Characterization and properties of Pleurotus mutilus fungal biomass as adsorbent of the removal of uranium(VI) from uranium leachate

Characterization and properties of Pleurotus mutilus fungalbiomass as adsorbent of the removal of uranium(VI)from uranium leachate

Meriem Mezaguer • Nour el hayet Kamel •

Hakim Lounici • Ziane Kamel

Received: 27 March 2012 / Published online: 3 July 2012

� Akademiai Kiado, Budapest, Hungary 2012

Abstract Removal and recovery of uranium from dilute

aqueous solutions by dead fungal biomass (Pleurotus muti-

lus) have been studied by biosorption. The parameters that

affect the uranium(VI) adsorption, such as: pH solution,

temperature, biomass particle size and speed of stirring have

been investigated and optimized. The experimental data

were analyzed using pseudo-first-order and pseudo-second-

order equations. The Freundlich and Langmuir adsorption

models have been used for the mathematical description of

the adsorption equilibrium. The maximum uranium bio-

sorption capacity has been calculated. The value obtained

(636.9 mg g-1) showed that P. mutilus is a good adsorbent.

Also, the chemical bands involved in uranium link have been

identified. We have applied this biosorption to actual waste

uranium leachate, the results are satisfactory and promising.

Keywords Pleurotus mutilus � Uranium � Leachate �Biosorption � Kinetics

Introduction

The removal of radionuclides such as uranium from

aqueous solutions, especially from contaminated sources, is

an important topic in environmental control.

Uranium is a radioactive element with many long lived

isotopes. The management of such radionuclide obeys to

the concepts of management of high-level radioactive

waste, as the removal/confinement principle as well as the

multi-concept barrier safety concept [24]. Thus, an ade-

quate solution for the disposal of uranium is to concentrate

and confine it in a sorbent matrix, before storing the waste

in a safe manner. This practice is usually employed in

bioremediation procedures in lands contaminated by

radioactive waste residues.

Many processes have been proposed for uranium(VI)

removal from industrial waste waters and radioactive

wastes. Chemical precipitation, ion exchange, and solvent

extraction are among the most commonly used methods,

each has its merits and limitation in application [17].

The biosorption is one of the promising technologies for

the removal of toxic metal from industrial waste and natural

waters. This technology has distinct advantages over con-

ventional methods. It is nonpolluting, easy to operate, offers

high efficiency of treatment of waste waters containing low

metal concentrations, and possibility of metal recovery [9].

Furthermore, the biosorption process offers a potential

benefit that is the low cost biomass, available in abundance

as sorbent; many biomasses remaining useless waste in

pharmaceutical industries [2, 12].

Pleurotus mutilus (noted P. mutilus) is a biomass used

by SAIDAL antibiotic complex at Medea, Algeria to pro-

duce a ‘‘pleuromutilin’’ antibiotic for veterinary use. Huge

quantities of residual P. mutilus biomass resulting from the

antibiotic extraction process are disposed after incineration.

So, we attempt to find an interesting use of this waste

through the removal of uranium from a radioactive effluent.

The adsorption of metals on P. mutilus has been per-

formed for copper and cyanide ferrous ions [3, 7]. The

biosorption of uranium on Pleurotus is not described yet.

However, several microorganisms are known to uptake

uranium by biosorption mechanisms [1, 4, 5, 21].

M. Mezaguer (&) � N. Kamel � Z. Kamel

Centre de Recherche Nucleaire d’Alger, 2 Bd Frantz Fanon,

B.P. 399, Alger-RP, Alger, Algeria

e-mail: [email protected]

H. Lounici

Ecole Nationale Polytechnique d’Alger, 10 Avenue Hassen Badi,

B.P. 182, El Harrach, Alger, Algeria

123

J Radioanal Nucl Chem (2013) 295:393–403

DOI 10.1007/s10967-012-1911-y

In the present work, we try to validate valorization of

this waste biomass as a biosorbent for uranium(VI) by

investigating the influence of different experimental

parameters on uranium uptake, such as pH solution, tem-

perature, biomass particle size and speed of stirring.

For this purpose, we correlate different kinetic and

adsorption models, determine the corresponding kinetic

parameters, identify the chemical bonds involved in ura-

nium link on P. mutilus, and finally apply the results to

remove uranium from a laboratory radioactive waste.

