Chelating ion exchange and antimicrobial studies

International Journal of Engineering and Creative Science, Vol 1, No. 1, 2018
www.ijecs.net
20
Chelating Ion-Exchange and Antimicrobial
Studies of Newly Synthesized Copolymer Resin
Derived From P-Hydroxybenzoic Acid, And
Thiosemicarbazide
Dr.KamlakarNandekar*
*Department of Chemistry, G. H. Raisoni Polytechnic, Nagpur-440028
Abstract: The Copolymer (p-HBTF-I) was synthesized by condensation of p-hydroxybenzoicacid and thiosemicarbazide with
formaldehyde in the presence of 2M HCL as a catalyst at 126 ± 2 0
C for 5 hrs. with molar proportion of reactants. The
copolymer (p-HBTF-I) was characterized by elemental analysis, FT-IR, UV-Visible 1H-NMR Spectroscopy. The chelating
ion-exchange property of this polymer was studied for five metal ions viz. Cu (II), Ni (II), Co (II), Zn (II), and Pb (II) ions.
The chelating ion-exchange study was carried out over a wide range of pH, shaking time and in mediaof various ionic
strengths. The copolymer possesses antimicrobial activity for certain bacteria such as B. Subtilis, ,E.Coli, S. Typhi .
Keywords: Synthesis, condensation, ion-exchange, resins.
_____________________________________________________________________________________
*Corresponding Author :Dr. K. A. Nandekar , Email: kamlakar.nandekar@raisoni.net
Ph: 07104-232318, 236102 Fax: 07104-236100 , Mob- 09371228501
_____________________________________________________________________________________________________
I. Introduction
The presence of heavy metals in the environment is a
cause of concern due to their acute and long term toxicity.
Cadmium, Mercury, Iron, Nickel, Lead are the hazardous
metals present in environmental area. The removal of these
metals needs certain technique; Ion-exchange is one of the
powerful techniques for this purpose. Ion-exchange has
attained the status of a unit operation in chemical
industries and has mostly replaced operations like
distillation and other traditional methods of separations.
The heavy metal ion toxicity has increased substantially
because of the use of metal ions as catalyst in various
industries. Many methods such as electrodeposition,
coprecipitation and solid-liquid extraction have been
developed for pre-concentration and removal of metal ions
[1-4]. However, the metal ion removal by chelating ion-
exchange resin using batch equilibration method has
gained rapid acceptance because of its wide variety of
sorbent phases, high degree ofselectivity, high loading
capacity and enhanced hydrophilicity [5-6]. Ion-
exchangers are widely used for the treatment of radioactive
wastes from nuclear power stations [7-8].
Ion-exchange resins have attracted much interest
in the recent years due to their application in waste water
treatment, metal recovery and for the identification of
specific metal ions [9-10]. Chelating ion-exchange
properties of the resin involving poly [(2, 4-
dihydroxybenzophenone) butylene] and its polychelates
with transition metals are reported [11]. Salicylic acid
andmelamine with formaldehyde copolymer found tohave
higher selectivity for Fe3+, Cu2+ and Ni2+ ionsrather than
Co2+
, Zn2+
, Cd2+
and Pb2+
ions [12]. Resins synthesized by
condensation of mixtures of phenol or hydroxybenzoic
acid with formaldehyde and various amines have also been
reported [13]. The metal ion uptake capacity increases with
increasing mole proportions of the copolymer synthesized
from substituted benzoic acid [14].
The adsorption behavior of these metal ions are
based on the affinity differences towards the chelating
resins as functions of pH, electrolyte concentrations and
shaking time. The copolymer resin under investigations are

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21
found to be cation exchanger having both ion-exchange
group and chelating group in the same polymer matrix and
the resin can be used selectively for the purpose of
purification of waste water. One of the important
applications of chelating and functional polymers is their
capability to recover metal ions from waste solution.
