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8Journal of Siberian Federal University. Engineering & Technologies, 2017, 10(3), 327-336
УДК 628.386
Deep Purification Technogenic Solutions of Nickel Ions (II) by the Modified Aluminosilicate
Olga I. Pomazkina, Elena G. Filatova, Oksana V. Lebedeva and Yury N. Pozhidaev*
National Research Irkutsk State Technical University 83 Lermontov Str., Irkutsk, 664074, Russia
Received 10.01.2017, received in revised form 13.02.2017, accepted 19.03.2017
There studied an adsorption method for purifying technological solutions of nickel (II) ions modified aluminosilicates. The obtained adsorption isotherms. Experimental data were processed using the models of Langmuir, Freundlich, BET and Dubinin-Radushkevich. Defined constants for these equations. It is shown that the adsorption on aluminosilicates modifiedpoly-1-vinylimidazole best describes the model of Freundlich the adsorption on aluminosilicates modified poly-4-vinylpyridine - Langmuir. The model of Dubinin-Radushkevich is used to calculate the free energy of adsorption. For all modified aluminosilicates, the value offree energy of adsorption, indicates an ion exchange mechanism, and fixation the ions of Nickel (II) has a chemical nature.
Keywords: deep water purification, adsorption, modified aluminosilicates, nickel ion (II).
Citation: Pomazkina O.I., Filatova E.G., Lebedeva O.V., Pozhidaev Yu.N. Deep purification technogenic solutions of nickel ions (II) by the modified aluminosilicate, J. Sib. Fed. Univ. Eng. technol., 2017, 10(3), 327-336. DOI: 10.17516/1999-494X-2017-10-3-327-336.
© Siberian Federal University. All rights reserved
Corresponding author E-mail address: efila@list.ru, olga_pomazkina@mail.ru
*
Глубокая доочистка техногенных растворов от ионов никеля (II)
модифицированными алюмосиликатами
О.И. Помазкина, Е.Г. Филатова, О.В. Лебедева, Ю.Н. Пожидаев
Иркутский национальный исследовательский технический университет Россия, 664074, Иркутск, ул. Лермонтова, 83
Изучен адсорбционный способ очистки техногенных растворов от ионов никеля (II) модифицированными алюмосиликатами. Получены изотермы адсорбции. Экспериментальные данные обработаны с применением моделей Ленгмюра, Фрейндлиха, БЭТ и Дубинина-Радушкевича. Определены константы этих уравнений. Показано, что адсорбцию на алюмосиликатах, модифицированных поли-1-винилимидазолом, наилучшим образом описывает модель адсорбции Фрейндлиха, на алюмосиликатах, модифицированных поли-4-винилпиридином - Ленгмюра. Модель Дубинина-Радушкевича использована для расчета свободной энергии адсорбции. Для всех модифицированных алюмосиликатов значение свободной энергии адсорбции указывают на ионообменный механизм, а закрепление ионов никеля (II) имеет химическую природу.
Ключевые слова: глубокая доочистка воды, адсорбция, модифицированные алюмосиликаты, ионы никеля (II).
Introduction
Natural aluminosilicates characterized by high adsorption properties in relation to ions of metals, is widely used in wastewater treatment. One of the most common natural aluminosilicate is clinoptilolite. It exchanges the capacity that y reaches 2,64 mEg/g [1]. It is known that in the case of adsorption of ions of divalent metals with the clinoptilolite, as well as other types of aluminosilicates [2], the maximum values of exchange capacity are not achieved. So, the value of the exchange capacity of heulandite is of 1,47 mEg/g [3]. When the ion adsorption Sr (II) natural heulandite value exchange capacity was 3,14-6,22 mg/g depending on the initial metal concentration 10-1000 mg/dm3 [4].
The ion exchange capacity of the aluminosilicate is one of the main parameters that characterize their adsorption and technological properties. The amount of adsorption of metal ions can be significantly increased by means of the modification of aluminosilicates.
