CC BY
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ISSN 2522-1841 (Online) AZERBAIJAN CHEMICAL JOURNAL № 1 2023 155
ISSN 0005-2531 (Print)
UDC 547.556:547,241
PURIFICATION OF WATER SYSTEMS FROM URANIUM SALTS USING ACRYLONITRILE-STRUCTURED TRIPLE CO-OLIGOMERS OF 4-ISOPROPENIL-PHENOL, FORMALDEHYDE AND 4-(1-METHYL)-1-DIMETOXSI-
PHOSPHORYLETHYL)PHENOL
M.R.Bairamov, Sh.J.Guliyeva, G.M.Mehdiyeva, M.A.Agayeva
Baku State University
Received 27.07.2022 Accepted 08.09.2022
The article presents the results of three-component condensation of 4-isopropenylphenol, formaldehyde and 4-(1-methyl)-1-dimethoxsiphosphorylethyl)phenol cooligomers, their structuring with acrylonitrile. In order to include the carboxyl group in the structure of the cross-linked copolymer, hydrolysis was carried out in the presence of an aqueous solution of potassium hydroxide. The process of sorption of uranyl ions from model aqueous systems by structured (crosslinked) with acrylonitrile and their product of hydrolyze. The structure of the cross-linked copolymer was confirmed by IR spectroscopy data. It has been established that the process of sorption of uranyl ions is significantly affected by the pH of the medium. The best results in the extraction of uranyl ions by the sorbent are achieved at pH 7-8 (at room temperature, the degree of their sorption is ~89-93%, and SCS is ~229-239 mg/g). It has been established that the process is completed within 24 hours, cross-linked co-oligomers can be reused after desorption of uranyl ions by mineral acids.
Keywords: uranyl ions, sorbents, cross-linked copolymers, regeneration.
doi.org/10.32737/0005-2531-2023-1-155-161 Introduction
One of the environmentally justified ways to purify water systems from radio-nuclides, heavy metals, and other harmful substances is the use of effective sorption materials, both synthetic, cross-linked polymers, and hybrid (in combination with organic and inorganic) [1-8 ].
In recent years, new phenol-formaldehyde novalacs have been worked out that are used for the synthesis of cross-linked copolymers by the interaction of formaldehyde with mixtures of phenol, phenolphthalein (or phthal-containing monophenol) and m-cresol [9] or formaldehyde with mixtures of phenol, phenolphthalene and phthalimide-containing bis-phenols in the presence of an acid catalyst [10].
The paper [11] describes a new synthesis of phenol-formaldehyde resins that do not contain residual formaldehyde using aldehyde precursors (4-hydroxybenzaldehyde and vanillin) based on lignin.
A two-stage method was carried out for converting them into reactive bifunctional aldehyde precursors, the use of which made it possible to create resins with high thermal properties.
Reactive furfuryl-formaldehyde resins used as raw materials in the production of cross-linked materials are developed on the basis of furfuryl alcohol and formaldehyde (at different low ratios) [12].
It should be noted that in modern technologies for the purification of water systems from various pollutants, modified phenol-formaldehyde resins and compositions based on them continue to attract the attention of researchers, which is largely due to both the availability of raw materials for their production and their rather high sorption properties [13].
Various methods are used to obtain cross-linked sorption materials intended for the extraction of uranium compounds. Thus, in [14], a sorption material intended for the selec-
tive extraction of uranyl ions from the template synthesis: by introducing a template (uranyl sulfate particles) into binary systems consisting of salicylaldoxime or 4-vinyl-pyri-dine in methoxyethanol or in ternary systems consisting of salicylaldoxime and vinylpyridine in methoxyethanol, followed by their radical copolymerization with styrene and divinylben-zene.
From the cross-linked copolymers obtained in this way, uranyl ions are removed by treatment with 6M HCl, and a sorption material with a given pore size and high selectivity is obtained.
The technology of self-assembly of synthetic sorption materials, for example, ion exchangers using a template, is also described in [15].
