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Aqueous Ferriferous Scavenging with Waste Plastic-Cellulose
Composite for Remediation
Cyprian Yameso Abasi*, Sheila Yabiteigha, Douye Parkinson Markmanuel, Onyinyechi Gift Aliene
Department of Chemical Sciences, Niger Delta University, Wilberforce Island, Bayelsa State, Nigeria
*Corresponding Author
DOI : https://doi.org/10.51583/IJLTEMAS.2024.131103
Received: 07 November 2024; Revised: 20 November 2024; Accepted: 22 November 2024; Published: 29 November 2024
Abstract: This work was conducted to investigate the adsorptive removal of iron (III) ions from simulated and ferriferous water
using unmodified and modified waste PET-bottle/coconut husk composites. The waste PET-bottle/coconut husk composites were
prepared by melt mixing and modified using ferric and ferrous chloride. The composites were characterized using the Fourier
Transform Infrared (FTIR) spectroscopy. The adsorption process was carried out using batch method while residual adsorbate
concentration in solution was determined using Atomic Absorption Spectroscopy (AAS) analysis. The residual equilibrium
concentrations results were applied to the kinetics, equilibrium and intraparticle diffusion analyses. The kinetics results of the
adsorption showed that the most fit model based on the R
2
values for the unmodified is the second order with a value of 0.79,
while that of the modified composite correlated with the pseudo first order with an R
2
value of 0.95. The highest rate constant was
2.29 g/mg min for PFO for the unmodified implying the shortest exposure and contact time per unit mass of adsorbent. The
Freundlich and Sips isotherm models both correlated at 97% with the unmodified composite, while the Freundlich model was the
most fit model for the modified composite with an R
2
value of 0.87. Q
max
calculated from Langmuir isotherm was 6657.91 and
7939.32 mg/g for unmodified and modified composites respectively, indicating a higher sorption potential for the modified
composite. The modified composite gave a far higher and near unity R
2
value of 0.96 for intraparticle diffusion than the
unmodified composite with 0.46.
Keywords: Plastic, waste, composites, modified, unmodified, isotherms, kinetics,
I. Introduction
Groundwater contamination with iron is a widespread issue; the World Health Organization recommends a level of less than 0.3
mg/L, although the concentrations typically vary from 0 to 50 mg/L (WHO, 2022). Iron is found in two forms; iron (II) which is
soluble and does not cause any issues on its own, and iron (III) which is insoluble and formed by the oxidation of iron (II) when it
comes in contact with oxygen in the air or through action of iron related bacteria. Iron (III) forms insoluble hydroxides in water.
Water that contains iron (III) creates visual and practical problems such as colour, odour, brown staining, and deposition in water
distribution systems, resulting in excessive turbidity. Groundwater that contains iron is frequently visibly reddish-brown or
orange in colour, discolouring clothing and imparting an unpleasant taste.
Most groundwater samples from the Niger Delta region include a significant amount of iron, which is a major undesirable
contaminant. Iron concentration levels above the WHO permissible limits for groundwater quality have been observed in
boreholes in some parts of the South East (Aralu, Okoye, Abugu et al., 2023; Osuagwu, Uwaga and Inemeawaji, 2023).
Electrical resistivity assessment of boreholes also showed high concentration levels of iron above WHO permissible limits in
parts of Niger Delta of Nigeria (Oghale & ThakGod , 2023)
Scientists have a keen interest in removing iron from groundwater, and there are a number of techniques for doing so, including
ion exchange (Gahlot et al., 2022), oxidation (Thinojah & Ketheesan, 2022), chemical precipitation (Morosini et al., 2014),
supercritical fluid extraction (Kiselev & Iacovelli, 2022), and accumulation by aquatic macrophytes (Coimbra and Borges, 2023).
This study provides elucidation on the scavenging potential of composites prepared from waste materials for the uptake of iron
(III) ions from aqueous solution and ferriferous groundwater in real time, which is a menace in some places in the Niger Delta
area.
