EXTRACTION OF IONS OF SOME TRANSITION ELEMENTS AND THEIR AMMONIA COMPLEXES FROM SOLUTIONS ON NA-CLINOPTYLOLITE AND NA-MORDENITE Текст научной статьи по специальности «Химические науки»

AZERBAIJAN CHEMICAL JOURNAL № 2 2022 ISSN 2522-1841 (Online)

ISSN 0005-2531 (Print)

UDC 661.183.628.3+549.67

EXTRACTION OF IONS OF SOME TRANSITION ELEMENTS AND THEIR AMMONIA COMPLEXES FROM SOLUTIONS ON Na-CLINOPTYLOLITE AND Na-MORDENITE

F.T.Mahmudov, M.A.Ragimli, Z.A.Jabbarova, Sh.Z.Efendiyeva, S.A.Aliyeva, V.Kh.Aliyeva, T.N.Askerova, S.M.Sultanov, A.S.Humbatova, S.A.Mamedova

M.Nagiyev Institute of Catalysis and Inorganic Chemistry, NAS of Azerbaijan

sara.soltanova69@gmail.com

Received 11.01.2022 Accepted 18.02.2022

Modified natural zeolites in the Na-form (clinoptilolite tuff of the Aydag and mordenite of the Chananab deposits in Azerbaijan) were studied in order to extract cations of the transition and heavy metals water and industrial liquid waste. The equilibrium and kinetic characteristics of the sorption process under static and dynamic conditions have been studied. Distribution isotherms of exchange ions between Na forms of zeolites with chloride (Ni2+, Co2+, Cu2+, Zn2+, Cd2+) and nitric acid (Hg+, Ag+) solutions have been obtained. It has been found that the increased selectivity of Na-zeolites to metal cations is due to their pronounced selectivity with respect to Ag+ ions over the entire range of concentration changes in solution and solid phase, as well as to cations in the ammonium form ([Ni(NHs)6]2+, [Co(NH3)6]2+, [Cu(NHs)4]2+, [Cd(NH3)6], [Zn(NHs)4]2+) from low selectivity and selectivity to cations in the usual form. This fact makes it possible to extract the studied cations from the mixture in the form of ammonia, in accordance with the established range of selectivity of Na-zeolites to non-ferrous cations and their ammonia complexes.

Keywords: transition metal ions, Na-clinoptilolite, Na-mordenite, diffusion, the thermodynamic equilibrium constant.

doi.org/10.32737/0005-2531-2022-2-34-39

Introduction

Zeolites are known for their adsorption, ion exchange, and catalytic properties. The main advantages of natural zeolites are their chemical, thermal and radiation resistance, low cost, as well as large reserves of deposits. However, their low capacity and poor filtration ability, which prevents the sorption process from being carried out under dynamic conditions, indicate the need to obtain new modified forms of zeolites with improved sorption characteristics [1-6].

Modified natural zeolites [7, 8] which are effective ion-exchange materials, show a certain selectivity to cations of a number of transition and heavy metals from solutions. To develop methods for extracting these ions from aqueous solutions and industrial liquid waste, the equilibrium characteristics of the studied ions were studied.

To determine the important parameter of sorption statics, the thermodynamic constant of ion-exchange equilibrium, the equilibrium characteristics of sorbents were calculated. Calculations of ion-exchange equilibrium are based on taking the sorption isotherm.

Experimental part

The necessary cationic forms of zeolites were obtained under dynamic conditions by

washing them at room temperature with a 0.1 N NaCl solution. Modified samples of zeolites were air-dried to an air-dry state and stored in glass jars with ground stoppers.

