Efficient adsorption of Europhtal onto activated carbon modified with ligands (1E,2E)-1,2-bis(pyridin-4-ylmethylene)hydrazine (M) and (1E,2E)-1,2-bis(pyridin-3-ylmethylene)hydrazine (SCH-4); Response surface methodology

Article abstract of DOI:10.1039/c5ra03622d

Porous activated carbon was modified with (1E,2E)-1,2-bis(pyridin-4-ylmethylene)hydrazine (M) and (1E,2E)-1,2-bis(pyridin-3-ylmethylene)hydrazine (SCH-4). Characterization was performed using different techniques such as SEM, FTIR and ¹H NMR analysis. Then, these new adsorbents were used for the efficient removal of Europhtal (sulfonated cobalt phthalocyanine). Response surface methodology (RSM) was used to achieve operational conditions for the efficient removal of Europhtal using an activated carbon modified with novel ligands. To investigate the individual effect of variables involved and the effect of their possible interactions on the adsorption process, several systematic experiments were designed by varying the variables such as pH, sonication time, adsorbent dosage and dye concentration in the range of 2.0-11, 2-8 min, 0.005-0.035 g and 4-30 mg L^-1, respectively. The optimum values of pH, sonication time, adsorbent dosage and Europhtal concentration were found to be 7, 2 min, 30 mg L^-1 and 0.03 g for the sample modified with M and 7, 5 min, 30 mg L^-1 and 0.03 g for the one modified with SCH-4, at which the removal percentages were more than 98%. Adsorption equilibrium data were well fitted to the Freundlich model with maximum adsorption capacities of 56.69 and 17.84 mg g^-1 for M and SCH-4, respectively. The study of adsorption kinetics indicated that the dye uptake process follows the pseudo second-order and saturation type rate expressions for each ligand.

Full text of DOI:10.1039/c5ra03622d

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Efficient adsorption of Europhtal onto activated carbon modified with ligands (1E, 2E)-1,2-
bis (pyridin-4-ylmethylene) hydrazine (M) and (1E, 2E)-1,2-bis (pyridin-3-ylmethylene)
hydrazine (SCH-4); Response surface methodology
a
M. Ghaedi* , E. Alam barkatb, A. Asfarama, B. Mirtamizdoustc, A.A. Bazrafshana, S. Hajati*d
a Chemistry Department, Yasouj University, Yasouj 75918ꢀ74831
, Iran.
b Chemistry Department, Islamic Azad University, Fars Science and Research Branch, Fars, Iran.
c Department of Chemistry, Faculty of Science, University of Qom, 37185ꢀ359 Iran.
d Department of Physics, Yasouj University, Yasouj 75918ꢀ74831, Iran.
*Corresponding authors at: Chemistry Department, Yasouj University,
Yasouj 75918ꢀ74831, Iran, Tel/Fax: +98 741 2223048.
Eꢀmail address: m_ghaedi@mail.yu.ac.ir; m_ghaedi@yahoo.com (M. Ghaedi); and at: Department of Physics,
Yasouj University, Yasouj 75918ꢀ74831, Iran. Tel/Fax: +98 741 2223048;
Eꢀmail address: hajati@mail.yu.ac.ir; (S. Hajati).
1

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Abstract
Porous activated carbon was modified with (1E, 2E)ꢀ1, 2ꢀbis (pyridinꢀ4ꢀylmethylene) hydrazine
(M) and (1E, 2E)ꢀ1, 2ꢀbis (pyridinꢀ3ꢀylmethylene) hydrazine (SCHꢀ4). Characterization was
performed using different techniques such as SEM, FTIR and H1NMR analysis. Then, these new
adsorbents were used for efficient removal of Europhtal (Sulfonated Cobalt Phthalocyanine).
Response surface methodology (RSM) was used to achieve operational conditions for efficient
removal of Europhtal using activated carbon modified with novel ligands. To investigate the
individual effect of variables involved and the effect of their possible interactions on the
adsorption process, several systematic experiments were designed by varying the variables such
as pH, sonication time, adsorbent dosage and dye concentration in the range of 2.0ꢀ11, 2ꢀ8 min,
0.005ꢀ0.035 g and 4–30 mg Lꢀ1, respectively. The optimum values of pH, sonication time,
adsorbent dosage and Europhtal concentration were found to be 7, 2 min, 30 mg Lꢀ1 and 0.03 g
for the case modified with M and 7, 5 min, 30 mg Lꢀ1 and 0.03 g for one with SCHꢀ4at which,
the removal percentages were more than 98%. Adsorption equilibrium data were well fitted to
Freundlich model with maximum adsorption capacities of 56.69 and 17.84 mg gꢀ1 for M and
SCHꢀ4, respectively. The study of adsorption kinetics indicated that the dye uptake process
follows the pseudo secondꢀorder and saturation type rate expressions for each Ligand.
