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Sorption of Radionuclides

January 2015
International Journal of Pharmaceutical Sciences Review and Research 34(1 19):122-130

January 2015
34(1 19):122-130

Authors:

Mayank Modi

University of Turku

Nishad Dash

VIT University

Sangeetha Subramanian

VIT University

Chitin, chitosan, chitin-and chitosan-derivatives, living and dead fungi, and modified fungal biomass have been used for their ability to sorb metals, radionuclides, dyes and ions from water, waste water, soil and other contaminated sources. These sorbents are based on chitin, contain a large number of functional groups such as hydroxyl and amino groups enabling them to exhibit high sorption potential. Chitin and related-derivatives owing to their low cost, high sorption capacities, ease of use and ability to regenerate have found significant acceptance for removal of radioactive pollutants. Biosorption using fungi has been achieved with surprising success. This review includes fungi from divisions of Ascomycota, Basidiomycota and Zygomycota due to the presence of chitin and chitosan as significant components of their cell walls. In this review, an extensive list of chitin, chitosan, chitin-and chitosan-derivatives, living and dead fungi, and modified fungal biomass from vast literature was reviewed and their sorption capacities for a variety of radionuclides as available are shown.

: Sources of chitin and the source organisms.

…

: Adsorbents, Radionuclide, Adsoprtion capacity, Kinetics model & Isotherm, and Reference.

…

Some radionuclides along with their activities and health effects.

…

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Int. J. Pharm. Sci. Rev. Res., 34(1), September – October 2015; Article No. 19, Pages: 122-130 ISSN 0976 – 044X

International Journal of Pharmaceutical Sciences Review and Research

Available online at

www.globalresearchonline.net

122

Mayank Kumar Modi, Piyush Pattanaik, Nishad Dash, Sangeetha Subramanian*

School of Bio Sciences and Technology, VIT University, Vellore, Tamil Nadu, India.

*Corresponding author’s E-mail: sangeethasubramanian@vit.ac.in

Accepted on: 17-07-2015; Finalized on: 31-08-2015.

ABSTRACT

Chitin, chitosan, chitin- and chitosan- derivatives, living and dead fungi, and modified fungal biomass have been used for their ability

to sorb metals, radionuclides, dyes and ions from water, waste water, soil and other contaminated sources. These sorbents are

based on chitin, contain a large number of functional groups such as hydroxyl and amino groups enabling them to exhibit high

sorption potential. Chitin and related-derivatives owing to their low cost, high sorption capacities, ease of use and ability to

regenerate have found significant acceptance for removal of radioactive pollutants. Biosorption using fungi has been achieved with

surprising success. This review includes fungi from divisions of Ascomycota, Basidiomycota and Zygomycota due to the presence of

chitin and chitosan as significant components of their cell walls. In this review, an extensive list of chitin, chitosan, chitin- and

chitosan- derivatives, living and dead fungi, and modified fungal biomass from vast literature was reviewed and their sorption

capacities for a variety of radionuclides as available are shown.

Keywords: Chitin, Chitosan, Radionuclides, Adsorption.

INTRODUCTION

he recovery or removal of radionuclides from sea

waters and waste waters is a challenging problem.

According to the fundamental principles of

radioactive waste management, radionuclide waste

minimization is required to be done in an effective

manner. The principal sources of radionuclides are soil,

rocks, sea water and tailings of mineral processing

activities. Increase in the amount of radionuclides in the

environment has occurred due to a number of

anthropological activities like mining, benefaction of

radionuclides from their ores, processes related to

nuclear power plants and the manufacture of atomic

weapons, and use of radionuclides in medical diagnosis

and treatment techniques. These applications of

radionuclides produce various solid and liquid wastes

containing a cocktail of different isotopes. These wastes

are known to cause intense toxicological impacts and

destructive illnesses for human1. Table 2 gives the

activities and health effects of some radionuclides.

Hence, United State Environmental Protection Agency

(USEPA) and World Health Organization (WHO) have

directed maximum concentration level of uranium in

drinking water to be 0.030 and 0.015 mg/L, respectively

(WHO, 2004).

The new advanced treatments for the removal of these

hazardous materials has reached its endeavours recently.

The most commonly used methods for the removal and

recovery of radionuclides includes adsorption, membrane

filtration, solvent extraction, reductive precipitation, bio-

precipitation, biosorption, dialysis, chromatography, and

ion exchange methods2,3. Among these different

techniques, adsorption is the economically feasible

technique and it has been developed as the guaranteed

procedure for water and wastewater treatment.

The use of natural polymers as adsorbents has gone

through a new shift, especially polysacchrides like chitin

and its derivative chitosan. Henrni Braconnot, a French

Professor first discovered chitin in mushrooms, in 1811.

Later in 1820s chitin was also isolated from insects4.

Chitin contains 2-(acetylamino)-2-deoxy-D-glucose units

connected via β-1, 4 linkages. Chitin is the second most

abundant polymer in nature after cellulose. It can be

extracted from crustacean shell such as prawns, crabs,

fungi, insects and other crustaceans.

Some sources of chitin and source organisms have been

shown in Table 1. Chitin (Fig. 1a) is depicted as cellulose

with one hydroxyl group on each monomer replaced with

an acetyl amine group. This increases hydrogen bonding

between nearby polymers, providing the chitin-polymer

matrix greater strength.

