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CHEMICAL PROBLEMS 2023 no. 1 (21) ISSN 2221-8688
85
UDC 547.3
SYNTHESIS OF CARBOXYLATE TYPE SORBENT BASED ON COOLIGOMERS OF 2-PROPENYLPHENOL AND FORMALDEHYDE AND STUDY OF THEIR FUNCTIONAL PROPERTIES FOR SORPTION OF URANYL IONS IN MODEL SYSTEMS
M.R. Bayramov, A.M. Maharramov, G.M. Mehdiyeva, Sh.J. Guliyeva, M.A. Aghayeva
Baku State Universitety Z. Xalilov str., 23, Baku AZ1148 e-mail: guliyevashahla@hotmail.com
Received 10.10.2022 Accepted 17.12.2022
Abstract: Alkaline synthesis of double co-oligomers of 2-propenylphenol and formaldehyde (synthons) was carried out at 92-950C, for 3 hours and ratio of 1:2.5 mol (their yield are 93% of theory)Interaction of maleic anhydride with the obtained olygomers at 800C in the presence of 0.5% benzoyl peroxide for 10 hours produced copolymers of a three-dimensional cross-linked structure (with a yield of 90%). By treating them with hot water, a sorbent was obtained to contain both propenyl and carboxylate fragments in the structure -active centers of chemisorption. The functional sorption properties of the copolymer were studied under static conditions, in model water systems. The influence of the pH of the medium, the concentration of uranyl ions and the exposure time on the degree of their sorption at room temperature were studied and it was found that the best results are achieved at pH 6 and for 24 hours (R=93%). Uranyl ions can be easily desorbed with mineral acid and the crosslinked copolymers can be reused. Keywords : formaldehyde, 2-propenylphenol, oligomers, uranyl ions, sorption, desorption DOI: 10.32737/2221-8688-2023-1-85-92
Introduction
The development of effective sorption methods for the purification of water systems from heavy metals, radionuclides, and other environmentally hazardous substances is one of the priority areas of chemical science [1-4]. Sorption methods based on the use of cross-linked polymeric materials with various active adsorption sites, such as amino, sulfo, carboxy, and other groups, occupy an important place among them [5]. They can be used alone or in combination with inorganic modifiers to isolate and even concentrate trace amounts of ions from environmental objects, which is often impossible when using other purification methods.
While developing new sorption polymeric materials, the main attention is paid to the availability of used monomers, solvents, and other excipients, as well as the simplicity of the technology for implementing their synthesis processes. In this regard, syntheses using
various alkenylbenzenes, maleic anhydride, acrylonitrile, formaldehyde, and other available compounds attract the greatest attention of researchers [6,7].
The work [8] describes the synthesis of phenol-formaldehyde co-oligomers based on phenol and formaldehyde, which are further used to obtain a cross-linked material. First, the interaction of o-benzoyl-benzoic acid chloride with phenol in the presence of a ZnCl2 catalyst synthesizes 3-phenyl-3(4)-hydroxyphenyl) phthalide which is then introduced into the polycondensation reaction with formaldehyde in the presence of catalytic amounts of ammonia at their various ratios (from 5:95 to 40:60% wt). In this case, phenol-formaldehyde co-oligomers of the resole type are formed, which are used as raw materials for the synthesis of heat-resistant cross-linked copolymers.
Composite polymeric material intended for the adsorption of uranyl ions from natural
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CHEMICAL PROBLEMS 2023 no. 1 (21)
and waste waters, as indicated in [9], can be synthesized by graft copolymerization of polyacrylamide and chalkocarboxylic acid.
Our studies have previously shown [10] that effective sorbents for the extraction of uranyl ions from aqueous systems are cross-linked copolymers based on alkenyl-substituted phenols, formaldehyde, and maleic anhydride.
This article presents the results of the synthesis of cross-linked copolymers containing phenol hydroxyl, propenyl and carboxylate
fragments in the structures; results of the study of their functional sorption properties with respect to uranyl ions from model aqueous systems under static conditions (depending on the pH of the medium, the concentration of uranyl ions, time, and other factors) on sorption capacity of the sorbent (SCS) and, finally, the degree of their extraction (R, %).
