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CHEMICAL PROBLEMS 2021 no. 4 (19) ISSN 2221-8688
203
UOT 541.64:543.544
REMOVAL OF RHODAMINE 6G DYE FROM WATER SOLUTION BY ALT-MALEIC ANHYDRIDE-STYRENE COPOLYMER, CROSS-LINKED WITH HEXAMETHYLENEDIAMINE
O.H. Akperov, F.M. Kamranzadeh, E.O. Akperov
Baku State University, Z. Khalilov., 23, AZ1148 Baku, Azerbaijan , e-mail: [email protected]
Received 28.10.2021 Accepted 10.12.2021
Abstract: The article provides data on the use of crosslinked with hexamethylenediamine alt-maleic anhydride-styrene copolymer, as a sorbent for the remove of the Rhodamine 6G dye from aqueous solution. The effect of the pH, sorbent amount, contact time, temperature and dye concentration on sorption was studied. The obtained data were processed in the coordinates of the Langmuir, Freundlich and D-R models equations and the values of the equilibrium sorption capacity and mean sorption energy were determined. The found value of the mean sorption energy from D-R equation Ed=4.556<8.0 kJ mot1, indicated that the sorption of Rh6G by synthesizedpolymer-sorbent has physical character. Also, thermodynamic parameters, like standard Gibbs free energy (AG°), standart enthalpy change (AH°) and standart entropy change (AS°) were determined. The positive values of AG° confirm the nonspontaneous of adsorption process, and the positive value of AH° (12.464 kJ mol-1) suggested that the adsorption was endothermic in nature. The positive value of AS° (0.0271 kJ mot1 K-1) shows the increasing randomness during adsorption process. Keywords: adsorption, cross-linked polymer, hexamethylenediamine, ishoterms, rhodamine 6G DOI: 10.32737/2221-8688-2021-4-203-214
1. Introduction
The physical, chemical and biological methods applied for removal of dyes from aqueous solutions include coagulation, flocculation, biological oxidation, solvent extraction, chemical precipitation, reverse osmosis, ion exchange, filtration and membrane process. Among these methods, the adsorption method is widespread in which complex process equipment is not required and is relatively easy to perform. [1]. The removal of Rhodamine 6G from aqueous solutions was achieved by adsorption using poly (fumaric acid-co-acrylic acid) as adsorbent surface [2]. Several variables that affect the adsorption were studied, including adsorbent dosage, contact time, pH, temperature and ionic strength. The equilibrium adsorption data were analyzed using Langmuir, Freundlich and Temkin models. The results indicate that hydrogel has a strong capability of removing Rhodamine 6G dye directly from aqueous solutions.
Sulfonated poly (styrene-alt-maleic
anhydride) microspheres were prepared from poly (styrene-alt-maleic anhydride) by sulfonation reaction and its adsorption behavior as an efficient adsorbent for the removal of organic dyes was systematically studied [3]. Results indicated that the adsorbent had more adsorption ability for cationic dyes as compared to poly (styrene-alt-maleic anhydride). The cross-linking poly (N-vinyl caprolactam-co-maleic acid) microparticles used in the adsorption of Rhodamine 6G from aqueous solution [4]. The effect of different parameters such as initial pH, adsorbent dose, temperature, initial dye concentration, and contact time on their dye adsorption capacity was studied using the batch-adsorption technique. The equilibrium adsorption data were better fitted with Langmuir isotherm, model. The maximum adsorption capacities at pH = 10 was found 2012 mg/g for Rhodamine 6G. The experimental data were well described by the pseudo-second order model. The spent ground coffee powder was
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CHEMICAL PROBLEMS 2021 no. 4 (19)
used as an effective adsorbent to remove Rhodamine dyes from aqueous solutions and the adsorption kinetics and isotherm behaviors were studied and compared [5]. The effects of temperature, ionic strength, solution volume and the co-existing anions on the sorption behavior were also investigated. The results showed that the adsorption capacity increased as the sorbent dosage and contact time increased; however, there was no changes observed due to the increase in temperature. The Rh 6G adsorption kinetics followed pseudo-second order model and the equilibrium data were found to fit Freundlich model. Magnetic biochar-sorbent was prepared using Fe3O4 nanoparticle composites onto the surface of biochar derived from rice husk, and the removal of Rhodamine 6G dye by magnetic biochar was studied [6]. Kinetic, isotherms and thermodynamic studies were carried out to investigate the adsorption mechanism of Rhodamine 6G dye on magnetic biochar surface. Rhodamine 6G removal efficiency of Fe3O4-composited biochar proved higher than that of pristine biochar with maximum efficiency of 94% removal. The adsorption isotherm and kinetic studies indicated that the Langmuir model, pseudo-first order and pseudo-second order models described well the Rhodamine adsorption onto magnetic Fe3O4-biochar. Batch sorption
experiments were carried out for the removal of Rhodamine 6G from aqueous solution using Palm Shell Powder as adsorbent [7]. The operating variables studied were adsorbent mass, solution pH, contact time and initial dye concentration. In order to investigate the mechanism of sorption, adsorption data were modeled using the pseudo-first-order and pseudo-second order equations. It was found that the adsorption kinetics followed a pseudosecond order model. Equilibrium isotherm was analyzed using the Langmuir and the Freundlich isotherms. The parameters for each model have been determined. The exhaustive capacity was 105.0 mg g-1 for Rh6G at 25 °C. The negative value of free energy change indicated the spontaneous nature of adsorption.
