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ISSN 2522-1841 (Online) AZERBAIJAN CHEMICAL JOURNAL № 4 2022 ISSN 0005-2531 (Print)
UDC 544.72
ADSORPTION OF Fe (III) IONS ON MODIFIED ADSORBENT: ADSORPTION
ISOTHERMS
E.J.Eyyubova1, Kh.J.Nagiyev1, S.E.Mammadov1, A.A.Matin2, F.M-Chiragov1
!Baku State University 2Azarbaijan ShahidMadam University, Tebriz, Iran
esmira024@yahoo.com
Received 16.08.2022 Accepted 22.09.2022
This work is devoted to the synthesis of a new type of adsorbent based on maleic anhydride styrene copolymer (MAST) and N^-diphenylguanidine (S) and its modification with 4,4'-(ethane-1,2-diylbis(azanylylidene))bis(pentane-2-one) (S+R). Adsorption study of Fe (III) ions with this adsorbent has been carried out. Effects of the pH value, contact time, ionic strength and the initial concentration of metal ions on the adsorption capacity of the product have been studied. In the course of research, several adsorption isotherms and kinetic models have been studied and the equilibrium data has been found to agree well with the pseudo-second-order model, and the pseudo-second-order model can describe the adsorption process. The results best fit the Langmuir adsorption isotherm model. The studies have shown that compared to the initial product (S), for which the adsorption capacity was 404.88 mg/g, the reagent-modified adsorbent (S+R) shows higher adsorption capacity over Fe(III) ions which is equal to 890.68 mg/g. Synthesized adsorbent was characterized by the Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray Spectroscopy (EDS) and Ultraviolet-visible Spectroscopy (Uv/Vis). Temperature stability of adsorbent has been studied by thermal analysis methods (TG, DTA, DDTA).
Keywords: Fe (III), Adsorption, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), Ultraviolet-visible Spectroscopy (Uv/Vis).
doi.org/10.32 73 7/0005-2531-2022-4-33-42 Introduction
Heavy metal ions are in the number of the most widely spread and toxic pollutants of environment. Pollution of water resources by theses heavy metal ions can cause big harm to humanity. Heavy metal ions are released onto water and air from different industries such as chemical manufacturing, mining, battery manufacturing and etc. Thus they need to be cleaned before using. So that extraction of these ions from different objects is a serious concern.
Number of technologies applied for the removal of ions from industrial effluents is numerous. Among them adsorption is one of the simple and cost effective techniques. Activated carbon is commonly used as an adsorbent material due to its large surface area, micro porous structure, high adsorption capacity and high degree of surface reactivity. Moreover, the presence of different surface functional groups on activated carbon, especially oxygen groups such as carboxylic, carbonylic, lactonic and phenolic lead to the adsorption of ions of heavy metals.
Various inorganic materials have also been used as effective materials for removal of different metal ions [1-3].
However, most of these technologies have shown limitations in removing the toxic pollutants from different natural objects and environment. Therefore, development of cheap and safe remediation technologies is urgently needed [4-7].
Over the last years the considerable success has been achieved in using of different organic and inorganic adsorbents for the selective concentration of elements [8-10]. From this point of view, polymeric chelating sorbents show high activity [11-14].
Among them, polymeric adsorbents based on modifications of maleic anhydride with various copolymers deserve special attention [15-18].
Previously, we studied the adsorption of various metal ions by using a copolymer of maleic anhydride and styrene, modified with various amines [19-21].
The present work is dedicated to studying the adsorption of ferric ions from its salt solu-
tions using the adsorbent, synthesized on the basis of maleic anhydride styrene copolymer with N^-diphenylguanidine, modified with 4,4'-(ethane-1,2-diylbis(azanylylidene))bis(pentane-2-one). The resulting adsorbent was used for pre-concentration of ferric (III) ions. Various factors affecting adsorption, i.e. effects of pH, initial metal concentration, contact time and desorption process were studied. Several isotherm and kinetic studies were also studied during the current research work. Adsorbent was characterized by the Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray Spectroscopy (EDS), Ultraviolet-visible Spectroscopy (Uv/Vis), etc.
