Journal of Environmental Treatment Techniques  
2019, Volume 7, Issue 3, Pages: 450-455  
J. Environ. Treat. Tech.  
ISSN: 2309-1185  
Journal web link: http://www.jett.dormaj.com  
Valorization of Balanites aegyptiaca Seeds from  
Mauritania: Modeling of Adsorption Isotherms  
of Caffeine from Aqueous Solution  
1
2
Abdoulaye Demba N’diaye * and Mohamed Sid’Ahmed Kankou  
1Laboratoire de Chimie, Service de Toxicologie et de Contrôle Qualité, Institut National de Recherches en Santé Publique, BP  
6
95, Nouakchott, Mauritanie  
2
Unité de Recherche Eaux Pollution et Environnement, Département de Chimie, Faculté des Sciences et Techniques, Université  
de Nouakchott Al-Aasriya, BP 880, Nouakchott, Mauritanie  
Received: 07/07/2019  
Accepted: 19/08/2019  
Published: 20/08/2019  
Abstract  
This paper focuses on the development and characterization of low cost sorbent to Balanites aegyptiaca seeds without  
treatment and its application in the adsorption of caffeine in aqueous solution. The Balanites aegyptiaca seeds were characterized  
by using physicochemical parameters, Scanning Electron Micrograph (SEM) and Fourier Transform Infra-Red spectroscopy  
(
FTIR). Batch sorption experiments are intended to identify the adsorption isotherms of the caffeine on the Balanites aegyptiaca  
seeds. Four isotherm models (Freundlich, Langmuir, Redlich–Peterson and Sips) were tested for modeling the adsorption  
-1  
isotherms by nonlinear method. The maximum adsorption capacity was found to be 4.28 mg g . Based on data obtained in this  
study, it can be concluded that the Balanites aegyptiaca seeds are a promising sorbent.  
Keywords: Balanites aegyptiaca seeds, sorbent, caffeine, nonlinear, isotherms  
1
membrane treatment [8] and electro coagulation [9].  
1
Introduction  
However, most of these methods suffer from some  
disadvantages such as the high cost, the low efficiency, and  
high energy consumption limit the wide application of  
these technologies.  
Caffeine (C  
8
H
10  
4
N O  
2
) (figure 1) is one of the most  
consumed stimulating substances [1]. Caffeine has a high  
water solubility and low octanol–water partition coefficient  
2; 3]. Due to the low efficiency of conventional  
[
In recent years, immense research has been focused  
towards valorization of agricultural or industrial wastes for  
their uses in the water and wastewater treatment  
consequently; this strategy reduces the treatment cost and  
contributes to ecofriendly development. The adsorption is  
considered as promising and an interesting alternative to  
operate mainly using biomaterials [10-15].  
wastewater treatment process, caffeine has been detected in  
many surface water and ground water [4; 5].  
Balanites aegyptiaca is a tree native to Africa and the  
Middle East and all parts of the plant are used in traditional  
medicine [16]. In this research, the cheapest and abundantly  
available in Mauritania aegyptiaca balanites seeds have  
been used as adsorbent to remove caffeine from aqueous  
solution.  
Several techniques were performed to characterize the  
Balanites aegyptiaca seeds such as physicochemical  
parameters, Scanning Electron Micrograph (SEM) and  
Fourier Transform Infra-Red spectroscopy (FTIR). The  
retention capacity of caffeine onto the Balanites aegyptiaca  
seeds is investigated with using the non-linear parameter  
equation of Langmuir, Freundlich, Sips and Redlich –  
Peterson isotherm models.  
Figure 1: Molecular structure of caffeine  
Some treatment technologies are introduced to remove  
caffeine from water and wastewater, including  
electrochemical degradation [6], ultrafiltration [7],  
Corresponding author: Abdoulaye Demba N’diaye,  
Laboratoire de Chimie, Service de Toxicologie et de  
Contrôle Qualité, Institut National de Recherches en Santé  
Publique, BP 695, Nouakchott, Mauritanie. E-mail :  
abdouldemba@yahoo.fr.  
450  
Journal of Environmental Treatment Techniques  
2019, Volume 7, Issue 3, Pages: 450-455  
C Ce  
   
V
i
m
2
Materials and methods  
(1)  
q   
e
2
.1 Caffeine solutions  
Caffeine, in analytical purity and used in the  
experiments directly. The caffeine solutions were prepared  
by diluting stocks solution to appropriate concentrations  
when needed.  
where q  
e
is quantity of caffeine per g of Balanites  
-1  
aegyptiaca seeds (mg g ), is initial solution  
-1  
concentration of caffeine (mg L ), C  
solution concentration of caffeine (mg L ), m is the  
Balanites aegyptiaca seeds weight (g), and V is volume of  
the solution (L).  