Chitosan was discovered in 1859 by Professor C. Rouget.

Chitosan (Fig. 1b) is composed of randomly distributed β-

(1-4)-linked D-glucosamine and N-acetyl-D-glucosamine.

It is prepared by treating shrimp and other crustacean

shells with alkali sodium hydroxide4.

Chitosan can be used as an adsorbent to remove

radionuclides due to the presence of amino and hydroxyl

groups, which serve as the active sites. This biopolymer

represents an appealing alternative to other biomaterials

on account of its physico-chemical characteristics,

chemical stability, high reactivity, magnificent chelation

behaviour and high selectivity towards pollutants.

Chitosan has been modified by several methods either

physical or chemical to enhance its physical properties to

achieve greater adsorption capacity for different

radionuclides. Different shapes of chitin and related-

derivatives such as beads, hydrogels, membranes, films,

Sorption of Radionuclides

Review

Article

Int. J. Pharm. Sci. Rev. Res., 34(1), September – October 2015; Article No. 19, Pages: 122-130 ISSN 0976 – 044X

International Journal of Pharmaceutical Sciences Review and Research

Available online at

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123

resins and microspheres have been examined for their

adsorption efficiency of various pollutants.

Figure 1: a) Chitin; b) Chitosan

In the present work, the aim is to review of the

adsorption potential (adsorption capacities) of chitin and

related-derivatives for various radionuclides e.g. uranium,

thorium, americium, cesium, technetium, etc.

Table 1: Some radionuclides along with their activities

and health effects.

Radionuclides Activity Health Effects

Uranium-238 3.3 × 10-7 Ci/g Heavy damage to

kidney

Thorium-232 1.1 x 10-7 Ci/g Tumours and

Leukaemia

Strontium-90 1.5 x 102 Ci/g Bone cancer

Uranium-233 9.5 x10-3 Ci/g Renal and CNS

damage

Thorium-234 2.3 x 104 Ci/g Lung and pancreatic

cancer

Cesium-137 8.8 x 101 Ci/g Cancer and burns

Europium-152 1.9 x 102 Ci/g Cancer

Americium-241 3.2 Ci/g Cancer

Strontium-85 2.4 x 104 Ci/g Bone cancer

Strontium-89 2.9 x 104 Ci/g Cancer, Affects foetus

in pregnant women

Cobalt-60 1.1 x 103 Ci/g High risk of cancer

Manganese-54 8.3 x 10-3 Ci/g Cancer

Cerium-141 2.8 x 104 Ci/g Cardiovascular

collapse

Technetium-99 1.7 x 10-2 Ci/g Soil pollution and

degradation

Iodine-129 1.6 x 10-4 Ci/g Affects thyroid

Europium-154 1.5 x 102 Ci/g Cancer

Nickel-63 4.6 x 10 Ci/g Cancer

Radium-226 3.7 x 1010 Ci/g Lymphoma, bone

cancer

Table 2: Sources of chitin and the source organisms.

Source of Chitin Some source organisms

Cell walls of fungi Higher basidiomycetes

Exoskeletons of arthropods

(crustaceans & insects)

Crustaceans: crabs

lobsters and shrimps

Insects: Beetle

Radulae of molluscs Cuttlefish, snails and slugs

Internal shells of

cephalopods Bigfin reef squid

Squids -

Octopus -

Chitin- and Chitosan- Derivatives for Radionuclides

Removal

Radionuclides are a very significant category of

environmental pollutants that can harm human health as

well as impact other terrestrial and aquatic organisms.

Chitin- and chitosan-derivatives can be regarded to their

unique properties such as high hydrophobicity, presence

of many functional groups, flexible structure and high

chemical reactivity.

Natural Chitin and Chitosan

Shrimp shells is one of the major sources of chitin. Chitin

extracted from decalcified shrimp shells has been used to

investigate the ability to adsorb uranium from solutions5.

An absorption capacity of 7.484mg/g was observed at

optimum conditions. Langmuir isotherm model was

followed. The kinetic modeling data indicates the rate of

sorption to follow pseudo second-order. The mechanism

of uranium adsorption by chitin involves 3 steps: a)

interaction between uranium ions and the chitin chain; b)

adsorption of uranium ions by chitin network; and c)

hydrolysis of the formed complex followed by

precipitation of hydrolyzed compound6,7.

Removal of technetium-99 (99Tc), iodine-129 (129I), and

cesium-137 (137Cs) from contaminated ground water and

sediments using Chitosan was investigated8. The sorption

of Cs on sediments is stronger compared to Tc and I as

corroborated by the Kd value which is quite high for Cs.

Coprecipitation efficacy of 233U, 239Pu, 241Am, 152Eu, 90Sr,

90Y, and 60Co by low-molecular-weight chitosan (LMWC,

MW=5 kDa) and high-molecular-weight chitosan (HMWC,

MW=700 kDa) was investigated9. Experiments showed

LMWC to be a more effective coprecipitant than HMWC.

LMWC was synthesized from HMWC via enzymatic action

of S. Kurssanovii 10. Using HMWC, the degree of

coprecipitation (α) was found to be 99% for 233U and

241Am, 80% for 152Eu and 90Y, and 85% for 239Pu.