Keywords: Europhtal; Response surface methodology; (1E, 2E)ꢀ1,2ꢀbis (pyridinꢀ4ꢀylmethylene)
hydrazine (M); (1E, 2E)ꢀ1,2ꢀbis (pyridinꢀ3ꢀylmethylene) hydrazine
2

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1. Introduction
The effluents composed of synthetic dyes arrive from different sources to the environment.
Dyes are widely utilized in various industrial activities such as coloring, paper, textiles,
cosmetics and food1ꢀ3. Their complex (aromatic) molecular structures cause increase in their
resistance to heat, oxidizing agent and biodegradation. Most dyes are toxic and harmful to some
microorganisms and prevent from their catalytic activity 4. The toxicity of dyes on plant, animal
and human health is not wellꢀknown 5, 6. Several versatile approaches including ion exchange,
photoꢀoxidation processes, flocculation, precipitation, microbiological decomposition and
ozonation are applied for wastewater treatment and water quality enhancement. Low cost and
easyꢀtoꢀprepare adsorbents are the best for wastewater treatment and pollutants removal via the
adsorption process7ꢀ14. The adsorption process provides an attractive alternative for water
treatment, while is easy to handle, requires less maintenance and produce smaller amounts of
sludge5, 15ꢀ17. Most of adsorbents have high abundance and cheep, while have drawbacks such as
poor mechanical and heat resistance and relatively limited adsorption capacity for dyes18ꢀ20. Thus
modification of adsorbents and improvement of their properties viz. reactive centers and surface
area is a great demand. A catalyst solution comprising 30% of sulphonated cobalt phthalocyanine
(Europhtal under the name 802) is generally used to remove mercaptan from hydrocarbon based
on either its solution or liquid catalyst loaded on activated carbon. This catalyst is extensively
applied in numerous refineries worldwide and it is necessary to develop novel materials and
methods for its removal from various media. In this regard, development and search for novel
adsorbent, especially nanoscale adsorbents are good choice to improve the characteristic
performance of removal procedure. Huge number of reactive centers and sites on the surface of
nanomaterials make them suitable for trapping other species. Activated carbonꢀbased adsorbents
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with unique porous reactive sites in the presence of versatile reaction centers like hydroxide,
carboxylic and amide groups are good materials for subsequent modification through hydrogen
bonding, πꢀ π bonding and electrostatic reactions. Various organic reagents and chelating agents
can be used for the modification on the surface of such adsorbents leading to more improvement
in removal process performances.
The present work focuses on the synthesis of (1E, 2E)ꢀ1, 2ꢀbis (pyridinꢀ4ꢀylmethylene)
hydrazine (M) and (1E, 2E)ꢀ1, 2ꢀbis (pyridinꢀ3ꢀylmethylene) hydrazine (SCHꢀ4) as well as on
1
their subsequent loading on AC followed by the characterization by SEM, FTIR and HNMR.
Then, the potential feasibility of Mꢀ and SCHꢀ4ꢀ loaded AC for the Europhtal removal (as
response) was investigated and the influences of various variables on the response were
investigated and optimized. Statistical analysis was applied on the experimental data and results
to make a predictive model and test the validity. The kinetic and equilibrium data were analyzed
to understand the adsorption mechanism by applying different models to fit the experimental
data.
2. Materials and methods
2.1.
Materials and instruments
The Europhtal (Table 1) was purchased from Sigma Aldrich and its stock solution (100 mgLꢀ1)
was prepared in double distilled water. Europhtal concentration was determined by measuring
and analyzing the absorbance spectra before and after each experiment by a 2800ꢀDR (UV–Vis)
spectrophotometer at 664 nm. An ultrasonic bath with heating system (Bandelin sonorex) at
frequency 40 kHz with power of 130 W was used for the ultrasoundꢀassisted adsorption
procedure. For pH measurements a Metrohm pH meter modelꢀ780 was used. The morphology
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and size distribution of the Mꢀ and SCHꢀ4ꢀloaded AC were observed by scanning electron
microscopy (SEM Hitachi Sꢀ4160) under an acceleration voltage of 15 kV. The FTIR spectra of all
;
compounds were recorded by using a JASCOꢀFTIRꢀ480 instrument in the range of 4000–400
cmꢀ1 with KBr as disc.
2.2.