Problem Statement
It is no longer a news from a faraway land that plastics are a threat to human life and the environment. Due to the abundance and
the common use of plastic products and materials, virtually all countries in one form or the other are victims of plastic pollution.
The theme of the World environment day in 2023 was “Beat plastic pollution”. The caption was to raise awareness of the
critical issues of the useful, yet dangerous product all over the world. Polyethylene terephthalate (PET-RIC 1) bottles is one major
plastic product commonly found wasted after use. Though, there is a growing campaign and drive for reducing, reusing and
recycling to cut down on the surge of plastic pollution, there is need to diversify the recycling method. One of the ways is the
production of composite materials of waste plastics. This work assessed the adsorption capacity of unmodified and modified
waste PET bottles/coconut husk composite used for the uptake of iron (III) in aqueous solutions.
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II. Materials and Methods
Materials and Apparatus
Coconut Husk, Waste Polyethylene terephthalate (PET) bottles, Ferric Nitrate (Fe (NO
3
)
3
), Ferrous Chloride (FeCl
2
), Ferric
Chloride (FeCl
3
), Sodium Hydroxide (NaOH), (Reagents produced by Loba Chemie PVT LTD, India) Distilled water, Hot plate,
Weighing balance, Pipettes, Beakers, Volumetric flasks, Thermometer, Filter papers, Speed shaker, pH meter, Spatula, Kegs,
Oven, Non-stick pot, Sample containers, Storage containers, Grinding machine, 150, 300, 600 µm sieves.
Preparation of Coconut Husk
Coconut husk was obtained from a coconut vendor from Amarata in Yenagoa city in Nigeria. The husks were collected, washed,
dried and pulverized. It was sieved into 150 μm, 300 μm and 600 μm mesh sizes and stored in various containers and labeled
accordingly for further use. The 300 μm mesh size coconut husk was used to prepare the composite.
Preparation of Waste Polyethylene Terephthalate (PET) Bottles Matrix
Used and discarded Polyethylene terephthalate (PET) bottles were collected and shredded to smaller sizes. They were washed,
dried and stored for use to form the composite.
Preparation of Unmodified Composite
75 g of shredded waste Polyethylene terephthalate (PET) bottles was weighed into a non-stick pot and placed on the hotplate for
40 minutes for it to melt at a temperature of 100
o
C. When it was molten,15g of sieved coconut husk was added to it and stirred
until a homogeneous solid was formed. It was then removed from the pot and placed on a white tile to cool before it was
pulverized by a grinding machine and sieved to 150, 300 and 600μm mesh sizes .The various weighed composites were washed
with distilled water, oven-dried for 40 minutes and stored in their separate containers and labeled accordingly. The 300 μm
composite was later used to prepare the modified composite.
Preparation of Modified Composite
0.75 M ferric chloride (FeCl
3
) and 0.25 M ferrous chloride (FeCl
2
) solution was prepared which is a modified method adopted
from Yamamura et al., (2009) in which 50 mL of the solution was measured to a beaker; 28 g of the composite was weighed into
the solution. 5 M sodium hydroxide was also prepared and the mixture was precipitated by droplet addition of sodium hydroxide
(NaOH) to the beaker containing the iron solution and the composite. The mixture was stirred intermittently as the sodium
hydroxide was added until it got to pH 10.9. The mixture was stirred for one hour, after which it was rinsed with distilled water
till it got to a 7.3 pH. The process was repeated and the modified composite was placed in an oven to dry for 45 minutes.
Fourier Transform Infrared Spectrometer (FTIR) Analysis
Functional groups determination and analysis of the prepared composites were carried out using the Fourier Transform Infrared
(FTIR) Spectrometer in both the modified and unmodified PET/Coconut husk composite.
Preparation of Stock and working Solutions
A 1000 ppm stock solution was prepared by dissolving 4.3189 g of iron (III) nitrate in 1000 mL volumetric flask. From the stock
solution, 20 mL was measured into a 500 mL volumetric flask and filled to obtain 40 ppm working solution to carry out the
measurements for effect of time. Also 20, 40, 80, 160 and 320 ppm working solutions were prepared to carry out the
measurements for effect of concentration.
