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ISSN 2522-1841 (Online) ISSN 0005-2531 (Print)
AZ9RBAYCAN KIMYA JURNALI № 2 2018
27
UDC 541.6; 546.284; 183,5; 620.19; 532.72
SORBENT OBTAINED ON THE BASIS OF NANOCOMPOSITE MATERIALS IN SORPTION PROCESSES A.I.Yagubov
M.Nagiyev Institute of Catalysis and Inorganic Chemistry, NAS of Azerbaijan
chemistry-bsu@rambler. ru
Received 25.12.2017
Nanocomposite materials on the basis of organic bentonite and polyvinyl pyrrolidone were produced. Characteristic properties of nanocomposite material were studied using physical methods. The use of nanocomposite materials in sorption process of heavy metal ions (Pb2+ , Mn2+) from model solutions was shown. It was established that under optimum conditions (pH«5, t=600C) this material exhibits selective sorption capacity (0.0029 and 0.003 mol/g) to these ions. The impact of amount of sorbent and sorbate on sorption process (pH=5-7) of uranium isotopes ( U, U, U) from clayish suspensions with natural clinoptilolite was established. Static sorption capacity SSC=34.5 mg/g of active clinoptilo-lite to these ions under optimum mode was detected.
Keywords: bentonite, sorption, nanocomposite, water treatment, ion exchange.
Bentonite clays modified with organic surfactants are used for variety fields of application [1-6]. The physical and chemical properties of or-gano-clays were studied. For this purpose the modern methods of analysis (IR spectroscopy, X-ray method, derivatography) were used. Modification of bentonites with organic, as well as long chain organic amines in aqueous solution was studied. It was determined that sorption capacity of bentonite minerals to ionic and nonionic dyes depends on cation-exchange capacity, concentration of amine salts, size of alkyl radical and contacting time. The parameters of structural porosity of ben-tonite mineral and its modified forms were determined by BET equation (Table 1).
Table 1. Parameters of structural porosity of natural and modified bentonites
Sorbent A mmol/g S, cm2/g V, cm3/g Reff, cm
DSB* 0.20 48.0 0.0805 0.006
DSB, modified in
aqueous medium 0.37 89.12 0.0927 0.007
DSB, modified in
organic medium 0.34 81.91 0.0844 0.004
* Dash Salakhly bentonite
In the Table 1 Am - monolayer capacity, S - size of specific surface of an adsorbent, V - total volume of an adsorbent pores, reff - effective pore radius of an adsorbent.
Substitution of inorganic cations with organic cations causes the expansion of a crystalline lattice. For this reason the possibility of transition of nonpolar organic molecules to free spaces in adsorbent appears. This condition in
amine bentonites is considered as a specific surface sum. The use of surfactants causes the formation of organophilic layer and particles in or-ganophilic layers of bentonite, which decreases the surface energy on interphase boundary and increases the distance between silicate layers. This facilitates the penetration of big molecules to inter-wrapper spaces of a bentonite. It was determined by the method of X-ray structural analysis that during modification of bentonite with organic amines the size of its pores increases from 9.6 to 17.4 A. At the exchange with inorganic cations depending on the size and charge of cation the size of a pore varies from A 9.6 to 13.5 A. The adsorption of methylene blue, rhodamine G and other cation active dyes from model solutions on hydrophibized bentonite has been studied. It was defined that sorption capacity of hydrophibized bentonite increases more than twice compared with natural bentonite. According to the results of studies on production of nanocomposites based on nano bentonite the use of bentonites in polymer nanocompo-sites has been determined and this impacts positively on their polymer properties, as well as the increase of technical parameters. The structure and properties of organo bentonite and polymer (polyethylene) material were studied using IR and X-ray diffraction methods. 3-5% of organo bentonite was added as filler to synthesize a polymer. It is shown that when comparing IR spectra of organo bentonite with polymer there were observed new adsorption bands corresponding to organo bentonite (Figure 1).