Chitosan granules and nanofibres were prepared for

sorption of 238U and 137Cs 11. It was found that U(VI)

sorption on bare granules (chitogran- C) and those cross-

linked by glutaraldehyde (chitogran-Cs) ocurred by

Int. J. Pharm. Sci. Rev. Res., 34(1), September – October 2015; Article No. 19, Pages: 122-130 ISSN 0976 – 044X

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external diffusion whereas for freshly formed granules

(chitogran-M) sorption occurred due to internal diffusion.

Cross-linking resulted in increased strength and stability

for the chitogran in acidic solutions but reduced sorbent

capacity. Cs sorption remained unaffected in presence of

competing ions. Recovery of chitogran was achieved with

elution by 0.02 M sulfuric acid and 0.6 M ammonium

bicarbonate for Cs and U respectively. Nanofibrous

chitosan containing materials provided quicker sorption

and more extraction. The sorption associated with Nickel

on chitosan was investigated12. Being a tracer was

employed radioisotope 63Ni. The influence of contact

time, effect of pH and effect of foreign ions on sorption of

nickel on chitosan was studied. The percentage of nickel

sorption on chitosan in the observed initial pH ranging

was 97 %.

Magnetite containing products

Chitosan impregnated with magnetite nanoparticles was

synthesized to examine the removal of uranium ions from

water and sodium carbonate solution showed a

desorption efficiency of 94 %13. A novel adsorbent was

prepared in the form of magnetic chitosan beads for the

removal of Sr2+14. The kinetic data correlated the

adsorption process by intra particle diffusion model. The

FTIR study revealed that –NH2majorly took part in the

sorption of Sr2 by magnetic chitosan beads.

With the help of an in-situ process, novel magnetic

chitosan composite particles of average size 40µm and

saturation magnetization of 24 emu/g were prepared and

evaluated for decontamination of radioactive waste

water15. Sorbent characterization by SEM, EDX, FTIR and

magnetization measurements was done which showed

that the target ions were bound and their surface

distribution was uniform. The composite under study was

found to have higher adsorption for uranyl (666.67 mg/g)

and thorium (312.50 mg/g) ions. Repeated adsorption

and desorption cycles showed that the material may be

regenerated and reused.

An amine bearing chitosan was reported by Elwakeel for

the sorption of uranium16. SEM analysis of TEPA@MCHS

beads after U(VI) adsorption showed a smooth surface

with small particles on surface, instead of the multi-

microporous, rough surface with appended pores before

adsorption. Elution of the uranium ion loaded resin with

0.5 M Hydrochloric acid was found to reach 98%

desorption.

Imprinted Chitosan

Chitosan modified via metal ion imprinting (MIP)

technique has been prepared to selectively uptake Co(II)

from solutions17. MIP chitosan was found to have

maximum sorption compared to NIP (Non-Imprinted)

chitosan in citrate solution. MIP showed selectivity for

Co(II) in presence of competing Fe(II) while NIP showed

similar sorption capacities for both. Sorption of Co(II) by

MIP from NAC formulations that are strongly complexing

displays its use in the preferential sorption of Co(II) from

complexing solutions. Elution with 0.25 M sulphuric acid

solution in batch process gave nearly 100% desorption

was achieved in 1 hr.

Application of surface ion-imprinting concept and sol–gel

process in preparation attapulgite-supported-chitosan

polymer for the selective adsorption of Ce(III) from

aqueous solution was studied18. The optimum pH was

observed to be 4.0, during which the mass of Ce(III)-MIPs

was over 0.12 g and quiescent time was over 15 min. The

adsorption rate towards Ce(III) nearly reached to 100%.

Ce(III)-MIPs have well regenerative capacity which was

evident from the adsorption capacity of Ce(III)-MIPs after

four regenerations that slightly decreased.

Composite Products

A novel adsorbent poly(methacrylic corrosive)-joined

chitosan/bentonite (CTS-g-PMAA/Bent) composite was

synthesized for uranium (VI) adsorption19. The process

followed Langmuir isotherm model. It was also found that

CTS-g-PMAA/Bent was mechanically and chemically

robust for the recovery of U (VI) from aqueous media as

well as industrial waste.

Poly(methacrylic acid) – grafted composite/bentonite, a

novel composite matrix, was prepared. Batch

experiments were conducted to study the extent of Th(IV)

adsorption20. The adsorption capacity of PMAA-g-CTS/B

was found to be 99.8%. Repeated adsorption–desorption

experiments showed that PMAA-g-CTS/B (the adsorbent)

had a high potential for the removal and recovery of

Th(IV) from aqueous media.

A novel chitosan/clinoptilolite (CS/CPL) composite was

used for adsorption of UO22+ and Th4+ ions from

radioactive solutions21. The adsorption process was

spontaneous (∆G◦ <0) and endothermic (∆H◦ >0). The

results obtained in the desorption process indicated 0.1M

Na2CO3 as the best desorption agent for the UO22 ions,

while for the desorption of the Th4+ ions, the best results

were obtained with 0.1M HCl solution thereby indicating

the reusability of the adsorbent.

