Synthesis of novel porous tannin-phenol-formaldehyde cation exchange resin from Terminalia arjuna ( Kumbuk )

ions, proteins and some other biomolecules. In this study, tannins extracted from Terminalia arjuna phenol content. The ion exchange capacities of the resins the properties further. A monovalent cation, Na estimate the adsorption properties of both sulfonated and ion exchanger in aqueous media at different pH values. Fourier out to characterise the synthesised resins. Scanning electronic morphology of the resins produced. Sulfonated tannin-phenolthe highest adsorption capacity for the metal ion used (Na), as the porogenic agent to create the porous structure through emulsion templating process. Synthesised porous resin contains μm and nm scale porous structures.


INTRODUCTION
Common metal removal methods are technically et al., 2008).Although ion exchange is more effective, a high capital expenditure is usually required for such systems.Hence, producing a resin based on natural materials is more economically viable (Yu et al., 2008).
The use of tannin based compounds as ion adsorbents et al ., 1991).Randall (1977) examined the suitability of various barks as ion exchange substrates.Although tannin can adsorb ions, to use tannin as an adsorbent in applications such as ion exchange resins.This problem can be overcome by et al. (1997)  high selectivity, fast adsorption kinetics and high removal capability at pH 6.5.Zhang and Sun (2001) developed a biporous anion exchange resin for protein chromatography incorporating solid granules and solvents as the porogenic medium.

Determination of total polyphenolic content
folin-ciocalteau method.Commercially available folin-3 pipetted out to a 100.00 cm 3   as standards.Aliquots (1.00 cm 3 ) of the gallic acid 3 Thereafter, 4.00 cm 3   and kept at room temperature for 2 h.The absorbance polyphenolic content in the extracted crude tannin

Preparation of TFR and TPFR
For the preparation of TFR, a 20.000 g sample of As the second part of the procedure, 50.00 mL of mixing of hexamine, and reduced to 250 rpm before the 10 min at the same speed.
at 80 o at room temperature in a desiccator before being cut into a Soxhlet extractor using acetone as the solvent for 7 ds cool and stored in a desiccator.

Determination of IEC for monovalent cations
About 5.000 g of the Na + forms of sulfonated and the IEC of the monovalent cation, Na + The Na + form of the sulfonated and unsulfonated resins + form using 0.1 M HCl solution as H + through the resin columns at a rate of 3 cm 3 min -1 .The + phenolphthalein as the indicator to calculate IEC.

Scanning electron microscopic (SEM) studies
obtained using a scanning electron microscope (Hitachi

Synthesis of tannin-phenol-formaldehyde resins (TPFR)
Coconut oil is a commonly used vegetable oil produced When considering the fatty acid composition, coconut oil contains a higher (Table 2).As unsaturated fatty acids are more susceptible to oxidative reactions, according to fatty acid activity coconut oil is expected to oil.Therefore,

September 2017
Journal of the National Science Foundation of Sri Lanka 45 (3) lead to side reactions.As the reaction mixture is heated only up to 80 o C, the not affect the process.
Hexamine is considered as a hardener in industry.In of formaldehyde.Hexamine releases formaldehyde to

Determination of IEC of resin systems
The IECs obtained for unsulfonated different tannin to phenol ratios and the IECs of sulfonated resin systems are The h had a tannin/phenol ratio of 1:1.

simple tannin formaldehyde resin that does
It is due to the acidic character of the phenolic hydroxyl groups present in the resin .With increasing incorporation of phenol into the reaction mixture, the IEC increased as 2. started to to prepare a column to use in ion exchange studies.resin indicates that it According to the studies of Arasaretnam and , the measured in a an increase of phenol units in the TPFR system increases available ion exchange sites.
The introduction of strong acidic groups (SO 3 -) to the TFR and TPFR systems using sulfonation has increased the effect of sulfonation groups restrict the sites for sulfonation because of the complex branched structure of the tannin molecules.steric hindrance by separating the tannin molecules, providing more sites for sulfonation in both phenol and tannin molecules.