Experimental part
Chemicals and reagents. Standard solution of Fe (III) ion by using 10-1 mol L-1 solution of FeCl3, which we synthesized from the reduced iron dissolved in HNO3 and HCl. Equilibrium concentration of metal ions was determined in the liquid phase by the 2,2 -([1,1-biphenyl]-4,4'-diilbis(diazen-2,1-diyl)bis(ben-zene-1,3,5-triol)C18H18O6N4 (R) as reagent with concentration 5.010-4 mg L-1 using adsorption spectrophotometry at 490 nm, pH 5.0 [22]. Beer's law is observed in the 0.056-1.12 mkgg-1 range of metal ion concentration. Adsorption process was investigated by using 1.010-2 mg-L-1 solution of FeCl3 in water.
To study the effect of pH on the adsorption capacity of adsorbents with relation to Fe (III) ions, different pH buffers from 1 to 5 were
used [23]. Buffer solutions were prepared using 0.1 mol L-1 of NH3 OH and 0.1 mol L CH3COOH.
Ionic strength effect was studied using 2 mol L-1 of KCl solution.
Adsorbent synthesis. Adsorbent synthesis was carried out by the known technique [24]. For each experiment, 3 g of maleic anhydride-styrene copolymer was measured and the appropriate amount of amine was added to a flask. N,N'-diphenylguanidine was solved in ethanol. Reaction proceeds in the presence of formalin at 333.15-343.15 K and lasts approximately 30-40 min.
The reaction is carried out in sandy bath by continuous mixing. Since the reaction is carried out in aqueous medium, anhydride groups of copolymer subject to hydrolysis.
Because of the mutual influence of formaldehyde and amine nonstable carbonylamine is formed. The resulting carbonylamine mutually interacts with carboxyl groups of macromol-ecule and the amine fragment is part of the mac-romolecule.
To remove the remnants of reaction product, sorbent has was washed several times with distilled water. Then constant mass was dried in vacuum desiccators at 323 K, grinded and skipped through sieve with 0.14 mm of pore diameter.
Modification of adsorbent by the reagent. Adsorbent MAST-N,N'-diphenylguanidine (S) was modified with 4,4'-(ethane-1,2-diylbis-(azanylylidene))bis(pentane-2-one) (R) (Scheme 1).
O CH3
CH,
CH3 O
Scheme 1. Molecular structure of the reagent.
N
For that purpose, S and R were taken in different stoichiometric ratios 5:1, 10:1, 15:1 and 20:1. The reagent was dissolved in ethanol and added to the adsorbent previously dried in muffle furnace. The resulting mixture was stirred regularly for 6 hours and left for drying. Resulting product was used as adsorbent for removal of Fe(III) ions from aqueous solutions. The studies have shown that maximum adsorption capacity is at S:R=20:1 and equal to 890.68 mg-g-1.
Adsorption experiments. Batch adsorption studies of Fe (III) were carried out at room temperature. For each experiment, 2 ml of metal
ion solution with a known concentration (1.0x10-
2 1
mol L"1) was added into 50 ml conical flasks. 50 mg of sorbents and 18 ml of appropriate pH were added into each flask. pH of solutions was adjusted with Ionomer I-130 pH meter. Mixtures were kept for 24 h. Then the contents of flasks were filtered, i.e. the solid and liquid phases were separated. After that, from each flask 1 ml of sample was taken, diluted with photometric pH 5, and the final concentrations of Fe (III) ions were determined in the filtrate using ultraviolet-visible absorption at 490 nm.
The removal of metal ions from the solution and the metal uptake in the solid state or surface loading, qe(mg g-1) were calculated using the following equations below:
R, % =
Cn — C,
CP
100
(1),
Where R is a percentage metal ion removal.
qe
(Co — Ce)V
m
(2),
where C0 is the initial metal ion concentration (mg L-1), Ce is the equilibrium metal ion concentration (mg L-1), V is the volume of the solution (L), and m is the mass of adsorbent (mg).
Desorption process. Desorption studies were carried out using different inorganic acid solutions HNO3, HCl, H2SO4 and HClO4 with concentrations 0.5 mol L-1. For that experiment 50 mg of modified adsorbent was weighed and added to the conical flasks. 2 ml of metal ion solution and 18 ml of optimal adsorption pH were added into each flask. Mixtures were kept for 24
h. After that, the contents of flasks were filtered and the resulting solid phase was left for drying.