Experimental Procedure for Adsorption Kinetics
1000 ppm of iron(III) solution was prepared, labeled and stored, after which 40 ppm of the solution was prepared and stored in a
bottle. 0.1 g of the unmodified and modified composites each, were respectively weighed into sample bottles, then 10 mL of the
40 ppm iron solution was measured into each sample bottle and they were shaken using the speed shaker at a constant speed of
250 rpm for 5, 10, 20, 40, 80, 160 and 220 minutes. After the shaking, they were decanted and the residual solution was taken for
Atomic Absorption Spectroscopy (AAS) analysis.
Experimental Procedure for Adsorption Isotherm
Working solutions of iron of 20, 40, 80, 160 and 320ppm were prepared and was stored in bottles. 0.1 g of the unmodified
composite and 0.1 g of the modified composite were weighed into various sample bottle and the various concentrations of the
iron solutions were added to the bottles. The unmodified composite solution was shaken at a constant speed of 250 rpm for 80
minutes, while the modified composite was shaken for 160 minutes. After the shaking, they were decanted and the supernatants
were taken for Atomic Absorption Spectroscopy (AAS) analysis.
Experimental Procedure for Groundwater adsorption
Water sourced from the ground was collected from a point around the university campus and the iron (III) content was found to
be 16.740 ppm by AAS. 0.1g of the unmodified composite was weighed into sample bottles and 10 mL of the iron water was
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measured into bottles and shaken for 80 minutes after which it was taken for Atomic Absorption Spectroscopy (AAS) analysis.
Also, 0.1g of the modified composite was weighed into sample bottles, 10 mL of the water was added and they were shaken at a
constant speed of 250 rpm for 160 minutes then it was taken for Atomic Absorption Spectroscopy (AAS) analysis.
Data Analysis for Ion Scavenging Capacity of Composites
The amount of ferric ions adsorbed on the unmodified (PCH) and modified (MPCH) composites were calculated thus:
V……………………………… (1)
Where,
Q
e
= quantity adsorbed at equilibrium (mg/g)
C
e
= final concentration of the metal ion at equilibrium (mg/L)
C
o
= initial metal ion concentration (mg/L)
V = Volume of the adsorbate (L)
M = mass of the adsorbent (g)
The percentage of ferric ions adsorption from aqueous solution was calculated thus:
…………………………(2)
Where,
A% = percent of metal ion adsorbed
C
e
= final concentration of the metal ion at equilibrium (mg/L)
C
o
= initial metal ion concentration (mg/L)
Adsorption Kinetics
The kinetics was studied using first-order, second-order, pseudo first-order, pseudo second-order and Elovich using the following
non-linear equations respectively.
………………………………. (3)
Where,
k
1
= rate constant per minute
q
e
= equilibrium adsorption capacity (mg/g)
q
t
= adsorbate adsorbed onto adsorbent at time t (mg/g)
t = time (minutes)
……………………………… (4)
Where,
k
2
= rate constant per minute
q
o
= equilibrium adsorption capacity (mg/g)
q
t
= adsorbate adsorbed onto adsorbent at time t (mg/g)
t = time (minutes)
) ………………………………… (5)
Where,
q
e
= equilibrium adsorption capacity (mg/g)
q
t
= adsorbate adsorbed onto adsorbent at time t (mg/g)
k
1
= rate constant per minute
t = time (minutes)
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……………………………….. (6)
Where,
k
2
= rate constant per minute
q
t
= adsorbate adsorbed onto adsorbent at time t (mg/g)
q
e
= equilibrium adsorption capacity (mg/g)
t = time (minutes)
………………..(7)
Where,
q
t
= adsorbate adsorbed onto adsorbent at time t (mg/g)
β = desorption constant
α = initial adsorption rate (mg/g.min)
Adsorption Isotherms
Equations 8 through 12 show the isotherm models applied for adsorption of iron(III) ions by the unmodified and modified
composite, namely: Langmuir, Freundlich, Temkin, Redlich-Peterson (R-P), and Sips isotherms, respectively.