4000
3500
3000
2500 2000 Wave number, cm-1
1500
1000
500
Fig. 1. 1 - natural bentonite, 2 - organo bentonite; 3 - polymer; 4 - polymer organo bentonite obtained during the synthesis; 5 - organo bentonite polymer in benzene; 6 - organo bentonite polymer dissolved in ethyl alcohol.
4
Adsorption bands of 3259, 3110, 1717 cm-1 formed in IR spectrum are related to amine groups and acidic residues. Adsorption bands in a polymer are more intensive than adsorption bands in organo bentonites. Due to the interaction between polymer and organo bentonite filler, formed new valence waves are shown in IR spectrum. The changes in the structure (organo bentonite-polymer) by RDA were characterized and these changes were found out. Active centers (acid and basis) of samples with monocation form based on bentonites from Ali-Bayramli and Gizil Dara deposits were studied [4]. Results of the studies determined that active centers of samples are not very different from one another by nature and power. However, the nature and power of acidic centers in bentonite samples of Gizil Dara deposit are relatively higher. This difference is explained with the fact that there is a genetically related mixture with montmorillonite in bentonite of Ali-Bayramli deposit.
The structure of polymer nanocomposite, polymer polyvinylpyrrolidone (PVP) and octa-decylaminobentonite (ODAB) obtained in the laboratory was studied using X-ray analysis method.
Obtained nanocomposites were tested as sorbents during the sorption of cations and heavy metals (Pb2+, Mn2+, Co2+, Cd2+). It was determined that studied sorbents have selective sorption capacity to Pb2+, Mn2+, Co2+, Cd2+ ions (Table 2).
Table 2. Experimental results of sorption of ions of heavy metals and phenol from canal waters on natural and Na-bentonite
Dash Salakhly bentonite Sorption, mg/g
Phenol Fe 3+ Mn 2+ Cu 2+ Zn 2+
0.4 0.08 0.012 0.03 0.02
Natural 40 6.98 9.64 2.38 1.68
Na-form 50.71 8.09 11.84 1.01 1.97
The researches were discovered that sorbent based on nanocomposite material of
2+ 9+
Pb2+ and Mn2+ relative to ions has a selective sorption capacity (0.0029 and 0.003 mol/g). Optimum conditions of the process (pH~5, t=600C) worked out elaborated.
Ionic content of the river Aras and canal waters spring from this river was studied and it
was determined that these waters contain sufficient quantity of ions of the heavy metals. Sorption of ions of the heavy metals on natural and Na-bentonite was studied. Unlike natural bentonite Na-bentonite has high sorption capacity to these ions [5, 6].
The agreement for joint research works on "Study of the impact of mineral fertilizers and layered natural mineral on plants and their application in agriculture" was signed for scientific cooperation with the laboratory "Mineral fertilizers" at the Institute of Soil Science and Agro Chemistry of ANAS.
The influence of Dash Salakhly bentonite on mineral fertilizers was tested, to study gradual adsorption of "nitrogen" by plants and assimilation in soil during washing with rain waters field experiments were performed with ly-simeter under grape plants in mountain-brown soils of Shamakhy district.
The researches on the sorption of non-ionic organic dyes are continued. Na-mono-cation forms of bentonite from Agdara and Gizil Dara deposits were obtained and the sorption of Ni2+ and Cr3+ ions on Dash Salakhly bentonite was examined.
Bentonite samples of monocation forms Pb2+, Mn2+, Co2+, Cd2+, Zn2+, Ni2+, Cr3+, Cu2+ were processed with 15 mg/l solutions of MnSO4, Pb(NO3)2, rhodamine G and methylene blue. Sedimentation character of sorbent samples was studied. It was shown that at different temperatures (100, 200 and 4000C) on thermally processed samples, despite different natures of Zn2+ and Cu2+ ions sharp differences between colloidal fractions are not observed. Monocation forms were derived from bentonite samples of different deposits by ion-exchange method.