In this case uranyl sulfate was also used as a template, which forms a complex with di-ethylallylamine in an aqueous medium. By introducing this complex into a system with styrene and divinylbenzene and carrying out the copolymerization process, a cross-linked mate-
wastewater of a power reactor was obtained by rial is synthesized, from which the introduced ions are removed by simple washing. It was found that it has high sorption properties with respect to uranyl ions in a wide pH range (11-6) [16].
This article presents the results of our studies on the use of cross-linked copolymers obtained by structuring triple co-oligomers of 4-isopropenylphenol, formaldehyde and 4-(1-methyl)-1 -dimethoxyphosphorylethyl)phenol with acrylonitrile and obtained on their basis products of hydrolize as a sorbent for extraction of uranyl ions from model water systems.
Experimental part
4-(1 -methyl)-1 -dimethoxyphosphoryl ethyl)-phenol used in policondensation process was obtained by the reaction p-izopropenylphenol with dimethylphosphite in the presence of high temperature initiator by known method at the temperature 1300C for 20 h [17]. In this case formed two izomers according to the following scheme:
Used in this work cooligomers prepared by the reaction of triple condensation of 4-isopropylpenylphenol, formaldehyde and 4-(1-methyl)-1 -dimethoxyphosphorylethyl)phenol, at their ratio 1:2:1 (mol) respectively in the pres-
ence of KOH (0.5% to the mixture). Yield was 94%. Formaldehyde was used as formalin (36% water solution of formaldehyde). Reaction scheme:
CH20
(C2H5)2P=0
(C2H5)2P=0
Structuring of the ternary cooligomer of 4-isopropylpenylphenol, formaldehyde and 4-(1-methyl)-1-dimethoxyphosphorylethyl)phenol with acrylonitrile was carried out earlier by us according to the method [18-21] in the presence of the initiator DIBN at temperature 80oC for 510 h.
The structure of prepared oligomer conformed by NMR and IR spectroscopy.
OH OH
(CH30)2
H2Ç
CH—COOH
The yield of the obtained copolymer is 90% (from theory). The structure of the hydrolysis product was confirmed by IR spectroscopy data. The signal of the carboxyl group (1712 cm-1) is detected in the hydrolysis product in comparison with the spectrum of the initial cross-linked copolymer [20].
In order to identify the functional sorption properties of cross-linked copolymers, laboratory studies of sorption in aqueous systems containing uranyl sulfate of various con-
Further, in order to include a carboxyl group in the structure of the crosslinked copol-ymer, the resulting crosslinked copolymer was treated with a calculated amount of an aqueous solution of potassium hydroxide.
In this case carried out hydrolysis of ni-trile group in the structured cooligomers.
Reaction scheme:
centrations were carried out at a temperature of 24 hours.
To adjust the pH of the aqueous solution, we used ammonium acetate solutions prepared on the basis of distilled water, 0.1 M acetic acid, and 0.1 M ammonia (in a certain ratio).
The sorption process was studied in a static mode based on a comparison of the concentration of UO22+ ions in water before and after sorption. Measurements were made using an HPGe y-spectrometer with a germanium detector (made in the USA).
The activity of the U isotope in solution (before and after sorption) was used to calculate the degree of sorption of UO2 ions, as well as the static capacity of the cross-linked copolymer (SCS).
Co-C
R = --100%
Co
m-,
SCS = — • 1000
rn.2
Co - 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, % mi - is the mass of the taken sorbent, mg m2 - is the mass of the extracted substance, mg SCS - is the sorption capacity of the sorbent, mg/g.
In order to reveal the influence of the pH of the medium on the sorption indices, experiments were carried out in a wide range of pH (from 1 to 14) at a temperature of 25 C and a time of 24 hours. The mass of the sorbent i s 30 mg, the volume of the aqueous solution used for the sorption process is 50 ml.
The results of these experiments are presented in the form of curves of the dependence of the degree of extraction of uranyl ions (R, %) and SCS (mg/g) on the pH of the medium in Figure 1.
The initial concentration of UO22+ - ions in the solution is 154.3 mg/l, the activity of the
235U isotope is 80.9 Bk/l.
