NaCI. MPCM was found to adsorb molybdenum and technetium simultaneously from the solution at solution pH 3.
  • the column was prepared with MPCM that was loaded initially with Mo (VI), Batch equilibrium process was used to adsorb 6,25 mmole Mo (VI)/ g MPCM at 298 K when the equilibrium concentration of Mo (VI) in the solution was 54 mmolc/L and the initial pH of the solution was 3,0. Approximately 1.125 gram of Mo (Vi) loaded MPCM was used to prepare a 2.5 cm 3 bed. A saline (0 9% NaCl) solution spiked with 0.25 mM pertechnetate/L was passed through the column using a peristaltic pump at a flow rate of l mL mirs during the run.
  • FIG 16 shows that the pertechnetate anion has affinity towards available surface sites of MPCM in the presence of molybdenum (MoOr ⁇ ) anion. It was observed that at 10 bed volumes, approximately 15% of the inlet concentration of pertechnetate was eluted with saline (0.9% NaCI) solution. H may be noted that approximately 60% of the inlet perleehnetaie concentration was obtained in the eluent that was collected at 20 bed volumes (FIG. 15). The column reaches saturation fairly quickly for technetium while an additional 40 bed-volume of technetium spiked saline solution w3 ⁇ 4s passed through the column.
  • MoOr ⁇ molybdenum
  • Pertechneiate is soluble in water; therefore, deionized water was used to regenerate technetium from the column, H was observed that only 1% of technetium was desorbed from the MPCM bed using 10 bed volumes of water. Preliminary studies show that complete recovery of technetium from the MPCM is challenging even using when different concentrations of NaCI solution, St was observed that approximately 50 bed volumes of 1 ,5% NaC! was required to regenerate 10% of w Te from the column. Similar amounts of low concentration acid solutions ( ⁇ I ) of HCi, H 2 SQ4, and HNO 3 , were also used, without any significant regeneration. In another attempt, the MPCM sorbent was oxidized with different concentrations of potassium permanganate or hydrogen peroxide, to study the effect of oxidation on adsorptson/desorption of technetium on to the oxidized MPCM sorbent.
  • MPCM was oxidised with different concentrations of hydrogen peroxide with or without the presence of transition metal catalysts. Temperature was also varied. The oxidation studies of MPCM with hydrogen peroxide were performed to determine whether controlled oxidation alone would improve technetium recovery from the technetium loaded MPCM, The concentration of hydrogen peroxide was varied from !% to 5%, Batch technique was used to adsorb technetium onto oxidized MPCM, The regeneration of technetium from the oxidized MPCM was conducted in a column. The column was prepared with 0, 12 pmoie of ?9 Te / gram of oxidized MPCM. The column was regenerated to desorb technetium from the oxidized MPCM using 0,9% NaCI solution.
  • MPCM was also oxidised using potassium permanganate n solution.
  • concentration of potassium permanganate in the solution and the oxidation time was determined based on trial and error.
  • concentrations of potassium permanganate and the pH of the solution were varied from 0.1% to 5% and 3 to 1 1, respectively.
  • the oxidation time was varied from 30 minutes to 24 hours.
  • the surface charge analysis of oxidized and non-oxidized MPCM loaded with Mo (VI) was also performed to elucidate the shoveehnetate (T cCA ) adsorption pattern on oxidized MPCM.
  • HMhO L species cart be formed, which is also a powerful oxidant.
  • KMnCb Korean Organic Chemicals
  • the formation of colloidal MnCh is possible due to the reaction of MnQ A with H ⁇ and depending on the acidity of the solution which may further undergo reaction with H ⁇ to produce Mi 2* in solution.
  • Ahmed et a!, 2002 reported permanganate oxidation of chitosars as an acid catalyzed reaction that led to formation of diketo-acid derivatives of chltosan.
  • the MPCM loaded with both 3S Mo and "Mo was transferred to a column (0.5 cm* 3.2 cm with poiytetrafluoroethylene (PTFE) frit at the bottom). Two ends of the column were closed with silicon rubbe septum. The column was thoroughly rinsed with de-ionized water to remove any molybdenum solution on the surface of the MPCM, The rinsed sample was collected from the column using evacuated vials. The column was eluted with saline (0.9% NaCi) solution after allowing it maximum time required to bui!d-up the daughter product 93 ⁇ 4B Tc from the decay of the remaining "Mo in the column.