Equipment. Absorbances of solutions were determined using absorption spectropho-tometry. Concentrations of Fe (III) ions were determined by flame atomic absorption spec-trometry using AAS-1N equipped with hollow-cathode lamps for Fe (III). All measurements were carried out in acetylene-air flame. pH values of solutions were measured using Ionomer I-130 with glass electrode. Scanning electron microscope (SEM), JSM-6610LV, equipped with energy-dispersive X-ray spectroscopy (EDS), was used for surface analysis. Ultraviolet-visible spectroscopy was studied on Specord 250 PLUS (Analytik Jena) 2010.
Results and discussions
SEM/EDS analysis. Figure 1 below shows SEM and EDS results of the surface layer of adsorbent S before and after modification by reagent R.
Based on the EDS peaks, we can say that the main elements present in adsorbent S and S+R are C and O atoms, the amounts of which are shown in the Table 1 and Table 2.
EDS also confirms presence of N atoms in the composition of modified form.
In the SEM image spots show the rough and porous surface of the adsorbent, which lead to the increasing of adsorption capacity.
Adsorption of reagent R on adsorbent S is represented in the SEM. Figure 1, depicting the surfaces of particles after adsorption, clearly shows that the caves, pores and surfaces of adsorbent were covered with R and, as a result, the surface became smooth. It can be seen that during adsorption the 4,4'-(ethane-1,2-diylbis-(azanylylidene))bis(pentane-2-one) (R) the adsorbent structure changed.
Results of UV/Vis spectroscopy (Figures 2, 3) show that the adsorbent modified with reagent S+R (red line 2) shows higher adsorption ability compared to initial product S (blue line 1), which can be explained due to the fact that number of functional groups involved in modified product is higher compared to S.
0 2 4 6 Б 10 12 14 16 Полная шкала 18151 им п. Курсор: 0.000' кэВ
ЮОмкт ' Электронное изображение 1
vf I 9
* w
•CS
b ЮОмкт 1 Электронное изображение 1 0 2 4 6 8 |Полная шкала 5470 имп. Курсор: 0 000 10 12 14 k:IB
Fig. 1. SEM and EDS results of adsorbent before and after modification with reagent.
Table 1. EDS results of S
Table 2. EDS results of S+R
Element Weight% Atomic% Comp.% Formula
C K 27.28 33.32 99.96 CO2
S K 0.02 0.01 0.04 SO3
O 72.70 66.67
Overall 100.00
Element Weight% Atomic% Comp.% Formula
C K 26.10 32.04 95.65 CO2
N K 0.83 0.87 3.20 N2O5
S K 0.43 0.20 1.08 SO3
Cl K 0.07 0.03 0.00
O 72.56 66.86
Overall 100.00
Ultraviolet-visible spectroscopy
2.?
Э.5
2'-""-"' I.« , ZOO
Wavelength, nrr
100 ä? 80 S 60 I 40
I 20 t 0
200
S+R
700
Wavelength, nm
Fig. 2. Ultraviolet-visible spectroscopy of S and S+R.
S
ra ~ i«,
■liU HO biû Wavelength, rim
Fig. 3. Ultraviolet-visible spectroscopy of R, S+Fe(III) and S+R+Fe(III).
Thermal analysis. TG, DTA and DDTA curves of the adsorbent (S) and its modified form (S+R) before and after adsorption were investigated.
TG/DTA curves show 4 thermal decomposition steps for each compound. For S greatest mass loss 44.24% is observed at temperature range 353-4220C with DTG peak at 390.50C. Greatest mass loss 39.93% for S+R is observed at temperature range 346.5-415.90C with DTG peak at 387.50C. After metal ion adsorption greatest mass loss 32.6% for S+Fe(III) is at 507.5-653.70C with DTG peak 558.30C For S+R+Fe(III) - 33.1% at 475-647.90C with DTG peak 547.6. Detailed data are given in Tables 3, 4 below.
Table 3. Thermogravimetric parameters of adsorbent (S)
Based on the results of thermal analysis, it's possible to say that the depths of S and S+Fe(III) peaks in endothermic processes differ little. Therefore, we can conclude that adsorption process proceeds not due to the formation of a chemical bond between functional groups, but due to adsorption on the surface of the adTime of reaching of sorption equilibrium. The influence of contact time on the removal of Fe(III) ions from its salt solutions by
sorbent. Thus, Fe(III) ions are located in the pores of sorbents.