The sorption of Ag+, Hg2+, Ni2+, [Ni(NH3)6]2+, Co2+, [Co(NH3)6]2+, Cd2+, [Cd(NH3)4]2+, Zn2+, [Zn(NH3)4]2+, Cu2+, [Cd(NH3)4]2+ cations has been studied from solutions on Na-forms of clinoptilolite and mordenite until equilibrium is reached. The determination of metal cations was carried out by the colorimetric method on KFK-2: the silver ion (Ag+) in model dilute solutions and in the wastewater of the photographic industry was determined using the indicator n-dimethyl-aminobenzylidene rhodanide; for nickel ions in sewage and in various industrial wastes in the form of Ni2+ and [Ni(NH3)6]2+ with the addition of dimethylglyoxime nickel salt and any oxidizing agent, for example, a saturated aqueous solution of bromine, to an alkaline solution of nickel salt. To determine the content of Co2+ and [Co(NH3)6] ions, the nitrosa-R-salt indicator was used; the determination of Zn2+ and [Zn(NH3)4]2+ ions in solutions was carried out using the rhodamine indicator C (or rhodamine B). Determination of copper ions Cu2+ and [Cu(NH3)4]2+ in solutions was carried out with

the reagent THAB (R) and using the indicator rhodamine C. To control the content of Hg2+ ions in solution at its microgram concentrations, an extraction-photometric method was used, based on the formation of a colored compound with pinoverdol [9-10].

Determination of ions Zn2+ and [Zn(NH3)4]2+, Ni2+ and [Ni(NH3)6]2+, Cu2+ and [Cu(NH3)4]2+, Cd2+, [Cd(NH3)4]2+ in pure solutions was carried out by the method of complexometric titration using the indicator eriochrome black T. When determining the content of silver and mercury ions in aqueous solutions, along with the above methods, for comparison, the Volhard volumetric titrimetric method was used.

The clinoptilolite tuff of the Aydag deposit contains an average of 80-85% clinoptilo-lite and has the following chemical composition in %: SiO2 - 65.9; M2O3 - 12.2; Fe2Os - 1.01; CaO - 4.05; Na2O - 2.55; K2O - 1.18; H2O -6.20. The mordenite tuff of the Chananab occurrence contains an average of 75-80% mordenite, has the following composition, %: SiO2 -(68.71-71.51); M2O3 - (12.44-14.54); Fe2O3 -(0.52-1.09); CaO - (1.67-2.72); SrO - (0.150.17); Na2O - (1.9-2.29); K2O - (1.05-3.30); H2O - (10.45-11.50) [11].

In dynamic experiments, nitric acid (Ag+,

Hg2+) and chloride (Ni2+, Co2+, Zn2+, Cd2+, Cu2+) solutions of these ions at a rate of 5 ml/min until the sorbents are completely saturated with them. Then, the columns with the sorbent were washed with distilled water to completely remove the retained ions from the pores of the zeolites. After determining the total content of ions in the filtrates, the sorbed amounts of ions were calculated. Next, the total dynamic exchange capacity of the sorbent was calculated in mg-equiv./g. In static and dynamic experiments, sieving fractions with an average particle size of r=0.041 cm were used to determine the absorption capacity of the studied ions. The specified fraction is the most acceptable, since at a lower fraction, the filtration of solutions in columns is difficult, and at a fraction above the specified capacity, the absorption of the studied ions gradually decreases.

The method of static experiments for determining the equilibrium exchange capacities

of modified zeolites for the studied ions was as follows: samples of zeolites in an amount of 1 g (based on absolute dry weight) were loaded into flasks with a capacity of 250-300 ml with ground stoppers and filled with nitric acid and chloride solutions (V=100 ml), respectively, with different concentrations of the above ions (from 1-10-4 to 110-1 N).

The flasks were transferred to a shaker, and their contents were mixed until sorption equilibrium was established. Based on the content of ions in equilibrium solutions, isotherm curves were plotted in the following coordinates: sorbed amounts of ions (a, mg-eq/g -Cequal, mg-eq/ml) - equilibrium concentrations of ions. Based on the isotherms, the equilibrium absorption capacities of sorbents were determined, corresponding to the saturation region of the curves in mg-eq/g. Ammine complexes of the studied ions [Ni(NHs)6]2+, [Co(NHs)6]2+, [Cu(NH3)4]2+, [Zn(NH3)4]2+ and [Cd(№)4]2+ were obtained by adding an ammonia solution to chloride solutions of the corresponding ions until a stable complex was established in the pH range of 8-11 [12]. From kinetic experiments, the time of the establishment of equilibrium of the corresponding ions was determined, changing in the range of 8-24 hours.