Results and its discussion
As can be seen from Figure 1, the pH of the medium has a significant effect on the process of sorption of UO22+ - ions. In an acidic environment (at pH 1-5), the sorption process, one might say, practically does not proceed. At pH 4-6 sorption degree of UO2 ions approximately was 35-37%. While increasing of pH up to 9-12 sorption degree of uranyl ions was not more 40% (practically was not changed). Best results are achieved at pH 7-8. The degree of sorption in this case reaches an average of ~89-93%, SCS is ~ 229-239 mg/g.
Table 1 shows the results of studies on the effect of duration on the process of sorption of uranyl ions (at pH 7-8).
Effect of medium pH on R, % and SCS, mg/g: 1 - R, %UO2; 2 - q, mg/g UO2.
Table 1. Effect of duration on the process of sorption of uranyl ions (pH 7, initial concentration of uranyl ions 154.3 mg/l )____
Time, hour Conc. UO22+ - ions after sorption, mg/l R, % SCS , mg/g
0.25 149.3 3.2 8.3
0.5 145.6 5.6 14.5
1 115.1 25.4 65.3
2 102.9 33.3 85.7
4 88.4 42.7 109.8
6 70.1 54.6 140.3
8 56.5 63.4 163.0
10 45.8 69.7 179.2
12 35.4 77.1 198.2
24 16.9 89.0 229.0
27 16.4 89.4 229.8
30 16.8 89.1 229.2
Table 2. Effect of the concentration of uranyl ions (C0, mg/l) on the degree of sorption and SCS of the sorbent
Ao , Bk/l A, Bk/l C0 , mg/l Ce , mg/l SCS, mg/g, R , %
22.6 9.3 38.0 15.6 37.3 58.9
27.1 10.2 45.6 17.2 47.3 62.3
44.3 13.0 74.4 21.9 87.5 70.7
83.6 13.1 140.6 15.5 208.5 89.0
117.4 27.1 197.4 45.6 253.0 76.9
154.8 56.0 260.1 94.1 276.6 63.8
183.2 81.5 322.0 143.2 298.0 55.5
Table 1 shows the results of studies on the effect of duration on the process of sorption of uranyl ions (at pH 7-8).
As can be seen from the data in Table 1, within 1 hour, the degree of sorption of uranyl ions from the aqueous medium is ~25%. With an increase in the sorption time to 4 hours 43% at 8 hours 63%. The maximum binding of uranyl ions by the tested crosslinked copolymers reaches 89% at a duration of 24 hours. The SCS is 229.0 mg/g. A further increase in the holding time of the system to 27 and 30 hours, we can say that it does not have a noticeable effect on the course of the sorption process.
Obviously, the extraction of uranyl ions from an aqueous solution is carried out by their interaction with the phenolic hydroxyl and the carboxyl group. The participation of the phosphorus atom in the complex formation is also not ruled out.
It was found that using mineral acids (HCl, H2SO4). It is possible to carry out desorption of bound uranyl ions and reuse cross-linked copolymers. Thus, the results of the studies carried out allow us to conclude that it is possible to use triple co-oligomers of 4-isopro-penylphenol, formaldehyde and 4-(1-methyl)-1-dimethoxyphosphorylethyl crosslinked with ac-rylonitrile) phenol as a sorbent for purification of water systems from uranium salts.
Conclusions
1. Triple cooligomers of 4-isopropylpe-nylphenol, formaldehyde and 4-(1-me-thyl)-1 -dimethoxyphosphorylethyl)phe-nol, which structured by acrylonitrile were undergo to hydrolysis, firstly were stydied as a sorbents for extracting of uranyl ions from model water systems.
2. Influence of the pH of media, the concentration of uranyl ions, the influence of time to the sorption process were studied. It was revealed, that the maximal sorption of uranyl ions riched (up to 93%) in environment pH 7-8, for 24%.
3. Adsorbed uranyl ions by structured copolymer sorbent can be easily desorbed by mineral acids and can be used several times.