Table 4. Thermogravimetric parameters of (S+Fe(III)) and (S+R+Fe(III))_
Compound Temperature range, °C Weight loss, % DTG peak
49.8-250.6 15.56 83.8
S+Fe(III) 217.6
351.9-409.2 15.11 376
507.5-653.7 32.6 558.3
35.9-262.7 16,49 214.4
S+R+Fe(III) 341.3-410 26.23 378.9
475-647.9 33.17 547.6
Effect of pH on the Fe (III) removal efficiency. The pH effect on adsorption of S and S+R ions of Fe(III) was studied by the following technique: 50 mg of modified adsorbent was weighed on analytical scales and added to 50 ml flask, 2 ml of ferric ions and 18 ml of correspondent pH were added to flask. To determine the pH effect on the Fe(III) ions, it was varied from 1 to 5. The mixture was kept for 24 h. After that the absorbance was measured. It was found that the sorption degree of metal ions strongly depends on pH. The results have shown that the maximum sorption of Fe(III) ions is observed at pH 5.0.
As it s seen adsorption of Fe(III) increased with increasing pH. At pH lower values, adsorption of Fe(III) is decreased due to the fact that some amine groups are protonated to NH3+ form, i.e. the number of binding sites available for adsorption is reduced. At pH higher values, 5.0 adsorption increases. considered sorbent. Contact time was varied from 0 to 240 min. Samples were obtained from solutions at set times and concentrations of
and its modified form (S+R)
Compound Temperature range, 0C Weight loss, % DTG peak
59.4-242 16.59 85.1
S 212.3
353-422 44.24 390.5
548.9-710.4 27.5 647
S+R 40.2-241.7 346.5-415.9 554.5-695.1 18.58 39.93 29.87 215.4 387.5 621.2
metal ions in the samples were determined using absorption spectrophotometry at 490 nm, pH 5. Concentrations of Fe(III) ions in solution were determined using a calibration curve. As we see adsorption degree gradually increased at the beginning and after approximately 2 hours became constant. So, investigations have shown that adsorption of Fe(III) ions by synthesized adsorbents reaches its maximum level after 120 minutes for S and 180 minutes for S+R.
Effect of initial concentration of Fe (III) ions on adsorbent's sorption capacity.
The influence of initial concentration of Fe(III) ions on adsorption capacity of used sorbents was studied. The process was carried out in the range of concentration between 0.2-10" 3 molL-1 and 10 10"3 molL-1 at pH 5. For that purpose, 50 mg of sorbent was weighed, the correspondent concentrations of metal ion solution and pH 5 were added into flasks and left for 24 h. Investigation have shown that the maximum adsorption is observed when the metal ion concentration is 0.610"3 molL-1 for S and 8.010"3 molL-1 for S+R. Adsorption capacity gradually increases and reaches its maximum value, after that it starts to fall.
As we can see compared to S (445.02 mg-g"1) in case of modified product adsorption capacity increases almost two times and is equal to 890.68 mg-g"1. Such a big increasing of adsorption capacity in case of S+R is because of large number of functional groups in composition after modification with the 4,4'-(ethane-1,2-diylbis(azanylylidene))bis(pentane-2-one).
The obtained results of maximum adsorption capacities were compared with the data
given in the references. Adsorption capacities of different materials are shown in Table 5.
Results are illustrated in Figure 4.
It shows that compared to most given adsorbent the current work has some privileges in values of qmax.
Desorption process. Present study includes investigation of desorption of Fe(III) ions by S and S+R. Considered process was carried out by using different mineral acids (HNO3, HClO4, HCl and H2SO4) with their concentration of 0.5 molL-1. Investigations have shown that 0.5 mol L"1 solution of HNO3 both for S and S+R has the highest effect on Fe(III) desorption.
Adsorption isotherms. Several adsorption models were studied to explain the equilibrium relationship between adsorbent and adsorbate and to determine the maximum adsorption capacity of adsorbent with relation to investigated metal ions. Adsorption isotherms were obtained by varying the initial concentration of Fe(III) ions from 0.210"3 mol L-1 to 8.010"3 mol L-1. In this article several isotherms have been studied, namely Langmuir, Freundlich and Dubinin-Radushkevich models [23].
Langmuir isotherm. Langmuir isotherm is the simplest model for monolayer adsorption. This model is based on the assumption that molecules are adsorbed at a fixed adsorption site.