Ultrasoundꢀassisted adsorption method
A batch process was used to evaluate the performance of Europhtal adsorption onto Mꢀ and
SCHꢀ4ꢀloaded AC in presence of ultrasound. Adsorption experiments were performed in a
cylindrical glass vessel by adding 0.02 g of either of adsorbents into 50 mL of Europhtal solution
at known concentration (4 and 30 mg Lꢀ1) at pH 7 that optimized by CCD. The vessel was
immersed in an ultrasonic bath for 2.8 min time at room temperature. After this time, solutions
were analyzed for determining the final Europhtal concentration by using a UV–Vis
spectrophotometer set at a wavelength of 664 nm. The experiments were also performed in the
initial dye concentration range of 5–40 mg Lꢀ1 to obtain adsorption isotherms. The dye removal
percentage (R %) was calculated using the following equation:
C0 − Ct
R% =
×100 ,
(1)
C0
where C0 and Ce (mg Lꢀ1) are the initial and equilibrium dye concentrations in aqueous solution,
respectively. Adsorbed dye amount (qe (mg gꢀ1)) was calculated by the following mass balance
relationship:
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C ꢀC V
(
)
0
e
qe =
,
(2)
W
where, V (L) is the volume of the solution and W (g) is the mass of the adsorbent.
2.3. Preparation of AC from acorn
The seed shells correspond to approximately 25% of the whole acorn. In order to separate shell
from seeds, about 2 kg of acorn was cooked in a 1.0 L glass beaker for 2 h. afterwards, the acorn
seeds were immersed in 2 L of deionized water and heated to boil for two more hours in order to
remove the water soluble phenolic compounds and to avoid from their releases during the
adsorption experiments. Subsequently, the acorn wastes were washed with distilled water and
dried at 70 °C in an airꢀsupplied oven for 8 h and was grounded thereafter in a diskꢀmill and
sieved (70–100 mesh) subsequently. Sieved mass were then performed carbonization process in
argon atmosphere at the temperature increase rate of 5 °C/min to the final temperature of 500 °C
and kept for 1 h. The mass was then cooled and washed thoroughly several times by distilled
water and dried 21.
2.4. Synthesis of (1E, 2E)ꢀ1,2ꢀbis(pyridinꢀ4ꢀylmethylene)hydrazine (M)
1 ml (11 mmol) of hydrazine was added dropwise to a solution of isonicotinaldehyde (2.35 mL,
22 mmol) dissolved in ethanol (15 mL). Two drops of acetic acid were added and the mixture
was stirred at room temperature for 24 h. The yellow solid that formed (with yield=73%) was
filtered and washed several times with ethanol/ether (1:1) (See Fig. 1a for synthesis procedure).
2.5.
Synthesis of (1E,2E)ꢀ1,2ꢀbis(pyridinꢀ3ꢀylmethylene)hydrazine (SCHꢀ4)
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1 mL (11 mmol) of hydrazine was added dropwise to a solution of nicotinaldehyde (2.4 mL, 20
mmol) dissolved in ethanol (15 mL). Two drops of formic acid were added and the mixture was
stirred at room temperature for 24 h. The product (with yield=73%) was filtered and washed in
the same way as done for ligand M (See Fig. 1b for synthesis procedure).
2.6.
Central composite design (CCD)
To reduce the number of experiments required, a standard CCD (with 31 experiments) under
RSM was applied. It helped us to determine regression model equations and operating conditions
at which the maximum R% (as response) is achieved22ꢀ24. Moreover, the advantage of this
procedure is the possibility of finding the effects of interaction between each pair of the variables
involved such as pH (x1), sonication time (x2), adsorbent dosage (x3) and Europhtal concentration
(x4) on the response (R %) in addition to their individual effects. As mentioned above, two
materials were used as adsorbent which are Mꢀ and SCHꢀ4ꢀloaded activated carbon. The ranges
of variation were set as 2ꢀ11 for the pH, 2ꢀ8 min for the sonication time, 0.005ꢀ0.035 g for the
adsorbent amount, and 4ꢀ30 mg Lꢀ1 for the Europhtal concentration (See Tables 2 and 3). CCD
has been discussed in detail in Refs. 13, 19, 25. In general, the following equation may be used to
model the experimentally obtained response versus variables involved.
4
4
4
4
R% = β0
+
β
x +
β
x2 +
β
ij xi xj
(3)
∑
∑
∑∑
i
i
ii
i
i=1
i=1
i=1 j=1
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In this equation, β0, βi, and βii are constant coefficients corresponding to zeroꢀ, firstꢀ and secondꢀ
order terms, respectively. βij is the coefficient of interaction term. Depending on the extent to
which each term plays a role this model may be varied.
2.7.
Model fitting and statistical analysis
The CCDꢀbased experimental data were analyzed, using Minitab software version 17.0, to be
fitted to a secondꢀorder polynomial equation and then the regression coefficients were obtained.
The analysis of variance (ANOVA) was performed to justify the significance and adequacy of
the developed regression model. The adequacy of the model was also evaluated by calculating
the determination coefficient (R2) in addition to testing it for the lack of fit.