Experimental

Biomass preparation

The crude biomass was washed with tap water, then with dis-

tilled water, and dried for 48 h at 65 �C in a Prolabo 250

steamroom. Then, it was powdered with a mortar and pestle set,

and was passed through sieves of different mesh sizes to get the

different particles sizes: (100–200 lm), (200–250 lm),

(250–315 lm), (315–400 lm), (400–500 lm), (500–630 lm)

and ([630 lm). All biomass fractions were stored at room tem-

perature before characterization and biosorption experiments.

Biomass characterization

The biomass pH was measured in ultra-pure water. The

biomass apparent density (qapp) was determined by pyc-

nometry using ethanol (Normapur, Prolabo) as a wetting

liquid. The residual humidity (H) was determined by suc-

cessive drying/weighing steps several times until the fun-

gus reached a constant weight.

The rate of organic matter (Rorg) was determined after

calcination at 600 �C for 2 h, and the rate of mineral matter

(Rmin) was deduced from the difference between the total

amount of biomass and the amount of organic matter. The

specific surface area (A) was measured by the BET method in

nitrogen at -196 �C using a Mastersizer-2000 instrument.

The microstructural characterization was determined by

Fourier transform infrared spectroscopy (FTIR) using a

Nicolet-380 instrument, and scanning electron microscopy

(SEM) using a Philips ESEM XL 30 FEG instrument. The

chemical composition of biomass was determined by a

Philips Magix-Pro X-ray fluorescence spectrometer (XRF).

Biosorption tests

Uranium(VI) solutions were prepared from a commercial

uranium nitrate: UO2(NO3)2�6H2O (Mallinckrodt Chemi-

cal). The pH of the solutions were adjusted to required

values by using either hydrochloric acid, HCl (Fluka,

37 %), or ammonia, NH4OH (Fluka, 25 %).

The adsorption experiments were carried out by batch

method. 0.5 g of biomass were contacted with 150 ml of

uranium solution under stirring at a speed of 315 rpm at

room temperature (&25 ± 1 �C). The supernatant was

separated by centrifugation at 104 rpm during 5 min.

Periodic samplings of the adsorbate are analyzed using a

Philips Magix-Pro XRF spectrometer, in order to assess the

uranium concentration in the solutions, 200 ll of solution

were analyzed. The accuracy of the method is about 3 ppm,

the relative error on measurements is 0.02 %, and the CSE

is 0.19 %. All the experiments were performed twice.

The amount of the biosorbed uranium per unit of bio-

mass (mg of U g-1 of dry biomass) at the equilibrium was

calculated using the following relation:

q ¼ C0 � Cð Þ � V

Wð1Þ

where C0 and C are respectively the uranium concentra-

tions (mg l-1) in the solution before and after the bio-

sorption, V is the solution volume (l), and W is the amount

of biomass (g).

Kinetic modeling

The kinetics of uranium uptake was modeled using the

pseudo first-order Lagergren’s equation and the pseudo

second-order Ho’s equation [13].

The pseudo-first-order sorption relation can be expres-

sed as follows:

1

qt¼ k1

q1

1

tþ 1

q1

ð2Þ

where q1 and qt are the amount of adsorbed uranium

(mg g-1) at the equilibrium time and at t time, respec-

tively; and k1 is the adsorption constant (min-1). The

values of k1 are calculated from the slope of the plot: 1/qt

versus 1/t.

The pseudo-second-order sorption relation can be

expressed as follows:

t

qt¼ 1

k2 � q22

þ 1

q2

t ð3Þ

where q2 is the amount of adsorbed uranium (mg g-1) at the

equilibrium, qt is the amount of the total solute adsorbed at

t time (mg g-1) and k2 is the kinetic constant (g mg-1 min).

A plot of t/qt versus t gives a linear relationship for the

applicability of the model. Both the intercept and slope of the

linear fit represent (k2) and (q2), respectively.

Equilibrium modeling

The adsorption curves were plotted by Langmuir and

Freundlich adsorption isotherms’ relations. These two

394 M. Mezaguer et al.

123

equilibrium isotherm models are primarily used to interpret

the efficiency of metals sorption [28].

The Langmuir isotherm is applicable for hyperbolic

adsorption data. It is similar to the relation used for

Michaelis–Menten enzymatic kinetics, and describes the

single monolayer adsorption of metal ions to a finite

number of ligand sites on the cell surface.

