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CHEMICAL PROBLEMS 2018 no.3 (16) ISSN 2221-8688
323
UDC 541.64:546.791:547.56
PURIFICATION OF WATER FROM URANYL-IONS BY NEW SORBENT OF
CARBOXYLATE TYPE
aA.M. Maharramov, aM.R. Bairamov, a G.M. Askarova, bJ.A. Naghiyev, aM.A. Agayeva, aSh.J. Guliyeva, a G.M. Hasanova
aBaku State University Z.Xalilov str., 23, Baku AZ1148, Azerbaijan Republic; e-mail: [email protected] bNational Nuclear Research Centre of Azerbaijan Inshaatchilar ave. 4, Baku, AZ 1073
Received 02.05.2018
The hydrolyzed ternary copolymer of styrene, maleic anhydride and 1,3-bis(2-propenylphenoxy)-propane was studied as sorbent for extraction of uranyl-ions out of aqueous systems. The influence of pH medium, concentration of uranyl-ions, quantity of sorbent, duration of sorption and other factors on main indices of the sorption process was analyzed. The analysis of isotherms of sorption of uranyl-ions was performed through the use of Langmuir and Freundlich 's equations. The possibility of using the copolymer both in concentrated and diluted solutions established. Keywords: cross-linked copolymers, isotherms of sorption, regeneration, sorption, uranyl-ions
INTRODUCTION
As is known, the development of effective methods of purification of aqueous systems from ions of heavy metals, radionuclides and other harmful substances is one of the priority directions of the chemical science [1-3].
In spite of the fact that recently there have been proposed the various sorption methods of purification from above-mentioned toxicants, an emphasis is laid on making new materials with high functional properties, especially as regards sorbents of complex-forming type which can be easily regenerated and reused [4].
Radionuclides in aqueous solutions are usually in the hydrolyzed form which largely accounts for their behavior in the sorption processes, ion exchange, extraction, etc. In the
compounds, the uranium shows a valence state (from 2 to 6). However, in the aqueous
medium, U(VI) is the most stable in the form
2+
of UO2 -ions to create mononuclear and polynuclear hydroxocomplexes [5].
The works [6] revealed that for effective
2+
binding of UO22+-ions from aqueous solutions it'd be appropriate to use the synthetic sorbent-hydrolized cross-linked copolymer of styrene, maleic anhydride and 1,3-bis-(2-isopropenylphenoxy)-butane developed by us.
The paper deals with the synthesis of cross-linked copolymer of styrene, maleic anhydride and 1,3-bis-(2-propenylphenoxy) propane to examine them as sorbent for purification of aqueous solutions from uranyl salts.
EXPERIMENTAL PART
The radical ternary copolymerization reaction of styrene, maleic anhydride and 1,3-bis-(2-propenylphenoxy)-propane (at their ratio 1:2:0,2 mol) was analyzed with a view of preparing a new sorbent with cross-linked structure. The last one was synthesized
(Williamson reaction) through the interaction of 2-propenylphenol with 1,3-dibromopropane (in the presence of alcohol solution of KOH and promoter KY). The copolymerization was carried out in a medium of solvating solvent (200% of dioxane). As a template there was
used a linear copolymer of styrene with maleic anhydride (4% per taken reagents).
The copolymerization process was carried out in the presence of initiator -dinitrile of azoizobutyric acid (1% per mixture of monomers), at temperature 80°C during 10 hours.
In the end of template synthesis aimed at separating a pore agent (linear copolymer of styrene with maleic anhydride) from cross-
linked copolymer, it was extracted (at the Soxhlet apparatus) first by acetone, then by toluene. The cross-linked copolymers were dried up at temperature 40-50°C for 2 hours in the vacuum box with yield ~95% (thereof).
The last ones were further treated by hot water for 2 hours with the aim of opening anhydride rings and preparing a sorbent with carboxyl groups in their structure:
—CH-CHj-
-HC—CH— I I HOOC COOH
—' x-
HC
o—(CHj)3—O
z
y
To reveal the possibility of use of last one as sorbent for extraction of uranium compounds, comprehensive laboratory explorations in static conditions were carried on model systems consisting of solutions with sertain concentration of uranyl sulfate in distilled water. To regulate pH medium, ammonia acetate solutions through mixing corresponding volumes of 0,1M CH3COOH with 0,1M NH3 were used. Also, fixanal HCl was used.
An estimation of sorption properties was
238
carried out by determination of isotope U activity in aqueous phase (before and after sorption) by y-spectrometer HPGe with germanium detector (made in USA).
The influence of UO22-ions concentration of pH, quantity of sorbent, endurance time and other parameters on
degree of their sorption (R, %) and sorption capacity of sorbent (SCS, mg/g) was analyzed.