3. Results and discussion
3.1.
Characterization of adsorbent
1
FTIR and HNMR spectra of the ligand M were acquired and shown in Fig. 2. The FTIR
absorption band at 1628 cmꢀ1 of the Imine factor, νC=N, confirms the formation of the Schiffꢀbase
ligand. Some important absorption bands of the ligands are given in Table 4 and in good
agreement with what has been reported 26, 27
.
1
Fig. 3 shows the FTIR and HNMR spectra of the ligand SCHꢀ4. The absorption band
appeared around the frequency 1625 cmꢀ1 in the FTIR spectrum of the Ligand SCHꢀ4,
corresponds to νC=N, confirming the formation of the Schiffꢀbase ligand. Detailed absorption
bands of this ligand are given in Table 4, consistent to that reported elsewhere 28.
The morphology of nonꢀmodified AC (Fig. 4(a)) and that of modified one with either ligand
M (Fig. 4(b)) or SCHꢀ4 (Fig. 4(c)) were characterized by SEM showing approximate particle
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size in the range of 40ꢀ80 nm. The surface modification is clearly seen after the deposition of
ligands onto AC (Figs. 4(b) and 4(c)).
3.2.
Central composite design (CCD)
Total 31 experiments (runs) were designed by Minitab software version 17.0. The tests for
significance of regression model for both responses were evaluated and the results of ANOVA
tests are presented in Table 5. From ANOVA, the factors with pꢀvalues less than 0.05 were
distinguished to be significant. The pꢀvalues (0.343 and 0.0554 for M and SCHꢀ4 data,
respectively) corresponding to the lack of fits for the models applied indicated nonꢀsignificant
lack of fit. However, the model for predicting R% of Europhtal corresponding to either Mꢀ or
SCHꢀ4ꢀbased adsorbent was reconstructed to filter out nonꢀsignificant factors. Thus the
predictive models were applied as follow:
R%Europhtal = 64.9 +5.49 x1 +2228x3 −2.416 x4
−0.827 x12 −71468x32 +179.7 x1x3 +69.7 x3x4
for Mꢀloaded AC,
(4)
(5)
R%Europhtal =114.3+0.25x1 −1.77x2 +1761x3 −5.92 x4 −0.584x12 −
0.686 x22 −43475x32 +0.032242 +0.2195x1x4 +0.491x2 x4 +36.4 x3x4
for SCHꢀ4ꢀloaded AC,
Positive and negative signs in each equation imply synergistic and antagonistic effect of the
variables, respectively. The values of determination coefficient (R2) were found to be 0.985 and
0.968 for the Europhtal removal percentage by using Mꢀ and SCHꢀ4ꢀloaded AC, respectively,
confirming the good agreement between the experimental and predicted values.
3.3.
Response surface methodology
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The curvature natures of Fig. 5 and 6 show the response surface plots of removal (%) and
confirm strong interaction among variables.
Fig 5(a) and 6(a) strongly supports that elevating the adsorbent amount and dye concentration
lead to enhance in Europhtal removal percentage. The increase in the amount of dye
concentration leads to decrease in its removal percentage. The low and high initial dye
concentrations have opposite trend. The small ratio of solute concentrations to nonꢀoccupied
reactive adsorbent sites cause acceleration of dye adsorption and subsequent increase in removal
percentage, while saturation of adsorption sites is associated with reduce in removal percentage
at higher amount of target compounds. The opposite correlation among initial Europhtal
concentration, removal percentage and actual amount of adsorbed Europhtal clearly indicate the
dependency of Europhtal adsorption to its initial concentration.
Fig. 5(b) shows the combined effect of adsorbent and pH on adsorption of Europhtal onto
adsorbent at constant Europhtal initial concentration (30 mg Lꢀ1). Raising pH leads to significant
influence on removal percentage and at constant pH, removal percentage increases with raising
the M value. The Europhtal removal decreases at lower amount of adsorbent and approximate
constant trend was seen at higher amount of adsorbent.
The increase in amount of adsorbent leads to significant decrease in sonication time (Fig. 6b),
while the removal percentage at fixed sonication time has positive correlation with amount of
adsorbent.
Fig. 6(d) shows the interaction of pH with initial Europhtal concentration and their relation with
removal percentage. The pH has positive correlation with removal percentage, while higher pH
and lower adsorbent concentration led to achievement of lower removal percentage. At low
initial pH, protonation of the adsorbent functional groups led to generation of positive charge and
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appearance of the strong attractive forces between the Europhtal molecule and adsorbent surface
(increase in removal percentage).
3.4.