As a result of investigation it has been determined that genetically related compounds in bentonite have a high impact on the activity of acidic and basic centers. Thus, the power of acidic and basic centers in genetically related bentonite samples are much less expressed. And it in its turn leads to weakening of the power of active centers and sorption capacity decreases. Possibility of these cases is confirmed with derivatographic analysis. Physical and chemical
properties of bentonite from Agdara deposits were studied and important results were obtained. Researches on studying colloidal characteristics of Agdara bentonite are being continued. Na- and Ca-forms of thermally processed bentonite were characterized using the method of Scanning Electron Microscopic analysis. Entropy and enthalpy of adsorption of Zn2+ ions were calculated by temperature dependences of equilibrium distribution coefficient. Optimum
2+ 9+
conditions of extracting Zn and Cu ions on Na-bentonite from ore waters were developed and tested in industrial scale in Islamic Republic of Iran. Selectivity of sorbent extraction to Cu2+ and Zn ions of waste waters makes up 90 and 95 %, correspondingly.
Waste water which is obtained after processing of ore, was first leached with Ca(OH)2 to pH~11, where a number of the components are released in the form of a deposit, but the rest of water is passed through column containing activated carbon and Na-bentonite. If in the column containing activated carbon 60-65% of
2+ 2+
Cu and Zn ions are extracted then in Na-bentonite they will be 90-95% (Figure 2).
Fig. 2. Technological circuit for extraction of Cu2+and Zn2+ ions fro m waste waters of ore processing: 1 - flotation tank, 2 - tank for a mixture, 3 - tank for weak flow, 4 -primary deposition, 5 - equalizing tank, 6 - bioreactor for hydrolysis, 7 - antacid bioreactor, 8 - acetate tank, 9 - tank for methane, 10 - reactor of an active sludge, 11 - tank of biological deposition, 12 - tank for mixing chlorine, 13 -carbon filter, 14 - bentonite UV-filter, 15 - place for storing active sludge, 16 - system for lime transfer, 17 -system for atom transfer, 18 - system for chlorine transfer.
Comparing with natural bentonite the sorption capacity of Na-bentonite to these ions increases 1.5 times, i.e., increases from 2.8 to
4.2 mg/equ [2, 6-9]. The process of isolating natural radionuclides from different suspensions in addition to being a global scientific-technical problem it is included into the list of topical radio ecological and scientific problems of the Republic of Azerbaijan. For extraction of radioactive elements (uranium, thorium, radium etc.) from clayish suspensions the methods of chemical deposition, solvent extraction, membrane diffusion and sorption are used. Sorption differs from all these methods for its effectiveness, expedience and technological realization. Sorption method does not form chemical wastes, has high selectivity and is easily used from technological point of view. For long-term storage of radionuclides silicagel, zeolite and other inorganic sorbents are used as a permanent system. Organic natural sorbents are useful for the treatment of radionuclides after extracting from solution. Sorption laws of other radionuclides with clinoptilolite taken from Aydag deposit of Tovuz district, in clayish suspension were studied. The dependence of uranium sorption with natural clinoptilolite in clayish suspension on pH, sorbent mass, as well as desorption of uranium from sorbent was studied. Table 3 shows the effect of concentration of pH suspension on the sorption of
UO2+ ions.
The reason of low sorption capacity of sorbent (SCS) at pH=1 and pH=2 is that in a solution H+ ions with high concentration are directed to desorption in equilibrium sorp-tion-—-desoiption. At high pH in suspension equilibrium changes its direction towards sorption. In
solutions pH=1 and pH=2 uranyl [ UO^+ ] exists
as bivalent cation. At high value of pH in solution uranyl exists as monovalent hydroxyl cation
[UO2(OH)]+, [UO2(UO3)M(OH)]+ and insoluble
hydroxide UO2(OH)2.
Optimum conditions for desorption of clinoptilolite with different mineral acids were studied to reuse a sorbent and separate adsorbed radioactive elements. Desorption of clinoptilolite containing 1.7 Vc/g or 8.1 mg/g of uranyl with 50 ml of solutions of nitric and hydrochloric acids of various concentrations was studied and the results were shown in Figure 1.