The current work provides results on removal of Rhodamine 6G dye from aqueous solutions using the cross-linked with hexamethylenediamine alt-maleic anhydride-styrene copolymer (HMSC) as an adsorbent. The effects of pH, sorbent dosage, contact time, temperature and initial dye concentration on the sorption degree were investigated. The equilibrium adsorption data were analyzed using Langmuir and Dubinin-Radushkevich models. Besides, kinetic and thermodynamic parameters of the adsorption process were determined and possible sorption mechanism suggested.
2. Experimental part
2.1. Materials and Methods
Maleic anhydride (MA) was recrystallized from benzene, styrene (St) -distilled (temp.144-1450C),
azobisisisobutyronitrile (AIBN)-crystallized
Its molecular weight is 479.02 g mol-1, UV-absorption maximum is at 524 nm (Aldrich). UV-vis spectra were measured on a UV-vis SPECORD 210 PLUS (Germany) in the range of 190-800 nm. SEM measurements were
from ethanol. The structure of cationic dye Rhodamine 6G-chlor dye with empirical composition C28H31CIN2O3, is as follows:
carried out by a model JEOL JSM-7600F (Japan) scanning electron microscope and pH was measured by the pH- meter pH-420 Akvilon (Romania).
2.2. Sorbent preparation
Preparation of the HMSC was carried out in two stages: synthesis of the alternating maleic anhydride-styrene copolymer (alt-MASt) and cross-linking of the copolymer with hexamethylenediamine (HMDA). The alt-MA-
St was synthesized according to the known procedure [8] by radical polymerization of MA and St in benzene at 800C in the presense AiBN as an initiator. Polymerization is followed by formation of donor-acceptor complex
^/i-MA-St was cross-linked with HMDA according to the following procedure: 2.0 g copolymer is mixed with 4.0 g HMDA at 600C for 2 hours. After the obtaining solid mass is washed with distilled water and acetone, and
dried at 400C in a vacuum oven. The structure and composition of the cross-linked a/i-MA-St which used as a sorbent to remove the Rh 6G dye from water solution, is follows:
2.3. Adsorption Experiments
A stock solution dye with concentration 500 mg L-1 was prepared in double-distilled water and the experimental solutions with the desired concentration were obtained by dilutions stock solution. Experiments to study the adsorption of the Rh 6G dye with a synthesized sorbent were
carried out according to the procedure, described in the works previously published by us [9,10]. The sorption degree Rh 6G dye (%) and sorption capacity (mg g-1) of the sorbent were calculated by the equations (1) and (2), respectively.
(C - C )
Sorption degree (%) = —-- x 100% (1)
C 0
Sorption capacity (mq q-1) = C)xVso! (2)
Co and Ce (mg L-1) are initial and equilibrium solution subjected to sorption, and mSorb (g) is concentrations of Rh 6G, respectively the weight of sorbent. Respectively, Vsol (L) is the volume of the dye
msorb
3. Results and discussion
3.1. Effect of pH
The effect of pH on the Rh6G dye sorption degree was investigated at an initial dye concentration 75 mg L--1, sorbent weight of 3.0 g L--1, sorption time of 30 min and temperature of 200 C. Under these conditions, the pH of the solution changed in the range 3-9. The results show that in a strongly acidic medium (pH=3) the sorption degree is low (7.4%). For cationic dyes, the lower adsorption of the dye at strong acidic medium is likely due to the presence of excess H+ ions which compete with cationic groups of the dye at the active sites of the
adsorbent [11]. Thus, the high values of the sorption degree at above pH=3 are explained by electrostatic attraction forces between the immobilized negatively charged sorbent and the positively charged dye. It revealed that the maximum estimate of sorption degree (25.2%) is observed in pH= 6. In considering the relatively high sorption rate in pH 6, a series of subsequent experiments were performed in pH 6. likely due to the presence of an excess H+ ions.