In this article, we describe the synthesis of a
copolymer derived from p-hydroxybenzoic acid,
thiosemicarbazide and formaldehyde (p-HBTF-I). The
synthesized The metal ion uptake capacity of the
copolymer resin by batch equilibrium method for Co 2+
,
Ni2+
, Cu2+
, Zn2+
, and Pb2+
ions in different electrolytes,
pH range and time intervals are also examined and
reported for the first time.The copolymer possesses
antimicrobial activity for certain bacteria such as S.
subtilis, , E. coli, S. typhi have been reported [19].
Copolymer resin is characterized by elemental analysis,
spectral studies (FTIR, 1
H NMR ) [15], The surface
features of the copolymer resin are established by SEM.
II-METHOLOGY
2.1. Starting materials
The entire chemical used in the synthesis of various new
copolymer resins were procured from the market and were
analar or Fluka or chemically pure grade. Whenever
required they were further purified by standard methods
like thin layer chromatography, reprecipitation and
crystallization which are generally used for the analytical
purification purpose.
2.2. Synthesis of p-HBTF-Icopolymer resin
The new copolymer resin p-HBTF was synthesized by
condensing p-hydroxybenzoic acid (0.1 mol) and
thiosemicarbazide (0.1 mol) with formaldehyde (0.2 mol)
in a mol ratio of 1:1:2 in the presence of 2 M 200 ml HCl
as a catalyst at 126 0
C ± 2 0
C for 5h, in an oil bath with
occasional shaking, to ensure thorough mixing. The
separated copolymer was washed with hot water and
methanol to remove unreacted starting materials and acid
monomers.
The properly washed resin was dried, powdered and then
extracted with diethyl ether and then with petroleum ether
to remove p-hydroxybenzoic acid- thiosemicarbazide
Fig.1: Suggested structure of p-HBTF-I copolymer
resin
formaldehyde copolymer which might be present along
with p-HBTF-I copolymer. The yellow color resinous
product wasimmediately removed from the flask as soon
as reaction period was over and then purified.
The copolymer was purified by dissolving in 10% aqueous
sodium hydroxide solution, filtered and reprecipitated by
gradual drop wise addition of ice cold 1:1 (v/v)
concentrated hydrochloric acid / distilled water with
constant and rapid stirring to avoid lump formation. The
process of reprecipitation was repeated twice. The
copolymer sample p-HBTF-I thus obtained was filtered,
washed several times with hot water, dried in air,
powdered and kept in vacuum desiccator over silica gel.
2.3. Ion-exchange property
The ion-exchange property of the p-HBTF-I copolymer
resin was determined at three different variations given
below.
2.3.1. Determination of metal uptake in thepresence of
two different electrolytes and their different
concentrations
The copolymer sample (25 mg) was suspended in an
electrolyte solution (25 ml) of known concentration. The
pH of the suspension was adjusted to the required value

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22
using either 0.1 M HNO3 or 0.1 M NaOH. The suspension
was stirred for 24 h at 30ºC. To this suspension 2 ml of 0.1
M solution of the metal ion was added and pH was
adjusted to the required value. The mixture was again
stirred at 30ºC for 24 h. The polymer was then filtered off
and washed with distilled water. The filtrate and the
washing were collected and then the amount of metal ion
was estimated by titrating against standard EDTA
(ethylenediaminetetraacetic acid) at the same pH
(experimental reading). The sameThe same titration has
been carried out without polymer (blank reading). The
amount of metal ion uptake of the polymer was calculated
from the difference between a blank experiment without
polymer and the reading in the actual experiments. The
experiment was repeated in the presence of several
electrolytes .Metal ion, its pH range, buffer and indicator
used and colourchange are given in Table 1.
Table:1Summarised Procedure for EDTA Titration
Note: *No buffer used therefore pH was adjusted by using
either dil. HNO3 or dil. NaOH
The metal ion uptake can be determined as:
Where Z (ml) is the difference between actual
experimental reading and blank reading; X (mg) is metal
ion in 2 ml ,(0.1 M metal nitrate solution) before uptake;
and Y (mg) is metal ion in 2 ml (0.1 M metal nitrate
solution) after uptake. By using this equation the uptake of
various metal ions by resin can be calculated and
expressed in terms of millimols per gram of the
copolymer.