The synthesis of cross-linked copolymers was carried out according to the scheme below:
Experimental part
During the work we used:
- 2 propenylphenol, obtained by a known method [11], Tmelt 36.5-370C
- formalin (37% formaldehyde aqueous solution)
- maleic anhydride - reactive, recrystallized from a benzene solution, Tmelt 540C.
a) Synthesis of double co-oligomers of 2-propenylphenol and formaldehyde
To three-necked flask equipped with a thermometer, a stirrer, and a reflux condenser 13.4 g (0.1 mol) of 2-propenylphenol and 0.2 g (0.005 mol) of NaOH dissolved in 10 ml of water were added. The mixture was heated to 40-450C, then 20.8 ml of formalin was added to the mixture, and co-oligomerization was carried
out with stirring for 3 hours at a temperature of 92-950C. Upon completion of the process, the mass was washed several times with warm distilled water and dried under vacuum. The yield of double co-oligomers is ~19.4 g (93% of theory). They are solids with grey color, highly soluble in acetone, cyclohexanone, ethanol. M.p. 110-1150C.
The structures of double co-oligomers and obtained cross-linked copolymers were confirmed by IR spectroscopy data. The IR-spectrs on a Varian 3600 FI-IR spectrophotometer (Bruker, Germany). The absorption bands at 647, 723, 754, 802, 883 cm-1 belong to the bending vibrations of aromatic CH bonds characteristic of the aromatic ring of
2-propenylphenol, the absorption bands at 1146, 1212 cm-1 refer to the bending and stretching vibrations of C-0 -groups, absorption bands at 1372 cm1 - to bending vibrations of C-H bonds at CH2 and CH3, bands at 2875, 2925, 2962, 3332 cm-1 - to stretching vibrations of the OH group.
To determine the molecular weight of the synthesized co-oligomers and MWD fractions, laboratory studies were carried out on a Kovo gel chromatograph (Czech Republic) equipped with a refractometric detector and two columns
filled with Separon SQX adsorbent (particle size 7 p,m, diameter 100A). The process of separating cooligomers into fractions was carried out at a temperature of 250C.
Separate fractions were eluted with a polar solvent (dimethylformamide). Its feed rate to the column was 0.3 ml/min. In the work, polyethylene glycol was used as a standard. For the determined molecular weight, a plot of lgM versus uR was plotted. Calculations were proceeded from the equation [12]:
Ci C2 v = 1 2
lg M
1/ w
M = S Mw. M =
w S I I n
S Mi
where Mw is the average molecular weight;
Mn - number average molecular weight;
Mi - molecular weight corresponding to the i-th area;
wi - is the mass fraction of the i-th part.
b) Structuring of double co-oligomers of 2-propenylphenol and formaldehyde with maleic anhydride
The process of structuring (crosslinking) of co-oligomers with maleic anhydride was carried out in glass ampoules in the presence of benzoyl peroxide initiator. Calculated amounts of cooligomers, maleic anhydride, and benzoyl peroxide were loaded into the preliminarily prepared ampoules. The ampoules were cooled with dry ice, evacuated and sealed in a stream of nitrogen, then were transferred to an ultrathermostat (at a temperature of 80°C), where they were kept for 5-6 h.
Upon completion of the structuring process, the crosslinked copolymers were separated from the soluble ones in a Soxhlet apparatus by treatment with boiling benzene.
c) Hydrolysis of the synthesized cross-linked copolymers with water
The crosslinked copolymers were treated with hot distilled water for 2 hours in order to open the anhydride groups and obtain structures containing succinic acid fragments.
The structure of the obtained carboxylate type crosslinked copolymer material was confirmed by IR spectroscopy data. The structure of the resulting carboxylate type crosslinked copolymer was confirmed by IR spectroscopy data. The absorption bands at 753, 815, 883 cm-1 refer to bending vibrations of aromatic CH bonds characteristic of the aromatic ring of 2-propenylphenol, the absorption bands at 1147, 1206 cm-1 refer to bending and stretching vibrations of the C-0 group, absorption at 1376, 1463 cm-1 - to bending vibrations of C-H bonds at CH2 and CH3, bands at 1650, 1714 cm-1 - to stretching vibrations of the C=O group, bands at 2928, 2964, 3388 cm-1 to the stretching vibrations of the OH group.
d) Method for determining the sorption properties of cross-linked copolymers (with respect to uranyl ions)
To reveal the possibility of using the synthesized cross-linked copolymers as a sorbent for the extraction of uranyl ions from model aqueous systems, a HPGe y-spectrometer
(with a germanium detector, manufactured by Canberra, USA) was used.