Optimization
The profile for desirable option with predicted values in the Minitab software was used for the
optimization of the process (Fig. 7). The profile for desirable responses was chosen after
specifying the DF for each dependent variable (removal percentage) by assigning predicted
values. The scale in the range of 0.0 (undesirable) to 1.0 (very desirable) was used to obtain a
global function (D) that its maximum (100%) value concern to Europhtal adsorption was
achieved in this research.
Maximum removal (>98.8%) was obtained at optimum conditions set as: 2 min of time, 0.03 g of
adsorbent, initial Europhtal concentration of 30 mg Lꢀ1 at pH 7 by ACꢀM and 5 min of time, 0.03
g of adsorbent, initial Europhtal concentration of 30 mg Lꢀ1 at pH 7 by ACꢀSCHꢀ4. The validity
of duplicate assenting experiments at the optimized value of all parameters was investigated. The
results were closely correlated with the data obtained from optimization analysis using CCD.
3.5. Adsorption equilibrium study
Common isotherm models such as Langmuir, Freundlich, Temkin and Dubininꢀ
Radushkevich (DꢀR) are generally applied to discuss the equilibrium characteristics of the
adsorption process29ꢀ32. The constant parameters of the isotherms equations for this adsorption
process and their correlation coefficient (R2) are summarized in Table 6. Based on the linear
29
form of Langmuir isotherm model (according to Table 6), the values of KL (the Langmuir
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adsorption constant (L mgꢀ1)) and Qmax (theoretical maximum adsorption capacity (mg gꢀ1)) were
obtained, respectively, from the intercept and slope of the plot of Ce/qe vs Ce..
30
The parameters of Freundlich isotherm model
such as KF and 1/n (the capacity and
intensity of the adsorption) were calculated from the intercept and slope of the linear plot of lnqe
versus lnCe, respectively (See Table 6). The values of 1/n were found to be 0.283 and 0.3385
corresponding to MꢀAC and SCHꢀ4ꢀAC, respectively, which show the high tendency of the
adsorbents for the adsorption of Europhtal. Furthermore, high R2 values (0.992 and 0.994 for Mꢀ
AC and SCHꢀ4ꢀAC, respectively) show the suitability of Freundlich isotherm model for fitting
the experimental data over the whole concentration range.
The heat of adsorption and the adsorbent–adsorbate interaction were evaluated by using
Temkin isotherm model 33. B is the Temkin constant related to heat of the adsorption (J molꢀ1), T
is the absolute temperature (K), R is the universal gas constant (8.314 J molꢀ1 Kꢀ1) and KT is the
equilibrium binding constant (L mgꢀ1). R2 values obtained from applying this model are lower
than that corresponding to the Freundlich and Langmuir model. Therefore, it is concluded that
the Freundlich isotherm represents a better fit to experimental data than the Langmuir isotherm.
Another commonly used model to explain equilibrium data for the adsorption onto a surface
in liquid phase is DubininꢀRadushkevich (DꢀR) 32 which is used to estimate the porosity apparent
−1
free energy and the characteristics of adsorption. In the D–R isotherm, K (mol2 (kJ2) ) is a
constant related to the adsorption energy, Qmax (mg g−1) is the theoretical saturation capacity, ε is
the Polanyi potential. The slope of the plot of lnqe versus ε2 gives K and the intercept yields the
Qm value. The mean free energy of the adsorption (E) is known as the free energy change when
one mole of ion is transferred from the solution to the surface of the sorbent is calculated. The
value of correlation coefficient obtained from DꢀR model is much lower than that from other
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isotherms mentioned above. This means that the D–R equation represents the poorer fit to the
experimental data compared to other isotherm equations.
3.6. Kinetics study
In order to examine the mechanism of adsorption process such as mass transfer and chemical
reaction, a suitable kinetic model is needed to analyze the rate data. Many models such as
homogeneous surface diffusion model, pore diffusion model and heterogeneous diffusion model
(also known as pore and diffusion model) have been extensively applied in batch reactors to
34,
describe the transport of adsorbates inside the adsorbent particles
35. The kinetics of
Europhtal adsorption onto MꢀAC and SCHꢀ4ꢀAC was assessed using different models such as
38
39
pseudoꢀfirstꢀorder 36, pseudoꢀsecondꢀorder 37, intraparticle diffusion
and Elovich
models
(See Table 7). Among these models the criterion for their applicability is based on the respective
correlation coefficient (R2) and agreement between experimental and calculated value of qe. The
high values of R2 (~0.999) and good agreement between two qe values obtained from applying
pseudoꢀsecondꢀorder kinetic model indicate that the adsorption of Europhtal on either of MꢀAC
and SCHꢀ4ꢀAC follows this model (Table 7).