The linearization of Langmuir isotherm can be expres-

sed as follows:

Ce

qe

¼ 1

qmax

1

KL

þ Ce

qmax

ð4Þ

where qe is the uranium concentration on the adsorbent at

the equilibrium (mg g-1). It is also called the equilibrium

adsorption capacity. Ce is the uranium concentration in the

solution at the equilibrium (mg l-1); qmax, is the maximum

adsorption capacity of the adsorbent (mg g-1); and KL is

the Langmuir constant or the separation factor.

The plot of Ce/qe versus Ce is a straight line, with the

slope (1/qmax) and the intercept (1/qmax KL).

Langmuir separation factor (RL) can be expressed in

terms of a dimensionless constant which is calculated using

the following mathematical relation:

RL ¼1

1þ KLC0

ð5Þ

The values of RL indicate the kind of adsorption:

– for RL [ 1: the isotherm is unfavorable,

– for RL = 1: the isotherm is linear,

– for 0 \ RL \ 1: the isotherm is favorable,

– for RL \ 0: the isotherm is irreversible

The linearization of Freundlich relation is:

ln qe ¼ ln KF þ1

nln Ce ð6Þ

where qe is the uranium uptake capacity at the equilibrium

(mg g-1), and Ce is the residual uranium concentration in

the solution (mg l-1). Kf represents Freundlich constant

which is a measure of the adsorption capacity. 1/n is the

adsorption intensity.

Results and discussion

Biomass characterization

Physical characteristics

The physical characteristics of biomass are given in

Table 1. These results show that biomass is mainly made

by organic matter. It is slightly acidic, low hygroscopic and

its specific surface area decreases with the rise of the

particles’ size.

Infrared spectroscopy

The FTIR analysis allows the identification of biomass

main functional groups, including those implied in the

biosorption phenomena.

The complex FTIR spectra of native biomass (Fig. 1)

shows the presence of R–NH2 aminogroups (amino acids,

proteins, glycoproteins, etc.), carboxylic acids groups (fatty

acids, lipopolysaccharides, etc.), sulfonates and phosphates

functional groups (Table 2).

SEM microscopic observations

The SEM observations of the biomass show its porosity,

(Fig. 2). The biosorbent particles have a rough porous

surface that favors the increase of the total specific area. In

addition, the micropores on the fungal biomass could

reduce the diffusion resistance at the biomass superficial

layer, and then facilitate the particles mass transfer because

of their large internal surface.

The biomass XRF analysis

The studied biomass is composed, in a large part (about

95 %), of organic matter, (see Table 3). The fungus con-

tains also about 3 % of nitrogen that is a protein constit-

uent, and a few amounts of phosphorous, potassium, zinc

and iron. These metals probably participate as cofactors for

several enzymes. It can be notes the presence of silicon,

which comes from the Decalite used for the biomass

filtration.

Optimization of the biosorption parameters

Effect of pH on uranium biosorption

The pH level of solution plays an important role in the

biosorption of uranium on biomass. It has an effect on both

the speciation of uranium in the aqueous solution and the

binding sites located on the biomass surface [15].

Table 1 Physical characteristics of biomass

Particle

size (lm)

pH H (%) qapp

(g cm-3)

Rorg

(%)

Rmin

(%)

A (m2 g-1)

100–200 6.20 2.4 1.32 95.8 4.2 0.129

200–250 6.25 2.4 1.32 95.8 4.2 0.120

250–315 6.26 2.4 1.30 95.8 4.2 0.108

315–400 6.23 2.4 1.28 95.8 4.2 0.090

400–500 6.20 2.4 1.27 95.8 4.2 0.068

500–630 6.25 2.4 1.25 95.8 4.2 0.043

C630 6.25 2.4 1.22 95.8 4.2 0.030

Characterization and properties of Pleurotus mutilus 395

123

Uranium loading by P. mutilus increased with increasing

pH from 2 to 5 (Fig. 3) exhibiting a maxima of 250 mg g-1

at pH 5. This result agrees with those reported in several

studies on biosorption of uranium [5, 11, 29].

At pH values higher than 5, the solubility of metal

complexes decreases, provoking a bulk precipitation of

these species, which become easily removable from the

solution by filtration [6].

