RSC Advances
ARTICLE
DOI: 10.1039/C4RA04780J
Journal Name
EXPERIMENTAL
was then treated with aniline in presence of triethylamine in
DMF to get N-[5-(8-hydroxyquinoline)methyl]aniline
ANHQ).
Materials
19,20
(
Aniline (99.5%, Merck) was distilled under reduced pressure.
Uranyl nitrate hexahydrate (99%, Spectrochem), ammonium
per sulphate (98% Sigma Aldrich), potassium dichromate (99%
Merck) and arsenazo III (analytical grade purity, Fluka) were
used as received. All other chemicals used in this work are of
reagent grade and were used as received. The solutions were
prepared in distilled water.
Synthesis of imprinted homopolymer (IPANHQ)
Briefly, 5 mL of concentrated HCl, 0.5 g of ANHQ and 0.5 g of
UO (NO ) .6H O were stirred for 30 minutes to form the pre-
2
3 2
2
polymerization mixture. The ratio of ANHQ to uranyl ion was
taken as 1:2. The polymerization was initiated by addition of
ammonium persulphate (1:1 ratio with the monomer) dissolved
in distilled water, with vigorous stirring, when a green
precipitate starts to form. Then total volume of the reaction
mixture was made to 25 mL by adding distilled water and
reaction was continued for 4 h. The precipitated polymer was
filtered and washed with distilled water until the washings were
Extraction of uranyl ion from imprinted polymers
(
Leaching)
Uranyl ion was leached from the imprinted polymer by stirring
the polymer in 1M HCL for the required period of time. Non
imprinted polymers were also leached, although they do not
contain uranyl ion, to maintain the same environment during
SPE studies. The leached polymers are indicated by the
notation (L).
0
colorless. The polymer was then dried in an oven at 50 C. The
corresponding non imprinted polymer was prepared by the
same procedure in the absence of uranyl ion (NIPANHQ).
Synthesis of imprinted copolymer (IFPAN)
Solid Phase Extraction Studies
In SPE studies, preconcentration was done with appropriate
amount of the polymer from 100 mL of aqueous phase volume
having 100 µg of uranyl ion, adjusted to pH=7.0 using 10 M
ammonium acetate buffer. Preconcentrated uranium was eluted
from the polymer using 1M HCl and determined by
spectrophotometry.
Imprinted copolymer of ANHQ with aniline (IFPAN) was
synthesized by the following procedure. Briefly, 5 mL of
concentrated HCl, 0.5 mL of aniline, 0.15 g of ANHQ and 0.15
g of UO (NO ) .6H O were stirred for 30 minutes to form the
-
3
2
3 2
2
pre-polymerization mixture. The ratio of ANHQ to uranyl ion
was taken as 1:2. The polymerization was initiated by addition
of ammonium persulphate dissolved in distilled water, with
vigorous stirring, when a green precipitate starts to form. Then
total volume of the reaction mixture was made to 25 mL by
adding distilled water and reaction was continued for 4 h. The
precipitated polymer was filtered and washed with distilled
water until the washings were colorless. The polymer was then
Method for determination of uranyl ion.
To the filtrate obtained after solid phase extraction was added 5
mL of 1:1 hydrochloric acid, 2 mL of 0.1% arsenazo III
solution in a 25 mL standard flask and made upto the mark with
distilled water. The absorbance of uranium–arsenazo III
1
6
complex was measured at 656 nm.
0
dried in an oven at 50 C. The corresponding non imprinted
Synthesis of imprinted polyanilne (IPAN-1) with potassium
dichromate
The method for synthesis with potassium dichromate was
polymer was prepared by the same procedure in the absence of
uranyl ion (NIFPAN) (Yield-69%). The scheme for the reaction
is given in Fig. 1.
1
7
modified from the report of Chowdhary et al. The ratio of
aniline to oxidant was taken as [An]/[OX]=2.0, [HCl]=2.4 M
and [K Cr O ]=0.11 M. Briefly, 5 mL of concentrated HCl, 0.5
2
2
7
mL of aniline and 0.05 g of UO (NO ) .6H O were stirred for
2
2
3 2
3
polymerization was initiated by addition of K Cr O , with
0 minutes to form the pre-polymerization mixture. The
2
2
7
vigorous stirring, when a green precipitate starts to form. Then
total volume of the reaction mixture was made to 25 mL by
adding distilled water and reaction was continued for 4 h. The
synthesis was done with and without purging of nitrogen gas.
The precipitated polymer was filtered and washed with distilled
water until the filtrate was colorless. The polymer was then
Fig. 1: Schematic diagram for synthesis of IFPAN
CHARACTERISATION
0
dried in an oven at 50 C. The corresponding non imprinted
A Shimadzu computer controlled double beam UV-Vis
spectrophotometer UV-2401PC (Shimadzu, Kyoto, Japan), was
used for measuring absorbance. pH of all the sample solutions
were adjusted using a digital pH meter LI-120 (ELICO,
Hyderabad, India) with accuracy of 0.01 pH unit. The FTIR
spectra were recorded on Bruker FT-IR spectrometer. SEM
images were taken using a Carl Zeiss EVO Edn: 18 Cryo
Environmental SEM Instrument. Thermogravimetric analysis
were done using a TG/DTA-6200 (SII Nano Technology Inc.,
Japan)
polyaniline (NIPAN-1) (Yield-73%) was prepared by the same
procedure without the uranyl ion.
Synthesis of imprinted polyanilne (IPAN-2) with
ammonium persulphate
The same procedure was followed with ammonium persulphate
as the initiator maintaining a 1:1 ratio of monomer to initiator.
The corresponding non imprinted polymer was prepared by the
same procedure without the uranyl ion (NIPAN-2)(Yield-77%).
Synthesis of imprinted polyanilne with increased amount of
uranyl ion with PDC (IPAN-3) and APS (IPAN-4)
The same procedure was used but with increased amount of
uranyl ion [0.066 M] to see whether this would increase the
binding sites inside the polymer and hence the percentage of
removal. The ratio of aniline to uranyl ion was taken as 4:1.
Synthesis of N-[5-(8-hydroxyquinoline)methyl]aniline
RESULTS AND DISCUSSION
We have synthesized different imprinted polymers for the
removal of uanyl ion. Initially imprinting was done in aniline
matrix using both potassium dichromate (PDC) (IPAN 1) and
ammonium persulphate (APS) (IPAN 2) as initiators. A fairly
good uptake and an imprinting effect of 2.0 (the ratio of removal
by IPAN to that by NIPAN) was observed during SPE studies at
(
ANHQ)
For functionalisation of aniline, 8-hydroxyquinoline was
-3
neutral pH with 10 M ammonium acetate as buffer. This
prompted us to further investigate on the possibilities of
1
chloromethylated following the method of Burckhalter, which
8
2
| J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 2012