To assess the effectiveness of their action,
the content of 238U and 235U isotopes in an aqueous solution (before and after sorption) was measured under specified conditions [13]:
Where Au235 and Au238 is the activity of radionuclides 235U and 238U, respectively, ^u235 and
'"i ... 235 238
AU238 are the half-lives of radionuclides U and U, respectively, NA is the Avogadro number,
"rj "jj" m m 235 238 • j^JJ j^JJ
m 235 and m 238 are the masses of radionuclides U and U respectively, M -v' and A-z 238 are the
235 238 •
atomic masses of radionuclides U and U, respectively, '< - u - are the half-lives of
23 5 23 8
radionuclides U and U respectively.
ZZZ 1000 mg/g [14]
C0 - concentration of uranyl ions in solution before sorption, mg/L
C - concentration of uranyl ions in solution after sorption, mg/L
R - is the degree of sorption, %
msorb - is the mass of the taken sorbent; mg
mpogl is the mass of the extracted substance; mg
SCS - is the sorption capacity of the sorbent, mg/g
Results and its discussion
The results of gel chromatographic studies showed that synthesized by us the double co-oligomers of 2-propenylphenol and formaldehyde are comparatively low molecular weight compounds. The average molecular weights of Mw and Mn are respectively 5580 and 1440 ( Mw / Mn 3.87 ) According to MWD, ~65% falls on the relatively high molecular weight (Mw 7040, Mn 5050, Mw / Mn 1.57), low molecular weight part is ~ 35% (Mw 760, Mn 580, Mw / Mn 1.31). This can obviously be explained by the effect of phenolic hydroxyl on the termination of growing cooligomeric chains during the synthesis of double cooligomers of 2-propenylphenol and formaldehyde.
The structures of the obtained cooligomers contain reactive propenyl groups, which can easily participate in the reaction of radical copolymerization with maleic anhydride in the presence of various initiators, in particular benzoyl peroxide (through the intermediate formation of a donor-acceptor complex with charge transfer). Apparently, the reaction of
graft copolymerization occurs first, and three-dimensional structures are formed at the late stages of transformations. As is known, the density of the network is dependent not only upon the structure of the initial co-oligomers (synthons), but also on the nature of the cross-linking comonomer, in particular, maleic anhydride, and, finally, on the structuring conditions. They have high thermal properties, as evidenced by the results of DTA and TG analyses.
Table 1 shows the results of studies into the influence of the pH of the medium of the initial concentration of uranyl ions and the duration of the process, the degree of their extraction (R,%) from the model aqueous system, as well as the static capacity (CEC) of the used crosslinked copolymer. It found that a high degree of sorption (93%) with an initial concentration of uranyl ions of 155.2 mg/l is achieved at pH 6, time 24 h. SCS is 240.7 mg/g. A further increase in pH to 7-8 leads to a decrease in the degree of sorption of uranyl ions
to an average of ~75%, while the SCS is ~195.0 results of these studies showed that pH 6 can be mg/g. With a further increase in pH to 10-13, a considered the best conditions for the extraction sharp decrease in sorption occurs. Thus, the of uranyl ions from an aqueous solution.
