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International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
182
T1: P–49
Synthesis of geopolymer materials based on metakaoline
and their potential application as sorbents
Kamila Brylewska
1,2
, Magdalena Król
1
, Arkadiusz Knapik
1
,
Kamil Wojciechowski
1
, and Włodzimierz Mozgawa
1
1
Faculty of Materials Science and Ceramics, AGH University of Science and Technology,
al. Mickiewicza 30, 30-059 Krakow, Poland, e+mail: kamilaaa@agh.edu.pl
2
Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow, Poland
Geopolymers are a subgroup of amorphous inorganic aluminosilicates with structural
elements similar to those of crystalline zeolites. Their structure features alumina [AlO
4
] and
silica [SiO
4
] tetrahedra joined together with oxygen atoms [1]. The negative charge of [AlO
4
] is
compensated by the presence of alkali metal ions, such as Na
+
or K
+
. These materials are used in
chemical technology as additives to cement or slag alkali binders, among others. Other
applications of geopolymers include building materials and environmental protection.
The degradation of the natural environment as a major consequence of human activity has
been ongoing for a long time. This is true especially with regard to water, which is contaminated
primarily with heavy metal cations. For this reason, materials with excellent sorptive properties,
such as geopolymer materials, are highly desirable. These materials are environmentally
friendly, and are used as sorbents of heavy metal cations [2]. For example, Zhang et al. [3]
studied geopolymers based on fly ash and immobilized Cr
6+
, Cd
2+
, and Pb
2+
ions. It was also
confirmed that geopolymers can have high adsorption capacity regarding methylene blue and
Cu
2+
[3].
The aim of the study was to synthesize geopolymer materials and to evaluate their properties
in the context of their potential use as self-supporting zeolite membranes. For this purpose,
metakaolin activated with solution of sodium silicate and sodium hydroxide was used. The raw
material composition expressed in SiO
2
/Al
2
O
3
and Al
2
O
3
/Na
2
O molar ratios and the activation
temperature were selected so as to correspond to the basic chemical compositions and synthesis
conditions of A, X and sodalite zeolites. The obtained materials were evaluated in terms of their
structural and textural properties using XRD, SEM, and FT-IR. It was demonstrated that it is
possible to obtain zeolite structures in the form of composite with an amorphous matrix. The
selected materials were used in the sorption of selected heavy metal cations (Ni
2+
, Zn
2+
, Pb
2+
and
Cd
2+
) from aqueous solutions. It was found that the analyzed geopolymerization process allows
to obtained a material with a potential application as heavy metal sorbent.
Keywords: geopolymers; heavy metal cations; IR spectroscopy
Acknowledgments
This work was financially supported by the National Science Centre in Poland as part of grant no.
2015/17/B/ST8/01200.
References
[1] J. Davidovits, J. Mater. Educ. 16 (1994) 91-139.
[2] L. Zheng, W. Wang, Y. Shi, Chemosphere 79 (2010) 665-671.
[3] J. Zhang, J.L. Provis, D. Feng, J.S.J. Van Deventer, J. Hazard. Mater. 157 (2008) 587.
XIV
h
International Conference on Molecular Spectroscopy, Białka Tatrzańska 2017
183
T1: P–50
Influence of alkali metal cations/type of activator on the structure of
alkali-activated fly ash – ATR-FTIR studies
Piotr Rożek1, Magdalena Król
1
, Arkadiusz Knapik
1
,
Damian Chlebda
2
, and Włodzimierz Mozgawa
1
1
Faculty of Materials Science and Ceramics, AGH University of Science and Technology,
al. Mickiewicza 30, 30-059 Kraków, Poland, e-mail: mkrol@agh.edu.pl
2
Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland
Geopolymers are inorganic, amorphous to semi-crystalline materials. They are synthesized
by alkali-activation (e.g. by alkaline hydroxides) of fly ash, metakaolin or other aluminosilicate
source. Geopolymers exhibit thermal, acidic and alkaline resistance as well as relatively high
compressive strength [1]. These properties are related to the structure of geopolymers, i.e. chains
of [SiO
4
] and [AlO
4
] tetrahedrons connected by oxygen bridges [2]. Formation of such Si–O–Al
chains, which create a three-dimensional network is called “geopolymerization”. Main product
of geopolymerization is amorphous aluminosilicate gel (N-A-S-H). Crystalline phases, such as
hydroxysodalite, calcite, and zeolites were also identified in geopolymeric matrices. Presence of
alkaline cations provides electrical charge balance of the geopolymer framework [3]. IR spectra
may be successfully used to observe structural changes during geopolymerization [4].
Attenuated total reflectance FTIR spectroscopy technique (ATR) is used for in situ studies, also
in geopolymers research [5, 6]. The aim of this work is to investigate geopolymerization of fly
ash activated with different hydroxides by means of ATR-FTIR.
Coal fly ash was a starting material. Alkali-activation was conducted with sodium hydroxide
(NaOH), potassium hydroxide (KOH), and lithium hydroxide (LiOH). Molarity of the
hydroxides solutions was 8 M. Water content was kept at the water/solid mass ratio of 0.4. ATR
with a zinc selenide focusing element which is in direct contact with the diamond and heated
plate was used for in situ IR spectra measurement. Geopolymer paste was put to the ATR cell
immediately after being mixed and then sealed with Teflon tape. Spectra have been collected at
1 minute intervals in the range of 4000–650 cm
–1
at 80°C.
Changed in the aluminosilicate structure of the spectra has been detailed analyzed. This
changed mainly affect both the integral intensity and FWHM of bands in the range of 4000–650
cm
–1
, however dehydration and carbonation process can be also analyzed based on obtaining
results.
Keywords: ATR-FTIR; fly ash; geopolymerization; alkali hydroxides
Acknowledgment
This work was financially supported by the National Science Centre in Poland under grant no.
2015/17/B/ST8/01200.
References
[1] M. Jin, Z. Zheng, Y. Sun, L. Chen, Z. Jin, J. Non-Cryst. Solid. 450 (2016) 116.
[2] J. Davidovits, J. Therm. Anal. 37(8) (1991) 1633.
[3] D. Khale, R. Chaudhary, J. Mater. Sci. 42(3) (2007) 729.
[4] M. Król, J. Minkiewicz, W. Mozgawa, J. Mol. Struct. 1126 (2016) 200.
[5] C.A. Rees, J.L. Provis, G.C. Lukey, J.S.J. Van Deventer, Langmuir 23(15) (2007) 8170.
[6] C.A. Rees, J.L. Provis, G.C. Lukey, J.S. van Deventer, Langmuir 23(17) (2007) 9076.
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