Hutnické listy č.7/2013, roč. LXVI
ISSN 0018-8069
Ekologie, recyklace, druhotné zpracování materiálu
Environmental Protection, Recycling, Secondary Material Processing
The Use of the Monoionic Form of Montmorillonite for Removal of Toxic
Organic Pollutants
Použitie monoiónovej formy montmorillonitu na odstránenie toxických
organických zlúčenín
Ing. Veronika Janíková1, Ing. Róbert Janík, PhD.1, prof. Ing. Eugen Jóna, DrSc.1
University of Alexander Dubček in Trenčín, Faculty of Industrial Technologies, I. Krasku 491/30, 020 01 Púchov,
Slovak Republic
1
Montmorillonite is one of the most important clay minerals and it is typical for huge expandability. It is able to
accept not only water into the interlayer, but also toxic organic compounds and it has a positive effect in relation to
its using in environmnet. Montmorillonite has been used in pharmacy and in industry of buildings and as insulating
material. Prepared monoionic form of montmorillonite was Cu2+-MMT and used organic compounds were benzene
and phenol. These compounds have variety of utilisations, for example in production of plastic, in rubber industry
and in pharmacy and a lot of phenols can be found in nature. For the investigation and acquisition of results, we
used an XRD diffraction and IR spectroscopy. After interaction Cu 2+-MMT with benzene and phenol, we can see a
movement of diffraction peak in comparison to monoionic form. It is proven that benzene and phenol are present
into the interlayer space. The application of IR spectroscopy was useful for finding new absorption bands which can
be attributed to benzene (vibration of aromatic ring) and phenol (vibration of ν(OH) group).
Keywords: Montmorillonite, benzene, phenol, XRD diffraction analysis, IR spectroscopy
Montmorillonit je jedným z najvýznamnejších predstaviteľov ílových minerálov, pričom medzi jeho výhody patrí
jeho vrstevnatá štruktúra, ktorá pozostáva zo siete tetraédrov a oktaédrov. Montmorillonit sa vyznačuje vysokou
expandabilitou štruktúry, čo znamená, že je schopný prijať do svojho medzivrstvia nielen vodu, ale aj toxické
organické zlúčeniny, čo dokazuje jeho výhodné využitie najmä z hľadiska životného prostredia. Svoje využitie
montmorillonit nachádza aj vo farmaceutickom a stavebnom priemysle. Jednou z pripravených monoiónových
foriem montmorillonitu bola meďnatá forma montmorillonitu (Cu2+-MMT), pri ktorej došlo k interkalácii toxických
organických zlúčenín do medzivrstvia montmorillonitu. Pre prácu boli vybrané organické látky zo skupiny
aromatických zlúčenín, benzén a fenol. Tieto toxické látky majú široké využitie v rôznych odvetviach priemyslu,
s čím je spojená aj kontaminácia životného prostredia týmito látkami. Benzén nachádza svoje využitie v oblasti
výroby plastov, syntetických vlákien, gumy, farbív ale aj liekov a pesticídov. Využitie fenolu je najmä pri výrobe
plastov, syntetických živíc a liečiv, no množstvo fenolov a fenolových éterov sa nachádza aj v prírode. Vhodné
analytické metódy, ktoré dokazujú skutočnosť, že montmorillonit dokáže tieto toxické látky prijať do medzivrstvia
a tým zabrániť úniku do okolia, boli RTG difrakčná analýza a IČ spektroskopia. Po interakcii Cu2+-MMT
s benzénom a fenolom je na RTG difrakčnom zázname viditeľný posun difrakčného píku v porovnaní s Cu2+-MMT,
čo dokazuje interkaláciu týchto organických zlúčenín do štruktúry MMT. Na zázname IČ spektra Cu2+-MMT po
interakcii s benzénom a fenolom možno pozorovať nové absorpčné pásy, ktoré možno priradiť vibráciám skeletu
aromatického kruhu, pričom pri fenole možno pozorovať výrazný absorpčný pás, ktorý možno priradiť pásom ν(OH)
skupín, zapojených do vodíkovej väzby.
Kľúčové slová: Montmorillonit, benzén, fenol, RTG difrakčná analýzy, IČ spektroskopia
Montmorillonite belongs to the smectic clays with
layered structure and exhibits a swelling behaviour
resulting from the weak attraction between the oxygens
on the bottom and top of the tetrahedral sheets [1, 5].