When extracting ions Ni (II) from aqueous solutions by Serbian clinoptilolite from deposits , the exchange capacity of aluminosilicate increases with an increase in temperature from 1,9 mg/g at 298 K to 3,8 mg/g 319 K [5]. In [6], the amount of adsorption of the ions Ni (II) from aqueous solutions enriched the finely divided clinoptilolite being about 13,03 mg/g. When clinoptilolite modification with chitosan, the amount of adsorption of the ions Ni (II) significantly increases and reaches 247 mg/g [7].
It is known that the standards of maximum permissible concentrations of pollutants in effluents from year to year is reduced, therefore, it is necessary to produce the most complete removal of heavy metal ions.
The purpose of this work is to study the possible extraction of ions Ni (II) from aqueous solutions using modified aluminosilicates Eastern Transbaikalia.
Experiment
As object of research there used natural aluminosilicates Eastern Transbaikalia. In the experiments there used the pre-screened on a sieve fraction size of 1,0 mm. Polymers for modification of natural aluminosilicate: poly-1-vinylimidazole (PVIM) and poly-4-vinylpyridine (PVP) were received with binary radical polymerization according to the method [8]. To 1 g of the aluminosilicate was added 1 g of polymer, 18 ml of ethanol. The resulting mixture was stirred for 6 hours at 20 °C on an electromagnetic stirrer. After this time the aluminosilicate was separated from the solution by filtration, washed with water and ethanol, dried oven dried at 100 °C for 2 hours. The resulting product was weighed, the weight gain was calculated. In the process of modifying a polymer consolidation occurs on the surface of the aluminosilicate.
The presence of characteristic of natural and modified aluminosilicate structural groups was confirmed by IR spectroscopy. IR spectra were obtained on a spectrophotometer "Specord 75IR".
In the IR spectra of modified aluminosilicates manifested intense absorption bands in the region 794 and 727 cm-1, characteristic for stretching vibrations of when Al-O. The intense absorption band of 1040 cm-1 corresponds to asymmetric stretching vibrations of the relations Si-O-Si. The absorption band of 3441 cm-1 confirms the presence of communications O-H. There is a shift characteristic absorption bands of the pyridine nitrogen atom in the high frequency region from 1596 to 1601 cm-1, azole cycle from 1508 to 1497 cm-1.
The study of adsorptive properties of the modified aluminosilicate in relation to the heavy metal ions was carried out on the model solutions prepared from reagents qualification "chemically pure": NiSO4 7H2O; and distillized led water.
Selecting the the initial concentration of model solutions substantiated the real composition of industrial waste water. The content of nickel ion (II) in solution determined the by standard techniques [9,10].
The absorption capacity under study aluminosilicates was studied by static method. In the method ofthe batches of constannilg) and varying concentrations ofrom 5to 200 mg/l). The investigated sortions eere prepared 1(Ю ml^hemass rotioof liquid оМюШ pl^ess was 1:100. The amount of ndoo rptюr[(mmoit5) was careufatcdbythe formula:
C - C
A = 4 ^ • V, m
where C0 and Cequ. - the source metal and the equilibrium concentration in the solution, mmol/l; V - the volume of solution l; m - mass of sorbent of g.
Results and discussion
Assessment of the adsorption capacity of modified aluminosilicates in relation to ions of Nickel (II) was carried out on the basis of the analysis of adsorption isotherms. Adsorption equilibrium time corresponding to the constancy of the concentration of nickel (II) in solution was 2 hour. The obtained isotherms areshowninFig.1.
As it can be seen from the presented data (Fig. 1), the maximum value of adsorption in the region of low concentrations are aluminosilicates modified with PVP. The average value of adsorption when the modification is increased 3 times and reached 17 mg/g.
ttis known that eqnilibriumipthe adsorption systemdepends on thf nature of interaction between bdsorbent-bdso rbate illy. Model of apsorptifn oS LangmFiy FrchndliclE BET, Dnbinin-Radushkevich andstУnrs describe these interactions in diffdreyt ways [! 2] .So elntidationwos the p ossible applicability erf -^TKS mentioneOmodeirin tUetnlespretationor ebpcrimd ytíPreouhs:
Oaur, iso Lynamuir lroahesmeydOtian has the form
K c
A = A„-, (t)
wurre A -s 0Уe clir:te;nt vaiun adnohptioo ^rtк^ias; A-n maximum umount oo agsootinni mmollg; K - constast o. ndsonption ec[utribribm; d^.- aaulliУrmmconcentrationoa heav. metal sows, mmol/dmO
The obtained experimental results were processed using the Langmuir equation, given in linear ferm.