Table 1. Effect of medium pH and uranyl ion concentration on R and SCS (initial uranyl ion
concentration 155.2 mg/l)
pH Concentration of uranyl ions in water solution after sorption, mg\L Sorption degree of uranyl ion (R,%) SCS , mg/g
1 143.1 7.8 20.2
2 120.9 22.1 57.2
3 88.1 43.2 111.8
4 54.6 64.8 167.7
5 20.7 86.7 224.2
6 10.8 93.0 240.7
7 36.6 76.4 197.7
8 38.9 74.9 193.8
9 91.2 41.2 106.7
10 101.3 34.7 89.8
11 116.4 25.0 64.7
12 109.7 29.3 75.8
13 135.4 12.8 33.0
14 115.6 25.5 66.0
The results of these studies showed that slightly acidic environment (pH 6 ). the effective degree of recovery is achieved in a
Table 2. Influence of duration on the process of sorption of uranyl ions (pH 6, initial concentration
of uranyl ions 155.2 mg/L)
Time, hours Concentration of uranyl ions in water solution after sorption, mg\L Sorption degree of uranyl ion (R,%) SCS , mg/g
0.25 144.3 7.0 18.2
0.5 136.2 12.2 31.7
1 121.5 21.7 56.2
2 102.3 34.1 88.2
4 76.8 50.5 130.7
6 51.2 67.0 173.3
8 45.1 70.9 183.5
10 32.6 85.3 204.3
12 29.7 80.9 209.2
20 14.2 90.9 235.0
24 10.7 93.1 240.8
27 10.8 93.0 240.7
30 10.7 93.1 240.8
Table 3 shows the results of studies to identify the duration of the process of sorption of uranyl ions (initial concentration of 155.2 mg/L, pH 6). With a further increase in the exposure time to 27 and 30 hours, the indicators of the sorption process practically do not change.
It was established that the process of trapping uranyl ions by cross-linked copolymers was also significantly affected by the holding time. A 50% degree of their extraction is achieved in 4-5 hours. The maximum degree of extraction (more than ~93%) occurs for at a duration of 24 hours. Obviously, the process of binding uranyl ions by a carboxylate copolymer is preceded by their diffusion.
1. Ivanov V.M., Antonova E.V., Uskova E.N. Sorption concentration of copper, lead and iron on carriers modified with 8-hydroxyquinoline and its derivatives. Vestnik moskovskogo universiteta. Serija himija - Bulletin of Moscow University. Chemistry series. 2009, series 2, vol. 50, no. 3, pp. 169-180. (In Russian).
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Table 3 shows the results of studies into the influence of the concentration of uranyl ions in an aqueous solution of their extraction (R) and SCS (at pH 6, time 24 hours).
As can be seen, depending upon the initial concentration of uranyl ions, the degree of their extraction (R) varies from 63.2 to 93%. At low concentrations (38.0 and 45.6 mg/l), R does not exceed ~63-66%, the maximum value of R (93%) is achieved when using a solution containing 140.6 mg/l of uranyl ions, while SCS is 217.8 mg/g. With a further increase in their concentration to 197.4 and 260.1 mg/L, the sorption indices average 70%. Thus, the synthesized sorbent can be used both in dilute and concentrated solutions.
4. Roshchina T.M., Shonin N.K., Lagutova M.S. Adsorption of water, diethyl ether, in mixtures with grafted perfluorohexyl coatings. Journal of Physical Chemistry, 2009, vol. 83, no. 2, pp. 361-369. DOI: 10.1134/S0036024409020253
5. Basargin N.N., Kosolapova N.I. Physicochemical properties of sorbents based on aminopolystyrene and 4-amino-N-azobenzenesulfamide. Journal of Physical Chemistry. 2007, vol. 81, no. 3, pp. 532-535.
6. Basargin N.N., Oskatskaya E.R. Physical and chemical properties of polystyrene complexing p-substituted sorbents with a functional amino group. Journal of Physical Chemistry. 2006, vol. 80, no. 1, pp. 127-131.
7. Pokonova Yu.V. Carbon adsorbents and ion exchangers from petroleum asphaltene copolymer. Solid Fuel Chemistry. 2011, no. 1, pp. 42-46.
Table 3. Effect of the initial concentration of uranyl ions in aqueous solution on R and CEC (pH 6,
sorption time 24 h)
A0, Bk\L A, Bk\L C0 mg\L Ce, mg\L R,% SCS, Mr/r
22.5 7.6 38.0 12.8 66.3 42.0
27.0 9.9 45.6 16.8 63.2 48.0
44.0 8.3 74.4 14.1 81.1 100.6
83.1 5.8 140.6 9.9 93.0 217.8
116.7 34.8 197.4 58.9 70.2 230.9
153.9 45.7 260.1 77.4 70.3 304.6
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transformations and applications. Advances in Chemistry. 2015, vol. 84, no. 12, pp. 1258-1278.