………………………. (8)
Where,
k
l
= Langmuir sorption equilibrium constant (L/mg)
C
e
= concentration of sorbate in the solution at equilibrium (mg/L)
q
m
= maximum amount of metal ion adsorbed by unit mass adsorbent (mg/g)
q
e
= amount of metal ion adsorbed per unit mass at equilibrium (mg/g)
……………………. (9)
Where,
n = Freundlich exponent (dimensionless)
C
e
= concentration of sorbate in the solution at equilibrium (mg/L)
q
e
= amount of metal ion adsorbed per unit mass at equilibrium (mg/g)
k
f
= Freundlich equilibrium constant (mg/g)
…………………….. (10)
Where,
k
T
= Temkin equilibrium constant (mg/g)
C
e
= concentration of sorbate in the solution at equilibrium (mg/L)
q
e
= amount of metal ion adsorbed per unit mass at equilibrium (mg/g)
………………………. (11)
Where,
C
e
= concentration of sorbate in the solution at equilibrium (mg/L)
q
e
= amount of metal ion adsorbed per unit mass at equilibrium (mg/g)
a
RP
= Redlich-Peterson constant (mg/L)
k
RP
= Redlich-Peterson constant (L/g)
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…………………………. (12)
n
s
= Sips exponent (dimensionless)
k
s
= Sips equilibrium constant (mg/L)
C
e
= concentration of sorbate in the solution at equilibrium (mg/L)
q
s
= amount of metal ion adsorbed per unit mass at equilibrium (mg/g)
Intraparticle Diffusion
The diffusion behaviour of the composites were assessed by Webber-Morris Intraparticle diffusion equation which takes the form
in (13)
…………………………..(13)
Where,
C = Constant related to the thickness of boundary layer (mg/g)
K
ID
= Intraparticle diffusion rate constant (mg/g/min
-1/2
)
Q
t
= Quantity of ions adsorbed at time t (mg/g)
III. Results and Discussion
Results
The FTIR results of unmodified PET/Coconut Husk Composite (PCH) and modified PET/Coconut Husk Composite (MPCH) are
shown in figures 1 and 2, while the inference and deductions from the spectra bands are given in table 1.
Figure 1: FTIR chart for Unmodified PET/Coconut Husk Composite (PCH)
Figure 2: FTIR chart for Modified PET/Coconut Husk Composite (MPCH)
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Figure 3: Variation of contact time on adsorption of ferric ions using unmodified PET/Coconut Husk composite (PCH)
Figure 4: Variation of contact time with adsorption of ferric ions using modified PET/Coconut Husk Composite (MPCH)
Figure 5: Influence of initial ion concentration on the adsorption of ferric ions using unmodified PET/Coconut Husk Composite
(PCH)
Figure 6: Influence of initial ion concentration on the adsorption of ferric ions using modified PET/Coconut Husk Composite
(MPCH)
0
20
40
60
0
0.5
1
1.5
0 50 100 150 200 250
% Adsorbed
Quantity Adsorbed Qe
(mg/g)
Time(min)
Effect of Time
Qe %ADS
0
100
200
0
2
4
0 50 100 150 200 250
% Adsorbed
Quantity adsorbed
Qe(mg/g)
Time(min)
EFFECT OF TIME
Qe % Ads
0
100
0
50
0 100 200 300 400
% Adsorbed
Quantity Adsorbed,Qe,
(mg/g
)
Initial ion concentration, Co,(mg/L)
Effect of initial ion concentration
(Unmodified)
Qe %ADS
0
50
100
0
20
40
0 100 200 300 400
% Adsorbed
Quantity adsorbed, Qe
(mg/g)
Initial ion concetration (mg/L)
Effect of initial ion
Concentration(Modified)
Qe % Ads
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Figure 7: Kinetic plots for the adsorption of ferric ions using unmodified PET/Coconut Husk Composite (PCH)
Figure 8: Non-linear Kinetic plots of the adsorption of ferric ions using modified PET/Coconut Husk Composite (MPCH)
Figure 9: Adsorption isotherms for the adsorption of ferric ions using unmodified PET/Coconut Husk Composite (PCH)