Table 3. The effect of pH suspension on sorption of UO2 + ions in natural clinoptilolite
pH 1 2 3 4 5 6 7 8 9
Ao, Vc/l 20.0±1.0
A, Vc/l 19.5±1.5 19.3±1.0 18.5±1.1 18.8±1.3 17.4±1.0 17.9±1.2 17.2±0.9 10.7±1.9 5.3±2.0
Co, mg/l 96±5
C, mg/l 94.1±7.2 93.3±4.8 89.2±5.3 90.3±6.3 84.9±4.8 86.3±5.8 83.2±4.3 51.7±9.1 25.6±9.6
{C-C}, mg/l 1.9 3.2 6.8 5.7 11.1 9.7 12.8 44.3 70.4
SSC, mg/g 0.6 1.2 2.3 1.9 4.0 3.2 4.3 14.8 23.5
R, % 2.0 4.1 7.1 5.9 11.6 10.1 13.3 46.1 73.3
A0 - U primary activation of isotope, A - U equilibrium activation of isotope, Co - initial concentration of uranyl ion, C - equilibrium concentration of uranyl ion, SSC - static sorption capacity, R - sorption degree.
During desorption of clinoptilolite with nitric acid in the concentration range of 0-20% desorption degree increases and maximum desorption (71.3%) of uranyl with clinoptilolite is achieved in 20% acid solution. It was established that desorption of uranyl from cinoptilo-lite is more effective with hydrochloric acid and desorption fully goes in 20% of acid solution.
Optimum conditions of uranium sorption with natural clinoptilolite occurs in the range of (5-7) pH of a solution, 12 g/l of sorbent concentration in a solution, primary concentration of uranyl in the range of 24.1-72.3 mg/l. It was also determined that when using 20% of nitric and hydrochloric acid, uranium is fully desorbed from sorbent, maximum sorption capacity estimate of a sorbent equals to 34.5 mg/g. The dependence of sorption processes on the amount of a sorbent and sorbate, pH medium of natural clinoptilolite of uranium (234U, 235U, 238U) and radium (226Ra, 228Ra) isotopes in clayish suspension was detected. Kinetic research of a sorption process shows that the sorption of uranium and radium in sorbents based on clinoptilolite consists of fast I stage (chemisorption) and slows II stage (diffusion). The main part of a sorbate is absorbed by a sorbent for 30 min. Thermody-namic parameters show that in used sorbent the sorption of uranium and radium is endothermal as a whole. It was established that when Gibbs free energy changes in optimum parameters of sorption the process goes directly towards sorption. Isotherms of sorption of uranium and radium isotopes in clinoptilolite from aqueous solution were expressed by Langmuir and Freundlich equations. Characteristic parameters of
sorption processes were determined according to the data using these equations.
The use of polymer nanocomposite materials based on organo clays and polyvinylpyr-rolidone (PVP) in sorption process of heavy metal (Pb2+, Mn2+) ions from model solutions was shown and this material has a selective sorption capacity (0.0029 and 0.003 mol/g) to these ions under optimum conditions (pH~5, t=600C). The impact of sorbent and sorbate amount in sorption process (pH=5-7) of urani-
23 4 2, j 5 238 um isotopes (234U, 235U, 238U) of natural clinop-
tilolite from clayish suspensions was determined. Static sorption capacity SSC=34.5 mg/g of an active clinoptilolite to these isotopes under optimum sorption mode was defined.
Results
1. The use of polymer nanocomposite materials based on organo clays and polyvi-nylpyrrolidone (PVP) in sorption process
of heavy metal (Pb2+, Mn2+) ions from
model solutions was shown and this material has a selective sorption capacity (0.0029 and 0.003 mol/g) to these ions under optimum conditions (pH~5, t=600C).
2. The impact of sorbent and sorbate amount in sorption process (pH=5-7) of uranium isotopes (234U, 235U, 238U) of natural cli-noptilolite from clayish suspensions was determined. Static sorption capacity SSC=34.5 mg/g of an active clinoptilolite to these isotopes under optimum sorption mode was defined.