Langmuir model can be described using the following equation [25]:
qmKLCe
qe = T+lLCe (3)
<J
m
Q.
m
•2 £ ■M
.
-a <
1000 800 600 400 200 0
0,002 0,004 0,006 0,008 0,01 Concentration, mol/L
0,012
Fig. 4. Effect of concentration on adsorption capacity.
Table 5. Comparison of adsorption capacities of different adsorbents for the adsorption of Fe(III) ions
Adsorbent Maximum adsorption capacity (qmax, mg-g-1) Reference
Hen eggshell 18.8 Rotliwala, Chevli and Maheshvari (2017)
Olive cake 58.47 Zaid Ahmed Al-Anber and Mohammad Al-Anber (2008)
Acanthaceaeactivatedcarbon 503 Hussain, Mohammed, Nallu2 and Arivoli(2012)
Chitin 3778 Karthikeyan, Muthulakshmi and Anbalagan (2005)
Extracellular polymericsubstances (EPS) 536.1±26.6 Tapia, Muñoz, González, Bláz-quez and Ballester (2011)
Husk of Cicerarientinum 72.16 Ahalya, Kanamadi and Rama-chandra (2006)
Malein-anhydride styrene copolymer+N,N -diphenylguanidine (S) 404.88 Present Work
Malein-anhydride styrene copolymer+N,N -diphenylguanidine (S)+4,4'-(ethane-1,2-diylbis(azanylylidene))bis(pentane-2-one) 890.68 Present Work
Where Ce (mmolL-1) is concentration of adsorbate in the aqueous phase at equilibrium, qe (mmolg-1) is the equilibrium adsorption capacity, qm is equal to qe for the complete monolayer and KL (Lmmol-1) is the Langmuir isotherm constant.
Linear plot of dependence of 1/qe versus 1/Ce is built. The values of the qmax and KL were calculated from the slope and the intercept of the plot, respectively.
The essential characteristic of the Lang-muir isotherm can be represented by a separation factor called equilibrium parameter (RL) and has the following form:
1
RL = T+bc0 (4)
where b is the Langmuir constant (Lmmol-1), C0 is the initial concentration of adsorbate (mmolL-1). The value RL indicates the isotherm type. A value between 0 and 1 shows favorable adsorption process.
Results show that RL lies between 0 and 1 and is equal to 0.7 for (S) and 0.99 for (S+R), which shows that adsorption is favorable under the specified experimental conditions by Langmuir model. Also the value of the coefficient of regression R2=0.911 for (S) and R2=0.596 for (S+R) indicates that isotherm model fits good with experimental adsorption data.
Freundlich isotherm. The Freundlich isotherm model involves heterogeneous surface adsorption sites that have different adsorption
energies. The Freundlich model is described by the following equation [26]:
i
lnqe = lnKF + ~lnCe (5)
where Ce (mmolL-1) is adsorbate concentration at equilibrium, qe (mmolg-1) is the equilibrium adsorption capacity, KF is the Freundlich constant and 1/n the heterogeneity factor.
The lnqe versus lnCe graph has been built. The values of KF and 1/n were calculated from the graph and intercept of the graph, respectively.
KF indicates capacity of adsorption process (mg/g), n provides an approximation of adsorption intensity. A favourable adsorption is estimated when n is 1-10. The results show that the value of n is almost equal to 1, which indicates a favorable adsorption process. On the other hand, 1/n is considered as a function of adsorption strength. If value of 1/n is lower than 1 it means a normal adsorption, if 1/n>1 it shows a cooperative adsorption. In our case, 1/n= 1.026, which indicates a cooperative adsorption process.
Dubinin-Raduskhevich isotherm. The Dubinin-Radushkevich (D-R) model is used to explain adsorbent's porosity. The isotherm is obtained on the basis of the following equation [27]:
lnqe = lnqs - kD-R£2
(6)
where qs is the theoretical saturation capacity (mmolg-1), kD-R is the D-R isotherm constant related to the free energy of adsorption, and £ is
Polanyi potential that is related to the equilibrium concentration as follows:
s = RTln (1 +
K)
(7)
where R (8.314 Jmol-1K-1) is the gas constant and T (300 K) is the absolute temperature.