C
i
e
is equilibrium  
-1  
2.2 Sorbent and experimental procedures  
The used Balanites aegyptiaca seeds (Figure 2)  
were collected from the south of Mauritania. The Balanites  
aegyptiaca seeds were washed thoroughly with ultra pure  
water and sundried for 5 days. After, the seeds are broken  
and were ground and sieved to obtain particle sizes below  
2
.3 Equilibrium studies  
Several isotherm equations can explain solid–liquid  
adsorption systems, such as: Langmuir, Freundlich, Sips  
and Redlich-Peterson. The Langmuir adsorption isotherm  
assumes that adsorption takes place at specific  
homogeneous surface sites within the adsorbent and has  
found successful application in many sorption processes of  
monolayer adsorption. The Freundlich isotherm is an  
empirical equation employed to describe heterogeneous  
systems [20]. The Sips isotherm is a combination of the  
Langmuir and Freundlich isotherms, which represent  
systems for which one adsorbed molecule could occupy  
more than one adsorption site [21]. The Redlich–Peterson  
isotherm model combines elements from both the Langmuir  
and Freundlich equation and the mechanism of adsorption  
is a hybrid one and does not follow ideal monolayer  
adsorption. It is used as a compromise to improve the fit by  
Langmuir or Freundlich equation. The exponent “n” ranges  
between 0 and 1. For n = 1, Redlich–Peterson equation  
leads to Langmuir one [22]. All the used mathematical  
models for caffeine adsorption isotherm are shown in Table  
100 µm, dried in an oven at 105 °C for 24 h and stored in a  
dessicator before use.  
Figure 2: Balanites aegyptiaca seeds  
The pH of the Balanites aegyptiaca adsorbent was  
carried out according to Abdel-Halim et al (2006) [17]. The  
physicochemical parameters like the moisture, volatile  
matter and ash are determined by described methods [18].  
The determination of cellulose, lignin and hemicellulose in  
Balanites aegyptiaca seeds were analyzed by the procedure  
indicated by Li et al (2004) [19]. The morphology of the  
Balanites aegyptiaca seeds adsorbent was determined using  
SEM. The Balanites aegyptiaca seeds were analyzed by the  
FTIR spectroscopy to determine the surface functional  
groups. The wavenumber scanning is in the range of 650–  
1
.
Table 1: Mathematical models for sorption isotherms  
Isotherm  
Langmuir  
Freundlich  
Equation  
Parameter  
(
dimension)  
q K C  
m L  
-1  
e
q
m
(mg g )  
qe   
-1 −1  
L
K (mg L )  
1
 K Ce  
L
K
F
(mg/g) × (mg/L)  
1
e
/ n  
−n  
q  K C  
F
e
n
_
1
(mg g-1)  
4,000 cm .  
q
m
n
S
K Ce  
K
S
constant (L  
The sorption isotherms at ambient temperature are  
Sips  
qe  q  
m
n
e
m
obtained by mixing (70 rpm), for 6 hours, 0.5 g of Balanites  
aegyptiaca seeds with 50 mL of caffeine solutions with  
(1 K C ) mg−1)  
S
n
-
1
different concentrations varying from 10 to 100 mg L . At  
the end of each experiment the agitated solution mixture  
was micofiltered using micro filter and the residual  
concentration of caffeine was determined by High  
Performance Liquid Chromatography (HPLC). Ultra pure  
water and methanol (70:30 V/V) were used as a mobile  
K
RP  
n−1  
Redlich-  
Peterson  
RP  
e
(mg/g)×(mg/L)  
qe   
n
e
1RP  
C
α
RP  
n
2,  
The correlation coefficient R the Sum of the Squares  
-1  
2
) analysis is used  
phase at a flow rate of 1 mL min at a selected wave length  
of 254 nm. Ambient temperature (25 °C), pH (7.2) and all  
experimental parameters are constant throughout the  
of the Errors (SSE) and Chi-square (  
to fit experimental data with isotherm using the Excel®  
solver. The correlation coefficient R , SSE and  
2
2
values  
e
various tests. The caffeine uptake amount q (mg of  
caffeine per g of dried Balanites aegyptiaca seeds sorbent)  
was calculated using the equation (1):  
are determined respectively by following equations (2), (3)  
and (4):  
451  
Journal of Environmental Treatment Techniques  
2019, Volume 7, Issue 3, Pages: 450-455  
2
with a predominance of white spots (corresponding to  
silica, a like grafted component), on Balanites aegyptiaca  
seeds surface as confirmed by FTIR analysis.  
q -q  
exp mod  
(2)  
2
R =100 1-  
2
q -q  
exp  
avr  
2
SSE=  
q  q  
exp  
(3)  
(4)  
mod  
2
2
((qexp  
 qmod) / qmod)  
-1  
where qexp (mg g ) is equilibrium capacity from the  
experimental data, qavr is equilibrium average capacity from  
the experimental data and qmod is equilibrium from model.  