2.3.2. Estimation of rate of metal ion uptake as a
function of time
In order to estimate the time required to reach the
state of equilibrium under the given experimental
conditions, a series of experiments of the type described
above were carried out, in which the metal ion taken up by
the chelating resins was determined from time to time at
30ºC (in the presence of 25 ml of 1 M NaNO3 solution). It
was assumed that, under the given conditions, the state of
equilibrium was established within 24 h. The rate of metal
uptake is expressed as percentage amount of metal ions
taken up after a certain time related to that at the state of
equilibrium and it can be defined by the following
relationship:
The percent amount of metal ions taken up at different
times is defined as:
Where X is mg of metal ion adsorbed after 1 h and Y is mg
of metal ion adsorbed after 25 h. Then, by using this
expression, the amount of metal adsorbed by polymer after
specific time intervals was calculated and expressed in
terms of percentage metal ion adsorbed.
2.3.3. Evaluation of the distribution of metal ions at
different pH
The distribution of each of the five metal ions i.e., Co2+
,
Ni2+
, Cu2+
, Zn2+
, and Pb2+
ions between the polymer phase
and the aqueous phase was determined at 30ºC and in the
presence of 1 M NaNO3 solution. The experiments were
carried out as described above at different pH values. The
Summarised Procedure for EDTA Titration of cation
under investigation
Metal
Ion
pH
range
Buffer used
Indicator
used
Colour
Change
Cu2+
9-10
Dil.
HNO3/Dil.
NaOH*
Fast
Sulphone
Black-F
Purple
to green
Ni2+
7-10
Aq.
NH3/NH4CL
Mureoxide
Yellow
to
Voilet
CO2+
6 Hexamine
Xylenol
orange
Red to
Yellow
Zn2+
10
Aq.
NH3/NH4CL
Eriochrome
Black-T
Wine
red to
blue
Pb2+
6 Hexamine
Xylenol
orange
Red to
Yellow

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23
distribution ratio, D, is defined by the following
relationship.
Infrared spectra of all the newly synthesized
copolymers resins were scanned at Sophosticated
Analytical Instrument Facility, Punjab University,
Chandigarh in KBr pellet on Perkin Elmer Model 677 IR
spectrophotometer in the region 4000 to 400 cm-1
.
Scanning electron micrographs of newly synthesized
copolymer resins have been scanned at Sophisticated
Analytical Instrumentation Facility, STIC, Cochin
university, Cochin.The exact morphology and structure of
copolymer resin sample was investigated by SEM.The
SEM is the ultimate tool for deposits and wear debris
analysis, particle sizing and characterization, failure
analysis, contaminant analysis and metallurgical studies.
Thus by SEM micrographs morphology of the resins
shows the transition between crystalline and amorphous
nature. When compare to the other resins these copolymer
resins are more amorphous in nature, hence shows higher
metal ion exchange capacity.
III- RESULTS AND DISCUSSION:
The newly synthesized purified p-HBTF-I copolymer resin
was found to be yellow in color. The copolymer is soluble
in solvents such as DMF, DMSO and THF while insoluble
in almost all other organic solvents. The melting point of
p-HBTF-I copolymer resin is 186 0
C and the yield of the
copolymer resin was found to be 82 %.
3.1. Infrared spectra:
A broad band appeared in the region 3500-3200 cm-1
may be assigned to the stretching vibrations of phenolic
hydroxyl (-OH) groups exhibiting intermolecular hydrogen
bonding . The presence of -NH in thiosemicarbazide
moiety may be assigned due to sharp band at 2800-3200
cm-1
. The sharp band displayed at 1685-1430 cm-1
may be
due to the stretching vibrations of carbonyl group (C=O) of
both as well as (C=S) moiety . The bands obtained at 1400
– 1200 cm-1
suggest the presence of methylene bridges in
the polymer chain. The weak band appearing at 750 - 780
cm-1
is assigned to C – OH bond. 1, 2, 4, substitution of
aromatic ring is recognized from the bandsappearingat
1279, 1178, 1112, cm-1
respectively[14-15].