Adsorption energy was calculated y the following equation:
* (8)
E =
V2KD-
Linear plots of lnqe versus s2 are built. The values of qs and kD-R are calculated from the intercept and slope. The value of R2 is equal to 0.521. E is equal to 7.142 kJ mol-1. If E is between 8 and 16 kJ mol-1 then it indicates a chemi-sorptions process, while the value of E lower than 8 kJ mol- means a physical adsorption process. Thus, in our case 7.142 kJ mol-1 value of E means that a physical adsorption process is observed between S+R and Fe(m).
The results of adsorption isotherm studies are shown in Table 6.
Adsorption kinetics. The kinetic studies were also carried out by using batch adsorption experiments. For each experiment 50 mg of S and S+R was used. All experiment was performed with 10-2 molL-1 initial concentration of metal ion solution, at 300 K and optimal pH 5.0. The effect of contact time was studied by measuring adsorption of metal ions by using adsorbent S at various times (30, 60, 90, 120, 150, 180, 210 and 240 min).
Sorption kinetics might be useful for describing the mechanism of adsorption process. In this work we studied several kinetic models, including pseudo-first-order and pseudo-second-order.
Pseudo-first-order model. The adsorption kinetic data in this model is rated using pseudofirst-order equation (Lagergren's equation). It
helps to evaluate the adsorption degree by adsorption capacity. The equation is as follows:
ln(qe - qt) = lnqe - kit (9)
where qeand qt are adsorption capacities at equilibrium and time t (min), respectively (mgg-1) and k1 is the rate constant of pseudofirst-order adsorption (min-1). The ln(qe — qt) versus t graph is built. Values of k1 and qe were calculated from slope and intercept of the ln (qe — qt) versus t graph. The large difference between the experimental value of qe and the calculated qe(exp) shows that the pseudo-first order kinetic model is a poor fit for the adsorption process of sorbent S for Fe(III).
Pseudo-second-order model. Adsorption kinetics can also be explained by using pseudo-second-order model. For that purpose, the following equation is used
t 1 1
- = T—2+ — t (1°)
Rt K2le Re
where fc2is the rate constant of pseudo-second-
-1 -1
order adsorption (g mg min ) and kq2 is the initial adsorption rate (mg g-1min-1). The
versus t plot is built.
Values of k2 and qe were evaluated from the intercept and slope of the versus t plot.
For pseudo-second order kinetic model we can see that the experiment qe value qe (exp) and the calculated qe value qe(cal) are close to each other. Thus, the adsorption process of synthesized sorbent S and modified one S+R for Fe(III) can be well described by the pseudo-second order kinetic model.
The results of kinetic studies are shown in Table 7.
Table 6. Langmuir, Freundlich, and Dubinin-Raduskhkevic isotherm parameters for the adsorption of Fe(III) ions by adsorbents S and S+R
Adsorbent Langmuir Freudlich Dubinin-Raduskhkevich
1 ^ 4 'M & a j § & (m (1/n) & 's» cq & I k <N £ — o o (mo &
S 2.77 0.3 0.76 0.911 0.176 0.789 0.877 5.65 2.8 0.4x10-5 0.738
S+R 32.25 0.004 0.99 0.596 0.008 1.026 0.497 8.47 7.142 1x10-8 0.521
Table 7. Adsorption kinetic parameters
Pseudo-first-order Pseudo-second-order
qe, (exp), mg-g-1 k1, (min-1) qe (cal), mg-g-1 (R2) k2, (gmg-1min-1) qe (cal), mg-g-1 (R2)
S 182.216 0.008 1.72 0.982 0.125 200 1
S+R 87.120 0.027 1.35 0.958 0.0023 76.92 0.991
Conclusion
The present study have shown that the modification of adsorbent with reagent leads to increasing of adsorption capacity by at least two times, so that efficiency of extraction of Fe(III) ions by the corresponding product also increases. Thus, we may continue investigations in this field and modify adsorbent with other reagents. Comparison of maximum adsorption capacities qmax of different adsorbents for removal of Fe(III) ions shows that adsorbents used in present work have higher adsorption capacities 890.68 mg-g-1. These factors allow to say that synthesized products can be considered as effective materials for Fe(III) ions extraction of Fe(III) ions.