When studying the nature of the distribution of exchanging ions between Na-forms of high-silica clinoptilolite and mordenite with chloride (nickel, cobalt, copper, zinc, cadmium) and nitric acid (mercury, silver) solutions of transition metals, isotherms were obtained (Figure 1), characterized by a change in selectivity at reaching the certain concentration of the counterion in the zeolite phase, which is the difference between our studies and the works of the authors [13-15], while isotherms were constructed only with respect to cations in the form of ammoniates. In contrast to these works, we present equilibrium isotherms for the exchange of transition metal ions in the form of their usual and ammoniated forms. So, the ion exchange in [14] was carried out in the region of low concentration of ions with only ammic ions of copper, zinc, and cobalt. From Figure 1 one can see that Na-clinoptilolite and Na-mordenite show a pronounced selectivity to Ag+ ions in almost the

entire range of their concentration in solution

2+

and solid phase, while the cations Ni , Co Cu2+, Zn2+, Cd2+ and Hg2+ are characterized by insignificant selectivity in a limited range of changes in their concentration in solution and at a low content of these ions in the zeolite phase.

The asymmetric shape of exchange isotherms, with the appearance of S-shaped inflection, is a consequence of a change in the activity coefficient in the solid phase with a change in the molar fraction of the exchanged ion. In Figure 2, a slightly increased selectivity to ions is clearly observed: [Ni(NH3)6]2+, [Co(NH3)6]2+, [Cu(NH3)4]2+, [Zn(NH3)4]2+, [Cd(NH3)4]2+ in comparison with the cations Ni2+, Co2+, Cu2+, Zn2+ and Cd2+, since the inflections on the curves of complex ions (Figure 1) in comparison with simple ions are closer to the Y-axis related to the fractions ions in the solid phase. This makes it possible to extract ions in complex form from mixtures in the form of ammonia on Na-forms of clinoptilolite and mordenite.

Figure 2 shows that the sorption isotherms of ions of some transition metals in the form of simple and their ammonia-complex forms on Na-clinoptilolite, expressed in terms of equivalent concentrations of ions in the solid and liquid phases. Starting from 0.001 N concentration and below, the isotherms in all cases acquire a linear form, which indicates a uniform and stable distribution of the dissolved substance between the solution and the adsorbent [12].

To calculate the effective diffusion coefficient (Dint), which characterizes the intradiffusion mechanism, you can use the equation obtained by solving the Fick's diffusion equation for spherical particles with radius r:

2+

F = f =1 ^

S<*, tc n=i h

where

b =

(1)

(2)

For small values of t, a simpler equation is acceptable [16]

f =

sl = 6 dntt

kV tc

(3)

where Dint - the effective diffusion coefficient,

2 1

cm s- for exchanging ions, B - the exchange rate

constant, St - the amount of sorption corresponding to time t, mg-eq/g, Sœ - saturation, r - the sor-bent grain radius, cm; tc«3.14 is a constant value.

When studying the change in the chemical potential of the adsorbent, which is comparable in magnitude with the change in the chemical potential of the adsorbed substance, the Gibbs-Duhem equation is used [17]. In this case, the value of Ktermod for different-valent ions depends on the change in the concentration of ions in the solution. In the literature, there are works [18-19], in which the authors propose a method for calculating the value of the activity coefficient in the ionite phase and the thermo-dynamic constant of ion-exchange equilibrium. However, these methods have several inaccuracies. A critical analysis of these works is given in [20]. Having expressed the concentration of ions in the solution and the ion exchanger in terms of equivalent fractions of ions or terms of molar concentrations, the authors of [20] obtained several expressions for calculating the values of the thermodynamic equilibrium constants of ion exchange and the activity coefficients of ions in ion exchange processes, which are given below:

lnK'p Co

ZA

ln

Y АЦ

J N^dlnKC - J

dCo

lnK'r.