Note that respective experiments were carried out as follows: some quantities of copolymer and aqueous solution of uranyl-sulfate of a given concentration are loaded into a teflon cup with capacity of 100 ml. Then, 10 ml of 0.1M buffer solution was added to the mixture and its volume brought to 50 ml (a dilution with distilled water). The system is kept at a room temperature for some time,
after which in the aqueous solution it is
2+
determined a content of UO2 ions. Based on the obtained data R and SCS are calculated. The equilibrium of sorption of uranyl ions on the synthesized sorbent was examined at 293 K under static conditions. The equilibrium concentration of the uranyl ion have also been determined by y-spectrometer.
RESULTS AND DISCUSSION
Table 1 shows the results of research into the influence of pH medium on R and SCS (duration of endurance - 24 hours, quantity of sorbent - 20 mg). The
2+
concentration of UO2 -ions in the initial solutions in these series made up 236 mg/l and the activity - 235U Bq/l.
Table 1. Influence of pH of aqueous solution on R and SCS values
pH of solution Activity of isotope 235 U after sorption, Bq/l Concentration of UO22+ -ions in solution after sorption, mg/l R, % SCS, mg/g
1.0 120 236.0 0 0
2.0 109 214.4 9.2 54.1
3.0 104 204.5 13.3 79.7
3.85 89 175.0 25.8 152.4
4.8 65 127.8 45.8 270.4
5.7 31 61.4 74.0 236.6
6.2 30 57.2 75.8 436.9
8.0 32 62.9 73.3 432.7
9.0 92 181.5 23.1 136.2
10 120 236.0 0 0
11 115 226.2 4.2 24.6
12 120 236.0 0 0
13 117 230.1 2.5 14.8
14 118 232.1 1.7 9.8
In an effort to find the possibility of using the copolymer for UO22+-ions concentration from diluted solutions, we have carried out further experiments where initial concentrations alternated in a wider range (2.4
According to Table 2, the copolymer has high sorption properties in relation to UO22+-ions both in concentrated and diluted aqueous
mg/l to 778.8 mg/l). These studies were also carried out under static conditions at a room temperature and an optimum value of pH ~ 6. Duration of sorption was 24 hours. The obtained results are presented in Table 2.
2+
solutions. A degree of extraction of UO2 -ions from concentrated solution (with content ~ 190 mg/l UO22+-ions) is 92.4% where SCS is
2+
Table 2. Influence of UO2 -ions in the solution on R and SCS
Activity of isotope 235U , Bq/l Conc. of UO22+ -ions in water, mg/l R,% SCS, mg/g
before sorption after sorption before sorption after sorption
1.2 0.11 2.4 0.2 90.8 2.7
2.4 0.19 4.7 0.4 92.1 5.4
3.6 0.44 7.1 0.9 87.8 7.8
14.4 1.13 28.3 2.2 92.2 32.6
28.28 2.9 56.6 5.7 89.9 63.7
43.2 4.2 85.0 8.3 90.3 95.9
86.4 6.8 189.9 13.0 92.4 196.2
120.0 12.1 236.0 23.8 90.0 265.3
180.0 45.5 354.0 88.7 74.9 331.6
216.0 62.6 424.8 123.1 71.0 377.1
252.0 79.6 495.6 156.1 68.4 423.8
288.0 100.1 566.4 196.9 65.2 461.9
324.0 136.2 637.2 256.9 58.3 464.1
360.0 166.3 708.0 327.1 53.8 476.2
396.0 199.5 778.8 392.4 49.6 483.1
196.2 mg/g. Further increase of the ions To calculate the sorption constants, the
concentration in the initial solution makes up well-known Freundlich and Langmuir
to 236 mg/l and R to 90%, and SCS - to 265.3 equations were used.
mg/g. When used strongly concentrated An estimation of the distribution of
solutions (content 708.0 and 778.8 mg/l uranyl-ions on heterogeneous sorption surfaces
UO22+-ions), R value averages to ~50%. can be described by empirical Freundlich
equation
qe= KF + Q (1)
where KF - Freundlich constant characterizing the adsorption capacity n - surface heterogeneity index; 0< n < 1
In n ^ 1 a heterogeneity decreases and in n = 1, the Freundlich equation passes over to linear isotherm.
