complexant cellulose membrane for analytical

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XXV ARS SEPARATORIA – Toruń, Poland 2010
COMPLEXANT CELLULOSE MEMBRANE FOR ANALYTICAL
SEPARATIONS
Antoneta Doina RADU, Ludmila IARCA, Niculina Nina BADEA and
Gheorghe NECHIFOR
University, Politehnica of Bucharest, Faculty of Applied Chemistry and Materials
Science, Department of Analytical Chemistry and Instrumental Analysis, 1-5 Polizu
Street, Bucharest, sector 1, 011061, Romania, ghnechifor@gmail.com
Abstract
The heavy metals impurities from alcohols represent a major problem in the
reactions or processes which requires analytical purity of solvents. In this work, the
immobilization of amino benzo 15 crown ether and aza 15 crown ether on cellulose
membranes for heavy metals removal is studied. The cellulose membranes are
activated with KOH in ethyl alcohol and superficial alkali cellulose (Cell-O-K+) is
obtained. On the other hand, amino benzo 15 crown ether and aza 15 crown ether
are treated with cyanuric chloride in dioxan in the presence of triethyl amine. The
two components, activated membrane and amino crown ether derivative, are
introduced in dioxan at a reflux for 3 hours. The functionalized membrane is washed
with ethylic alcohol and bi distilled water.
The morphological and structural characterization of functionalized membrane
was realized by SEM microscopy, thermal analysis, FT-IR spectroscopy. The
obtained membranes were used for heavy metals removal from alcohols during a
nanofiltration processes.
1. INTRODUCTION
The cellulose membranes remain main materials for dialysis [1]. The
improvement of regenerated cellulose membranes for dialysis represents a
main objective of the research [2]. It is well known, for example the
treatments of membranes with heparin to prevent the blood coagulation [3]
or with carbon nanotubes for improvement of heavy metals ions retention
[4].
In this paper the immobilization of amino benzo 15 crown ether and aza
15 crown ether (CE) on cellulose membranes is studied.
2. MATERIALS AND METHODS
The cellulose membranes are activated with KOH in methanol, ethanol,
propanol or butanol and superficial alkali cellulose (Cell-O-K+) is obtained.
On the other hand, amino benzo 15 crown ether and aza 15 crown ether (CE)
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XXV ARS SEPARATORIA – Toruń, Poland 2010
are treated with cyanuric chloride in dioxan in the presence of triethyl amine.
The two components, activated membrane and amino derivative are
introduced in dioxan at reflux for 3 hours. The obtain membrane is washed
with ethyl alcohol and bi distilled water.
The morphological and structural characterization of functionalized
membrane was realized by SEM microscopy, thermal analysis, FT-IR
spectroscopy. The obtained membranes were used for heavy metals removal
from alcohols during a nanofiltration processes.
3. RESULTS AND DISCUSSIONS
Passive membranes have been used for separations ranging from
seawater desalination via reverse osmosis to the separation of particles with
microfiltration membranes. However, active membranes, achieved by
immobilization of macromolecules containing multiple functional sites to
nanofiltration membranes, allow for more selective separations. We have
designed a novel membrane system consisting of cellulose-based
nanofiltration membranes functionalized with amino benzo 15 crown ether
and aza 15 crown ether (fig. 1).
O
O
O
O
N
NH2 + Cl
O
Cl
O
O
O
Dioxan
O
N
N
O
Cl
N
NH
N
N
Cl
Cl
a
CH2OH
O
HO
HO
CH2OH
O
OH
HO
O
OH
O
O
CH2OH
OH
OH
HO
n-2
O
O
O
O
KOH
NH
O
O
Cl
N
N
N
O
O
NH
O
O
Cl
N
N
N
CH2O-K+
O
- +
CH2O-K+
O
HO
HO
OH
CH2OK
O
O-K+
HO
O
O
O
CH2OH
OH
HO
CH2O-K+
O
Cl
HO
HO
OH
n-2
OH
O
HO
O
O
O
CH2OH
OH
HO
OH
n-2
b
Fig. 1. The functionalization reaction of crown ether (CE) with cyanuric chloride
(a) and the reactions for functionalized cellulose membrane synthesis (b)
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XXV ARS SEPARATORIA – Toruń, Poland 2010
Only scanning electron microscopy were presented in this paper (Table
1), but FT-IR, thermal analysis EDAX and NMR were previously presented
[5].
Table 1. Scanning Electron Microscopy of tested membranes
Membrane type
Cellulose
Membrane
SEM section
SEM surface
Alkali Cellulose
Membrane
Cyanuric
Cellulose
Membrane
Amine Crown
Ether Cellulose
Membrane
To characterize the effects of membrane structure on complexation,
several factors must be examined. These include the density and amount of
selective crown ether available on the membrane support, the metal solution
XXV ARS SEPARATORIA – Toruń, Poland 2010
233
concentration, and charge and pore size effects on the rates of sorption [5].
This work is a support for sampling in analytical determination of
metallic ions from environmental samples (e.g. Lead).
4. CONCLUSIONS
This paper was intended to show the differences in the metal sorption
behavior for homogeneous and immobilized CE and the role of
functionalization.
Acknowledgements
The authors gratefully acknowledge the financial support of this research by
the UPB-CEMPDI-POSDRU Doctoral Project 2009, PNII 71-025 and PNII 71-034
research projects.
REFERENCES
[1] M. Mulder, Basic Principles of Membranes Technology, Kluwer Academic Publishers,
1997.
[2] D. F. Stamatialis, B. J. Papenburg, M. Gironés, S. Saiful, S. N.M. Bettahalli, S.
Schmitmeier, M. Wessling, J. Membr. Sci., 2008, 308, 1.
[3] Lan Wei, Chunhua Cai, Jiaping Lin, Tao Chen, Biomaterials, 2009, 30, 2606.
[4] G. Nechifor, S.I. Voicu, A.C. Nechifor, S. Garea, Desalination, 2009, 241, 341.
[5] G. Nechifor, S.I. Voicu, A.C. Nechifor, Proceeding of EMS-SS-2010, Bucharest, June,
14-18, 2010.