For low pH, the uranium biosorption decreases because

of the abundance of H? and H3O? ions, which compete

with other ions, as uranyl, for the binding sites of the

biomass surface [22]. When the pH increase (at pH 5), this

phenomenon attenuates, and many ligands on the biomass

surface can be observed, such as: carboxyl, amino and

other phosphate groups, characterized by pK values in the

range of 3–5 [14].

503,72

594,48

676,59732,77840,82

901,32935,89970,47

996,40

1061,221108,76

1167,481251,38

1333,49

1376,71

1451,32 1644,66

1726,02

1737,831795,92

2716,45

2840,00

2924,76

3191,84

3451,14

3541,90

10 15

20

25

30

35

40

45

50

55

60

65

70

75

80

85

90

95

%Transmittance

500 1000

1500 2000

2500 3000

3500 4000

Nom

bre d'onde (cm-1)

Fig. 1 Infrared spectra of P. mutilus

Table 2 The infrared absorption bands and their corresponding

possible groups

Wave

number

(cm-1)

Functional groups Localization in the cell

wall

3,200 Primary and

secondary amine

N–H Amino acids

Peptide bonds

(peptidoglycan)

N-acetylglucosamine

N-acetylmuramic

2924.76 Aliphatic chain C–H CH3 of peptidoglycan

Ch3 of teichoic acid2,840

2722.70

1737.83 Carboxylic groups C=O Tetrapeptide mureic

Proteins

1726.02

1648.98 RNH2 (primary

amine)

N–H Peptide bonds

Primary and

secondary amide

Peptidoglycan

Proteins

N-acetylglucosamine

N-acetylmuramic

1451.32 Tertiary amide C=O Proteins

1377.08 RNH2 (primary

amine)

N–H Peptide bonds

Primary and

secondary amid

Proteins

N-acetylglucosamine

N-acetylmuramic

1254.76 Primary amine

R–NH2

C–N Amino acid

1167.48 R–CH2OH

(primary OH)

C–OH N-acetylglucosamine

N-acetylmuramic

997.71 Carbohydrate C–O–C N-acetylglucosamine

972.40

840.68 Phosphohydrate C–O N-acetylmuramic

C–O–P Proteins

P–O–P

C–O–P/

P–O–P

739.05 Thiol C–SH2 Radicals of cysteine and

methionine

590.31 –C–S–

S–C

Intra-protein SS bridge

between two cysteic

residues.

507.85 R–C–O–P–(OOH)

–O–C–R0O–P–O Phosphate ester

Disulfure S–S Phospholipid

Teichoic acids

Intra-SS-protein bridge

between two cysteine

residues


123

Effect of the biomass particle size on uranium biosorption

The greatest amount of adsorbed uranium is 250 mg g-1,

at the adsorption equilibrium. It is reached for a biomass

granulometry of 250–315 lm (Fig. 4).

The lowest value of the maximum rate of adsorbed

uranium is about 150 mg g-1. It is obtained for particles’

grains sizes greater than 630 lm.

The decrease of the particles size favors the uranium

transfer by increasing the contact between the biomass

external surface and uranium particles [16].

It can be noted that the smallest biomass size fractions

of 100–200 and 200–250 lm agglomerate in a pasty shape

in the liquid medium. This causes the reduction of the

biomass surface which is in contact with the solution, and

thus the rate of uranium adsorption is reduced.

Effect of stirring speed on uranium biosorption

The uranium adsorption capacity varies in the same order

with the stirring speed (Fig. 5). The maximum sorption

capacity was found for a stirring speed of 315 rpm.

It should be noted that, the use of an agitation higher

than 315 rpm causes a dispersion of biomass on the walls

of the container, which distorts the experience.

The increase in the stirring speed favors the diffusion of

uranium into the boundary layer adsorption which becomes

very thin and the diffusion coefficient of adsorbed species

increases. Parab et al. [20], reported that stirring speed

varies in the same order with the uranium adsorption on the

biomass.