lnK^

Co^ )

ln YBЦ =- J NAUdlnKC J

^^dCo

lnK^

lnK

therm. =-J lnKCdNАЦ -_ J — (6)

Co^ =1) n

co(nby=1) dCo

C«(N^ =1) n

(4)

(5)

where,

n=CA-ZA+CeZB , CO=CA +CB, dCo=dCA + dC|B ; kc • yJBJ3

KC =-1/z M , where Z A and Z B are

YAUA

the ion valences, C o and n are the total molar concentrations of the solution and the ion ex-

1/ZR

YBU

changer. At = 1, K^ = Kc, KC is the con-

YAAUA

centration constant of ion-exchange equilibrium.

In the Table, in parentheses, the values of Ktherm., calculated according to N.F.Chelishchev

n

1

i

0

k

[19]. However, the comparative values of Ktherm. on Na-mordenite, they differ sharply, especially in divalent ions. For example, if in Na-morde-nite the value of the term Ktherm. 11.90 times less than the value calculated by the Gorshkov-Tolmatov equation for Cd2+ ions, then for Zn ions this value is 227 times less. In our calculations, such a difference is not observed. This confirms the accuracy of our experiments since there are large discrepancies in the experiments calculated using the Gibbs-Duhem equation, using the Kielland ratio, there are unequal values at different concentrations of ions. Therefore, at different concentrations, it is necessary to determine Ktherm. each time, which is difficult when choosing sorbents for the sorption of industrial wastewater waste under dynamic conditions.

Taking into account the results given in Table 1, a series of selectivity (lyotropic series) of the studied cations on Na-clinoptilolite was established Aydag deposit and Na-mordenite Chananab manifestation Azerb. Rep. Despite the slight divergence in Deff of the studied ions, mainly in terms of static and dynamic exchange capacities and based on a comparison of the ob-

tained values of the thermodynamic constants of ion-exchange equilibrium, the series of selectivity of high-silica natural zeolites to non-ferrous metal cations and their ammonium complexes were obtained in the following form:

Na-clinoptilolite: Ag+>Hg2+>Cd2+>Zn2+ > Co2+>Ni2+>Cu2+

[Ni(NH3)6]2+>[Cd(NH3)4]2+>[Zn(NH3)4]2+> [Co(NH3)6]2+>[Cu(NH3)4]2+

Na-mordenite: Ag+>Cd2+>Hg2+>Zn2+>Ni2+> Co2+>Cu2+

[Cd(NH3)4]2+>[Ni(NH3)6]2+>[Zn(NH3)4]2+>

[Co(NH3)6]2+>[Cu(NH3)4] 2+

The difference in the comparison of ions in the lyotropic series for Na-clinoptilolite and Na-mordenite is characterized by a sharp decrease in selectivity for divalent cations when a certain concentration of them in the solid phase is reached due to the presence of two types of channels in the mordenite structure, which differ significantly in size, while for clinoptilolite there is a gradual decrease in selectivity with an increase in the content of the divalent cation in the zeolite.

1.00 0.80

»0.60

0.40 0.20

Д .

/

/

j /о

0 0.2

0.4

Xas-

0.6 0.8 10

Fig. 1. Isotherms of exchange of cations of transition metals and their ammonia complexes on Na-clinoptilolite and Na-mordenite at a concentration of C0 =0.1n; a) • - Na-clinoptilolite+Co2+ , o - Na-mordenite+Co2+, b) • - Na-clinoptilo-lite+[Ni(NH3)6]2+; A - Na-clinoptilolite+Ni2+, o - Na-mordenite+[ Ni(NH3)6]2+; x - Na-mordenite+Ni2+; c) • - Na-clinop-tilolite+[Cu(NH3)4]2+, o- Na-clinoptilolite+Cu2+, A - Na-mordenite+[Cu(NH3)4]2+, x - Na-mordenite+Cu2+, d) • - Na-clinoptilolite + [ Zn(NH3)4]2+, o - Na-clinoptilolite+Zn2+, A - Na-mordenite+[ Zn(NH3)4]2+, x - Na-mordenite+Zn2+; e)