Cross-linked Chitosan Products

Two chitosan derivatives: cross-linked chitosan (CRC) and

cross-linked chitosan after hydrolysis (CRCH) were

prepared for extraction of 137Cs, 85,89Sr, 152Eu, 241Am, 234Th

and 233U using batch and column methods22. The τ1/2

(Half-life) for U appeared to be in the range 120-150

minutes for CRC and CRCH. For other metal ions, the τ1/2

was found to be in the range from 240 – 254 min. The ion

uptake trend was as follows: UO22+> Th4+> Cs+> Eu3+>

Am3+> Sr2+ and the Kd value was found to decrease with

increasing acidity. CRCH has a higher uptake capacity

compared to CRC. However, CRC showed greater

selectivity for uranium due to the presence of nitrogen

donors for selective binding. Elution of uranium loaded

on CRCH with disodium carbonate gave 97% recovery and

more than 95% elution of Th was obtained with EDTA.

Int. J. Pharm. Sci. Rev. Res., 34(1), September – October 2015; Article No. 19, Pages: 122-130 ISSN 0976 – 044X

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Modified Chitin and Chitosan Products

Adsorption of Uranium (VI) from aqueous solution onto

modified chitosan, i.e., chitosan grafted with citric acid

was investigated23. Kinetic studies showed that the

adsorption rate was determined by interfacial boundary

diffusion mechanism. The adsorption capacity was found

to be 24 mg/g. Elution with 0.1 M NaHCO3 solution giving

a maximum recovery of 99.78%.

Sorption of 90Sr, 90Y, 137Cs, and 233U on newly synthesized

derivatives of HMWC and LMWC was examined24. The

following derivatives were synthesized Succinyl chitosan

Na salt (SHMWC), Succinyl chitosan Na salt (SLMWC) N-

(2-Hydroxybenzyl) chitosan (HBHMWC), Chitosan cross-

linked with 2-{2-[2-(2-formylphenoxy)ethoxy]ethoxy}

benzaldehyde (LMWCDA), N,O-(2-Hydroxy-2-N,N-

dicarboxymethyl)ethyl chitosan (IDA-HMWC), and N-(3-

Sulfo-3-carboxy)propionyl chitosan (N-SSLMWC). Of all

the derivatives, SLMWC and N-SSLMWC were found to be

soluble in solution at pH range 1 – 10. 90Sr did not sorb

effectively on any functional derivative.

To improve the adsorption properties of chitin it was

modified with dithizone for adsorption of 60Co25. Natural

and dithizone-modified chitin was characterized using

surface area analyzer and infrared spectroscopy.

Dithizone-modified chitin was found to have a greater

surface area than natural chitin. Adsorption of 60Co was

found to increase with pH on dithizone-modified chitin.

At low pH, protonation of active sites prevented

adsorption. The equilibrium time was found to be 180

minutes at which the adsorption reached 60 and 96% for

Ch and Di-Ch, respectively. The process is spontaneous

and exothermic, due to a positive enthalpy value.

Other Derivatives

Multiwall Carbon Nanotubes were used and modified to

be used with chitosan for U(VI) adsorption26. The removal

of U(VI) by MWCNTs and MWCNT-CS increased with

raising pH values at pH<7, and then decreased together

with raising pH values at pH>7.

The final results suggest that MWCNT-CS can be

employed for U(VI) preconcentration and other

lanthanides/actinides. Adsorption actions associated with

Sr(II) ions was reported using carboxymethylated chitosan

(CMCts)27.

The adsorption of Sr(II) ions discloses that minimizing pH

as well as improving ionic strength can reduce the actual

adsorption ability of Sr(II) ions.

The advantage of using chitosan cryogel modified with

pyridoxal-5´-phosphate for extraction of 152,154Eu(III) from

aqueous solutions was examined28. The chitosan cryogels

have an ultramacroporous structure with pores of

diameter range from 50-100 µm. Modification of chitosan

cryogel with pyridoxal-5´-phosphate improved the

sorption properties with respect to Eu(III).

A new inorganic ion-exchanger into biopolymer foams

combination biosorbent was prepared by immobilization

of Nickel–potassium ferrocyanide in highly porous discs of

chitin for the sorption of Cs(I) from near neutral

solutions29. SEM showed high porosity of the materials.

SEM-EDX analysis after Cs(I) sorption showed the

structure to be more compact. Sorption of individual

metals under comparable concentrations of Cs(I) followed

the sequence: Na(I) < Rb(I) < NH4+. The stability of the

sorbent was evidently demonstrated by the low release

of Ni and Fe during sorption process, and by the apparent

stability of Cs(I) during KCl elution confirmed the strong

interaction of cesium with the inorganic ion-exchanger.

Chitosan-tripolyphosphate (CTPP) beads prepared using

in-liquid curing method were used for the adsorption of

uranium from aqueous solution30. Experiments showed

the beads with higher cross-linking to have greater

adsorption capacity. The U adsorption capacity of lower

cross-linked beads decreased along with increase in pH of

the solution.

From the FTIR characterization data of the beads before

and after uranium adsorption, it is inferred that

phosphate groups play a greater role in the uranium

uptake by CTPP beads than the amino groups.

The successful removal of the hazardous 60Co and Eu

radionuclides from aqueous solutions was done by using

Chitosan benzoyl thiourea derivative31,152,154. X-ray

diffraction studies showed lowering of the crystallinity

with increasing the extent of substitution reaction.