Fig.2: Infra-Red Spectroscopy of p-HBTF-I
copolymer Resin
3.2 NMR Spectra:
All the four copolymers viz. p-HBTF-I exhibit singlet
signals in the region 2.3 – 2.8 () ppm which are due to
methylene protons of the Ar-CH2-Ar bridges. 1
H NMR
spectra of p-HBTF-I copolymers are shown in Fig.3 and
show a weak multiple signal (unsaturated pattern) in the
region 6.5 to 8.5 () ppm that is due to aromatic protons .
Triplet signal appeared in the region 3.0 to 4.1 () ppm can
be assigned to amino proton of – C – NH – CS - linkage.
Intense signal appeared in the region 3.5 to 4.5 () ppm
may be due to protons of methylenic bridges (CH2) of
polymer chain. Weak signal in the range of 7.5 to 8.2 ()
ppm is attributed to phenolic –OH proton (intramolecular
H - bond). A medium singlet peak appeared at 2.5 to 3 ()
ppm may be assigned to methyl protons of Ar – CO – CH3
group [14-15].

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Fig.3: NMR Spectroscopy of p-HBTF-I
copolymer Resin
3.3. Scanning Electron Microscopy (SEM):
The morphology of all the p-HBTF-I resin sample
was investigated by scanning electron micrographs at
different magnification, which is shown in Fig.4. It gives
the information of surface topography and defect in the
structure. The resin spherulites and fringed model. The
spherules are complex polycrystalline formation having as
good as smooth surface. The morphology of resin
copolymer shows also a fringes model of the crystalline
amorphous structure. The extent of crystalline character
depends on the acidic nature of the monomer. But the
photograph shows the fringed and scatted nature having
shallow pits represent the transition between crystalline
and amorphous. The resin exhibits more amorphous
characters with closed packed surface having deep pits.
Thus by SEM micrographs morphology of the resin shows
thetransition between crystalline and amorphous nature.
Fig.4: SEM of p-HBTF-I copolymer Resin
3.4. Ion-exchange properties
Batch equilibrium technique developed by De Geiso et al.
[16] was used to study ion-exchange properties of p-
HBTF-I polymer resin. The results of the batch
equilibrium study carried out with the polymer p-HBTF-I
are presented in Tables 1, 2 and 3. Five metal ions Cu2+
,
Ni2+
, Co2+
, Zn2+
, and Pb2+
in the formof aqueous metal
nitrate solution were used. The ion-exchange study was
carried out using three experimental variables such as a)
electrolyte and its ionic strength b) uptake time and c) pH
of the aqueous medium. Among these three variables,
twowere kept constant and only onewas varied at a time to
evaluate its effect onmetal uptake of the polymer similar to
the earlier co-workers [17-18].
3.5.1. Effect of electrolyte and its ionic strength on
metal uptake
We examine the influence of chloride, nitrate, chlorate at
various concentrations on the equilibrium of metal – resin
interaction . The amount of metal ions taken up by a given
amount of copolymer depends on the nature and
concentrations of the electrolyte present in the solution.
The results incorporated in Table. 2 shows that in the
presence of nitrate ions, the uptake of Cu2+
, Ni2+
, Co2+
,
Zn2+
, and Pb2+
ions increases with increasing
concentrations of the electrolyte. Where as the uptake of
Cu2+
, Ni2+
, Co2+
, Zn2+
and Pb2+
ions decreases with
increasing concentration of the chloride . This may be
explained on the basis of the stability constants of the
complexes with those metal ions.This may be due to the
chloride, ion forming strong chelates with metal ions,
while the other anions i.enitrate form weak chelates. The
position of the metal chelate equilibrium is less influenced
in the presence of nitrate ions than that of chloride ions.