In this work we have chosen two long, rigid bipyridylꢀbased ligands, (1E, 2E)ꢀ1,2ꢀbis (pyridinꢀ4ꢀ
ylmethylene) hydrazine and (1E, 2E)ꢀ1,2ꢀbis (pyridinꢀ3ꢀylmethylene) hydrazine to react with
Cobalt Phthalocyanine. They are natural ligands with tow suitable site for chelating to metals.
The “N” atoms in the aromatic rings (pyridyl groups) connect to metal centers. These ligands can
link two metals (or metals groups) 26, 27. Schematic diagrams for adsorption of this catalyst on
both new adsorbents were presented in Figs. 8, 9.
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3.7.
Application to Real Samples
In order to observe the efficiency of MꢀAC and SCHꢀ4ꢀAC for the removal of Europhtal dye
from real effluents, three effluent streams were collected separately and the adsorption
experiments were performed. Adsorption experiments were conducted using optimum
conditions. More than 96% of dye removal was achieved for all the effluents (Table 8).
4. Conclusion
Activated carbon was modified with ligands (1E, 2E)ꢀ1,2ꢀbis (pyridinꢀ4 ylmethylene) hydrazine
(M) and (1E,2E)ꢀ1,2ꢀbis (pyridinꢀ3ꢀylmethylene) hydrazine (SCHꢀ4) and characterized using
SEM, FTIR and H1NMR analysis. Very small amount of each adsorbent (0.03 g) was used for
efficient adsorption of Europhtal assisted by ultrasonication. Statistical modeling of the
experiments resulted in the prediction of optimal conditions at which very high percentage of
Europhtal is rapidly removed within a couple of minutes. Different models were applied to study
the isotherm and kinetics of adsorption process which respectively showed the applicability of
Freundlich isotherm and pseudoꢀsecondꢀorder kinetics for both adsorbents. The adsorption
capacities of MꢀAC and SCHꢀ4ꢀAC were found to be 56.69 mg gꢀ1 and 17.84 mg gꢀ1,
respectively.
Acknowledgement
The authors express their appreciation to the Graduate School and Research Council of the
Islamic Azad University, Fars Science and Research Branch for financial support of this work.
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17

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Figure captions:
Fig. 1 Procedure for the synthesis of a) (1E, 2E)ꢀ1, 2ꢀbis (pyridinꢀ4ꢀylmethylene) hydrazine. b)
(1E, 2E)ꢀ1, 2ꢀbis (pyridinꢀ3ꢀylmethylene) hydrazine.
1
Fig. 2. FTꢀIR and HNMR spectrum of the ligand (1E, 2E)ꢀ1, 2ꢀbis (pyridinꢀ4ylmethylene)
hydrazine (M)
1
Fig. 3. FTꢀIR and HNMR spectrum of the ligand (1E, 2E)ꢀ1, 2ꢀbis (pyridinꢀ3ꢀylmethylene)
hydrazine (SCHꢀ4)
Fig. 4. SEM of AC (a) Nonꢀmodified (b) modified by (1E, 2E)ꢀ1, 2ꢀbis (pyridinꢀ4ꢀylmethylene)
hydrazine (M) (c) modified by (1E, 2E)ꢀ1, 2ꢀbis (pyridinꢀ3ꢀylmethylene) hydrazine (SCHꢀ4).
Fig. 5. Response surfaces for the Europhtal removal by Mꢀloaded AC: (a) X1ꢀX3 and (b) X3ꢀX4
Fig. 6. Response surfaces for the Europhtal removal by SCHꢀ4ꢀloaded AC: (a) X1ꢀX4; (b) X2ꢀX4
and (c) X3–X4.
Fig. 7. Profiles for predicated values and desirability function for removal percentage of
Europhtal by ligands M and SCHꢀ4. Dashed line indicated current values after optimization.
Fig. 8. Reaction between (1E, 2E)ꢀ1, 2ꢀbis (pyridinꢀ4ꢀylmethylene) hydrazine and Cobalt
Phthalocyanine
Fig. 9. Reaction between (1E, 2E)ꢀ1, 2ꢀbis (pyridinꢀ3ꢀylmethylene) hydrazine and Cobalt
Phthalocyanine
18

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Table 1: Properties of the Europhtal dye
Product Identification
Trade Name
Appearance
Europhtal Additive 802
Blue Liquid Solution
Chemical Name or generic name
Sulfonated Cobalt Phthalocyanine (Sodium salt)
Molecular Structure
R:ꢀSO3H−, Cl−, OH−, Br−
−
−
−
R1: PhCH2 , NO2 , NH2
Chemical Formula
CAS Number
EINECS Number
shelf life
C32H16ꢀi N8Co(SO3Na)i
90294ꢀ83ꢀ0
290ꢀ971ꢀ9
Not limited when stored in normal conditions:
(temperature: 5 to 40 °C; relative humidity: less than 90 %)
(λ
), nm 664 nm
Maximum wavelength
USES
max
Desulphuration Catalyst for oils
Physical state
Colour:
Liquid
Blue
pH:
7.0 to 9.0
Decomposition temperature
Relative density (Water)
Solubility
> 300°
1,15
Soluble in water
Acute toxicity
Hazardous reaction with
LD 50> 2000 mg/kg (oral rat).