Figure 10: Adsorption isotherms for the adsorption of ferric ions using modified PET/Coconut Husk Composite (MPCH)
0
0.5
1
1.5
0 50 100 150 200 250
Q
t
(mg/g)
Time(min)
Kinetics
1ST ORDER 2ND ORDER PSO
0
2
4
0 50 100 150 200 250
Q
t
(mg/g)
Time (min)
Kinetics
1ST ORDER 2ND ORDER PFO PSO ELOVICH
-20
0
20
40
0 5 10 15 20 25 30
Quantity adsorbed, Qe
(mg/g)
Ce,(mg/L)
ADSORPTION ISOTHERMS
EXPT LANG FREUND
-50
0
50
0 10 20 30
Quantity adsorbed
Qe,( mg/g)
Ce,(mg/L)
ADSORPTION ISOTHERMS
EXPT LANG FREUND
TEMPKIN R - P SIPS
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Figure 11: Intraparticle Diffusion Plots for the adsorption of ferric ions using unmodified and modified PET/Coconut Husk
Composite.
IV. Discussion
Table 1: Fourier Transform Infrared Spectroscopy Characterization results of composites
S/N
Absorption Bands (cm
-1
)
Inference
Deduction
Unmodified
Modified
1
3425.4
3384.4
3425.4
Presence of OH group both
composites.
Second peak for the OH group in the
modified is due to the modification.
2
2967.0
2970.7
Presence of carboxyl
(COOH) group.
Difference in bands is due to
modification of composite.
Effect of Contact Time
The results of the effect of contact time on the adsorption of ferric ions by unmodified
and modified PET/Coconut Husk composites are shown in figures 3 and 4. PCH had a high adsorption at 5 minutes but reduced
at 40 minutes after which it rose and had its highest adsorption at 220 minutes, where the highest adsorption was at 45.72%. This
finding was similar to that observed by Khattak et al, (2017) who used magnetic carbon nanostructures made from biomass in
heavy metals elimination in drinking water and they observed that the uptake of the contaminants was very fast in the first few
minutes and this was interpreted to mean that there were more available sites for adsorption of the metals on the adsorbents.
Modified PET/Coconut Husk Composite (MPCH) was used in the adsorption Fe
3+
from solution. Its lowest adsorption was at 5
minutes and it increased steadily and got to its peak at 160 minutes, then dropped a little at 220 minutes. The highest percentage
of adsorption was 99.85% at 160 minutes. This behaviour correlated with Gunorubon and Chukwunonso (2018) who studied
ferric ions adsorption using activated carbon obtained from periwinkle shell where the percentage of ferric ions adsorption
increased as the contact time increases.
Influence of Initial Ion Concentration
The adsorption of Fe
3+
using unmodified PET/Coconut Husk Composite (PCH) was studied over varying concentrations: 20, 40,
80, 160 and 320 ppm. The plot in figure 5 shows it follows a steady rise, while its highest adsorption percentage was at 20 ppm
with 93.44%.
Similarly, the adsorption of Fe
3+
using modified PET/Coconut Husk Composite (MPCH) was also studied in varying
concentration: 20, 40, 80, 160, 320 ppm. The plot in figure 6 shows a steady progression that was close to a straight line.
Modified PET/Coconut Husk Composite (MPCH) has its highest adsorption percentage at 320 ppm with 91.56%.
Both adsorptions using the unmodified and modified PET/coconut husk composite showed that as amount of iron (III) adsorbed
increased, so the initial metal ion concentration increases. This can be credited to the fact that the adsorbents had available sites
to contain higher levels of metal ion concentrations. This finding was similar to what was observed by Abasi et al., (2011) where
the unaltered fruit endocarp of the raphia palm (Raphia hookeri) fruit was used to study the uptake of Pb
2+
, Fe
3+
, and Cd
2+
.