The amount of uptake of Co2+
, Zn2+
and Pb2+
ions by the
copolymer under the influence of nitrate is higher than that
of the other metal ions. This may be due to the Co2+
,
Zn2+
and Pb2+
ions form weak chelates with the anions of
the nitrate electrolytes [3- 4 ].
The amount of uptake of Cu2+
, Ni2+
, Co2+
, Zn2+
and Pb2+
ions by the copolymer under the influence of chloride, ions
is lower for all the metal ions. This may be due to the Cu2+
, Ni2+
, Co2+
, Zn2+
and Pb2+
ions form strong chelates with
the anions of the chloride, ions electrolytes. In addition,
the copolymer has more porosity.in its structure they can

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25
accommodate metal ions of specific size, easily into its
cavities and acts as a better cation-exchanger .
Table 2: Evaluation of the influence of different
electrolytes on the uptake of several metal ions a
.
3.5.2. Estimation of the rate of metal ion uptake as a
function of time
To determine the time required to reach the equilibrium,
the rates of ion absorption by p-HBTF-I copolymer resin
samples were measured for Cu2+
, Ni2+
, Co2+
, Zn2+
and Pb2+
ions. The term refers to the change with time when they
were in contact with the copolymer sample the experiment
results, which are shown in table 3. These results indicate
that the time taken for the uptake of the different metal ion
at a given stage depended on the nature of the metal ions
under the given conditions.
The experimental data, which are shown in
Table.3shows that, Cu2+
, Ni2+
ions required 6 h for the
establishment of equilibrium [ 1-4] whereas Co2+
, Zn2+
and
Pb2+
ions required 5 h for the establishment of
equilibrium. The experimental results revealed that the rate
of metal-ionuptake followed the order of Pb2+
> Co2+
> Zn
2+
> Ni 2+
> Cu2+
.
Table 3:Percentage of metal ion uptake b
at different
time (h)
3.5.3. Distribution ratios of metal ions at different pH
The effect of pH on the amount of metal ion
distributed between the two phases is given in Table 4
which reveals that the amount of uptake of metal ions by
the resin at equilibrium increases with increasing pH. The
study was carried out up to a definite pH value for the
particular metal ion to prevent hydrolysis of metal ion at
higher pH.
The p-HBTF-I copolymer resin takes up Pb2+
ions
more selectively than the other ions under study at all pH
values. Among the other ions taken up for the study, Cu2+
ions shows selective uptake under moderate pH values.
Further, Ni2+
, Co2+
, Zn2+
ions have lower distribution over
Metal
Ion
Electrolyte
Conc.
(mole/lit)
Weight of metal ion
(mg)taken up in presence
ofb
NaNO3 NaCl
Cu2+
0.01
0.05
0.10
0.50
1.00
0.31
0.38
0.47
0.57
0.58
0.59
0.50
0.45
0.34
0.30
NI2+
0.01
0.05
0.10
0.50
1.00
0.16
0.31
0.39
0.47
0.55
0.43
0.31
0.27
0.23
0.16
Co2+
0.01
0.05
0.10
0.50
1.00
0.31
0.39
0.42
0.54
0.66
0.43
0.35
0.28
0.24
0.16
Zn2+
0.01
0.05
0.10
0.50
1.00
0.17
0.26
0.35
0.52
0.74
0.65
0.52
0.35
0.24
0.17
Pb2+
0.01
0.05
0.10
0.50
1.00
0.39
0.61
0.77
1.38
1.8
1.49
1.24
0.97
0.86
0.58
Metal
ion
Percentage of metal ion uptake b
at
different time (h)
1 2 3 4 5 6
Cu2+
30 40 51 59 84 89
NI2+
15 24 33 39.5 56 88.5
Co2+
37 45 54.5 68 89.5 -
Zn2+
39 43 50.5 70.5 89.5 -
Pb2+
34 45 52.5 77 89.5 -

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26
the pH range from 2.5 to 6.5. This can be explained as the
weak stabilization energy of the metal chelates formed
from Ni2+
, Co2+
, Zn2+
ions. In the present investigation it
is observed that the order of the distribution of the metal
ions are Pb2+
> Cu2+
> Ni2+
> Zn2+
> Co2+
.