3.2. Effect of contact time
Contact time is an important parameter, because this factor determines the sorption kinetics of a sorbate at its given initial concentration. The effect of contact time on Rh 6G sorption by sorbent was investigated at different contact time varying between 10 and 120 min at 20°C
(Table 1). These results indicated that as time increases the removal of Rh 6G increases to a certain point of equilibrium. During the first 20 min of the sorption 8.7% of the total amount of Rh 6G was immobilized.
Table 1. Effect of time on sorption degree (Rh 6G initial concentration 200 mgL-1, F=0.04L, sorbent dosage 3.0 gL-1, 20°C)
Time, min 20 30 40 60 80 100 110 120
Sorption degree, % 8.7 12.2 15.4 19.1 24.3 28.5 30.6 31.1
The state of dye equilibrium in the HMSC structure is reached after 110-120 min. At that time, 30.6-31.21% of Rh 6G were removed by
3.3. Effect of sorbent dosage
The sorbent amount for sorption is changed from 1.0 to 4.0 g L-1. The obtained results show that noticeable change of extent of sorption happens when there is rise in quantity of a sorbent up to 3.0 g to L-1. A further increase in the amount of sorbent practically not lead to a
sorbent. Therefore, the contact time equal to 110 min was considered to be sufficient for sorption of Rh 6 G by sorbent.
change in the degree of sorption. Therefore, the amount of sorbent 3.0 g L-1 was taken as the working amount and used in subsequent experiments. The experimental results of removing Rh 6G dye from sulfur depending on the amount of sorbent are shown in Table 2.
Table 2. Effect of sorbent dosage (Rh6G concentration 200 mg L-1, V=0.04 L, 20°C,110 min)
Sorbent dosage, gL-1 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Sorption degree, % 11.5 17.3 21.2 27.3 30.6 31.1 31.0
3.4. Temperature effect
The purpose of this research is to ascertain the effect of temperature on the sorption of Rh6G dye by the HMSC. The effect of temperature on the removal of Rh6G dye in aqueous solution by HMSC was studied by varying the temperature between 20 and 60° C at the initial dye concentration of 200 mg L-1, pH 6, sorbent dosage 3.0 g L-1 and contact time 110 min. The data presented in Table_3 showed that adsorption of dye by the HMSC increased
as the temperature increased. This behavior confirms that the adsorption of dye had an endothermic nature. This is because with increasing temperature, the attractive forces adsorbent surface and Rh6G are weakened and the sorption decreases. The results of the temperature dependence of sorption are used to determine the thermodynamic parameters of the sorption process.
Table 3 . Effect of temperature on sorption degree (initial Rh 6G concentration 200 mg L 1,
sorbent dosage 3,0 g L-1 ,V=0.04 L, 110 min.
Temperature, °C 20 30 40 50 60 Sorption degree, % 30.6 36.3 40.0 43.7 45.1
3.5. Effect of the Rh6G initial concentration
Experimental results relating to the change in of the dye layer Rh 6G from 75 mg L to 220 mg sorption rate and sorbent content at retardation L-1 are shown in Table 4.