O- = -O-+o-O-.-O_. (S)
A Aol Au K ^«s.
The resuhs are ig•eutntcdlnaig.2 .
From graphic lineardependency (Fig.2). The largest segment of the line that intersects with the ordinate axis, themaroinal valhe enadsorrninb A^ ynit tOclit)ye enoOeiire -c aУsos>tk)n cnuiiibrium constant of thn K, thevaluer ed wUlcnareyresenren inTabie S.
From the above data (Table t) shows that the maximum value of the marginal quantities the adsorption characteristic for aluminosilicates modified PVIM. The obtained equations allow to calculate the amount of adsorption of nickel (II) ions modified by adsorbents.
C. mmol/dm3
Fio.r.Thdadsorption isotherms
0 50- 100
1/Cecu, dm3/mmol
Fig. 2. The adsorption isotherm in coordinateslinear formof theLangmuir equation
150
Table 1. Parameters of the Langmuir model
Modifiers -Aco, mmol/g mg/g K Thelinearformof theLangmuir equation R2
PVIM 0,289 17,023 8,693 1/A = 0,39871/Cecu + 3,466 0,689
PVP 0,251 1-4,8520 25,165 1/A = 0,1582 1/Cecu+ 3,9811 0,956
It isknownthat in tUe mediumfillingthe adi^t^rbe^j^t; surface are widely used
empirical Freundlich equation [12]:
A = K • C"
(3)
where A - adsorption quantity mmol/g; Cecu. - equilibrium concentration of heavy metal ions, mmol/dm3; Kf andn - constants.Most usetheFreundlich equationin logarithmic form:
lgA = lgKf+1/n-lgCe,
(4)
To investigated the modified aluminosilicates constructed according to the linear Freundlich equation logarithmic form (Fig. 3) from which the constant Kf and n (Table 2) are defined.
Adsorption centers Freundlich models have different energy values, and above all there is a filling of active adsorption centers with maximum energy. The constants Kf and n enable the comparison of the adsorption capacity of the modified aluminosilicate. When the concentration of the nickel ion (II) in a solution of 1 mol/l of the adsorption of the ions is equal to a constant Kf, and the parameter n indicates the intensity of adsorbent-adsorbate interactions. Thus, the nickel ion adsorption (II) on silica-alumina modified PVIM flows faster in the initial period of time, and in the case of the adsorbent, modified PVP is most intensive interaction adsorbent nickel ion(II).
lg A
□ pvim O pvp
OQ
o
2
Fig. 3. The adsorption isotherm in coordinates linear form of Freundlich equation
Table 2.The model parameters Freundlich
Medibers ohe linear form of tin Freundlico equptioo Kf F R
PVPM tgA = ^039+ 11-1Cecu. 0,915 0,692 0,945
PVP lgAan-nfOf + ffMO-igCV,. 038 2,27V 0,906
For adescrintifn of yll typf s ofiidti^iptic^ii isothe rmsjusih^g Tl^^eciunion of the
isothermmultilayer adsorption BET:
A =_A.^^_, (5)
(1 -C/C0)-[14- (c-1)(C/C0)]
Ahere so p adsorFtion qnantity Amd/g; A- iimiting monoldyrr aa^^r]ptwn coojacity mmol/g; c n fonstantSor o givenodsoapStonsostem is diape^y reigtyg to Hie henrdУdeF0ropd i)radaorption; C, C0 - equilibrium and the initial concentration of heavy metal ions, mmol/dm3. AdsorptionBET equation inalinearform:
C/C0 1 c -1 -0-=-+--C/C0. (6)
Using the equation of BET adsorption in linear form, built adsorption isotherms for the studied aldminosilicates (Fig. 4).
From linear dependencies shown in Fig. 4, the tangent of the angle of inclination of the straight and the size of the segments, direct intercept with the ordinate axis, determine the limiting adsorption capacity of monolayer A and c (tabl. 3).