Smectites are expandable clay minerals with the
structure 2:1 [2]. Montmorillonite aggregates have three
different spaces, i.e. interlayer space, inter-particle
space and inter-aggregate space. Therefore, all clay
minerals are porous containing pores of varied size and
shape [3]. Clay minerals are widely used in a range of
many applications in relation to ceramics and refractory
materials, foundry binding sands and moreover, they are
also used in paper production, as catalysts or additives
into polymeric materials. These minerals are especially
interesting as barriers in toxic and nuclear waste
deposits [4]. Clays which belong to the phyllosilicate
groups and they are very interesting materials from the
aspect of the adsorption. On the other hand, clay
minerals are known to be excellent adsorbents and it
could be used for elimination of various organic
compounds from water [5]. In the mechanochemical
adsorption study of organic compounds by expanding
montmorillonite, the clay is ground with excess of the
organic compound [6]. Montmorillonites are widely
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Ekologie, recyklace, druhotné zpracování materiálu
Environmental Protection, Recycling, Secondary Material Processing
used in a range of applications because of their high
cation exchange capacity, swelling capacity, high
surface areas and consequential strong adsorption as
well as absorption capacities. They can be even used as
reinforcement material in polymer-clay nanocomposites
due to the particles with one dimension in the
nanometer range [7, 8]. These clay properties can be
enhanced by converting the montmorillonite to an
organoclay by ion exchange of the cation with a
surfactant molecule. The surface properties of these
organoclays are changed significantly from hydrophilic
to hydrophobic. These clays then have useful properties,
for example, the removal of oil from potable water and
other toxic chemicals as well as humic materials or
substance from water. These modified clay minerals
represented by organoclays stand for a family of
materials which have many application in a range of key
areas, such as adsorbent of organic pollutants,
rheological control agents, reinforcing fillers for plastics
and electric materials. The influence of montmorillonite
surfaces on the chemical and physical properties of
adsorbed H2O molecules has been the subject of a
number of recent studies using structural,
thermodynamic, spectroscopic, and computational
methods [7]. As a result of rapid development of
chemical and petrochemical industries, the earth surface
and ground waters are polluted by various organic and
inorganic chemicals, such as phenolic compounds, dyes
and heavy metals [9]. Many organic compounds have
been classified as hazardous pollutants because of their
potential toxicity to human health [10]. Benzene and
phenol or phenolic compounds are very harmful to
organisms even at very low concentration due to their
toxicity, foul odour and carcinogenic properties. These
compounds are present in effluents of the petroleum
refining, coke furnaces, batteries, coal gasification
plants, ply board manufacturing industries, etc [11].
There are many methods for the removal of organic
pollutants from aqueous solutions, such as adsorption,
chemical precipitation, ion exchange, membrane
processes, biological degradation, chemical oxidation
and solvent extraction [10]. One of the main problems
in the environmental field is the intrusion of toxic
contaminants from waste disposal and other sources into
the subsoil and underlying ground water supply [12].
The organic derivatives also found application as
rheological control agents in aqueous and nonaqueous
dispersions and they have been used as lubricants,
drilling fluids, greases, oils, and paints. High chemical
and mechanical resistance and low coefficient of
frication are attractive features from the aspect of the
application of organoclays as commercially used selflubricating materials. Clay minerals are frequently used
in industry [13]. XRD spectral analysis and many other
techniques are very useful for materials characterisation.
Many authors have used these techniques for various
materials characterisation. This article describes only
XRD diffraction and IR spectroscopy [14].
Hutnické listy č.7/2013, roč. LXVI
ISSN 0018-8069
Results and discussion
A preparation of Cu2+-montmorillonite
The stock of CuCl2 solution with concentration c = 1
mol.dm-3 and water was added to Ca2+-MMT. This
prepared suspension was mixed for five hours per day
and after 24 hour this process was repeated. After
sedimentation, solution of CuCl2 and water was poured
but solution of CuCl2 and water was added to the
suspension again. This mentioned process was repeated
five times. As a result, CuCl2 was washed by water until
Cl- was eliminated completely. A present of Cl- was
investigated by solution of 2% AgNO3. After this
process, Cu2+-MMT was dried by heating at 60°C. After
drying, this sample was crushed to a powder and
prepared for following analysis.