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2-PROPENiLFENOL V9 FORMALDEHiD 9SASINDA KARBOKSiLAT TiPLi SORBENTiN SiNTEZi V9 MODEL SiSTEML9RD9 URANiL iONLARINA QARÇI ONUN XASS3L3RÎNiN ÖYR9NiLM9Si
M.R. Bayramov, A.M. Maharramov, G.M. Mehdiyeva, Ç.C. Quliyeva, M.A. Agayeva
Baki Dövht Universiteti, AZ-1148, Z.Xdlilov kûç. 23, Azdrbaycan, Baki e-mail: guliyevashahla@hotmail.com
Xülasa: 2-propenilfenol va formaldehidin (sintonlarin) ikiqat sooliqomerlarinin qalavi içtirakinda sintezi 92-950C temperaturda, onlarin nisbati 1:2.5 mol götürülmakla 3 saat müddatinda aparilmiçdir. Çixim ~93% taçkil edir. Malein anhidridinin sintez olunmuç sooli qomer ila 800C temperaturda 0.5% benzoil peroksid inisiatoru içtiraki ila 10 saat arzinda qarçiliqli tasiri tikili sopolimer amala gatirir. Çixim ~90% taçkil edir. Onlari qaynar su ila bir neça dafa yuyaraq, daha sonra asetonla ekstraksiya edarak, strukturunda aktiv kimyavi sorbsiya markazlari - ham propenil, ham da karboksilat fraqmentlari olan sorbent alinmiçdir. Sopolimerin sorbsiya xassalari statik çaraitda, model su sistemlarinda tadqiq edilmiçdir. Mühitin pH-i, uranil ionlarinin qatiligi va zamandan asililginin onlarin sorbsiya daracasina tasiri ôyranilmiç va müayyan edilmiçdir ki, an yaxçi natica pH 6-da va 24 saat arzinda alda edilir (R = 93%).
Uranil ionlari mineral turçu ila asanliqla desorbsiya edila bilir va tikili sopolimer takrar istifada edila bilar. Açar sözlar: formaldehid, 2-propenilfenol, oliqomerlar, uranil ionlari, sorbsiya, desorbsiya
СИНТЕЗ КАРБОКСИЛАТНОГО СОРБЕНТА НА ОСНОВЕ СООЛИГОМЕРОВ
2- ПРОПЕНИЛФЕНОЛА И ФОРМАЛЬДЕГИДА И ИССЛЕДОВАНИЕ ЕГО ФУНКЦИОНАЛЬНЫХ СВОЙСТВ ПО ОТНОШЕНИЮ К УРАНИЛ-ИОНАМ В
МОДЕЛЬНЫХ СИСТЕМАХ
М.Р. Байрамов, А.М. Магаррамов, Г.М. Мехтиева, Ш.Дж. Кулиева, М.А. Агаева
Бакинский государственный университет, AZ-1148, ул. З.Халилова, 23, г.Баку, Азербайджан e-mail: guliyevashahla@hotmail.com
Аннотация: Осуществлен щелочной синтез двойных соолигомеров 2 -пропенилфенола и формальдегида (синтонов) при соотношении 1:2.5 моль, температуре 92-950С и времени 3 час (выход 93 % от теорет). Взаимодействием малеинового ангидрида с последними при температуре 800С в присутствии 0.5% бензоилпероксида в течение 10 час получены сополимеры трехмерной сшитой структуры (с выходом 90 %). Обработкой их горячей водой получен сорбент, содержащий в структуре одновременно пропенильный и карбоксилатные фрагменты - активные центры хемосорбции. Исследованы функциональные сорбционные свойства сорбента в статических условиях в модельных водных системах. Изучено влияние pH среды, концентрации уранил-ионов и времени выдержки на степень их сорбции при комнатной температуре и выявлено, что наилучшие результаты достигаются при pH 6 и времени 24 час (R=93 %). Связанные уранил-ионы можно легко десорбировать минеральной кислотой и сшитые сополимеры повторно использовать. Ключевые слова: формальдегид, 2-пропенилфенол, соолигомеры, уранил-ионы, сорбция, десорбция