Water sample was obtained from the water facilities in real time to test for the adsorbent capacities; the Fe (III) concentration in
the real water sample was measured to be 16.74ppm. On using unmodified PET/Coconut Husk Composite (PCH) to carry out the
0
1
2
3
0 50 100 150 200 250
Q
t
(mg/g)
t
0.5
(min
0.5
)
WEBER- MORRIS INTRAPARTICLE
DIFFUS ION
MPCH PCH
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adsorption, its adsorption percentage was 72.08%, while modified PET/Coconut Husk Composite (MPCH), had an adsorption
percentage of 76.25%. This result also indicates that the modified composite is of a better performance than the unmodified in
real time.
Based on the information provided in Table 2, the non-linear adsorption kinetics of unmodified PET/coconut husk (PCH)
exhibited coefficient of determination (R
2
) of nil, nil, 0.07, 0.73, and 0.79 for the PFO, Elovich, PSO, first-order, second-order
models, respectively. The obtained nil values for the PFO and Elovich models indicate that the adsorption process does not
conform to those specific models. Pseudo second-order had a low R
2
value of 0.07; first-order had a value of 0.73 while the
second-order had a value of 0.79 thereby making the adsorption to have a greater control by second-order kinetics by comparison.
Table 2: Kinetic Parameters of Adsorption for Unmodified (PCH) and Modified(MPCH) PET/Coconut Husk
PCH
MPCH
KINETICS
PARAMETERS
VALUES
VALUES
First order
q
o
(mg/g)
K
1
R
2
0.42
-0.005
0.73
1.00
-0.005
0.72
Second order
q
o
(mg/g)
K
2
R
2
0.44
-0.007
0.79
1.15
0.002
0.62
PFO
q
e
(mg/g)
K
1
R
2
0.64
2.29
Nil
2.65
0.02
0.95
PSO
q
e
(mg/g)
K
2
R
2
0.77
0.26
0.07
3.34
0.005
0.93
Elovich
α (mg/g.min)
β
R
2
-0.64
2.00
Nil
0.19
1.68
0.88
Column 2 of Table 2 shows the results for the non-linear adsorption kinetic parameters using modified PET/coconut husk
(MPCH) with coefficient of determination (R
2
) of 0.62, 0.72, 0.88, 0.93, and 0.95 for second order, first-order, Elovich, PSO and
PFO models respectively. The kinetic models used, proved that PFO and PSO had values that were close to unity (0.95 and 0.93),
but pseudo first-order had a higher value of 0.95 thereby making the adsorption a pseudo first-order prevalent adsorption, which
implies physisorption was more prevalent than chemisorption with the adsorbent.
Unmodified PET/coconut husk composite (PCH) had a lesser coefficient of determination when compared to modified
PET/coconut husk composite (MPCH), this may be due to the modification.
Table 4: Table showing the values of Adsorption Isotherm Parameters for unmodified PET/Coconut Husk composite (PCH)
PCH
MPCH
ISOTHERM
PARAMETERS
VALUES
VALUES
Langmuir
q
m
(mg/g)
K
L
(L/g)
R
2
6657.91
9.62 X 10
-5
0.53
7939.32
7.76 X 10
-5
0.49
Freundlich
k
F
(mg/g)
n
R
2
2.26 x 10
-11
0.12
0.97
8.22 x 10
-10
0.14
0.87
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Temkin
k
T
(mg/g)
b
T
R
2
5.29
0.63
0.37
7.16
0.31
0.37
Redlich-Peterson
k
RP
(L/g)
a
RP
(mg/L)
g
R
2
-0.11
9.43 X 10
-9
6.61
0.95
-0.25
1.4 X 10
-5
4.42
0.78
Sips
q
S
(mg/g)
k
S
(mg/L)
n
S
R
2
1.00
1.01 X 10
-6
8.40
0.97
-0.89
4.67 X 10
-6
5.32
0.79
From the data presented in Table 4, the coefficients of determination (R
2
) for the Temkin, Langmuir, Redlich-Peterson,
Freundlich, and Sips models were computed to be 0.37, 0.53, 0.95, 0.97, and 0.97 respectively, for the unmodified PET/coconut
husk composite (PCH). For the modified PET/coconut husk composite (MPCH), the coefficients of determination obtained for
the Temkin, Langmuir, Redlich-Petersen, Sips and Freundlich models were 0.37, 0.49, 0.78, 0.79 and 0.87 respectively.