A preparation of Cu2+-MMT with benzene and with
phenol
Benzene (0.18 g) was added to 1 g of Cu2+-MMT and
this solution was mixed with 100 ml of distilled water.
Solution was mixed until MMT was completely
solvated and when the reaction was complete. The end
of the reaction was indicated by change of colour in
relation to original and mixed solution. When sample
became sediment, it was removed and the water was
evaporated from solution. The preparation of Cu2+MMT with phenol was performed in the same way as it
was in the case of preparation of sample with benzene.
Phenol (8.4 g) was added to 1 g of Cu2+-MMT and this
solution was mixed with 100 ml of distilled water.
XRD diffraction analysis
In Fig. 1, we can see a movement of peak maximum d001
to the 2 Theta (x) and that movement has a direction to
the left leading to lower values. It means that there is the
interlayer distance for Cu2+-MMT after interaction with
benzene and phenol. In relation to Cu2+-MMT with
benzene, the size of interlayer space is 0.22 nm and in
the case of combination with phenol, the given size is
0.28 nm. This fact is also presented in table 1.
Fig. 1 XRD diffraction of Cu2+- montmorillonites
Obr. 1 RTG difrakčný záznam Cu2+-montmorillonitov
100
Hutnické listy č.7/2013, roč. LXVI
ISSN 0018-8069
Ekologie, recyklace, druhotné zpracování materiálu
Environmental Protection, Recycling, Secondary Material Processing
Tab. 1 A values of interlayer distances from XRD diffraction analysis for
studied samples of Cu2+-MMT
Tab. 1 Hodnoty medzivrstvia vybraných vzoriek Cu2+-MMT získané
pomocou RTG difrakčnej analýzy
sample
Δd001/[nm]
2 Theta/[°]
d001/[nm]
Cu2+-MMT
7.06
1.25
Cu2+-MMT + B
6.00
1.47
+ 0.22
Cu2+-MMT
5.80
1.53
+ 0.28
+P
evident absorption band in comparison to IR spectra
band relating to benzene. The given mentioned facts
lead to conclusion that benzene is electroneutral from
the aspect of electron charge and its entering into
interlayer space is better without orientation to
interlayer. On the other side, phenol has an –OH group
as well as a dipole moment which causes its orientation.
Literature
Infrared spectroscopy
In Fig. 2, we can see IR spectrum of Cu2+-MMT and
Cu2+-MMT after interaction with benzene and phenol.
The biggest change in spectrum of Cu2+-MMT was after
interaction with phenol. New absorption bands are
observed at 1317, 1295, 1168 and 1151 cm-1 and it can
be attributed to stretching vibration of C–O groups and
deformational vibrations of C–OH. In relation to IR
spectrum, we can see an absorption bands of Cu2+-MMT
+ phenol at 3230 cm-1. This given fact can be attributed
to groups of ν(OH) which are connected to hydrogen
bonds and they are more lower than bands of free O–H.
After interaction of Cu2+-MMT with benzene, we can
see the vibrations of aromatic ring and they are at 1592,
1502 and 1472 cm-1.
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Fig. 2 IR spectra of Cu2+-MMT and its organomontmorillonites
Obr. 2 Infračervené spektrá Cu2+-MMT a jeho organomontmorillonitov
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Conclusions
The aim of this measurement was to prove that not only
montmorillonite but also its monoionic form Cu2+-MMT
is suitable and can be widely used in industry. Toxic
organic compounds, such as benzene and phenol which
were used in this work are toxic for human and for
environment. Properties of MMT are closely connected
with the evidence that MMT is able to accept these
organic compounds to its interlayer. We can use Cu2+MMT to remove toxic organic compounds mainly in
water but also in soil as well as in the air. After
interaction of Cu2+-MMT with toxic organic
compounds, benzene and phenol were intercalated. The
better intercalation was observed for phenol. This fact is
confirmed by help of XRD diffraction and IR spectra.
XRD diffraction showed that movement of Cu2+-MMT
into the interlayer space was better after interaction with
phenol in comparison to interaction of Cu2+-MMT with
benzene. IR spectra give evidence that phenol has more
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101
Review: prof. Ing. Darina Ondrušová, PhD.
prof. RNDr. Mariana Pajtášová, PhD.