None under normal conditions of use.
19

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Table 2
Factors in CCD and their levels.
Levels
Low (ꢀ1) Central (0) High (+1)
Factors
X1: pH
ꢀα
2
2
0.005
4
+α
11
8
0.035
30
4.25
3.5
6.5
5
8.75
6.5
X2: Sonication time (min)
X3: Adsorbent (g)
X4: dye concentration (mg Lꢀ1)
0.0125
10.5
0.02
17
0.0275
23.5
20

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Table 3. Experimental runs and responses
M
SCHꢀ4
Europhtal R%
73.548
62.209
95.312
94.820
64.400
90.079
70.370
86.140
91.320
84.830
76.404
88.251
92.215
65.640
90.706
93.632
72.012
82.954
95.238
84.980
94.495
90.384
90.944
97.413
90.909
60.240
79.084
85.433
88.432
88.076
90.797
Run X1
8.75
X2
X3
X4
Europhtal R%
70.059
1
2
3
4
5
6
7
8
3.5
3.5
6.5
3.5
6.5
8.0
5.0
3.5
5.0
5.0
2.0
3.5
3.5
5.0
5.0
5.0
6.5
6.5
5.0
5.0
5.0
3.5
5.0
6.5
6.5
3.5
6.5
5.0
5.0
5.0
6.5
0.0125
0.0125
0.0275
0.0275
0.0125
0.0200
0.0200
0.0275
0.0200
0.0200
0.0200
0.0275
0.0275
0.0050
0.0200
0.0350
0.0125
0.0125
0.0200
0.0200
0.0200
0.0125
0.0200
0.0275
0.0275
0.0125
0.0125
0.0200
0.0200
0.0200
0.0275
10.5
23.5
23.5
10.5
10.5
17.0
17.0
23.5
17.0
17.0
17.0
23.5
10.5
17.0
17.0
17.0
23.5
23.5
4.00
17.0
30.0
10.5
17.0
23.5
10.5
23.5
10.5
17.0
17.0
17.0
10.5
56.111
87.209
94.230
76.219
92.277
64.070
90.285
90.079
78.930
88.537
93.181
95.977
48.863
89.030
95.454
65.934
52.189
97.159
90.545
84.120
81.976
90.545
94.525
95.348
64.102
79.6511
85.144
85.144
85.144
94.827
8.75
4.25
4.25
8.75
6.50
11.0
4.25
6.50
2.00
6.50
8.75
8.75
6.50
9(C)
10
11
12
13
14
15(C) 6.50
16
17
18
19
6.50
4.25
8.75
6.50
20(C) 6.50
21
22
6.50
4.25
23(C) 6.50
24
25
26
27
8.75
4.25
4.25
4.25
28(C) 6.50
29(C) 6.50
30(C) 6.50
31
8.75
21

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Table 4.
Wave numbers (cmꢀ1) of the vibrational modes of ligand
ligand
νC=N Imine
νC=N Imine
νCꢀN, νCꢀN aromatic
M
SCHꢀ4
2941.17
2925.95
1628.18
1625.28
1595.39, 1552.48, 1417.97
1586.23, 1482.09, 1417.00
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Table 5: Analysis of variance (ANOVA)
Source of
variation
M
Mean
SCHꢀ4
Fꢀvalue
Sum of
square
Mean
square
Sum of square
Dfa
Fꢀvalue
Pꢀvalue
Dfa
Pꢀvalue
square
X1
X12
127.729
500.791
2.319
1
1
1
1
1
1
1
1
127.729
17.9149
70.2394
0.3253
1.1787
500.0748
64.8171
71.7833
1.4443
0.2092
20.6383
0.0593
0.1079
0.5097
25.9304
1.4302
0.005484
0.000157
0.589131
0.319299
0.000001
0.000196
0.000148
0.274728
0.663497
0.003921
0.815772
0.753718
0.502087
0.002239
0.342826
88.295
249.621
114.514
68.180
1
1
1
1
88.295
12.9980 0.011295
500.791
2.319
249.621 36.7469 0.000914
114.514 16.8577 0.006316
X2
X22
8.404
8.404
68.180
10.0368 0.019366
X3
X32
3565.419
462.131
511.799
10.297
1.491
3565.419
462.131
511.799
10.297
1785.555 1
1785.555 262.8525 0.000004
171.012 25.1747 0.002410
171.012
45.679
53.054
11.573
25.270
164.866
0.055
1
1
1
1
1
1
1
1
1
X4
X42
45.679
53.054
11.573
25.270
6.7245
7.8101
1.7037
3.7200
0.041037
0.031384
0.239624
0.102025
X1X2
X1X3
X1X4
X2X3
X2X4
X3X4
1
1.491
147.147
0.423
1
147.147
0.423
1
164.866 24.2701 0.002640
0.055 0.0081 0.931297
366.998 54.0260 0.000325
0.769
1
0.769
3.634
1
3.634
366.998
50.325
184.878
1
184.878
10.197
7.130
50.325
7.4084
3.8784
0.034559
0.055384
LackꢀofꢀFit 101.970
10
6
263.462 10 26.346
40.758 6.793
3483.314 30
Pure Error
42.779
6
Total
5660.113
Degree of freedom
30
a
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Page 25 of 36
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Table 6: Various isotherm constants and correlation coefficients calculated for the adsorption of the Europhtal dye onto Ligands.