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Fe(III) iONLARININ MODÍFÍKASÍYA OLUNMU§ ADSORBENTLO ADSORBSÍYASI: ADSORBSÍYA
ÍZOTERMLORÍ
E.C.Eyyubova, X.C.Nagiyev, S.E.Mammadov, e.A.Matm, F.M.^iraqov
Hazirki i§ malein anhidrid stirol sopolimeri (MAST) va N^-dfenilquanidin (S) asasinda yeni növ adsorbentin sintezina va onun 4,4'-(etan-1,2-diylbis(azanililiden))bis(pentan-2-on) (S+R) ila modifikasiyasina hasr edilmi§dir. Bu adsorbentla Fe (III) ionlannm adsoibsiya tadqiqi apanlmi§dir. Mahsulun adsorbsiya qabiliyyatina pH dayarinin, tamas vaxtinin, ion qüvvasinin va ilkin metal ionlannm qatiliginin tasiri öyranilmi§dir. Tadqiqatlar zamani bir nega adsorbsiya izotermlari va kinetik modellar tadqiq edilmi§ va malum olmu§dur ki, tarazliq malumatlan psevdoikinci daracali modella yax§i uygunla§ir va psevdoikinci daracali model adsorbsiya prosesini tasvir eda bilar. Naticalar Lengmür adsorbsiya izoterm modelina an uygun galir. Tadqiqatlar göstardi ki, adsorbsiya qabiliyyati 404.88 mq/q-a barabar olan ilkin mahsul (S) ila müqayisada reagentila modifikasiya edilmi§ adsorbent (S+R)Fe(III) ionlanna qar§i (890.68 mq/q)daha yüksak adsorbsiya qabiliyyatina malikdir. Sintez edilmi§ adsorbent Enerji Dispersiv Rentgen Spektroskopiyasi (EDS) va Ultrabanöv§ayi Görünan Spektroskopiya (Uv/Vis) ila Skanedici Elektron Mikroskopiyasi (SEM) ila xarakteriza edilmi§dir. Adsorbentin temperatur sabitliyi termal analiz üsullan (TG, DTA, DDTA) ila tadqiq edilmi§dir.
Agar sözlzr: Fe (III), Adsorbsiya, Skanedici Elektron Mikroskopiya (SEM), Enerji Dispersiv Rengten Spektroskopiyasi (EDS), Ultraba növ§3yi Görünan Spektroskopiya (UB/Gör).
АДСОРБЦИЯ ИОНОВ Fe(III) НА МОДИФИЦИРОВАННОМ АДСОРБЕНТЕ: ИЗОТЕРМЫ АДСОРБЦИИ
Э.Дж.Эюбова, Х.Дж.Нагиев, С.Э.Мамедов, А.А.Матин, Ф.М.Чырагов
Настоящая работа посвящена синтезу нового типа адсорбента на основе сополимера малеинового ангидрида и стирола (ССМА) и ^№-дифенилгуанидина (S) и его модификации 4,4'-(этан-1,2-диилбис(азанилиден))бис-(пентан-2-он) (S+R). Проведено исследование адсорбции ионов Fe(III) этим адсорбентом. Исследовано влияние значения рН, времени контакта, ионной силы и исходной концентрации ионов металлов на адсорбционную способность продукта. В ходе исследований было изучено несколько изотерм адсорбции и кинетических моделей, и было установлено, что равновесные данные хорошо согласуются с моделью псевдо-второго порядка, и модель псевдо-второго порядка может описывать процесс адсорбции. Результаты лучше всего соответствуют модели изотермы адсорбции Ленгмюра. Исследования показали, что по сравнению с исходным продуктом (S), для которого адсорбционная емкость равнялась 404.88 мг/г, модифицированный реагентом адсорбент (S+R) проявляет более высокую адсорбционную емкость к ионам Fe(III), равную 890.68 мг/г. Синтезированный адсорбент был охарактеризован с помощью сканирующей электронной микроскопии (СЭМ) с энергодисперсионной рентгеновской спектроскопией (ЭДС) и ультрафиолетовой-видимой спектроскопии (УФ/Вид). Температурная стабильность адсорбента исследована методами термического анализа (ТГ, ДТА, ДДТА).
Ключевые слова: Fe (III), адсорбция, сканирующая электронная микроскопия (СЭМ), энергодисперсионная рентгеновская спектроскопия (ЭДС), спектроскопия в ультрафиолетовом и видимом диапазонах (УВ/Вид).