  • PTFE poiytetrafluoroethylene
  • the column was eluted with 9 mL saline solution that was collected subsequently in 3 individual evacuated vials of 3 mL each.
  • the eluate was obtained from the column at predetermined time intervals.
  • the eluate from each collection was analyzed for
  • FIG. 18 shows the elution profile of the column consisting of 0,5 gram of MPCM loaded with 2.47 mmole of Mo (VI) /gram of oxidized MPC where 1300 m € ⁇ activity is from adsorbed "Mo.
  • the column started eluting with saline (0.9% aC!) solution on the day after the column was prepared and the elution was continued over the period of 8 days.
  • elution S As shown in FIG, 18, more than 80% of the activity due to " m Tc is obtained within 9 mL of saline (0.9% NaCI) in where 62% of the available "Tc activity eluted in first 3 L volume of normal saline.
  • the second elution was collected at 24 hours after the first elution and shows that the " m Tc activity in the column ranged from 70% to 90% and can be recovered using 3 to 9 mL of saline solution. In all the cases, the eluate was dear, and the pH was in the range of 6 to 7.
  • the column was continuously eluted over the period of 8 days with an average -82 of the whole ""Tc eluted from the column.
  • FIG, 19 shows the percentage of " ra Tc and Mo (VI) released from the column over the period of 8 days.
  • the concentration of the Mo ( VI) in the eluates was within the range of 1% to 3% of the 6.25 mmole Mo (Vi)/ gram of MPCM in the column.
  • the process of capturing any molybdenum leakage from the column by passing it through add catalyzed MPCM is possible as shown in FIG, 15 thus reducing the Mo (VI) and Mn(Vli) concentrations in the eluent to extremely low levels.
  • S I leakage from the column can be achieved by controlling the pH of the saline (0,9% NaCl) solution within the range of 4 to 4.5 (FIG. 15). in that ease, an additional guard column will not be necessary to control the leakage of Mo (VI) from the column.
  • the generator in this case consists of MPCM loaded 3 ⁇ 4 Mo thus combines the performances of the chromatographic generator and the use of (n, y) "Mo,
  • the MPCM is able to hold up to 60 wl% of its body weight, in comparison with only 0.2 wt% in the alumina.
  • the potential for MPCM as an absorbent for the preparation of the "Mo/" m Tc generator has been explored using 1% Mo (Vi) solution spiked with "Mo (2 Ci/mL). It was observed that MPCM adsorbed Mo (VI) spiked with "Mo as per its demonstrated capacity from an aqueous solution at pH 3.
  • the oxidation of MPCM by either sodium chlorite or sodium hypochlorite solution was carried out at a solid to liquid ratio of 1 : 100, The oxidation time was varied from 30 minutes to 24 hours.
  • solution containing -0.02% chlorine, calculated as C at a pH range of 3 to 4.5 and an oxidation time of 2 hours was sufficient to oxidize MPCM partially to facilitate maximum uptake of molybdenum and also release of technetium from the MPCM sorbent.
  • the MPCM resins that were partially oxidized by sodium chlorite and sodium hypochlorite are denoted as MPCM- CIOs and MPCM-OCI, respectively, herein.
  • 5i shows a similar pattern to that of molybdenum loaded PCM that was oxidized by potassium permanganate.
  • molybdenum-99 was varied from 45 mC to 1.39 Ci (at the end of srradiation, or EOl), respectively.
  • the molybdenum loaded MPCM resins that were oxidized by different oxidizers were used to prepare respective chromatographic columns. The columns were then flushed with saline solution and the data are shown in Table ?,
  • the MPCM -CIOs and MPCM-OCI resins were further studied to evaluate their potential for molybdenum adsorption in presence of different concentrations of oxidizing agent in the solution.
  • the adsorption study was carried out for 24 hours using different concentrations of sodium chlorite and sodium hypochlorite (5 mM to 50 mM) which were spiked with t % molybdenum in solution (prepared from molybdenum salt, without radioactive molybdenum (Mo-99)).
  • the molybdenum solution pH was initially adjusted at ⁇ " 3.0 for all the experiments.