Table 4. Effect of dye concentration on sorption degree and sorption capacity (sorbent dosage 3.0 g
L-1, 110 min, 20°C, V=0.04L)
Initial concentration, mg L-1 75 100 125 150 175 200 220 Sorption degree, % 44.5 42.4 38.0 34.9 32.0 30.6 29.5
Sorption capasity, mg g-1 11.12 14.13 15.83 17.45 18.67 20.4 21.6
The results showed that the Rh 6G sorption onto sorbent were strongly affected by the initial dye concentration and as the initial Rh6G concentration increases, sorption degree decreases. The Rh 6G removal degree decreases from 44.5 to 29.5% when its initial concentration increases from 75 to 220 mg L-1. It is explained as being due to the fact that as dye concentration increased, the specific sites of a sorbent were saturated and exchange sites filled. Equilibrium sorption capacity of the sorbent was calculated in the initial Rh 6G
concentration range 75-220 mg L-1 at 20°C and for 110 min contact time. It revealed that the sorption capacity of the sorbent increased rapidly as the equilibrium concentration of Rh 6G increased. When the Rh6G concentration the constant value. It can be concluded that the experimentally maximum sorption capacity (qexp) of the sorbent at the equilibrium conditions is 20.4-21.6 mg g-1. The results obtained from the dependence of the sorption degree and the sorption capacity from initial concentration of the dye were developed in the
coordinates of the Langimur and Dubinin- calculated the valies of sorption process. Radushkevich isotherm equations and
3.6. Langmuir and Dubinin-Radushkevich isotherms
Langmuir isotherm describes monolayer adsorption based on the assumption that all the adsorption sites have equal adsorbate affinity and that adsorption at one site does not affect adsorption at an adjacent site. The Langmuir isotherm can be described by Eq (3)
Ce / qe = 1/ (qmax Kl) + Ce / qmax (3) Where Ce-is the equilibrium concentration of Rh 6G (mg L-1), qe- is the amount of the Rh 6G adsorbed at equilibrium (mg g-1), qmax—is the monolayer maximum adsorption capacity of the MSOT (mg g-1) and KL-is the Langmuir equilibrium constant (L g-1).
The Dubinin-Radushkevich (D-R) isotherm equation, which is more generally used to distinguish between physical and chemical adsorption, is given by the Eq (4)
ln qe= -Kd £2+MBdr (4)
Where Kd - is the D-R equation constant, BDR-theoretical isotherm saturation capacity (mole g-1), qe-is the sorption capacity (mol L-1) and e - is Polanyi potential, which is defined
by Eq (5)
e =RTln (1+1/Ce) (5)
Where Ce -is equilibrium concentration of the Rh6G (mot1), R- is universal gas constant (8.314 J mol1). The D-R constant can give the valuable information regarding the mean energy (E) of adsorption by the Eq (6)
E= 1 / (2 Kd) 1 (6)
The obtained experimental equilibrium data were examined with Langmuir and D-R isotherm models. The plot equations of the Langmuir and D-R equations are given in Fig.3 and Fig.4, respectively. The Langmuir and D-R isotherm parameters were calculated from the slope intercept of the plots and shown in Table 5. The calculated value of the maximum experimental sorption capacity from the Langmuir equation, (Fig.3) is equal to be 31.15 mg g-1, which are close to experimentally obtained value of equilibrium sorption capacity from sorption isotherm (21.6 mg g-1)
Fig. 3. Langmuir plot for sorption (pH 6, 30 min, Co= 75 - 220 mgL-1, V=0.04 L, sorbent dosage 3.0 gL-\ 20oC).
Fig. 4. D-R plot for sorption (pH 6, 110 min, Co= 75- 220 mg L-1, V=0.04 L, sorbent dosage 3.0 gL-1, 20oC).
Table 5. Langmuir and D-R equations parameters
Langmuir equation D-R equation
qmax, mg g-1 Kl, L mg- 1 Rl R2 Kd , kCmo/ - 1 Bdr, mo/ g-1 E, kCmo/-1 R2 31.15 0.0132 0.503-0.256 0.9927 0.024 0.08318 (39.84mq q-1) 4.556 0.9899
Obtained data shows the applicability of the Langmuir model indicating the formation of monolayer coverage of the dye molecules at the surface of the adsorbent. The essential feature of the Langmuir isotherm to identify the feasibility and favorability of the adsorption process can be expressed by a dimensionless constant called separation factor (Rl). The separation factor Rl was calculated using the Eq (7)
Rl = 1/ (1 +Kl Co) (7)
Where Co-is the initial Rh6G concentration (mg L-1). If 1>Rl>0, adsorption is favorable while Rl>1 represent unfavorable adsorption, and Rl = 1 represent linear adsorption while the
3.7. Sorption kinetics
Kinetic studies were carried out under optimized conditions from 10 to 100 min. The kinetic data obtained were fitted to linear form of Lagergren pseudo-first and pseudo-second order kinetic models [14]. The pseudo-first order kinetic model known as Eq (8)
/og (qe- qx) = /ogqe - 0.434K1T (8) Where qt and qe-are the amounts of dye adsorbed at time rand at equilibrium (mg g-1), respectively, and K1-is the rate constant of pseudo-first order adsorption process (min-1). The pseudo-second order kinetic model is expressed by the Eq (9)
t q = 1/( K2 qe2) + T/qe (9)
Where qt and qe-are the amounts of Rh6G sorbed at time t and at equilibrium (mo/ g-1), respectively, K2-is the pseudo-second order equilibrium rate constant (mo/e-1 min-1). Plots
adsorption process is irreversible if Rl = 0 [12]. The calculated values of Rl for different initial concentration of the Rh6G (75-220 mg L-1) were equal to be 0.503- 0.256 to indicate highly favorable adsorption for the Rh6G onto HMSC.