Table 4 : Distribution ratio Da
of Different Metal Ions
as a Function of pHb
4. Antimicrobial Screening of p-HBTF-I copolymer
resin.
Biological assay depends upon a comparison of the
inhibition of growth of microorganism by measuring the
concentration of the sample to be examined with the
known concentration of standard antibiotic. For the
antimicrobial analysis of p-HBTF-I copolymer the agar
diffusion method was employed. During the course of
time, the test solution diffuses and the growth of the
inoculated microorganisms such as B. subtilis, E. coli, and
S. typhi were found to be affected. The activity developed
on the plate was measured by measuring the diameter of
the inhibited zone in millimetres. The drug gentamycin
was used as the standard for bacteria [19-20].
Table 5: Antimicrobial activities of p- HBTF-Icopolymer
resin.
The diameters for the zone of inhibitions at different
concentration against the test bacteria are given in Table 5.
The standard antibiotic disc (Gentamycine disc 5μg ⁄disc)
inhibited the growth of B. Subtilis by 8-25 mm E. Coli by
18-25 mm, and S. Typhi by 2-25 mm.
S.Typhi E. ColiB.Subtillus
Fig.8: Antimicrobial screening of p- HBTF-I
copolymer resin.
The results of present antimicrobial assay revealed that
the p-HBTF-I copolymer showed inhibitory activity
against only B.subtilis, E. coli, S. typhi the tested
pathogens, suggesting that the presence of
thiosemicarbazide group may enhances antibacterial
activity (Fig. 8). As the p-HBTF-I content increases in the
copolymer, the effectiveness of the copolymers to inhibit
the growth of microorganism increases as expected [19-
20].
CONCLUSIONS
• A polymer p-HBTF-I based on the condensation reaction
of p-Hydroxybenzoic acid and thiosemicarbazide with
formaldehyde in the presence of acid catalyst was
prepared.
• The p-HBTF-I resin is a selective chelating cation
exchange polymer resin for certain metals.
• The uptake capacities of metal ions by the polymer resin
were pH dependent.
 The results of present antimicrobial assay revealed that
the p-HBTF-I copolymer showed inhibitory activity
against only B.subtilis, E. coli, S. typhi the tested
pathogens, suggesting that the presence of
thiosemicarbazide group may enhances antibacterial
activity .
 As the p-HBTF-I content increases in the copolymer, the
effectiveness of the copolymers to inhibit the growth of
microorganism increases as expected.
Metal
ion Distribution ratio of metal ion at different pH
2.5 3 3.5 4 5 6 6.5
Cu2+
9.88 15.69 18.86 26.55 38.10 75.72 168.7
NI2+
12.5 20.42 31.25 39.13 39.29 54.17 141.3
Co2+
7.07 10.56 13.33 37.33 51.28 44.44 90.91
Zn2+
7.41 29.96 55.56 83.33 88.89 98.50 116.6
Pb2+
45.7 59.26 104.3 165.08 466.6 800 1886.4
Organism
0.0625
To 1 mg
2.0 mg MIC mg
B. subtilis - 6 2
E. coli (ETEC) - 7 2
S. typhi - 5 2

www.ijecs.net
27
ACKNOWLEDGEMENT
Authors are thankful to the SAIF, Punjab University,
Chandigarh for carried out spectral analysis, thankful to
BIOGENICS, Hubli (Karnataka) for carried out
antibacterial screening, and also to the SICART,
Vallabhvidyanagar, Gujrat for carried out the thermal
analysis.
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