# US 10,500,564 B2 · Preparation of chitosan-based microporous composite material and its applications

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- Number: US 10,500,564 B2
- Document ID: US10500564B2
- Status: Granted
- Kind: B2
- Application number: 15/935,398
- Filed: 2018-03-26
- Published: 2019-04-11
- Granted: 2019-12-10
- Earliest claimed: 2011-03-17
- Assignees: Perma-Fix Environmental Services, Inc.
- Applicants: Perma-Fix Environmental Services, Inc.
- Inventors: Shameem Hasan
- Web page: https://patentgrep.com/patent/US10500564B2

## CPC

- B01J 20/24: Naturally occurring macromolecular compounds, e.g. humic acids or their derivatives
- B01D 15/08: Selective adsorption, e.g. chromatography
- B01J 20/0211: {Compounds of Ti, Zr, Hf}
- B01J 20/28026: {Particles within, immobilised, dispersed, entrapped in or on a matrix, e.g. a resin}
- B01J 20/2808: {being less than 2 nm, i.e. micropores or nanopores}
- B01J 20/3021: {Milling, crushing or grinding}
- B01J 20/3071: {Washing or leaching}
- B01J 20/3085: {Chemical treatments not covered by groups B01J20/3007 - B01J20/3078}
- C08B 37/003: {Chitin, i.e. 2-acetamido-2-deoxy-(beta-1,4)-D-glucan or N-acetyl-beta-1,4-D-glucosamine; Chitosan, i.e. deacetylated product of chitin or (beta-1,4)-D-glucosamine; Derivatives thereof}
- C08L 5/08: Chitin; Chondroitin sulfate; Hyaluronic acid; Derivatives thereof
- C22B 34/34: Obtaining molybdenum {(treatment or purification of solutions by adsorption on solids C22B3/24, by liquid-liquid extraction C22B3/26, by ion-exchange extraction C22B3/42; preparation of molybdenum involving liquid-liquid extraction, adsorption or ion-exchange C01G39/003)}
- C22B 59/00: Obtaining rare earth metals
- G21F 9/12: by absorption; by adsorption; by ion-exchange
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- C08B: POLYSACCHARIDES; DERIVATIVES THEREOF (polysaccharides containing less than six saccharide radicals attached to each other by glycosidic linkages C07H; fermentation or enzyme-using processes C12P19/00; sugar industry C13; production of cellulose D21)
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- C22B: PRODUCTION AND REFINING OF METALS (electrolytic C25); PRETREATMENT OF RAW MATERIALS
- G21F: PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR (radiation protection by pharmaceutical means A61K8/00, A61Q17/04; in cosmonautic vehicles B64G1/54; combined with a reactor G21C11/00; combined with X-ray tubes H01J35/16; combined with X-ray apparatus H05G1/02)

## Abstract

Microporous glutaraldehyde-crosslinked chitosan sorbents include a plurality of nanoparticles of a high Z element. The nanoparticles are disposed in the cross-linked chitosan-gluteraldehyde composite matrix and integrated with the cross-linked chitosan-gluteraldehyde composite matrix to reduce primary impact of high radiation flux and minimize radiolytic effect on said cross-linked chitosan-gluteraldehyde composite matrix. The plurality of nanoparticles is made from the high Z element such as hafnium (Hf). Methods of making and using the microporous glutaraldehyde-crosslinked chitosan sorbents, and a generator for the radioisotope 99Mo containing the sorbents.

## Claims

### Claim 1

A sorbent comprising:
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 wt % to produce a cross-linked chitosan-gluteraldehyde composite matrix which is resistant to degradation from exposure to beta and gamma radiation and from exposure to acids; and
a plurality of nanoparticles of a high Z element disposed in said cross-linked chitosan-gluteraldehyde composite matrix and integrated with said cross-linked chitosan-gluteraldehyde composite matrix to reduce primary impact of high radiation flux and minimize radiolytic effect on said cross-linked chitosan-gluteraldehyde composite matrix.

### Claim 2 (depends on 1)

The sorbent as set forth in claim 1 wherein said high Z element is hafnium (Hf).

### Claim 3 (depends on 2)

The sorbent as set forth in claim 2 wherein Hf is present in said cross-linked chitosan-gluteraldehyde composite matrix between 0.15 g and 0.35 g per grams of said cross-linked chitosan-gluteraldehyde composite matrix.

### Claim 4 (depends on 1)

The sorbent as set forth in claim 1 wherein the sorbent has increased selectivity for the sorption of 99Mo with respect to 99mTc.

### Claim 5 (depends on 1)

The sorbent as set forth in claim 1 further including an additive of sodium nitrate being present at 1 g/L.

### Claim 6

A method for preparing a radiation-resistant sorbent, comprising:
combining chitosan with water in the presence of an acid to form a chitosan gel;
adding glutaraldehyde to the gel to form a semi-solid mass in the presence of catalyst at 70° C., in where condensation polymerization of reaction mass occurs;
washing the semi-solid mass to remove unreacted glutaraldehyde and form a washed mass;
suspending the washed mass in aqueous base to form a neutralized crosslinked mass;
disposing a plurality of nanoparticles of a high Z element on the neutralized crosslinked mass; and
drying the neutralized crosslinked mass including the plurality of nanoparticles under vacuum to form the radiation-resistant sorbent.

### Claim 7 (depends on 6)

The method as set forth in claim 6 wherein said step of depositing is further defined as dispersing the plurality of nanoparticles made from hafnium (Hf) on the neutralized crosslinked mass.

### Claim 8 (depends on 7)

The method as set forth in claim 7 wherein said step of depositing is further defined as dispersing the plurality of nanoparticles made from hafnium (Hf) between 0.15 g and 0.35 per grams of the neutralized crosslinked mass on the neutralized crosslinked mass.

### Claim 9 (depends on 1)

A method of separating isotopes from mixtures thereof, comprising:
contacting a mixture of at least two isotopes with a radiation resistant sorbent according to claim 1 that preferentially sorbs at least one of said isotopes;
sorbing at least one of said isotopes onto or into said sorbent while one or more of the remaining isotopes are not significantly sorbed by the sorbent;
removing said one or more remaining isotopes from said sorbent.

### Claim 10 (depends on 9)

The method according to claim 9, wherein said at least two isotopes comprise 99Mo and 99mTc.

### Claim 11 (depends on 10)

The method according to claim 10, wherein said sorbent preferentially sorbs said 90Mo and wherein said 99mTc is not significantly sorbed by said sorbent.

### Claim 12 (depends on 9)

The method according to claim 9, wherein one of said isotopes is a cesium isotope.

### Claim 13 (depends on 12)

The method according to claim 12, wherein said one or more remaining isotopes comprise one or more isotopes present in a radioactive waste stream.

### Claim 14 (depends on 9)

The method according to claim 9, wherein the removing of the one or more remaining isotopes from the sorbent comprises contacting the sorbent with an eluent solution.

### Claim 15 (depends on 14)

The method according to claim 14, wherein the eluent solution comprises one or more oxidizers selected from the group consisting of a chlorite, a hypochlorite, a dichromate, and a metal oxide.

### Claim 16 (depends on 1)

A generator for 99Mo/99mTc, comprising the sorbent of claim 1.

### Claim 17 (depends on 1)

A method for separating or concentrating or both one or more heavy metals from a liquid stream, comprising contacting a liquid stream containing said one or more heavy metals with a sorbent according to claim 1, and sorbing one or more of said heavy metals thereon.