References
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2. Mamedova S.A., Heydarzade G.M., Yaqubov A.I. Poluchenie polimernix nanokompozitov na osnove orqanomodifisirovannix sloistix silikatov // Sb. statey po materialam mejdunarodnoy nauchno-prakticheskoy konferensii "Prioritetnie napravle-niya razvitiya nauki" Chast II. S.77-80. Moscva, 2017.
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4. Mamedova S.A., Teymurova E.M., Muradova N. M, Yaqubov A.I, Heyderzade G.M. Adsorbtion and collodial chemical characteristics of Dash Salakhly natural bentonite and its some monocation substituted forms at thermal treatment // European J. Anal. Appl. Chem. 2016. No 1. P. 23-27.
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8. MaMedova S.A., Osmanova U.H., Heydarzade G.M., Yaqubov A.I., Salimova T.A. Adsorbsiya metilena qoluboqo i rodamina G na hidrofobizi-rovannom bentonite // Chim. prom-st. 2016. T. 93. № 3. S. 7-76.
9. Ismaylova V.A., Ilyasova X.H., Yaqubov A.I., Muradova N.M., Nuriyev A.N. Issledovaniye adsorbsii asetona na modifisirovannix formax bentonita // Chim. prom-st. 2015. T. 92. №1. S. 37-40.
NANOKOMPOZÍT MATERÍALLAR OSASINDA ALINAN SORBENT SORBSÍYA PROSESLORÍNDO
O.Í.Yaqubov
Üzvi gil va polivinilpirrolidon asasinda nanokompozit material alinmiçdir. Nanokompozit materialin xarakterik xassalari fiziki metodlarla tadqiq olunmuçdur. Agir metal ionlarinin (Pb2+, Mn2+) model mahlullardan nanokompozit materialda sorbsiyanin tatbiqi gôstarilmiçdir. Mûayyanlaçdiriïmiçdir ki, hamin material optimal çaraitda (pH»5, t=600C) hamin ionlara qarçi seçici sorbsiya (0.0029 va 0.003 mol/q) tutumuna malikdir. Uran izotoplannin ( U, U, U) ^H=5-7) gil suspenziyalarindan tabii klinoptilolitda sorbentla sorbatin miqdarinin dayiçmasinin sorbsiya prosesina tasiri mûayyanlaçdirilmiçdir. Optimal çaraitda klinoptilolitin uran izotoplarina qarçi statik sorbsiya tutumlari tayin olunmuçdur (SST=34.5 mq/q ).
Açar sözlar : bentonit, sorbsiya, nanokompozit, suyun tamizbnmasi, ion d3yi§m3.
СОРБЕНТ, ПОЛУЧЕННЫЙ НА ОСНОВЕ НАНОКОМПОЗИТНЫХ МАТЕРИАЛОВ В
СОРБЦИОННЫХ ПРОЦЕССАХ
А.И.Ягубов
Получен нaнокомпозитный мaтеpиaл нa основе органического бентонита и поливинилпиppолидонa. Xapaктеpи-стические свойствa нaнокомпозитного мaтеpиaлa исследовaны физическими методaми. Покaзaно применение нaнокомпозитныx мaтеpиaлов в процессе сорбции ионов тяжелых метaллов (Pb+и Mn2+) из модельных paство-ров. Устaновлено, что в оптимaльныx условиях ^H^, t=600C) этот мaтеpиaл облaдaет избиpaтельной сорбци-онной емкостью (0.0029 и 0.003 моль/г) к этим ионш. Установлено влияние количеств сорбента и соpбaтa в
234 235 238
процессе сорбции ^H=5-7) изотопов ypaнa ( U, U, U) из глинистых суспензий природным клиноптило-литом. Определега стaтическaя соpбционнaя емкость ССЕ=34.5мг/г aктивного клиноптилолита к этим ионaм в ощи^льном сорбционном режиме.
Ключевые слова: бентонит, сорбция, нанокомпозит, очистка воды, ионный обмен.
AЗЕРБAЙДЖAHСКИЙ ХИМИЧЕСКИЙ ЖУРШ.Л № 2 2018