A summary of sorption capacities and conditions of chitin-

and related-derivatives for removal of different

radionuclides has been presented in Table 3. It is clear

from this vast literature survey the chitin- and related-

derivatives have been proved to be very useful in

sorption of radionuclides from different contaminated

sources. The mechanism of sorption is found to be

dependent on electrostatic interactions, chelation and ion

pair formation. The sorption process is influenced by

several factors such as pH, temperature, sorbent dosage,

ion concentration, contact time, presence of competing

ions, and characteristics of the radionuclide.

Fungal Biosorption for Radionuclide Removal

The term ’Biosorption’ can be used in a number of ways

like bioadsorption, bioabsorption and bioaccumulation to

describe sorption by living or dead biomass,

bioaccumulation, etc of a diverse array of substances

such as metals, radionuclides, and organics32. Biosorption

can be done by using bacteria, plants, fungi, algae, moss,

or other organic material. This review includes articles

concerned with fungal biosorption as it has been found

that chitin and chitosan are a major part of fungal cell

wall of fungi divisions: Ascomycota, Basiodiomycota and

Zygomycota. The functional groups provided by chitin and

chitosan in the cell walls of these fungi play a major role

in the biosorption processes of fungi.

Int. J. Pharm. Sci. Rev. Res., 34(1), September – October 2015; Article No. 19, Pages: 122-130 ISSN 0976 – 044X

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Table 3: Adsorbents, Radionuclide, Adsoprtion capacity, Kinetics model & Isotherm, and Reference.

Adsorbent Adsorbate Sorption Capacity

(mg/g) or Kd (mL/g)

Kinetic Model & Isotherm Reference

Shrimp Shells containing chitin U(VI) 7.484 Psuedo Second Order; Langmuir 5

Chitosan Tc(IV), I(I), Cs(I) Kd -54, 88, 134 - 8

Chitogran- M; Chitogran- Cs, Nano-fibrous

Chitosan U(VI), Cs(II), U(VI) 173.74, 264.41, 952 - 11

Chitosan Ni(II) 162.6 Langmuir 12

Magnetic chitosan beads Sr(II) 11.58 Langmuir 14

Magnetic Chitosan U(VI), Th(IV) 666.67, 312.50 Freundlich, Langmuir, and Dubinin–

Radushkevich

Tetraethylenepentamine modified magnetic

chitosan resin U(VI) 428.45 Pseudo first order and pseudo

second order; Freundlich, Langmuir,

and Dubinin–Radushkevich

Cobalt (II) imprinted chitosan Co(II) - - 17

Chitosan I(I) Kd -88 - 18

Poly(methacrylic acid)-grafted

chitosan/bentonite (CTS-g-PMAA/Bent)

composite (Prepared via Graft

Copolymerization)

U(VI) 117.2 Psuedo Second Order; Langmuir 1 9

Poly(methacrylic acid)-grafted

chitosan/bentonite (CTS-g-PMAA/Bent)

composite

Th(IV) 110.6 Psuedo Second Order; Langmuir 20

Chitosan/clinoptilolite U(VI), Th(IV) 328.32, 408.62 Psuedo Second Order; Langumir,

Freundlich & Sips

Cross-linked chitosan (CRC) UO2(II), Th(IV),

Cs(I), Eu(III) Kd -125, 44.7, 24.3,

1.54 - 22

Cross-linked chitosan after hydrolysis

(CRCH) Th(IV), Cs(I),

Eu(III), U(VI) Kd -203, 149, 125, 18.0 - 22

Chitosan grafted with citric acid U(VI) 22.3 Psuedo Second Order; Langmuir,

Freundlich and Redlich-Peterson

Natural Chitin, Dithizone-Modified Chitin Co(II) 27.25, 30.58 Psuedo First Order; Freundlich 25

Chitosan modified MWCNTs (Prepared via

Chemical Vapour Deposition and Low

temperature plasma technique)

U(VI) - Langmuir 26

Carboxymethylated chitosan (CMCts)

(Prepared via Gamma-ray irradiation) Sr(II) 99 Langmuir 27

Chitosan cryogel modified with pyridoxal-5´-

phosphate Eu(III) 7.85 Langmuir 28

Nickel–potassium ferrocyanide immobilized

onto chitosan foam Cs(I) 81 Psuedo Second Order; Langmuir 29

Chitosan-tripolyphosphate (CTPP) U(VI) 239.9 Psuedo Second Order; Langmuir and

Freundlich

Chitosan benzoyl thiourea derivative Co(II), Eu(III) 29.47, 34.54 Langmuir, Freundlich & Lagergren 31

Rhodosporidium fluviale strain UA2 Cs(II) 0.182 Langmuir 3 3

Pleurotus mutilus U(VI) 250 Psuedo Second Order; Langmuir and

Freundlich

Schizophyllum commune 4–39 (CYM-T

culture medium) U(VI) 240-280 - 35

Immobilized cells of Rhodotorula glutinis U(VI) 17.3 Psuedo First Order; Sips 36

Ca-alginate immobilized Trichoderma

harzianum U(VI) - - 37

Potassium nickel hexacyanoferrate-modified

Agaricus bisporus Cs(II) 6.576 Psuedo Second Order; Freundlich 38

Fusarium sp. #ZZF51 i n pure form,

formaldehyde, methanol, and acetic acid

treated forms.