Table 3 The biomass chemical composition determined by XRF

Element Composition (%)

Organic matter 95.8

N 3.364

Mg 0.034

Al 0.065

Si 0.254

P 0.216

S 0.042

Cl 0.006

K 0.163

Ca 0.025

Mn 0.001

Fe 0.009

Zn 0.002

Na 0.020

Fig. 2 SEM micrographs of P. mutilus (G 9500)

Fig. 3 Effect of initial solution pH on uranium biosorption (W =

0.5 g, Ci = 1,000 ppm, V = 150 ml, temperature = 25 ± 1 �C, stir-

ring speed = 315 rpm and ø = 315–400 lm)

Fig. 4 Effect of the biomass particle size on uranium biosorption

(pH = 5, W = 0.5 g, Ci = 1,000 ppm, V = 150 ml, tempera-

ture = 25 ± 1 �C, stirring speed = 315 rpm)


123

Effect of temperature on uranium biosorption

The maximum uranium adsorption capacity is obtained at a

temperature of 15 ± 2 �C (Fig. 6). The temperature

decrease favors the uranium adsorption on biomass. Thus,

the biosorption process is exothermic in nature.

Many authors have reported that the decrease in tem-

perature favors the adsorption of cationic species on the

biomass [16, 17, 25].

Effect of initial uranium concentration on biosorption

The uranium maximum adsorption capacity increases with

the uranium concentration in the solution, from 183 to

583 mg g-1 (Fig. 7). However, the rate of adsorbed

uranium decreases with the uranium starting concentration

(Fig. 8).

It can be deduced that for uranium low concentrations,

the ratio between the number of uranium free particles in

the solution and the available surface area for biosorption is

small. Consequently, the adsorbed uranium fraction is

independent of the uranium initial concentration in the

solution. However, for very high uranium starting con-

centrations, the number of sorption sites is lower than the

total uranium particles. Consequently, a part of these par-

ticles remains free in the solution and the fungus surface

saturates.

The kinetic modeling

It appears that the kinetic data can be better described by

Ho’s pseudo-second-order relation (Fig. 9b) comparatively

to Lagergren’s pseudo first-order relation (Fig. 9a).

This model (pseudo-second-order) has been described in

the literature as suitable for the adsorption in the case of

several biosorbents [1].

The equilibrium modeling

The variation of the equilibrium adsorption capacity qe as a

function of the uranium starting concentration is depicted

on Fig. 10. We can deduce that the experimental maximum

adsorption of uranium on P. mutilus is about 600 mg g-1.

The overall results show that both adsorption models are

applicable to describe data for the equilibrium adsorption

of uranium on P. mutilus. The Langmuir model (Fig. 11) is

more accurate than that of Freundlich (Fig. 12). Langmuir

Fig. 5 Effect of stirring speed on uranium biosorption (pH = 5,

W = 0.5 g, Ci = 1,000 ppm, V = 150 ml, temperature = 25 ± 1 �C,

and ø = 315–400 lm)

Fig. 6 Effect of temperature on uranium biosorption (pH = 5,

W = 0.5 g, Ci = 1,000 ppm, V = 150 ml, stirring speed = 315 rpm,

and ø = 315–400 lm)

Fig. 7 Effect of initial concentration on uranium biosorption

(pH = 5, W = 0.5 g, V = 150 ml, stirring speed = 315 rpm, tem-

perature = 15 �C and ø = 250–315 lm)


123

and Freundlich parameters characterizing adsorption

capacity of P. mutilus are given in Table 4.

The Langmuir constant, RL, are in the range 0–1

(Fig. 13). Thus, the isotherm is favorable, indicating a

beneficial uranium biosorption on biomass.

The Langmuir theoretical maximum adsorption of ura-

nium on P. mutilus is of 636.94 mg g-1, which is higher

than experimental value.

Similar results are reported by Akhtar et al. [1] for

uranium adsorption on Trichoderma harzianum fungus,

which have reported 612 mg g-1 of adsorbed uranium.

Bhainsa and D’Souza [5] studied the biosorption of ura-

nium on Aspergillus fumigatus and report a uranium

adsorption rate of 423 mg g-1.

(a)

(b)

Fig. 9 The linearized kinetic models of the uranium uptake on P.mutilus. a Pseudo-first-order, b pseudo-second-order

Fig. 11 The Langmuir adsorption isotherm for the uranium sorption

onto P. mutilus

Fig. 8 Variations of the rate of uranium adsorbed on P. mutilusversus the initial uranium concentration in the solution

Fig. 10 Variation of the equilibrium adsorption capacity qe versus

the initial uranium concentration in the solution


123

Application: separation of uranium from a leachate

by adsorption on P. mutilus

Chemical characterization of the uranium leachate

In this study we used a uranium leachate resulting from the

experience of extracting uranium from ore.