2
So that R ≤ 100 – the closer the value is to 100, the more  
perfect is the fit.  
3
Results and discussions  
Figure 3: FTIR Spectrum of balanites aegyptiaca seeds  
3
.1 Characterization of aegyptiaca balanites seeds  
The physicochemical properties of the Balanites  
aegyptiaca seeds adsorbent are shown in table 2. The pH of  
the aegyptiaca balanites seeds was found to be 6.12. From  
the proximate analysis, it was observed that moisture, ash,  
volatile matter 3.9 %, 5.7 % and 78.2 %, respectively. The  
cellulose, hemicellulose and lignin values of the Balanites  
aegyptiaca seeds, depending on soil properties and the  
plant’s development stage, are 41.3, 33.9 % and 15.2 %  
respectively.  
Table 2: Characterization of aegyptiaca balanites seeds  
parameters  
pH  
Moisture (%)  
Ash (%)  
values  
6.12  
3.9  
5.7  
Volatile matter (%)  
Hémicellulose (%)  
Cellulose (%)  
Lignin (%)  
78.2  
33.9  
41.3  
15.2  
(
a)  
The FTIR spectroscopy analyses of the Aegyptiaca  
Balanites seeds are given in figure 3. FTIR spectra for the  
Aegyptiaca Balanites seeds displayed a number of peaks  
pertaining to different functional groups. O–H stretching of  
the hydroxyl of the alcohols groups and bonded hydroxyl  
-1  
groups of cellulose: 3054.76 cm . The peak at 2987.39  
−1  
cm was assigned to C–H asymmetrical stretching of  
methyl groups on the surface of Balanites aegyptiaca seeds  
adsorbent. These groups were present on the lignin  
-1  
structure. The peak located at 1732.61 cm was  
characteristics of the carbonyl group stretching from  
-1  
carboxylic acids and ketones. The peak at 1421.93 cm was  
attributed to the stretch vibration of C–O from the carboxyl  
-1  
group. The peak at 1264.37 cm was due to the asymmetric  
bending vibration of the -CH group. The wave number  
3
-1  
observed at 1029.36 cm was due to the C-O group in  
carboxylic and alcoholic groups and shows the presence of  
Si-O-Si linkages. The analysis of the FTIR spectrum  
showed the presence of carboxyl and hydroxyl, these  
functional groups may be the major biosorption sites for  
caffeine removal. SEM slides of Balanites aegyptiaca seeds  
(
b)  
Figure 4: Scanning electron microscopy images for the Balanites  
aegyptiaca seeds sample magnified (a) ×5000 and (b) ×10000  
(
figure 4) revealed a stick shape of the prepared powder  
452  
Journal of Environmental Treatment Techniques  
2019, Volume 7, Issue 3, Pages: 450-455  
3
.2 Adsorption equilibrium isotherms determination  
considered a measure of the adsorption affinity [28].  
According the table 4, it is clear that nRP value approaches  
unity (0.77), indicated that the sorption data were more of  
Langmuir isotherm. It can be concluded that surface of  
Balanites aegyptiaca seeds homogenous for caffeine  
adsorption. The Sips isotherm suggests that the sorption  
capacity of Balanites aegyptiaca seeds to uptake caffeine to  
be 0.066 mg g . The maximum adsorption capacity  
predicted by the Sips isotherm was lower than Langmuir  
isotherm.  
Adsorption isotherms were analyzed according to the  
nonlinear form of Langmuir, Freundlich, Redlich–Peterson  
and Sips isotherms. The non linear method does not  
transform data sets; hence, no distortions are created in the  
original error distribution. Comparisons of linear and  
nonlinear regressions often concluded that the best  
parameter estimates were returned by nonlinear  
optimizations [23-25]. Equilibrium times between 2 and 4 h  
are reported for caffeine adsorption onto activated carbon  
-1  
[12; 26; 27]. Even so, Torrelas et al (2015) [27] highlight  
most of the adsorption process occurs in the first 5 min.  
Equilibrium time of 60 min is reported for caffeine  
adsorption onto Grape stalk, grape stalk modified by  
phosphoric acid and grape stalk activated carbon [13]. In  
our study, residence time selected was 6 h for Balanites  
aegyptiaca seeds adsorbent in order to optimize  
experiments duration without significant losses in  
adsorption capacities.  