The found value of the mean sorption energy from D-R equation Ed=4.556<8.0 kJ mo/-1 indicated that sorption of Rh6G by synthesized polymer-sorbent has physical character [13]. The theoretical isotherm saturation capacity of the sorbent (Bdr) from DR equation is equal to be 0.08318mmo/ g-1 (39.84 mg g-1).
of the equation of the pseudo-first and pseudosecond models are illustrated in Fig.5 and Fig.6, respectively.
Calculated parameters are placed in Table 6. Obtained data shows that the sorption process of the Rh6G from aqueous solutions with HMSC is better described by the pseudosecond kinetic model with determination coefficient 0.9907. Due to the fact that the correlation coefficient for the pseudo-second reaction is higher, it can be recognized that the sorption process occurs according to a pseudosecond reacting order. It should be noted that the value calculated for sorption capacity (38.2 mg g-1) from the pseudo-second order reaction graph is consistent with values obtained from the Langimur (31.15 mg g-1) and D-R (39.84 mg g-1) isotherms.
Fig. 5. Plot pseudo-first order model (Co = 200 mg L-1, pH=6, sorbent dosage 3.0 mgL-1, V= 0.04 L, 20°C).
Fig.6. Plot of pseudo-second order model (Co = 200 mg L-1, pH=6, sorbent dosage 3.0 mgL-1, V= 0.04 L, 20oC).
Table 6. Regression parameters for kinetic models
Kinetic model Pseudo-first order Pseudo-second order
Parameters qe,mgg-1 K1,min x R2 qe,mgg-1 K2, L g-1min-1 R2 41.50 0.0417 0. 9768 38.2 0.0006 0.9907
3.8. Adsorption thermodynamics
Thermodynamic parameters, like standard Gibbs free energy (AG°), standard enthalpy change (AH°) and standard entropy changes (ASwere determined in order to explain the
effect of temperature on the adsorption of Rh 6G by HMSC. These parameters can be calculated from the Eq's (10-12)
AGo = - 2,3 RT logKd (10) Kd = qe/Ce (11)
AG° = AHo - T ASo (12)
Where R-is the gas constant (8.314 J mole-1 K-1), T-is absolute temperature, Kd, - is equilibrium constant at the temperature T. The values of AH° and AS° were obtained from the slope and intercept of the plots of AGo versus T (Fig.8) and are placed in Table 7. The positive values of AG° confirm the nonspontaneous of
adsorption process, and the positive value of AH° (12.464 kJ mot1) suggested that the adsorption is endothermic in nature. The positive value of AS° (0.0271 kJ mol-1 K-1) shows the increasing randomness during adsorption process.
340
Fig. 8. Plot of AG° versus T (pH 6, 110 min, Co= 200 mg L-1, V=0.04 L, sorbent dosage 3.0 g L-1)
Table 7. Sorption thermodynamic parameters
Temperature, TK Thermodynamic parameters
AGo,k J mol-1 AH°,k J mol-1 ASo, k J mol-1K-1
293 +4.664
303 +4.184
313 +3.917 + 12.464 +0.0271
323 +3.628
333 +3.584
JOOO <000 ""ft GOOD 7QOO GOOD 90QQ 10000
Fig. 9. UV-vis spectra of the HMSC a) before and b) after sorption.
3.9. Adsorption mechanism
The assumption of the possible adsorption mechanism has been made on the basis of the UV-spectra of the sorbent before and after adsorption and on the mean sorption energy, calculated from the D-R isotherm. UV-spectra of the HMSC before and after sorption have been illustrated in Fig.9.
Fig. 9 shows that the UV-spectra of the sorbent before and after sorption are different. In the UV- spectra of the sorbent after sorption (Fig.9b) there new absorption maximum
appears which is not observed in the spectra of the sorbent before sorption (Fig.9a). The maximum 544 nm in the UV-vis spectra of the sorbent after adsorption corresponds to Rh 6G dye which is adsorbed onto surface of the sorbent.
The obtained data for mean energy E=4.256 kJ mol-1<8.0 kJ mol-1 from the D-R isotherm also indicated that the sorption of Rh 6G by synthesized polymer sorbent has physical character.