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SU SiSTEMLORiNiN URAN DUZLARINDAN 4-iZOPROPENÍLFENOL, FORMALDEHiD VO 4-(1-METÍL)-1-DÍMETOKSÍFOSFORÍLETÍL)FENOL iLO AKRÍLONÍTRiLÍN TÍKÍLÍ SOPOLiMERiNDON
íSTÍFADO EDiLMOKLO TOMÍZLONMOSÍ
M.R.Bayramov, §.C.Quliyeva, G.M.Mehdiyeva, M.A.Agayeva
Maqalada 4-izoproppenilfenol, formaldehid va 4-(1-metil)-1-dimetoksifosforiletil)fenolun ûçlû polikondenslaçmasindan ûçlû sooliqomer alinmiç va akrilonitril ila reaksiyasi aparilaraq tikili sopolimer alda edilmiçdir. Tikili sopolimerin strukturuna karboksil qrupunu daxil etmak ûçûn kalium hidroksidinin sulu mahlulunun içtiraki ila hidrolizi apanlmiçdir. Alinmiç tikili sopolimerin model sulu sistemlardan uranil ionlarinin sorbsiyasi prosesinin laboratoriya tadqiqat edilmiçdir. Alinmiç sopolimerin quruluçu IQ spektroskopiya vasitasi ila tasdiq edilmiçdir. Müayyan edilmiçdir ki, uranil ionlarinin sorbsiya prosesina mühitin pH-i ahamiyyatli daracada tasir edir. Sorbent tarafindan uranil ionlarinin çixarilmasinda an yaxçi naticalar pH 7-8-da alda edilir (otaq temperaturunda onlarin sorbsiya daracasi ~89-93%, SST isa ~229-239 mq/q-dir). Müayyan edilmiçdir ki, proses 24 saat arzinda tamamlanir, tikili sopolimer uranil ionlarinin mineral turçular tarafindan desorbsiyasindan sonra takrar istifada edila bilar.
Açar sözlzr: uranil ionlari, sorbentbr, tikili sopolimerbr, regenerasiya.
ОЧИСТКА ВОДНЫХ СИСТЕМ ОТ УРАНОВЫХ СОЛЕЙ С ПОМОЩЬЮ, СТРУКТУРИРОВАННЫХ АКРИЛОНИТРИЛОМ, ТРОЙНЫХ СООЛИГОМЕРОВ 4-ИЗОПРОПЕНИЛФЕНОЛА, ФОРМАЛЬДЕГИДА И 4-(1-МЕТИЛ)-1-ДИМЕТОКСИФОСФОРИЛЭТИЛ)ФЕНОЛА
М.Р.Байрамов, Ш.Дж.Кулиева, Г.М.Мехтиева, М.А.Агаева
В статье приводятся результаты лабораторных исследований сополимеров полученных трехкомпонентной конденсацией 4-изопропенилфенола, формальдегида и 4-(1-метил)-1-диметоксифосфорилэтил)фенола получены соолигомеры, дальнейшим структурированныем их акрилонитрилом. С целью включения карбоксильной группы в структуру сшитого сополимера, проведен гидролиз в присутствии водного раствора гидроксида калия. Изучен процесс сорбции уранил-ионов из модельных водных систем, структурированными (сшитыми) акрилонитрилом, тройными соолигомерами 4-изопропенилфенола, формальдегида и 4-(1-метил)-1-диметоксифосфорилэтил)фенола. Структура сшитых сополимеров подтверждена данными ИК-спектроскопии. Установлено, что на процесс сорбции уранил-ионов существенное влияние оказывает рН среды. Наилучшие результаты по извлечению уранил-ионов сорбентом достигаются при рН 7-8 (при этом степень их сорбции при комнатной температуре составляет ~89-93%, а CEC ~229-239 мг/г ). Установлено, что процесс завершается в течение 24 час, сшитые соолигомеры можно повторно использовать после десорбции уранил-ионов минеральными кислотоами.
Ключевые слова: уранил-ионы, сорбенты, сшитые сополимеры, регенерация.