For the unmodified PET/coconut husk composite (PCH), Redlich-Peterson, Freundlich, and Sips models respectively have
coefficient of determination values R
2
close to unity (0.95, 0.97 and 0.97). The investigation of the adsorption isotherm models
indicated that the unmodified composite exhibited the best correlation with Sips and Freundlich models. Notably, the Sips model
merges elements from both Langmuir and Freundlich models, highlighting the significant influence of the Freundlich model on
the adsorption process. The adsorption on the modified PET/Coconut husk composite demonstrates a close correlation to the
Freundlich model, as proven from the coefficient of determination (R
2
) of 0.87.
The modified PET/coconut husk composite (MPCH) had a lesser correlation when compared to the unmodified PET/coconut
husk composite (PCH) which was close to unity.
Also, the fact that both the unmodified and modified PET/coconut husk composites fitted closely to the Freundlich model shows
that they both possess heterogeneous adsorbent surfaces for multi-layer adsorption.
The nonlinear maximum adsorption capacities for unmodified PET/coconut husk composite (PCH) and modified PET/coconut
husk composite (MPCH) were 6657.91 and 7939.32 mg/g respectively.
Intraparticle Diffusion
The coefficient of determination (R
2
) obtained from the adsorption using the unmodified PET/coconut husk composite (PCH) and
the modified PET/coconut husk composite (MPCH) were both 0.9613.
Figure 11 shows that multi-linearity for modified and unmodified PET/coconut husk composites (MPCH and PCH) was observed
to be low with R
2
value of 0.9613. This value is close to unity for a linear function and thus it can be said that the adsorption with
both adsorbents was controlled by the intraparticle diffusion.
V. Conclusion
Waste polyethylene terephthalate (PET-RIC 1) matrix was successfully composited with waste coconut husk biomass. The
unmodified and modified composites were characterized and applied in the adsorptive scavenging of ferric ions in simulated and
real-time water through batch equilibrium, kinetic and intraparticle diffusion analyses. The results indicated that pseudo first-
order kinetics was the most favourable rate model for both the unmodified and modified composites in terms of the highest rate
constant (k
1
) of 2.29 g/mg min and the coefficient of determination (R
2
) of 0.95. This result corroborated with the multi-layer
Freundlich model with a coefficient of determination (R
2
) of 0.97 and 0.87 respectively for the unmodified and modified
composites, which is indicative of physisorption as the prevalent equilibrium. Thus the composite may also be reused after
desorption. Kinetic data puts the quantity of iron removed by modified composite to be 2.65 mg/g from PFO and 3.34 mg/g from
PSO, all of which far exceeded the quantity removed by the unmodified composite. The R
2
value of the intraparticle diffusion at
0.96 shows that the composites had significant internal pores that could take in metal ion particles and so remove them from
solution.
Conflict of interest
The authors do not have any form of conflict of interest in this work.
INTERNATIONAL JOURNAL OF LATEST TECHNOLOGY IN ENGINEERING,
MANAGEMENT & APPLIED SCIENCE (IJLTEMAS)
ISSN 2278-2540 | DOI: 10.51583/IJLTEMAS | Volume XIII, Issue XI, November 2024
www.ijltemas.in Page 21
Acknowledgement
The authors are grateful to the Niger Delta University for providing the laboratory space for this work.
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