Fig. 10. SEM image of sorbent after sorption (x19.000)
The SEM image in figure 10 shows that, the sorbent surface is not homogeneous after sorption. This is most likely due to the sorption
of the dye on the sorbent surface during the sorption process (the light areas correspond to the Rh 6G dye on the sorbent surface).
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УДАЛЕНИЕ КРАСИТЕЛЯ РОДАМИНА 6G ИЗ ВОДНОГО РАСТВОРА С АЛЬТ-СОПОЛИМЕРОМ МАЛЕИНОВЫЙ АНГИДРИД-СТИРОЛ, СШИТОГО С ГЕКСАМЕТИЛЕНДИАМИНОМ
О.Г. Акперов, Ф.М. Камранзаде, Е.О. Акперов
Бакинский государственный университет AZ1148, Баку, ул. З.Халилова, 23; e-mail: [email protected]
В статье представлены результаты по использованию альт-сополимера малеиновый ангидрид-стирол, сшитого гексаметилендиамином, в качестве сорбента для удаления красителя Родамина 6G из водного раствора. Было изучено влияние рН раствора, количества сорбента, времени контакта, концентрации красителя и температуры на степень сорбции красителя и равновесной сорбционной емкости сорбента. Полученные экспериментальные данные были обработаны в координатах уравнений изотермы Ленгмюра, Фрейндлиха и Дубинина-Радушкевича и определены аналитические параметры сорбции. Из графика уравнения Ленгмюра было определено значение сорбционной емкости (31.95 мг г-1). Рассчитанное значение энергии адсорбции из графика уравнения D-R составляет 4.556 кДж моль-1, что указывает на физическую природу сорбции красителя из водного раствора синтезированным сорбентом. Определены некоторые кинетические и термодинамические параметры процесса сорбции. Сорбция описывается псевдовторым порядком взаимодействия, положительные значения изменения энтальпии ДН°(12,464 кДж моль-1) указывают на эндотермический характер сорбции, а положительное значение изменения энтропии ДSo (0.0271кДж моль-1 K-1) доказывает об увеличении хаотичности при адсорбции. Ключевые слова: адсорбция, сополимер, изотермы, гексаметилендиамин, Родамин 6G
heksametIlendIamInlö t!k1lm1§ alt-maleIn anhIdrId!- stIrol bIrgö
POLlMERl !L3 RODAMlN 6G BOYAQ MADD3S1n1N SULU M3HLULDAN SORBSlYASI
O.H. 3kbarov, F.M. Kamranzada, E.O. 3kbarov
Baki Dövldt Universiteti, Baki Z. Xslilov, 23, AZ1148 Baki, e-mail: [email protected]
Maqalada Rodamin 6G boyaq maddasinin sulu mahluldan ^ixarilmasi ü?ün heksametilendiaminla tikilmi§ alt-malein anhidridi-stirol birga polimerindan istifada olunmasina aid naticalar verilmi§dirr. Sorbsiya daracasina pH-in, kontakt müddatinin, sorbentin miqdarinm, temperaturun va boyaq maddasinin ilkin qatiliginin tasiri öyranilmi§dir. Alinan tacrübi naticalar Langimür, Freyndlix va Dubinin-Radu^kevi? izoterm tanliklarinin koordinatlarinda i§lanilmi§, tarazliq sorbsiya tutumunun qiymati 31.95 mq q-1 alinmi§dir. D-R tanliyinin qrafikindan adsorbsiya enerjisi ü?ün hesablanmi§ qiymat £D=4.556<8.0 kC mol-1-dur, bu isa Rodamin-6G boyaq maddasinin sintez olunmu§ sorbentla sulu mahluldan sorbsiyasinin fiziki xarakterli oldugunu göstarir. Sorbsiyanin standart Gibbs enerjisi (AG°), entalpiya dayi§masi (AH°) va entropiya dayi§masinin (AS°) qiymatlari tayin olunmu§dur. AH°-in müsbat qiymati (12.464 kC mol1) va AG°-nin müsbat qiymatlari isa adsorbsiyanin spontan getmadiyini va endotermik xarakterli oldugunu göstarir. ASo-in müsbat qiymati (0.0271 kC mol 1 K -1) isa adsorbsiyanin gedi§inda xaotikliyin artdigini sübut edir. A^ar sözlar: Adsorbsiya, birga polimer, izotermlar, heksametilendiamin, Rodamin 6G