• - Na- linoptilolite+Ag , о - Na-mordenite+Ag ; f) • - Na-clinoptilolite+[Cd(NH3)4]2

- Na-clinoptilolite+Cd2

Д - Na-mordenite+[Cd(NH3)4]2 , x - Na-mordenite+Cd2 ; g), • - Na-clinoptilolite+Hg2 , о - Na-mordenite+Hg2

о

Fig. 2. Sorption isotherms of ions of some transition metals in the form of simple and their ammonia-complex forms on Na - clinoptilolite: 1 - 2Na+-[Cu(NH3)6] 2+ - 110-4 n; 2 - 2Na+-Cu2+ -110-4 n; 3 -2Na+-[Cd(NH3)4] 2+ - 110-4 n; 4 - 2Na+-[Ni(NH3)6]2+ -

6 - 2Na+ -Cd2+ -

110-4 n;

5

2Na+-Ni2+ - 110-4 n;

110-4 n; 7 - 2Na+-[Zn(NH3)4] 2+ -110-3 n; 8 - 2Na+ -

Co 2+-M0-3 h; 9

2Na+- Zn2+ •

110-3 n.

Table 1. Values of internal diffusion coefficients of static and dynamic exchange capacitances (SEC, DEC) and thermodynamic constant of ion-exchange equilibrium (Ktherm) of transition metal ions and their ammoniates on Na-clinoptilolite and Na-mordenite

Ionic radius Na-clinoptilolite Na-mordenite

Exchange ions of the coun- Deff., SEC, DEC, Kthermod . Deff., SEC, DEC, Kthermod

ter -ion, A0 cm2/sec mg-eq/g mg-eq/g cm2/sec mg-eq/g mg-eq/g

Na+-Ag+ 1.26 7.74 10-8 1.3734 1.302 0.7812 (3.16) 7.83 10 -8 1.2591 1.2213 0.6593 (6.31)

Na+-Hg2+ 1.12 2.97 10-8 1.1528 1.1218 0.4653 2.86 10 -8 0.7983 0.7816 0.1282

Na+-Ni2+ 0.78 5.91 10-8 0.8619 0.8512 0.0650 5.11 10 -8 0.7744 0.7588 0.0266

Na+-[Ni(NH3)6]2+ 7.58 7.73 10-8 1.0742 1.0551 0.1521 6.61 10 -8 1.0205 1.000 0.1471

Na+-Co2+ 0.82 4.21 10-8 0.8840 0.8723 0.0916 3.96 10 -8 0.8436 0.8165 0.0234

Na+-[Co(NH3)6]2+ - 5.33 10-8 0.9322 0.9146 0.1128 4.98 10 -8 0.8946 0.8714 0.0937

Na+-Cd2+ 1.03 4.05 10-8 0.9206 0.9050 0.1416 (0.060) 4.00 10 -8 0.9016 0.8816 0.13814 (0.0116)

Na+-[Cd(NH3)4]2+ - 5.94 10-8 1.0216 1.0055 0.2141 4.83 10 -8 0.9823 0.9693 0.1607

Na+-Zn2+ 0.83 3.72 10-8 0.8918 0.8793 0.1144 (0.043) 3.11 10 -8 0.8615 0.8393 0.0911 (0.0004)

Na+-Zn(NH3)4]2+ - 4.21 10-8 0.9527 0.9349 0.1782 4.13 10 -8 0.9012 0.8765 0.1346

Na+-Cu2+ 0.72 3.16 10-8 0.7026 0.6916 0.0334 (0.052) 5.07 10 -8 0.6814 0.6616 0.0208 (0.019)

Na+-[Ni(NH3)6]2+ - 5.93 10-8 0.9144 0.0772 0.0772 5.33 10 -8 0.8646 0.8448 0.0563