  • the samples were collected at different intervals and were analyzed for molybdenum uptake onto the resin.
  • Table 8 shows that, in the presence of sodium chlorite or sodium hypochlorite in the solution, the molybdenum uptake capacity of the oxidized MPCM resin was in the range of 5.21 mM (500 mg/g) to 6.25 mM (600 mg/g) of oxidized MPCM. Molybdenum started precipitating out slowly in the solution alter 12 hours of exposure when the oxidizer concentration in the solution was 45 mM or higher. No molybdenum precipitation in the solution was observed for the solution in which the concentrations of either sodium chlorite or sodium hypochlorite were in the range of 5 mM to
  • Molybdenum did not precipitate in the solution during first 4 hours of the exposure for any concentration of sodium hypochlorite that was used in this study.
  • MPCIVl-CtCfe was considered in this attempt to adsorb molybdenum in presence of different concentrations of sodium hypochlorite (NaOCI) as oxidizer in the 1% Mo solution.
  • NaOCI sodium hypochlorite
  • the molybdenum loaded MPCM-CIO2 was then used to prepare a chromatographic column.
  • Sodium chlorite and sodium hypochlorite were also mixed with saline solution in order to investigate their oxidizing effects on the release of both technetium and molybdenum from the column.
  • the columns were then Slushed with a saline solution mixed with 5 mM concentration of sodium chlorite and sodium hypochlorite, respectively, at pH 4.
  • the e!uaie mixture was further spiked with Te-99 (stoichlomeiricaliy equivalent to CI ofTc-99m per 10 mL) before being passed through the column.
  • Table 9 Typical oxidizer concentration (5 mM) in the elution solution and related metal ions release from the column.
  • Table i I shows the elution performance of a typical generator that was prepared by exposing !-g M PCM-Ci(1 ⁇ 4 resin to 100 mL of 1.390 "Mo in " 1% total molybdenum solution at an initial pH of -2 8. Analysis of the activity distribution indicated a Mo adsorption efficiency of 63 4%. The time of exposure of MPCM-CICb resin to molybdenum solution was 24 hours for these experiments. Following the adsorption cycle, the resin was thoroughly rinsed with de-kmked water to remove any adhered molybdenum from the surface.
  • the Tc-99m radioisotope in the form of an intermediate solution, is then passed through a guard column with alumina as an adsorbent.
  • the elution data were collected for three consecutive days and the data revealed that the elution contains a yield of > 90% of the theoretical amount of available front the generator.
  • the 3 ⁇ 4 ⁇ Mo in the eluent was less than 0, 15 m € ⁇ of "Mo per mCi of ⁇ “Te.
  • the eluent solution was further subjected to treatment with either 1 M sodium thiosulfate or sodium sulfite to neutralize the presence of oxidizer In the solution.
  • the use of sodium sulfite can efficiently neutralize the oxidizer that may present in the final eluent.
  • Typical composition of the eluent obtained from these experiments is given in Table 12,
  • the subsequent increase in the heat of adsorption may be attributed to lateral interactions between the adsorbed molybdenum ions, which are known to form complex molecules on a solid surface. It was expected that adsorption surface sites of the resin will be homogeneous energetically and. therefore, a constant heat of adsorption should be obtained. However, the resin surface seems to become heterogeneous energetically, because of the micro-porosity of the surface.
  • an amorphous titarha gel was prepared by acid catalyzed controlled hydrolysis and condensation of titanium isopropoxtde. See Hasan, S,, Ghosh, T.K., Preias, .A., Viswanath, D.S., and Boddu, V.M,“Adsorption of uranium on a novel bioadsorbent chitosan coated perlite” Nuclear Technology, 159, 59-71 , 2007; Sehaitka, i. FL, Wong, E.
  • the hydrolysis and condensation reaction was controlled by the ratio of water and titanium and W and titanium in the mixture, respectively.
  • the final pH of the mixture was approximately 2.0 and the final reactant stoichiometry' was Tk IF: HjO: H + 0,0132:039: 1 ,67:0.01 , Based on the concentration ratio of the reactants, the gel time was varied between 25 and 45 minutes,
  • a sol-gel solution of amorphous titania was mixed with ehitosan g .