U(VI) 21.42, 318.04, 311.95,

351.67 Psuedo Second Order; Langmuir and

Freundlich

Magnetically modified Rhodotorula glutinis U(VI) 73.5 Psuedo First Order; Langmuir 40

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Geotrichum sp. Dwc-1/attapulgite (Prepared

via Hydrothermal Process) U(VI) 125 Psuedo Second Order, Psuedo First

Order; Langmuir and Freundlich

Rhodotorula glutinis in pure form,

methanol, and formaldehyde treated U(VI) 98.4, 129,110 Langmuir and Freundlich 42

Immobilized Aspergillus fumigatus U(VI) 7.2 Psuedo Second Order; Freundlich

and Tempkin

Rhizopus arrhizus biomass cross-linked with

formaldehyde Am(II), U(VI) 62, 68 - 44

Fungal biosorption is very promising for the remediation

of radionuclides from diverse contaminated

environmental sources, it also offers opportunity for use

in recovery and preconcentration of commercially

important radionuclides from natural sources in which

radionuclides are present in largely diffused quantities.

Live Biomass

The biosorption behavior and mechanism of 137Cs on

Rhodosporidium fluviale (R. fluviale) strain UA233. It was

seen that the biosorption of 137Cs on the strain UA2 of R.

fluviale was fast and was also a pH-dependent process. A

substantial amount of 137Cs adsorption on UA2 was

observed within the range of pH 3-9, and the optimum pH

was found to be 5.0. The contact time was found to be 4

hours. HNO3 was found to be an efficient eluent with a

desorption percentage of 82.6.

Dead Biomass

Dead fungal biomass (Pleurotus mutilus) was used for

removal and recovery of U(VI) from aqueous solutions via

biosorption34. FTIR analysis before and after uranium

adsorption, demonstrated the role of amino, carboxylic,

sulfonates and phosphates functional groups in the

adsorption process. SEM shows the fungal biomass has

rough porous surface and the micropores increase the

total mass transfer area along with decreasing diffusion

resistance. The maximum capacity of 250 mg/g was

obtained at particle size of 250–315 um. Increasing

stirring speed causes diffusion of uranium into boundary

layer adsorption thus raising the diffusion coefficient. The

biosorption process is exothermic in nature. Maximum

adsorption capacity increased with increasing initial

uranium concentration in solution, but the rate of

uranium adsorbed decreases.

Sorption of Uranium by Schizophyllum commune from

aqueous solution was examined35. At initial uranium

concentration of 50 mg/l, binding capacities of 120–150

mg uranium per g dry weight were obtained and found to

be independent of pH. Analysis via a combination of

imaging techniques including HAADF and STEM showed

the ions to be accumulated on both, the cell wall and

intracellular. In S. Commune, the carboxylic groups were

found to be in Uranium complication.

Biosorption of uranium ions from diluted solution onto

immobilized Rhodotorula glutinis was carried out in a

batch reactor36. Sips isotherm model was found to be the

best. Kinetic data correlated with the pseudo-first-order

model. The sorption process was found to be

endothermic and spontaneous from the data obtained

from the free energy value.

Modified Biomass

Ca-alginate immobilized Trichoderma harzianum has been

used for the adsorption of uranium ions from aqueous

solution37. Immobilization of Trichoderma harzianum to

Ca-alginate increased the stability and uranium

biosorption capacity of the bio-adsorbent at 28 ± 2°C and

200 rpm. Ca-alginate immobilization clearly improved

biosorption capacity of uranium and the stability of the

biosorbent as indicated by the experimental results.

Sorbed uranium was also recovered in 200 ml of 0.1 N HCl

with greater than 99% of recovery.

Potassium nickel hexacyanoferrate(II) (KNiFC) modified

Agaricus bisporus was studied for cesium ion

adsorption38. The distribution coefficient was at interval

7,662–159 cm3g-1. From the desorption experiments it

was found that 0.1 M potassium chloride was the most

effective desorption agent but the complete desorption

of Cs ions from KNiFC-modified biosorbent could not be

attained.

Adsorption of U(VI) from waste water was carried out

using Fusarium sp. #ZZF51 biomass, a mangrove

endophytic fungus originated from South China Sea

coast39. To enhance the affinity of uranium sorption, the

fungus was treated with formaldehyde, methanol and

acetic acid which resulted in methylation of amino

groups, esterification of carboxyl groups, and acetylation

of hydroxyl and amino groups, respectively. The following

chemical modification lead to an increase in functional

providing more sites for uranium binding. The maximum

biosorption was obtained with acetic acid treated

biomass. FTIR analysis data indicated the functional

groups to play a key role in biosorption phenomenon.

In a batch system, the ability of magnetically modified

Rhodotorula glutinis to adsorb Uranium from aqueous

solution was examined40. With increasing biomass dosage

from 0.5 mg to 10 mg, uranium sorption ratio increased.

Sorption was found to be more efficient in dilute

solutions as a sorption ratio of 90% was obtained for <50

mg/L uranium concentration. Experimental effects for

different competing cations showed little effect on

uranium sorption. The sorption process is endothermic

and spontaneous implying it becomes favourable at

higher temperature.