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BOZÍ KEÇiD ELMENTLORÍ ÍONLARININ VO ONLARIN AMMONYAKLI KOMPLEKSLORÍNÍN Na-KLÍNOPTÍLOLÍT VO Na-MORDENÍTLO ÇIXARILMASI

F.T.Mahmudov, M.A.Rahimli, Z.O.Cabbarova, §.Z.Ofandiyeva, S.A.Oliyeva, V.X.Oliyeva, T.N.Osgarova, S.M.Sultanov, A.S.Hümbatova, S.A.Mamedova

Sudan va sanaye maye tullantilarindan keçid va agir metal kationlarinin çixarilmasi maqsadila Na-formada modifikasiya olunmuç tabii seolitlar (Azarbaycanin Aydag klinoptilolit tuflari va Çananab mordenit yatagi) tadqiq edilmiçdir. Statik va dinamik çaraitda sorbsiya prosesinin tarazliq va kinetik xüsusiyyatlari ôyranilmiçdir. Xlorid (Ni2+, Co2+, Cu2+, Zn2+, Cd2+) va nitrat (Hg+, Ag+) mahlullan ila Na formali seolitlar arasinda mübadila ionlarinin paylanma izotermlari qurulmuçdur. Müayyan edilmiçdir ki, Na-seolitlarin metal kationlarina qarçi seçiciliyi mahlulda va bark fazada Ag+ ionlarina göra dayiçmaz, habela [N^N^^]^, [Co(NHз)6]2+, [Cu(NHз)4]2+, [Cd(NHз)6]2+, [Zn(NHз)4]2+ ammikatlarinin açagi selektivlik va seçiciliya malik olmasi adi ionlar çaklinda olan kationlara nisbatan yüksakdir. Bu fakt Na-seolitlarin rangli kationlara va onlarin ammonyak komplekslarina müayyan edilmiç seçicilik diapazonuna uygun olaraq tadqiq olunan kationlari ammonyak çaklinda qariçiqdan çixarmaga imkan verir.

Açar sözlar: keçid metal ionlari, Na-klinoptilolit, Na-mordenit, diffuziya, tarazliq termodinamik sabiti.

ИЗВЛЕЧЕНИЕ ИОНОВ НЕКОТОРЫХ ПЕРЕХОДНЫХ ЭЛЕМЕНТОВ И ИХ АММИАЧНЫХ КОМПЛЕКСОВ ИЗ РАСТВОРОВ НА Na-КЛИНОПТИЛОЛИТЕ И Na-МОРДЕНИТЕ

Ф.Т.Махмудов, М.А.Рагимли, З.А.Джаббарова, Ш.З.Эфендиева, С.А.Алиева, В.Х.Алиева, Т.Н.Аскерова, С.М.Султанов, А.С.Гумбатова, С.А.Мамедова

Исследованы модифицированные природные цеолиты, в Na-форме (клиноптилолитовый туф Айдагского и морденит Чананабского месторождений Азербайджана) в целях извлечения катионов переходных и тяжелых металлов из водных и производственных жидких отходов. Изучены равновесные и кинетические характеристики сорбционного процесса в статических и динамических условиях. Получены изотермы распределения обменивающихся ионов между Na формами цеолитов с хлоридными (Ni2+, Со2+, Cu2+, Zn2+, Cd2) и азотнокислыми (Hg+, Ag+) растворами. Установлено, что повышенная избирательность Na-цеолитов к катионам металлов обусловлена их резко выраженной селективностью относительно ионов Ag+ во всем интервале изменения концентрации в растворе и твердой фазе, а также к катионам в аммиакатной форме ([N^NH^]2^ [CofNH^]2^ [C^NH^J2^ [CdCNH^]2^ [Zn(NH3)4]2+) от низкой селективности и избирательности к катионам в обычной форме. Этот факт дает возможность извлекать исследуемые катионы из смеси в виде аммиакатов, в соответствии с установленным рядом селективности Na-цеолитов к катионам цветных и их аммиакатных комплексов.

Ключевые слова: ионы переходных металлов, Na-клиноптилолит, Na-морденит, диффузия, термодинамическая константа равновесия.