Table 3 presents the calculated and n constants were revealed from the parameters of the Freundlich sorption. The KF linearized form of the equation
1
logfk = logtfp + - logCe
n
where Ce - concentration of uranyl ions in the solution after sorption qe- quantity of uranyl ions relating to sorbent, mg/g n - sorbent heterogeneity index
KF - sorption capacity constant determined experimentally
Table 3. Parameters of Freundlich sorption
Activity 235U before sorption, A0, Bq/l Activity 235U after sorption, A, Bq/l Concentration of uranyl-ions before sorption, C0, mg/l Concentration of uranyl-ions after sorption, Ce, mg/l log Ce SCS, Qe, mq/l log qe
1.2 0.11 2.4 0.2 0 2.7 0.081
2.4 0.19 4.7 0.4 0 5.4 0.069
3.6 0.44 7.1 0.9 0 7.8 0.111
14.4 1.13 28.3 2.2 0.347 32.6 0.068
28.8 2.9 56.6 5.7 0.756 63.7 0.090
43.2 4.2 85.0 8.3 0.917 95.9 0.086
86.4 6.6 169.9 13.0 1.113 196.2 0.066
120.0 12.1 236.0 23.8 1.377 265.3 0.090
180.0 45.1 354.0 88.7 1.948 331.6 0.267
216.0 62.6 424.8 123.1 2.090 377.1 0.326
252.0 79.6 495.6 156.5 2.195 423.8 0.369
288.0 100.1 566.4 196.9 2.294 461.9 0.426
324.0 135.2 637.2 265.9 2.425 464.1 0.573
360.0 166.3 708.0 327.1 2.515 476.2 0.687
396.0 199.5 778.8 392.4 2.594 483.1 0.812
log q,
■0,665 -0,428 -0,063 0,347 0,756 0,917 1,113 1,377 log C,
Fig. 1. Freundlich isotherm
To characterize the sorption process of built. The sorption isotherm constants were uranyl-ions, the Langmuir isotherm was also calculated by the following equations:
C = A_ + a^Ce a = Qmax aLCe
qe Kl KL . ^ 1 + aLCe
?
Ce - concentration of uranyl-ions in the solution after sorption, mg/l qe - quantity of connected sorbent of uranium, mg/g KL - sorption constant l/g
aL - constant characterizing the sorption energy l/mg Qmax - maximum sorption capacity of the sorbent, mg/g
The same Table presents the Freundlich isotherm constant. The Langmuir isotherm is shown in Fig. 2.
Fig. 2. Langmuir isotherm
An intercept at the intersection of a 1
straight line with ordinate axis corresponds to Rl = T~7C~
1 / KL. 1 + 0
According to the formula: Where b - Langmuir constant
Co - initial concentration of uranyl-ions in the solution, mg/l; were calculated RLof Langmuir isotherm.
It should be noted that if this constant will take the values in the range 0<RL <1, the
The data of Table 4 shows that the sorption process can be considered as profitable (RL = 0,047); maximum value of SCS (483.1 mg/g) = Co is reached at 778.8 mg/l.
To find the possibility of reusing the
As is seen from Table, when using
diluted solutions of hydrochloric acid, a degree
2+
of desorption of UO2 -ions doesn't exceed 24,2%.
When using an acid in the concentration
sorption process can be considered as profitable, at RL>1 - unprofitable and in RL = 0 - irreversible). The Freundlich and Lanqmuir isotherm constants are shown in Table 4.
copolymer, the experiments on its regeneration through the use of hydrochloric acid of various concentrations were carried out. The process proceeded at room temperature under static conditions for 24 hours. The results of these experiments are presented in Table 5.
(from 0.1 to 0.3 M), a degree of desorption of
uranyl-ions is 72.5 and 87.2%, respectively. A
2+
maximum degree of desorption of UO2 -ions (~ 97%) is attained when using an acid of 1M concentration.
Table 4. Freundlich and Lanqmuir isotherm constants
Sorbent Freundlich isotherm constants Lanqmuir isotherm constants
n Kf R2 Kl, aL, Rl Qmax,
l/g l/mg mq/g
Carboxylate containing copolymer 1.0026 12.31 0.989 13.61 0.0259 0.047 483.1
2+
Table 5. Results of desorption of UO2 -ions with hydrochloric acid (HCl)
Acid concentration, M Activity of isotope 235 U in aqueous solution, Bk/l Concentration UO2 -ions in aqueous solution (after desorption), mg/l Degree of sorption, %
0 1.25 2.46 1.2
0.00051 10.9 21.4 9.2
0.00075 19.5 38.35 16.5
0.003 28.5 56.25 24.2
0.005 39.5 77.68 33.5
0.001 56.7 111.41 48.0
0.05 75.4 148.29 63.9
0.1 85.6 168.35 72.5
0.3 102.9 202.37 87.2
0.75 110.2 216.73 93.4
1.5 114.4 225.0 96.9
2.0 112.4 221.05 95.3
CONCLUSION
Thus, the results of the analysis make it possible to recommend the cross-linked copolymer obtained by radical copolyme-rization of styrene, maleic anhydride
and new cross-linking comonomer-1,3-bis-(propenylphenoxy)-propane as sorbent for effective purification of aqueous solutions from uranium salts.