The maximum value of the monolayer adsorption capacity characteristic of aldminosilicates modified with PVP. Due to the fact that the constant c in the equation is a ratio of BET two equilibrium
- 332 -
C/C0
Fig. 4. Adsorptionisotherms in coordinates the linear form oftheequation BET
Table 3. Parameters BET model
Modifiere The linraroormBE-e elation mmol/g cl0-3 R
PVIM C/C 0 = 24,010fC/C0) + 0=78 A(1-CEC0) ( oi) 0,141 36,413 0, 868
PVP C/C 0 = 5,816(C/C°) + 0,789 A(1-C/C0) 0 0,151 8,371 0,84 6
constantsc = ls/k^is ^¡an also bacsnsideredtho equihbrium ennstanc, i^to cakiulate tl^at standard Gibbs eo^ergr theoe on be used:AG _ u/Pin c = - Ripen ^/Cg.
Th. equilibrium tcdiioeiotioii procoes daha were promssed oding o model isothetm Dubintn-RadusOkev irh
AtA^p^^), (7R
where k - constan(imoP/kd) eisTcirtedwiehtheadsTrodion <^n^:riidi e - Polyani poirntdal (DDi/rs^rs]] showing the isothermal operation of transfer mole of nickel ion (II) from the equilibrium volume of the solution to the adsorbent surface and defined by the expression.
e = RPtn(l+liC), (8)
where R - univerrd gor oonstard, kPmohK; Peatisrlutrtemperotuee.K. Dubinin-Ra^ehkevk1 equaik) g(ei -n la^^joritl^n:^-); form:
ln A= ln Am - k e2. (9)
Using the equation of adsorption Dubinin-RadusOkevich in a linear form, are built according to ln A = f (e2) (Fig. 5).
0 50 100 150 200
e2, kJ2/mol2
Fig. 5. Adsorption isotherms in coordinatesthe Hr^e^E^rform of the equationofDubinin-Radushkevich
Table 4. The parameters of the model Dubinin-Radushkevich
Modifiers The linear form of equation Dubinin-Radushkevich Am mmol/g k, mol 2/kJ2 E, kJ/ mol R
PVIM -ln A = - 0,745 + 0,045 s2 0,475 0,0045 10,54 0,874
PVP - ln A = - 1,393+ 0,012 s2 0,248 0,0019) 16,22 0,936
The slope of the represented straight segment and the intercept on the ordinate was determined constants k and Am. The model of Dubinin-Radushkevich indicates the nature of adsorption of the adsorbate on the adsorbent and can be used to calculate the free energy of adsorption:
E = (-2k) (10)
The results are shown in Table 4.
It is known that if the value of E is between 8 and 16 kJ/mol, the adsorption process takes place by ion exchange mechanism; if the value of E is less than 8 kJ/mol, the adsorption process is physical. In this case, for all modified aluminosilicates value of the free energy of adsorption, ion exchange mechanism at the point, and fixing of nickel ions (II) has the chemical nature of the [13-15].
From the analysis of the correlation coefficient values (Table 1-4) represented the Langmuir model, Freundlich, BET, Dubinin-Radushkevicht follows that the adsorption on aluminosilicates modified PVIM best describes the model of Freundlich adsorption on aluminosilicates modified PVP -Langmuir model.
At the modifying PVIM greatest convergence of results is obtained using the Freundlich equation. In the latter case, the modification of aluminosilicates PVP adsorption process best describe the adsorption model of Langmuir and Dubinin-Radushkevich.
Conclusions
1. Process of adsorption of ions of nickel (II) on the modified aluminosilicates is investigated, adsorption isotherms are constructed.
2. The obtained experimental datas are processed with application of models of Lengmyur, Friendlich, BET, Dubinin-Radushkevich. Constants of these equations are defined. It is shown that adsorption on aluminosilicates of the modified PVIM is in the best way described by model of adsorption of Friendlich, on aluminosilicates of the modified PVP - Lengmyur's model.
3. Dubinin-Radushkevich's model is used for calculation of the free energy of adsorption. For all modified aluminosilicates, value of the free energy of adsorption, point to the ion-exchange mechanism, and fixing of ions of nickel (II) has the chemical nature.
References
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