FTIR analysis
Figure 3 s a and its tannin extract in the range of 640 to 3990 cm -1 .The  3550 to 3100 cm -1 broad absorption band corresponds to -OH bridging groups et al., 2006) and the corresponding peak in the crude tannin sample is high in intensity compared to that of the dried bark sample.
-1 -1 absorption bands can be attributed to aromatic skeletal vibrations, representing C = C stretching (Steyermark, 1976).The tannin extract from the bark has a much stronger peak the tannin extract from the bark has a much higher concentration of aromatic compounds (Arasaretnam .The 1420 to 1330 cm -1 absorption band belongs to the O-H in plane deformation (Steyermark, 1976).The peaks at 1340 cm -1 in the crude tannin extract and 1367 cm -1 in the dried bark sample can be assigned to O-H in plane deformation.Again, the intensity of the band of crude tannin extract is stronger than the dried bark sample.The 1260 to 1000 cm -1 strong absorption band indicates C-O stretching vibrations in alcohol and phenol (Steyermark, 1976).The absorption band at 1199 cm -1 can be assigned to C-O stretching vibration and it has a much higher intensity in the extracted crude tannin (Steyermark, 1976;Stuart, 2005  This may be due to volume contraction occurring during resin polymerisation.The 1500 to 1400 cm -1 C = C stretching band intensity clearly decreases in the resin spectra compared to that of the tannin sample.This reduction of the band implies that crosslinking reactions have 3 s at 1157 cm -1 and this broad, intense peak can be attributed to S=O groups.The peak appearing in the -1 range, that can be assigned to phenolic -OH has been -1 ) to higher -1 ).Further, the appearance of a shoulder (3200 cm -1 ) can be seen in the sulfonated resin spectrum.The shoulder s to the -OH peak of tannins and unsulfonated resins, and indicates the groups.The peak around 3500 cm -1 can be assigned to free -OH groups.Hence, it can be concluded that sulfonation has liberated some of the hydrogen bonded -OH groups.some -OH groups represented by the shoulder around 3200 cm -1 .This results resin has been successfully sulfonated (Steyermark, 1976;Stuart, 2005; Pena et al

Scanning electron microscopic (SEM) image analysis
According to SEM images of the original resin system heterogeneities and those can be due to high condensed matrix.
In 7 (a) to (f)], it can be clearly observed that the resin system contains µm and nm scale pores and also some heterogeneities.Figure 7 (a) provides evidence that the prepared porous resin system is composed of both closed cell and open cell structures.

CONCLUSION
Tannin obtained from the dried bark of Terminalia arjuna increased by the incorporation of phenol molecules that When changing the tannin to phenol ratio, IEC also ratio resin system.Further, the IEC can be improved considerably by sulfonation using concentrated H 2 SO 4 .

Na +
The formation of tannin formaldehyde, tannin phenol the solution at pH 7. Stability of the resin system in all Synthesis of tannin-phenol-formaldehyde porous agent and hexamine as the crosslinker cum-catalyst.Its et al. (2014) synthesised an environmental friendly porous monolith using natural condensed castor oil as the porogenic agent, external phase and et al., 2014).The use of tannins extracted from Terminalia arjuna in tannin-phenol-formaldehyde synthesis has not been synthesise environmental friendly sulfonated TPFR METHODOLOGY Extraction of tannins from dried Kumbuk bark The bark layer of Terminalia arjuna at 68 o C for 1 h, and then extracted using petroleum ether at 45 o C for 1 h to remove nonpolar compounds.Finally, at 70 o concentrated using a rotary evaporator under reduced o C. n types Ferric tests, acid butanol tests and nitrous acid tests compounds, condensed tannins and ellagitannins, respectively.
.000 g of tannin, 10.000 g of phenol, and beaker and 0.700 g of pure p-toluene sulfonic acid (PTSA) mechanical mixer at 250 rpm for 20 min.About 0.420 g 250 rpm to ensure homogeneity of the emulsion.

3 3 Na 3 Na 3 Na
and the corresponding tannin extract in the range of 660 to 3990 cm -1 .The strong broad peaks at 1157 and 1143 cm -1 can be attributed to dimethylene ether linkages.The 840 to 730 cm -1 absorption bands can be assigned to the deformation vibration of C-H et al., 2006).Although this bond does not participate in any chemical reaction during polymerisation, a decreased peak intensity can be Na, 3 Na) compared to that of the tannin sample.

Figure 3 . 3
Figure 3.3 ATR spectra of Kumbuk bark sample and its extracted tannin

Figure 4
Figure 4: Figure 7 (b) is a closed structures in both µm and nm scale.

Figure 3 . 5
Figure 3.5 ATR spectra of KRT1P1SO3Na and modified resin systems Figure 5:

Figure 3 .
Figure 3.6 SEM images of KRT1P1SO Na system (original resin) in µm and nm scale 1.00 µm 500 nm

Figure 3 .
Figure 3.7 (a-f) SEM images of modified resin system in µm and nm scale

Figure 9 :
Figure 9: Figure 8: have studied the possibility of utilising Caesalpinia spinosa (Tara) tannin in the and characterised to remove various heavy metals by et al. (2006).

Table 3 :
values for different polyphenolic contents of sulfonated and unsulfonated resin systems