The leachate chemical composition, measured by XRF

analysis, shows that it contains about 830 ppm of uranium,

7190 ppm of sulfur coming from the sulfuric acid used in

the extraction process of uranium, 800 ppm of phosphorus,

370 ppm of iron, 450 ppm of aluminum and 340 ppm of

potassium (Table 5). These last elements probably come

from the ore rocks, which are rich in these elements.

The measured value of the leachate pH was equal to 1.

Increasing the pH of the leachate up to 5 was not feasible.

In the following part, only a solution of leachate with pH 2

is used.

When the pH is adjusted to the value of 2, there is a

precipitation of the elements.

The amount of uranium in the solid phase was deduced

from the uranium concentration in the leachate after

precipitation.

It can be noticed that almost 40 % of uranium was

precipitated along with other elements (Table 5).

Sodium reduces from 230 to 39 ppm after adjusting the

pH to 2. One can deduce that this alkali element precipi-

tates simultaneously with uranium.

Sodium is often a charge compensator in some chemical

uranium forms as lanthanides/actinides phosphates, which

have greater valences, and thus co-precipitate with alkali

elements [19]. Further analytical investigations are needed

to confirm this assumption.

Fig. 13 Variations of the separation factor (RL) versus the initial

uranium concentration in the solution

Table 4 The calculated kinetic parameters from the Langmuir and

Freundlich isotherms for the uranium adsorption by P. mutilus

Isotherm

model

qmax

(mg g-1)

KL

(l mg-1)

n KF

(mg g-1)

Correlation

coefficient r2

Langmuir 636.9 0.003209 – – 0.99

Freundlich – – 2.80 36.64 0.95

Table 5 The chemical composition in ppm of the uranium leachate

at pH 1, pH 2 and after adsorption

Element pH 1 leachate pH 2 leachate After adsorption

U 830 500 0

Ti 68 1.31 1

V 10 5.34 5.3

Cr 10 5.88 6.32

Mg 14 11.13 90

Cu 17.1 13.4 11

Y 17.1 16.49 15.47

Na 230 39 50

Mn 170 10 11.04

Al 460 350 400

Si 29 20 30

K 340 210 190

Ca 68 60 70

P 800 350 398

Fe 370 90 90

Ni 4.12 4.11 4.11

S 7,190 7,000 6,910

Fig. 12 The Freundlich adsorption isotherm of the uranium sorption

onto P. mutilus


123

The precipitates were separated by filtration and the

filtrate containing the residual uranium has been used for

the adsorption test.

Separation of uranium from the leachate by biosorption

The biosorption tests are conducted in the optimum con-

ditions except for pH (pH = 2, particle size: 250–315 lm,

a temperature of 15 �C and stirring speed of 315 rpm).

After adding the biosorbent to the filtered leachate, the

concentration of uranium was measured until it becomes

negligible. One can deduce that the total amount of ura-

nium in the leachate was shared between the precipitate

and the biosorbent.

The uranium adsorption capacity increases to a value

of 125 mg g-1 after 6 h of biosorption, and then tends

to stabilize at about 24 h (Fig. 14). This value

(&125 mg g-1) corresponds to 100 % of uranium

adsorption. This is confirmed by analyzing the aliquot by

XRF, no presence of uranium pick is noted. The pH of the

leachate after being treated with the biomass was around

1.7–1.8. The acidic particles, as H3O?, are participating to

the adsorption process.

Moreover, a partial absorption of copper, potassium and

sulfur from the solution can be observed (Fig. 15). For

sulfur, its concentration value decreases from 7,000 to

6,910 ppm.

However, concentrations of magnesium, sodium, alu-

minum, sulfur and phosphorus rise at the end of the bio-

sorption test. Concentrations of ions remaining in solution

after extraction are given in Table 5.

This unexpected result may be explained by the fact that

P. mutilus naturally contains several metals, which may be

released from the biomass under the effect of an acidic pH

(pH = 1 and 2 of the leachate).

Vijayaraghavan et al. [27] has reported that acid washes

of the biomass provoke a release of many metals in the

leachate. H3O? species replace the metallic cations in their

binding sites and the released cations become in a free state

in the solution.