A novel adsorbent of fungus/attapulgite (F/ATP)

composites was synthesized to study the removal of U(VI)

Int. J. Pharm. Sci. Rev. Res., 34(1), September – October 2015; Article No. 19, Pages: 122-130 ISSN 0976 – 044X

International Journal of Pharmaceutical Sciences Review and Research

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www.globalresearchonline.net

128

from a simulated aqueous solution41. The thermodynamic

data implied that the process was spontaneous and

endothermic. Adsorption-desorption experiments

indicated high sorption capacity of U(VI) (91%) over six

cycles.

In order to study the role played by various functional

groups in the cell wall, chemically modified yeast cells of

Rhodotorula glutinis were used for the biosorption of

Uranium42. Esterification of the carboxyl groups and

methylation of the amino groups present in the cells were

done by methanol and formaldehyde treatments,

respectively. The biosorption process was found to be

mainly dependent on ionic interaction and complexion

formation. Amino and carboxyl groups were concluded to

be the major functional groups that took part the in

uranium sorption process.

Biosorption of uranium (VI) particles by immobilized

Aspergillus fumigatus globules was explored in a batch

experiment43. The change and the refinement of non-

feasible Rhizopus arrhizus biomass were examined

through immobilization44. The experiment was done at

three different pH and most showed an absorbance of

95%.

Table 3 summarizes the sorption capacity and conditions

of reaction for different fungi and modified fungal

derivatives for radionuclide removal, respectively.

CONCLUSIONS AND FUTURE PERSPECTIVES

This review paper indicates that adsorption using

chitosan composites is becoming a promising alternative

to replace traditional adsorbents in removing

radionuclides from industrial waste water, ground water

and effluents. The effectiveness of the treatment

depends not only on the properties of the adsorbent and

adsorbate, but also on various environmental conditions

and parameters taken into account for the adsorption

process like pH, ionic concentration, temperature,

existence of competing ions in solution, initial

radionuclide concentration, contact time, rpm and

adsorbent dosage. These parameters should be taken

into account while examining the potential of

chitin/chitosan-derivatives. Due to its high hydrophilicity,

flexibility of polymeric chain and large number of primary

amino groups, chitosan can be regarded as a good

adsorbent for radionuclides like U(VI). Different

experimental studies have revealed the high potential for

adsorption of such impurities from the aqueous medium

by chitin, chitosan and their derivatives. One of the major

advantages of the use of these composites is the cost

factor i.e. the feasibility of the processes to be carried out

in large scale operations. Chitosan composites are one of

the chitosan-based materials that are economically

feasible because they are easy to synthesize and include

inexpensive chemicals. There have also been studies on

the possibilities of integrating biological removal of toxic

components from sewage and other wastes. It is clear

that some biosorption methodologies for the treatment

of heavy metals and radionuclide containing effluents

offer potentially effective and economical alternatives to

existing treatment technologies. Not only efficient

adsorption, but adsorption-desorption studies have also

revealed the highly efficient reusability of the chitin,

chitosan and their derivatives along with the fungal

biomass. This could dramatically lower down the cost of

this downstream processing step before releasing the

treated water or effluent into the environment safely.

This field has a lot of potential of improvement and

studies are still going on how to make the processes more

efficient and lasting in order to salvage the environment

and living beings from the toxic pollutants.

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Source of Support: Nil, Conflict of Interest: None.

Preparation of Graphene Oxide-Maghemite-Chitosan Composites for the Adsorption of Europium Ions from Aqueous Solutions

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The ability of Ca-alginate immobilized Trichoderma harzianum has been explored for removal and recovery of uranium from aqueous streams. Ca-alginate as polymeric support was selected after screening different matrices. Immobilization of Trichoderma harzianum to Ca-alginate improved the stability as well as uranium biosorption capacity of biosorbent at 28 ± 2 °C and 200 rpm. The suitability of packed bed column operations was illustrated by obtaining break through curves at different bed heights, flow rates and inlet uranium concentrations. The adsorption column containing 1.5 g dry weight of immobilized material has purified 8.5 L of bacterial leach liquor (58 mg/L U) before break through occurred and the biosorbent became saturated after 25 L of influent. Sorbed uranium was recovered in 200 ml of 0.1 N HCl resulting in 98.1-99.3% elution by 0.1 N HCl, which regenerated the biosorbent facilitating the sorp-tion-desorption cycles for better economic feasibility without any significant alteration in sorption capacity/elution efficiency.

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The chitosan grafted with citric acid via crosslinking with glutraldehyde (C-Gch) has been studied for removal of U(VI) from aqueous solution by batch method. The results showed that after grafting, its adsorption capacity for U(VI) was significantly enhanced. The effects on the adsorption including the contact time, the solution pH were investigated. The time dependent experimental data well fitted the pseudo- second-order model and the adsorption rate was controlled by intraparticle and boundary layer diffusion mechanisms. Langmuir Freundlich and Redlich-Peterson models were found to be the appropriate model for describing the adsorption equilibrium. From the results obtained, it could be concluded that, C-Gch is a potential adsorbent for removal of uranium from contaminated water sources.