  • the mixture was kept under stirring at 70°C for another 1 hr for complete reaction of ehitosan and amorphous titanium oxide.
  • the reaction with gluteraidehyde was performed by drop-wise addition of about 6 mL gluteraidehyde solution having a concentration of 50% to the addle ehitosan titania gd under continuous stirring at 7O 0 C, The pH of the final mixture was approximately 1.0, The mixture was kept under continuous vigorous stirring at 70 fJ C for another I hr to obtain a semi-solid gel.
  • chitosan based micro-porous composite material was prepared by cross-linking gluteraldehyde at 7(PC in the presence of catalyst.
  • MPCM was prepared in the laboratory via the phase inversion of liquid slurry' of chitosan dissolved in acetic acid and the aide! condensation of g!utaraldehyde for better exposure of amine groups ( Hs), The MPCM was characterized by scanning electron microscopy (SEM), which revealed its porous nature.
  • SEM scanning electron microscopy
  • Two MPCM based derivatives such as ox ized- PC and acid-catalvzed-MPCM were also prepared.
  • a "Mo/" ffi Tc generator based on low specific neutron captured produced molybdenum has been prepared using a novel MPCM resin as an adsorbent.
  • the oxidized MPCM resin is found to be capable of adsorbing >95% of available molybdenum from the 1% solution at solution pH 3.0 when solid to liquid ratio is 2: 100.
  • Almost 90% of available 93 ⁇ 4ff Tc was eluted with mainly saline solution (0.9% NaCi) from the generator.
  • the breakthrough of "Mo and the pH of the eluent that pass through an alumina guard column are within the United States Pharmacopeia (USP) and European Union Pharmacopeia (EUP) limits,
  • Nanopartides of high Z element of Hafnium were prepared by crystal growth or surfactant tempiating methods using Hafnium chloride as precursor.
  • Hafnium nanopartides were synthesized using either PEG-400 or Pluronic-123 as surfactant, The percentage of surfactant used to synthesize the nanopartides was varied from 4 to 20% by weight.
  • Th synthesis procedure involved three steps. In the first step, Hafnium Chloride (HfChG-SlhO) and a surfactant 'eit r PEG-400 or Piufon -S23 were mixed thoroughly in
  • the saline solution used to elute 9w ”Tc from the MPCM-Z was modified with additives such as sodium nitrate ⁇ 1 g/L) in an attempt to improve yield.
  • the " m Tc recovery was markedly better - about ⁇ 70%. It seemed evident that the MPCM-Z resin showed better performance In higher radiation Held produced by the " o compared to partially oxidized MPCM resin, A guard column with alumina as an adsorbent was used to keep “Mo in the eluent > 1 Ci of "Mo per mCI of "mTc.
  • the pH of the eluent was within 4,5 to 7,5, The elution contains a yield of > ⁇ 80% of the theoretical amount of " m Te available from the "Mo over the life of the generator,

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Abstract

L'invention concerne des sorbants microporeux de chitosane réticulé/glutaraldéhyde qui comprennent une pluralité de nanoparticules d'un élément Z élevé. Les nanoparticules sont disposées dans la matrice composite de chitosane réticulé-glutaraldéhyde et intégrées à la matrice composite de chitosane réticulé-glutaraldéhyde pour réduire l'impact primaire d'un flux de rayonnement élevé et minimiser l'effet radiolytique sur ladite matrice composite de chitosane réticulé-glutaraldéhyde. La pluralité de nanoparticules est fabriquée à partir de l'élément Z élevé tel que le hafnium (Hf). L'invention concerne également des procédés de fabrication et d'utilisation des sorbants microporeux de chitosane réticulé/glutaraldéhyde, et un générateur pour le radio-isotope 99Mo contenant les sorbants.
EP19718201.7A 2018-03-26 2019-03-18 Préparation de matière composite microporeuse à base de chitosane et ses applications Pending EP3774024A1 (fr)

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US15/935,398 US10500564B2 (en) 2011-03-17 2018-03-26 Preparation of chitosan-based microporous composite material and its applications
PCT/US2019/022666 WO2019190791A1 (fr) 2018-03-26 2019-03-18 Préparation de matière composite microporeuse à base de chitosane et ses applications

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