0,7  
0
0
,6  
,5  
0,4  
0,3  
Sips  
Redlich-Peterson  
Experimental data  
0
0
,2  
,1  
0
The three-parameter model, Langmuir and Freundlich  
have been applied to evaluate the fit by isotherm for the  
adsorption of caffeine onto Balanites aegyptiaca seeds by  
figure 5. According to Table 3, the coefficients of  
0
20  
40  
60  
80  
100  
Ce (mg L-1)  
2
correlation are very good (R ≥97.8 %), lower values of SSE  
2
and good  
for both models. The values of K  
L
and 1/n  
F
Figure 6: Three- parameters isotherms obtained using the non-  
linear method for the sorption of caffeine onto Balanites aegyptiaca  
seeds  
are less than unity indicating that the caffeine is favorably  
adsorbed by the Balanites aegyptiaca seeds.  
Table 4: Three-isotherm parameters for caffeine onto  
Balanites aegyptiaca seeds  
0
0
0
0
0
0
0
,7  
,6  
,5  
,4  
,3  
,2  
,1  
0
Sips  
Redlich-Peterson  
RP=0.0076  
RP=0.0081  
RP=0.77  
q
K
m
=0.066  
K
α
Langmuir  
S
=0.29  
=0.85  
Freundlich  
n
S
n
Experimental data  
2
2
R (%)=98.5  
R (%)=99.5  
SSE=0.0021  
SSE=0.0029  
2
2
=0.0127  
=0.0251  
0
20  
40  
60  
80  
100  
e
C )  
(mg L-1  
Although the values of adsorption capacity q  
m
for  
Figure 5: Two- parameters isotherms obtained using the non-linear  
method for the sorption of caffeine onto Balanites aegyptiaca seeds  
Balanites aegyptiaca seeds on caffeine removal are still  
smaller than the capacities of activated carbons and others  
treated materials [10;12-15], the Balanites aegyptiaca seeds  
without any treatment applied in this work can be  
considered a promising material to be used for caffeine  
adsorption. We can say that for to improve the retention  
capacity of caffeine from water and wastewater, the setting  
up of activation processes of the Balanites aegyptiaca seeds  
is necessary.  
Table 3: Two-isotherm parameters for caffeine onto  
Balanites aegyptiaca seeds  
Langmuir  
=4.28  
=0.0016  
Freundlich  
1/n =0.85  
=0.012  
q
m
F
K
L
K
F
2
2
R (%)=97.8  
SSE=0.0031  
2
R (%)=98.5  
SSE=0.0021  
4
Conclusions  
In this paper, the low cost adsorbent was prepared from  
2
=0.0322  
=0.0126  
Balanites aegyptiaca seeds, without any treatment. The  
prepared adsorbent were characterized by determining  
different parameter such as pH, moisture content, ash  
content, volatile matter, cellulose, hemicellulose, lignin,  
SEM and FTIR spectroscopy. The equilibrium isotherm  
data obtained during sorption of caffeine onto Balanites  
aegyptiaca seeds were fitted using different two and three-  
parameter models with using the non linear method.  
Among the tested three-parameter equations, the better  
and perfect representation of the experimental results of the  
adsorption isotherms is obtained using the Redlich-Peterson  
model (figure 6). According to Table 4, the coefficients of  
correlation are very good (≥99.5), lower values of SSE and  
2
good  
for the both models. It was reported that nRP is  
453  
Journal of Environmental Treatment Techniques  
2019, Volume 7, Issue 3, Pages: 450-455  
The isotherm data can well be fitted with Langmuir and  
electro-coagulation process with Fe electrode.  
Chemical Engineering Journal.2011; 169(1-3): 84–90  
10- Sotelo J.L, Rodriguez A.R, Mateos M.M, Hernandez  
S.D, Torrellas S.A, Rodriguez J.G. Adsorption of  
pharmaceutical compounds and an endocrine disruptor  
from aqueous solutions by carbon materials. Journal  
Environmental Science and Health B.2012; 47: 640–  
Redlich–Peterson models. The maximum adsorption  
-
1
capacity was found to be 4.28 mg g , compared with the  
adsorption capacities obtained by activated carbons and  
others treated materials for sorption of caffeine show that  
the Balanites aegyptiaca seeds are cheap and economically  
suitable for removal of caffeine from water and wastewater.  
652.  
1
1- Sotelo JL, Ovejero G, Rodríguez A, Álvarez S, García  
J. Study of Natural Clay Adsorbent Sepiolite for the  
Removal of Caffeine from Aqueous Solutions: Batch  
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Acknowledgments  
The author wish to thank Dr Mohamed Abderrahmany  
Senhoury from Materials Chemistry Research Unit,  
Department of Chemistry, Faculté des Sciences et  
Technique de l’Université de Nouakchott Al Aasriya for  
material characterization.  
1
2- Couto O M, Matos I, Da Fonseca I M, Arroyo P A, Da  
Silva E A, De Barros M.A S D. Effect of solution pH  
and influence of water hardness on caffeine adsorption  
onto activated carbons. The Canadian Journal of  
Chemical Engineering. 2014; 93(1): 68–77.  
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