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CHEM ENG J

A new adsorbent of fungus/attapulgite (F/ATP) composites was synthesized by one-pot hydrothermal carbonization method under mild conditions and characterized by scanning electron microscope, X-ray diffraction, thermogravimetric analysis and Fourier transform infrared spectroscopy. The characterized results showed that the fungus (Geotrichum sp. dwc-1) can be as a superior template for the assembly of nanoscale attapulgite by covalent bonding. According to batch experiments, the maximum sorption capacity of F/ATP for U(VI) was 125 mg/g at pH 4.0 and T = 303 K. The thermodynamic parameters calculated from sorption isotherms showed that U(VI) sorption on F/ATP was a spontaneous and endothermic process. The fixed-bed column experiment further demonstrated that F/ATP presented the excellent adsorption performance. It was determined from regeneration experiments that the F/ATP composites exhibited high sorption of U(VI) (∼91%) over six cycles. Therefore, F/ATP can be as a promising candidate for the removal of U(VI) from aqueous solution due to its low-cost, sustainable, and efficient feature.

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Article

Jan 2014

Fusarium sp. #ZZF51, mangrove endophytic fungus originated from South China Sea coast, was chemically modified by formaldehyde, methanol and acetic acid to enhance its affinity of uranium(VI) from waste water. The influencing factors about uranium(VI) adsorption such as contact time, solution pH, the ratio of solid/liquid (S/L) and initial uranium(VI) concentration were investigated, and the suitable adsorption isotherm and kinetic models were determined. In addition, the biosorption mechanism was also discussed by FTIR analysis. Experimental results show that the maximum biosorption capacity of formaldehyde-treated biomass for uranium(VI) at the optimized condition of pH 6.0, S/L 0.6 and equilibrium time 90 min is 318.04 mg g−1, and those of methanol-treated and HAc-treated biomass are 311.95 and 351.67 mg g−1 at the same pH and S/L values but different equilibrium time of 60 and 90 min, respectively. Thus the maximum biosorption capacity of the three kind of modified biomass have greatly surpassed that of the raw biomass (21.42 mg g−1). The study of kinetic exhibits a high level of compliance with the Lagergren’s pseudo-second-order kinetic models. Langumir and Freundlich models have proved to be well able to explain the sorption equilibrium with the satisfactory correlation coefficients higher than 0.96. FTIR analysis reveals that the carboxyl, amino and hydroxyl groups on the cell wall of Fusarium sp. #ZZF51 play an important role in uranium(VI) biosorption process.

A review of potential remediation techniques for Uranium (VI) ion retrieval from contaminated aqueous environment

Article

Sep 2014

Uranium is known for its toxicity and has been a nuclear hazard. Its radioactive nature has made it a cause of lung and bone cancer. The uranium content in water bodies in several countries has surpassed the maximum permissible limits. In such regions of radioactive contamination of local soil and groundwater, the chemical toxicity of uranium has tremendously aggravated health concerns. Large scale loss of aquatic species has been witnessed due to uranium contamination. Governments have imposed regulations and set standards to limit the disposal of uranium in water bodies. Owing to its ability of fission, uranium simultaneously finds its application is nuclear energy generation. It is also used as a shield against radiation, as ammunition in military weaponry, as a counterweight for aircraft control surfaces, in radiotherapy and on-stream analysis of a wide range of minerals. With an objective to advance the understanding, this article covers the various techniques for the recovery of uranium along with a wide range of removal agents, considering the various factors that affect uranium uptake. The techniques contemplated upon include adsorption, membrane filtration, phytoremediation, reductive precipitation, microbiological methods and bio-precipitation. The isotherm and kinetic models used in adsorption have been stated and a comparative evaluation of the above listed techniques has also been done.

Aqueous 99Tc, 129I and 137Cs removal from contaminated groundwater and sediments using highly effective low-cost sorbents

Article

Jan 2014

Technetium-99 (99Tc), iodine-129 (129I), and cesium-137 (137Cs) are among the key risk-drivers for environmental cleanup. Immobilizing these radionuclides, especially TcO4− and I−, has been challenging. TcO4− and I− bind very weakly to most sediments, such that distribution coefficients (Kd values; radionuclide concentration ratio of solids to liquids) are typically <2 mL/g; while Cs sorbs somewhat more strongly (Kd ∼ 50 mL/g). The objective of this laboratory study was to evaluate 13 cost-effective sorbents for TcO4−, I−, and Cs+ uptake from contaminated groundwater and sediments. Two organoclays sorbed large amounts of TcO4− (Kd > 1 × 105 mL/g), I− (Kd ≥ 1 × 104 mL/g), and Cs+ (Kd > 1 × 103 mL/g) and also demonstrated a largely irreversible binding of the radionuclides. Activated carbon GAC 830 was effective at sorbing TcO4− (Kd > 1 × 105 mL/g) and I− (Kd = 6.9 × 103 mL/g), while a surfactant modified chabazite was effective at sorbing TcO4− (Kd > 2.5 × 104 mL/g) and Cs+ (Kd > 6.5 × 103 mL/g). Several sorbents were effective for only one radionuclide, e.g., modified zeolite Y had TcO4−Kd > 2.3 × 105 mL/g, AgS had I− Kd = 2.5 × 104 mL/g, and illite, chabazite, surfactant modified clinoptilolite, and thiol-SAMMS had Cs+Kd > 103 mL/g. These low-cost and high capacity sorbents may provide a sustainable solution for environmental remediation.

Potentiality of uranium biosorption from nitric acid solutions using shrimp shells

Article