FTIR analysis after uranium biosorption

Comparison of biomass FTIR spectra before and after

uranium biosorption shows peaks’ transformations, due to

the cationic exchanges (Fig. 16a). The disappearance of the

peak at 1,770 cm-1 is observed corresponding to the C=O

bond lengthening of the COOH group belonging to the

tetrameric peptide or protein. The appearance of a peak at

1,546 cm-1 shows the stretching of both primary and

secondary amines, belonging to N-acetylglucosamine or N-

acetylmuramic, the peptide bonds of peptidoglycan or

proteins, respectively. Also, the peaks located at 587.1 and

506.57 cm-1 move to the values of 558.47 and

463.62 cm-1, respectively. These absorption frequencies

correspond either to the elongation of the O–P–O phos-

phoric ester bond or the S–S links. The phosphoric ester

bonds belong to phospholipids or teichoic acids, and the

disulphide S–S bonds belong to protein disulfide bonds

between two cysteines. The peak located at 678.37 cm-1 is

moved to 640.79 cm-1 corresponding to the C–S elonga-

tion of both CS–H2 and S–S–C groups, belonging to the

cysteine or methionine intra-protein bonds between two

cysteines.

Similar results have been reported in the literature, and

the involvement of these functional groups in the uranium

and cadmium biosorption has been described [8, 10, 18,

26].

Fig. 14 Variations of the uranium adsorption capacity from the

leachate on P. mutilus (pH = 2, ø = 250–315 lm, temperature of

15 �C, and stirring speed of 315 rpm)

Fig. 15 Chemical composition of the uranium leachate (ppm) before

and after adsorption


123

However, the peaks in 4,000–2,000 cm-1 frequency

region are unchanged (Fig. 16b). This area highlights the

CH adsorption bonds where CH groups do not contribute to

the binding of uranium onto the biomass. This non con-

tribution of CH linked in the adsorption of cadmium and

chromium is known for Hylocomium splendeus [23].

Conclusions

In this study, we have investigated the adsorption of ura-

nium on P. mutilus fungus, a by-product of the Algerian

pharmaceutical industry. The biomass has been prepared

and characterized. The uranium biosorption optimized

parameters were fixed to: pH 5, at 15 �C, speed of stirring

at 315 rpm and the biomass particle size in the interval of

250–315 lm.

The kinetic modeling of the adsorption is governed by a

pseudo second order model. The application of Langmuir

model gives a uranium maximum theoretical adsorption

capacity of 637.9 mg g-1.

The experiences of uranium separation from an actual

leachate at pH 5 failed and this feature has restricted us to

work at pH 2. Nevertheless, the result of separation at pH 2

was satisfactory (100 % adsorption of uranium from the

solution). But there is a partial adsorption of some elements

and release of the elements contained in the biomass in

middle.

463,62

558,47

640,79

1546,32

506,57

587,10

678,37

1770,02

15

20

25

30

35

40

45

50

55

60

65

70

75

80

85

90

95

100

%Transmittance

600 800

1000 1200

1400 1600

1800 2000

Nom

bre d'onde (cm-1)

(a)

Fig. 16 The infrared spectra of P. mutilus before (top) and after

(down) the uranium biosorption. a frequency region of

2,000–500 cm-1, b frequency region of 4,000–2,000 cm-1

15

20

25

30

35

40

45

50

55

60

65

70

75

80

85

90

95

100%Transmittance

2200 2400

2600 2800

3000 3200

3400 3600

Nom

bre d'onde (cm-1)

(b)

Fig. 16 continued


123

The FTIR analysis of biomass, before and after

adsorption, has highlighted the involvement of carboxylic,

amine, phosphoric and sulfuric bonds, in the adsorption

phenomenon.

These preliminary results are very promising showing

great perspectives in application of the P. mutilus as bio-

sorbent for uranyl ions in radioactive wastewater treatment

processes with a sustainable technology.

Acknowledgments We acknowledge Doctor Abed Belkassemi

from SAIDAL Medea for providing us biomass samples. We grate-

fully acknowledge the contribution of Doctor Salah Chegrouche from

Nuclear Research Centre of Draria (in Algiers) for his useful help.

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Characterization and properties of Pleurotus mutilus fungal biomass as adsorbent of the removal of uranium(VI) from uranium leachate

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