REFERENCES
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2. Maharramov A.M., Bairamov M.R., Agayeva M.A. et al. Akenylphenols: preparation, transformation and applications. Russian Chemical Reviews. 2015, vol. 84, no. 11, pp. 1258-1278
3. Maharramov A.M., Bairamov M.R., Garibov A.A. et al. The analysis of nitro-containing cross-linked copo-lymers of maleic anhydride and styrene as chelating sorbents for extracting uranyl-ions from water systems. Journal of Environmental Analytical Chemistry. 2017, vol.4, issue 3, pp. 14. Doi :10.41722380-2391.1000205
4. Perlova O.V., Sazanova V.F., Perlova N.A. and Yaroshenko N.A. Kinetics of Sorption of Uranium(VI) Compounds
with Zirconium-Silica Nanosorbents. Russian Journal of Physical Chemistry A. 2014, vol. 88, no. 6, pp. 1012-1019. DOI: 10.1134/S0036024414060223.
5. Magerramov A.M., Bairamov M.R., Garibov A.A. Investigation of the terpolymer of maleic anhydride, styrene and 1,4-di (4-isopropenyl-
phenoxy) butane as a sorbent for
2+
extraction of UO2 ions from aqueous systems. Zhurnal Prikladnoi Khimii -The Russian Journal of Applied Chemistry. 2011, vol. 84, no. 1, pp. 151-155.
6. Magerramov A.M., Bairamov M.R., Allahverdieva M.G. Investigation of sulphocathionite based on styrene copolymer and 1,4-di (4-isopropenylphenoxy) butane as a sorbent for the recovery of uranyl ions from aqueous solutions. Azerbaijan Technical University. Scientific proceedings. Fundamental sciences. 2010, vol. IX(35), no. 3, pp. 110-112.
ОЧИСТКА ВОДЫ ОТ УРАНИЛ-ИОНОВ С ПОМОЩЬЮ НОВОГО СОРБЕНТА КАРБОКСИЛАТНОГО ТИПА
аА.М. Магеррамов, аГ.М. Аскарова, аМ.Р. Байрамов, ьДж.А. Нагиев, аМ.А. Агаева, аШ.Дж. Гулиева, аГ.М. Гасанова
Бакинский государственный университет AZ1148 Баку, ул. З.Халилова, 23; e-mail: [email protected] Национальный центр ядерных исследований AZ1073, Баку, пр. Иншаатчылар, 4
Гидролизованный тройной сополимер стирола, малеинового ангидрида и 1,3-бис-(пропенилфенокси)пропана исследован в качестве сорбента для извлечения уранил-ионов из водных систем. Изучено влияние рН среды, концентрации уранил-ионов, количества сорбента, продолжительности сорбции и др. факторов на основные показатели
процесса сорбции. С применением уравнений Ленгмюра и Фрейндлиха проведен анализ изотерм сорбции уранил-ионов. Установлена возможность использования сополимера как в концентрированных, так и разбавленных растворах.
Ключевые слова: сшитые полимеры, изотермы собции, уранил-ионы, регенерация
SULUSiSTEMLЭRiN URANiL-iONLARDAN YEMKARBOШLAT TiPLiSORBENT
VASiTдSi П.д TдMiZLдNMдSi
аА.М. Ыэкэггэшог, "М.Я. Баугашог, а G.M. дsgэrova , ьС.'.Л. Naglyev, аМЛ. Agayeva, а§.С. Quliyeva, а О.М. Hэsэnova
С1ВаЬ Dдvlэt Universiteti АХ 1148 ВаЫ, Х.ХэНО Ыд., 23; e-ma.il: [email protected] ЬЫПМ N^9 Tдdqiqatlarl Mдrkдzi АХ 1073, ВаЫ, íщaatgllat рг., 4
8иЫ sistemlэrmdэn игапИ-юпШгтт tэmizlэnmэsi идип ЫёгоШ оЫптщ stirol, та1ет апЫёпЛ, 1,3-Ьis-(propenilfenoksi)propan эsasmda аШтц идШ sopolimerindэn sorЬent kimi istifadэ оЫпти^иг. Sorbsiya prosesinin эsas gдstэricilэrmэ muhitin pH-i, итпИ-юпаппт qatlllgl, sorbentin miqdarl, sorbsiya vaxtl vэ s. faktorlarm tэsiri дугэпИт^м. Lenqmиr vэ Егеу^Их tэnliylэrmdэn istifadэ edэrэk итпИ-юЫаппт sorbsiya izotermlэrinm tэhШi арагйт1^1г. Sopolimerin qatl vэ duru mэhlullarda istifadэsmm mumkunluyu tдsdiq edilmцdir. Адаг sдzlэr: ЫИИ polimer, sorЬsiya, жaml-юnlan, sorbsiya izotermlэri, regenerasiya