Isotherm
Parameters
M
SCHꢀ4
0.02 g
17.84
19.33
0.978
0.339
3.217
Equation
Plot
0.03 g
56.69
6.563
0.983
0.283
4.539
max (mg.gꢀ1)
Q
A plot Ce/qe versus Ce should indicate a
ꢀ1
Langmuir
Freundlich
Temkin
straight line of slope 1/Qm and an intercept K
of 1/(KaQm).
a (L mg )
R2
Ce/qe = 1/KaQm + Ce/Qm
Ln qe = ln KF + (1/n)ln Ce
qe = Bl ln KT + Bl lnCe
Ln qe = ln Qs – Kε2
1/n
K
The values of Kf and 1/n were determined
from the intercept and slope of linear plot of
ln qe versus ln Ce, respectively.
F (L mgꢀ1)
R2
B1
K
0.992
7.019
184.32
0.918
38.63
1.10
0.994
3.244
87.28
0.971
14.48
1.70
Values of B1 and KT were calculated from
the plot of qe against ln Ce.
T(L mgꢀ1)
R2
Qs (mg gꢀ1)
B×10ꢀ8
E
Values of Qm and B were calculated from
the plot of ԑ2 against ln qe.
Dubininꢀ
Radushkevich
6742
0.797
5423
0.933
R2
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Table 7: Kinetic parameters for the adsorption of the Europhtal dye onto Ligands
.
Value of parameters
Model
Equation
plot
Parameters
M
SCHꢀ4
5 mg Lꢀ1
0.087
1.060
0.914
40 mg Lꢀ1
0.126
k1(minꢀ1)
qe (calc) (mg gꢀ1)
R2
k2 (minꢀ1)
qe(calc) (mg gꢀ1)
R2
Plot the values of log (qeꢀqt) versus t to give
a linear relationship from which k1 and qe
can be determined from the slope and
intercept, respectively.
Plot the values of (t/qt) versus t to give a
linear relationship from which k2 and qe can
be determined from the slope and intercept,
respectively.
k
1
log(qe –qt )=logqe –(
)t
Firstꢀorder
kinetic
1.373
0.874
2.303
0.005
6.20
0.999
0.149
33.45
0.999
t
1
t
Pseudoꢀsecondꢀ
order kinetic
=
+
2
qt k2qe qe
Kdiff (mg gꢀ1 minꢀ1/2)
C (mg gꢀ1)
R2
0.226
4.790
0.972
2.477
99.89
0.940
0.715
30.163
0.920
1.1756
35.842
0.960
The values of Kdif and C were calculated
from the slopes of qt versus t1/2.
qt = Kdif t1/2 + C
Intraparticle
diffusion
β (g mgꢀ1)
α (mg gꢀ1 minꢀ1)
R2
Plot the values of (qt) versus ln(t) to give a
linear relationship from which α and β can be
determined from the slope and intercept,
respectively.
1
1
qt = ln(αβ) + lnt
Elovich
β
β
qe (exp) (mg gꢀ1)
5.989
33.139
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Page 27 of 36
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Table 8.
Percentage removal of the Europhtal dye from four different effluents (N=3).
Samples
Initial dye concentration
Removal (%)
(mg Lꢀ1)
30
MꢀAC
SCHꢀ4ꢀAC
99.21±0.7
99.12±1.21
96.63±2.5
96.45±1.7
River water
Sanitary wastewater
Industrial waste
99.50±1.4
98.75±2.5
97.54±1.9
97.62±2.1
30
30
30
Water output from the refinery
26

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Fig. 1
27

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Fig. 2
28